WebSVN – Kolibri OS – Path Comparison – / – /programs/develop/libraries/libpng/pngrutil.c Rev 1897 and /programs/develop/libraries/libpng/pngrutil.c Rev 3928

Regard whitespace Rev 1897 → Rev 3928

 /programs/develop/libraries/libpng/pngrutil.c
 ,8 → 1,8
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.5.1 [February 3, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.4 [September 14, 2013]
+ * Copyright (c) 1998-2013 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
 ,10 → 18,8
 #ifdef PNG_READ_SUPPORTED
-#define png_strtod(p,a,b) strtod(a,b)
 png_uint_32 PNGAPI
-png_get_uint_31(png_structp png_ptr, png_const_bytep buf)
+png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
 {
    png_uint_32 uval = png_get_uint_32(buf);
 ,7 → 38,7
 #define PNG_FIXED_ERROR (-1)
 static png_fixed_point /* PRIVATE */
-png_get_fixed_point(png_structp png_ptr, png_const_bytep buf)
+png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
 {
    png_uint_32 uval = png_get_uint_32(buf);
 ,10 → 85,10
 png_get_int_32)(png_const_bytep buf)
 {
    png_uint_32 uval = png_get_uint_32(buf);
-   if ((uval & 0x80000000L) == 0) /* non-negative */
+   if ((uval & 0x80000000) == 0) /* non-negative */
       return uval;
-   uval = (uval ^ 0xffffffffL) + 1;  /* 2's complement: -x = ~x+1 */
+   uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
    return -(png_int_32)uval;
 }
 ,7 → 112,7
 /* Read and check the PNG file signature */
 void /* PRIVATE */
-png_read_sig(png_structp png_ptr, png_infop info_ptr)
+png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_size_t num_checked, num_to_check;
 ,7 → 147,7
  * Put the type name into png_ptr->chunk_name, and return the length.
  */
 png_uint_32 /* PRIVATE */
-png_read_chunk_header(png_structp png_ptr)
+png_read_chunk_header(png_structrp png_ptr)
 {
    png_byte buf[8];
    png_uint_32 length;
 ,14 → 163,14
    length = png_get_uint_31(png_ptr, buf);
    /* Put the chunk name into png_ptr->chunk_name. */
-   png_memcpy(png_ptr->chunk_name, buf + 4, 4);
+   png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
-   png_debug2(0, "Reading %s chunk, length = %u",
-       png_ptr->chunk_name, length);
+   png_debug2(0, "Reading %lx chunk, length = %lu",
+       (unsigned long)png_ptr->chunk_name, (unsigned long)length);
    /* Reset the crc and run it over the chunk name. */
    png_reset_crc(png_ptr);
-   png_calculate_crc(png_ptr, png_ptr->chunk_name, 4);
+   png_calculate_crc(png_ptr, buf + 4, 4);
    /* Check to see if chunk name is valid. */
    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 ,7 → 184,7
 /* Read data, and (optionally) run it through the CRC. */
 void /* PRIVATE */
-png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
+png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
 {
    if (png_ptr == NULL)
       return;
 ,32 → 194,34
 }
 /* Optionally skip data and then check the CRC.  Depending on whether we
- * are reading a ancillary or critical chunk, and how the program has set
+ * are reading an ancillary or critical chunk, and how the program has set
  * things up, we may calculate the CRC on the data and print a message.
  * Returns '1' if there was a CRC error, '0' otherwise.
  */
 int /* PRIVATE */
-png_crc_finish(png_structp png_ptr, png_uint_32 skip)
+png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
 {
-   png_size_t i;
-   png_size_t istop = png_ptr->zbuf_size;
-   for (i = (png_size_t)skip; i > istop; i -= istop)
+   /* The size of the local buffer for inflate is a good guess as to a
+    * reasonable size to use for buffering reads from the application.
+    */
+   while (skip > 0)
    {
-      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
-   }
+      png_uint_32 len;
+      png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
-   if (i)
-   {
-      png_crc_read(png_ptr, png_ptr->zbuf, i);
+      len = (sizeof tmpbuf);
+      if (len > skip)
+         len = skip;
+      skip -= len;
+      png_crc_read(png_ptr, tmpbuf, len);
    }
    if (png_crc_error(png_ptr))
    {
-      if (((png_ptr->chunk_name[0] & 0x20) &&                /* Ancillary */
-          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
-          (!(png_ptr->chunk_name[0] & 0x20) &&             /* Critical  */
-          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE)))
+      if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
+          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
+          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
       {
          png_chunk_warning(png_ptr, "CRC error");
       }
 ,13 → 242,13
  * the data it has read thus far.
  */
 int /* PRIVATE */
-png_crc_error(png_structp png_ptr)
+png_crc_error(png_structrp png_ptr)
 {
    png_byte crc_bytes[4];
    png_uint_32 crc;
    int need_crc = 1;
-   if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
+   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
    {
       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
 ,269 → 278,521
       return (0);
 }
-#if defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) || \
-    defined(PNG_READ_iCCP_SUPPORTED)
-static png_size_t
-png_inflate(png_structp png_ptr, png_bytep data, png_size_t size,
-    png_bytep output, png_size_t output_size)
+/* Manage the read buffer; this simply reallocates the buffer if it is not small
+ * enough (or if it is not allocated).  The routine returns a pointer to the
+ * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
+ * it will call png_error (via png_malloc) on failure.  (warn == 2 means
+ * 'silent').
+ */
+static png_bytep
+png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
 {
-   png_size_t count = 0;
+   png_bytep buffer = png_ptr->read_buffer;
-   /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it can't
-    * even necessarily handle 65536 bytes) because the type uInt is "16 bits or
-    * more".  Consequently it is necessary to chunk the input to zlib.  This
-    * code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the maximum value
-    * that can be stored in a uInt.)  It is possible to set ZLIB_IO_MAX to a
-    * lower value in pngpriv.h and this may sometimes have a performance
-    * advantage, because it forces access of the input data to be separated from
-    * at least some of the use by some period of time.
-    */
-   png_ptr->zstream.next_in = data;
-   /* avail_in is set below from 'size' */
-   png_ptr->zstream.avail_in = 0;
+   if (buffer != NULL && new_size > png_ptr->read_buffer_size)
+   {
+      png_ptr->read_buffer = NULL;
+      png_ptr->read_buffer = NULL;
+      png_ptr->read_buffer_size = 0;
+      png_free(png_ptr, buffer);
+      buffer = NULL;
+   }
-   while (1)
+   if (buffer == NULL)
    {
-      int ret, avail;
+      buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
-      /* The setting of 'avail_in' used to be outside the loop, by setting it
-       * inside it is possible to chunk the input to zlib and simply rely on
-       * zlib to advance the 'next_in' pointer.  This allows arbitrary amounts o
-       * data to be passed through zlib at the unavoidable cost of requiring a
-       * window save (memcpy of up to 32768 output bytes) every ZLIB_IO_MAX
-       * input bytes.
-       */
-      if (png_ptr->zstream.avail_in == 0 && size > 0)
+      if (buffer != NULL)
       {
-         if (size <= ZLIB_IO_MAX)
-         {
-            /* The value is less than ZLIB_IO_MAX so the cast is safe: */
-            png_ptr->zstream.avail_in = (uInt)size;
-            size = 0;
+         png_ptr->read_buffer = buffer;
+         png_ptr->read_buffer_size = new_size;
          }
+      else if (warn < 2) /* else silent */
+      {
+#ifdef PNG_WARNINGS_SUPPORTED
+         if (warn)
+             png_chunk_warning(png_ptr, "insufficient memory to read chunk");
          else
+#endif
          {
-            png_ptr->zstream.avail_in = ZLIB_IO_MAX;
-            size -= ZLIB_IO_MAX;
+#ifdef PNG_ERROR_TEXT_SUPPORTED
+             png_chunk_error(png_ptr, "insufficient memory to read chunk");
+#endif
          }
       }
+   }
-      /* Reset the output buffer each time round - we empty it
-       * after every inflate call.
+   return buffer;
+}
+/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
+ * decompression.  Returns Z_OK on success, else a zlib error code.  It checks
+ * the owner but, in final release builds, just issues a warning if some other
+ * chunk apparently owns the stream.  Prior to release it does a png_error.
        */
-      png_ptr->zstream.next_out = png_ptr->zbuf;
-      png_ptr->zstream.avail_out = png_ptr->zbuf_size;
+static int
+png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
+{
+   if (png_ptr->zowner != 0)
+   {
+      char msg[64];
-      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
-      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
+      PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
+      /* So the message that results is "<chunk> using zstream"; this is an
+       * internal error, but is very useful for debugging.  i18n requirements
+       * are minimal.
+       */
+      (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
+#     if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+         png_chunk_warning(png_ptr, msg);
+         png_ptr->zowner = 0;
+#     else
+         png_chunk_error(png_ptr, msg);
+#     endif
+   }
-      /* First copy/count any new output - but only if we didn't
-       * get an error code.
+   /* Implementation note: unlike 'png_deflate_claim' this internal function
+    * does not take the size of the data as an argument.  Some efficiency could
+    * be gained by using this when it is known *if* the zlib stream itself does
+    * not record the number; however, this is an illusion: the original writer
+    * of the PNG may have selected a lower window size, and we really must
+    * follow that because, for systems with with limited capabilities, we
+    * would otherwise reject the application's attempts to use a smaller window
+    * size (zlib doesn't have an interface to say "this or lower"!).
+    *
+    * inflateReset2 was added to zlib 1.2.4; before this the window could not be
+    * reset, therefore it is necessary to always allocate the maximum window
+    * size with earlier zlibs just in case later compressed chunks need it.
        */
-      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
       {
-         png_size_t space = avail; /* > 0, see above */
+      int ret; /* zlib return code */
+#     if PNG_ZLIB_VERNUM >= 0x1240
-         if (output != 0 && output_size > count)
-         {
-            png_size_t copy = output_size - count;
+#        if defined(PNG_SET_OPTION_SUPPORTED) && \
+            defined(PNG_MAXIMUM_INFLATE_WINDOW)
+            int window_bits;
-            if (space < copy)
-               copy = space;
+            if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
+               PNG_OPTION_ON)
+               window_bits = 15;
-            png_memcpy(output + count, png_ptr->zbuf, copy);
-         }
-         count += space;
-      }
+            else
+               window_bits = 0;
+#        else
+#           define window_bits 0
+#        endif
+#     endif
-      if (ret == Z_OK)
-         continue;
-      /* Termination conditions - always reset the zstream, it
-       * must be left in inflateInit state.
+      /* Set this for safety, just in case the previous owner left pointers to
+       * memory allocations.
        */
+      png_ptr->zstream.next_in = NULL;
       png_ptr->zstream.avail_in = 0;
-      inflateReset(&png_ptr->zstream);
+      png_ptr->zstream.next_out = NULL;
+      png_ptr->zstream.avail_out = 0;
-      if (ret == Z_STREAM_END)
-         return count; /* NOTE: may be zero. */
-      /* Now handle the error codes - the API always returns 0
-       * and the error message is dumped into the uncompressed
-       * buffer if available.
-       */
+      if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
       {
-         PNG_CONST char *msg;
-#ifdef PNG_CONSOLE_IO_SUPPORTED
-         char umsg[52];
+#        if PNG_ZLIB_VERNUM < 0x1240
+            ret = inflateReset(&png_ptr->zstream);
+#        else
+            ret = inflateReset2(&png_ptr->zstream, window_bits);
 #endif
-         if (png_ptr->zstream.msg != 0)
-            msg = png_ptr->zstream.msg;
+      }
          else
          {
-#ifdef PNG_CONSOLE_IO_SUPPORTED
-            switch (ret)
-            {
-               case Z_BUF_ERROR:
-                  msg = "Buffer error in compressed datastream in %s chunk";
-                  break;
+#        if PNG_ZLIB_VERNUM < 0x1240
+            ret = inflateInit(&png_ptr->zstream);
+#        else
+            ret = inflateInit2(&png_ptr->zstream, window_bits);
+#        endif
-               case Z_DATA_ERROR:
-                  msg = "Data error in compressed datastream in %s chunk";
-                  break;
+         if (ret == Z_OK)
+            png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
+      }
-               default:
-                  msg = "Incomplete compressed datastream in %s chunk";
-                  break;
+      if (ret == Z_OK)
+         png_ptr->zowner = owner;
+      else
+         png_zstream_error(png_ptr, ret);
+      return ret;
             }
-            png_snprintf(umsg, sizeof umsg, msg, png_ptr->chunk_name);
-            msg = umsg;
-#else
-            msg = "Damaged compressed datastream in chunk other than IDAT";
+#  ifdef window_bits
+#     undef window_bits
 #endif
          }
-         png_warning(png_ptr, msg);
+#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
+/* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
+ * allow the caller to do multiple calls if required.  If the 'finish' flag is
+ * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
+ * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
+ * Z_OK or Z_STREAM_END will be returned on success.
+ *
+ * The input and output sizes are updated to the actual amounts of data consumed
+ * or written, not the amount available (as in a z_stream).  The data pointers
+ * are not changed, so the next input is (data+input_size) and the next
+ * available output is (output+output_size).
+ */
+static int
+png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
+    /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
+    /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
+{
+   if (png_ptr->zowner == owner) /* Else not claimed */
+   {
+      int ret;
+      png_alloc_size_t avail_out = *output_size_ptr;
+      png_uint_32 avail_in = *input_size_ptr;
+      /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
+       * can't even necessarily handle 65536 bytes) because the type uInt is
+       * "16 bits or more".  Consequently it is necessary to chunk the input to
+       * zlib.  This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
+       * maximum value that can be stored in a uInt.)  It is possible to set
+       * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
+       * a performance advantage, because it reduces the amount of data accessed
+       * at each step and that may give the OS more time to page it in.
+       */
+      png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
+      /* avail_in and avail_out are set below from 'size' */
+      png_ptr->zstream.avail_in = 0;
+      png_ptr->zstream.avail_out = 0;
+      /* Read directly into the output if it is available (this is set to
+       * a local buffer below if output is NULL).
+       */
+      if (output != NULL)
+         png_ptr->zstream.next_out = output;
+      do
+      {
+         uInt avail;
+         Byte local_buffer[PNG_INFLATE_BUF_SIZE];
+         /* zlib INPUT BUFFER */
+         /* The setting of 'avail_in' used to be outside the loop; by setting it
+          * inside it is possible to chunk the input to zlib and simply rely on
+          * zlib to advance the 'next_in' pointer.  This allows arbitrary
+          * amounts of data to be passed through zlib at the unavoidable cost of
+          * requiring a window save (memcpy of up to 32768 output bytes)
+          * every ZLIB_IO_MAX input bytes.
+          */
+         avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
+         avail = ZLIB_IO_MAX;
+         if (avail_in < avail)
+            avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
+         avail_in -= avail;
+         png_ptr->zstream.avail_in = avail;
+         /* zlib OUTPUT BUFFER */
+         avail_out += png_ptr->zstream.avail_out; /* not written last time */
+         avail = ZLIB_IO_MAX; /* maximum zlib can process */
+         if (output == NULL)
+         {
+            /* Reset the output buffer each time round if output is NULL and
+             * make available the full buffer, up to 'remaining_space'
+             */
+            png_ptr->zstream.next_out = local_buffer;
+            if ((sizeof local_buffer) < avail)
+               avail = (sizeof local_buffer);
       }
-      /* 0 means an error - notice that this code simply ignores
-       * zero length compressed chunks as a result.
+         if (avail_out < avail)
+            avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
+         png_ptr->zstream.avail_out = avail;
+         avail_out -= avail;
+         /* zlib inflate call */
+         /* In fact 'avail_out' may be 0 at this point, that happens at the end
+          * of the read when the final LZ end code was not passed at the end of
+          * the previous chunk of input data.  Tell zlib if we have reached the
+          * end of the output buffer.
        */
-      return 0;
+         ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
+            (finish ? Z_FINISH : Z_SYNC_FLUSH));
+      } while (ret == Z_OK);
+      /* For safety kill the local buffer pointer now */
+      if (output == NULL)
+         png_ptr->zstream.next_out = NULL;
+      /* Claw back the 'size' and 'remaining_space' byte counts. */
+      avail_in += png_ptr->zstream.avail_in;
+      avail_out += png_ptr->zstream.avail_out;
+      /* Update the input and output sizes; the updated values are the amount
+       * consumed or written, effectively the inverse of what zlib uses.
+       */
+      if (avail_out > 0)
+         *output_size_ptr -= avail_out;
+      if (avail_in > 0)
+         *input_size_ptr -= avail_in;
+      /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
+      png_zstream_error(png_ptr, ret);
+      return ret;
    }
+   else
+   {
+      /* This is a bad internal error.  The recovery assigns to the zstream msg
+       * pointer, which is not owned by the caller, but this is safe; it's only
+       * used on errors!
+       */
+      png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
+      return Z_STREAM_ERROR;
 }
+}
 /*
- * Decompress trailing data in a chunk.  The assumption is that chunkdata
+ * Decompress trailing data in a chunk.  The assumption is that read_buffer
  * points at an allocated area holding the contents of a chunk with a
  * trailing compressed part.  What we get back is an allocated area
  * holding the original prefix part and an uncompressed version of the
  * trailing part (the malloc area passed in is freed).
  */
-void /* PRIVATE */
-png_decompress_chunk(png_structp png_ptr, int comp_type,
-    png_size_t chunklength,
-    png_size_t prefix_size, png_size_t *newlength)
+static int
+png_decompress_chunk(png_structrp png_ptr,
+   png_uint_32 chunklength, png_uint_32 prefix_size,
+   png_alloc_size_t *newlength /* must be initialized to the maximum! */,
+   int terminate /*add a '\0' to the end of the uncompressed data*/)
 {
-   /* The caller should guarantee this */
-   if (prefix_size > chunklength)
+   /* TODO: implement different limits for different types of chunk.
+    *
+    * The caller supplies *newlength set to the maximum length of the
+    * uncompressed data, but this routine allocates space for the prefix and
+    * maybe a '\0' terminator too.  We have to assume that 'prefix_size' is
+    * limited only by the maximum chunk size.
+    */
+   png_alloc_size_t limit = PNG_SIZE_MAX;
+#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max > 0 &&
+         png_ptr->user_chunk_malloc_max < limit)
+         limit = png_ptr->user_chunk_malloc_max;
+#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
+      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+         limit = PNG_USER_CHUNK_MALLOC_MAX;
+#  endif
+   if (limit >= prefix_size + (terminate != 0))
    {
-      /* The recovery is to delete the chunk. */
-      png_warning(png_ptr, "invalid chunklength");
-      prefix_size = 0; /* To delete everything */
-   }
+      int ret;
-   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+      limit -= prefix_size + (terminate != 0);
+      if (limit < *newlength)
+         *newlength = limit;
+      /* Now try to claim the stream. */
+      ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
+      if (ret == Z_OK)
    {
-      png_size_t expanded_size = png_inflate(png_ptr,
-          (png_bytep)(png_ptr->chunkdata + prefix_size),
-          chunklength - prefix_size,
-,            /*output*/
-);           /*output size*/
+         png_uint_32 lzsize = chunklength - prefix_size;
-      /* Now check the limits on this chunk - if the limit fails the
-       * compressed data will be removed, the prefix will remain.
-       */
-#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
-      if (png_ptr->user_chunk_malloc_max &&
-          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
-#else
-#  ifdef PNG_USER_CHUNK_MALLOC_MAX
-      if ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
-          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
-#  endif
-#endif
-         png_warning(png_ptr, "Exceeded size limit while expanding chunk");
+         ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
+            /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
+            /* output: */ NULL, newlength);
-      /* If the size is zero either there was an error and a message
-       * has already been output (warning) or the size really is zero
-       * and we have nothing to do - the code will exit through the
-       * error case below.
+         if (ret == Z_STREAM_END)
+         {
+            /* Use 'inflateReset' here, not 'inflateReset2' because this
+             * preserves the previously decided window size (otherwise it would
+             * be necessary to store the previous window size.)  In practice
+             * this doesn't matter anyway, because png_inflate will call inflate
+             * with Z_FINISH in almost all cases, so the window will not be
+             * maintained.
        */
-#if defined(PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED) || \
-    defined(PNG_USER_CHUNK_MALLOC_MAX)
-      else if (expanded_size > 0)
-#else
-      if (expanded_size > 0)
-#endif
+            if (inflateReset(&png_ptr->zstream) == Z_OK)
       {
-         /* Success (maybe) - really uncompress the chunk. */
-         png_size_t new_size = 0;
-         png_charp text = png_malloc_warn(png_ptr,
-             prefix_size + expanded_size + 1);
+               /* Because of the limit checks above we know that the new,
+                * expanded, size will fit in a size_t (let alone an
+                * png_alloc_size_t).  Use png_malloc_base here to avoid an
+                * extra OOM message.
+                */
+               png_alloc_size_t new_size = *newlength;
+               png_alloc_size_t buffer_size = prefix_size + new_size +
+                  (terminate != 0);
+               png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
+                  buffer_size));
          if (text != NULL)
          {
-            png_memcpy(text, png_ptr->chunkdata, prefix_size);
-            new_size = png_inflate(png_ptr,
-                (png_bytep)(png_ptr->chunkdata + prefix_size),
-                chunklength - prefix_size,
-                (png_bytep)(text + prefix_size), expanded_size);
-            text[prefix_size + expanded_size] = 0; /* just in case */
+                  ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
+                     png_ptr->read_buffer + prefix_size, &lzsize,
+                     text + prefix_size, newlength);
-            if (new_size == expanded_size)
+                  if (ret == Z_STREAM_END)
             {
-               png_free(png_ptr, png_ptr->chunkdata);
-               png_ptr->chunkdata = text;
-               *newlength = prefix_size + expanded_size;
-               return; /* The success return! */
+                     if (new_size == *newlength)
+                     {
+                        if (terminate)
+                           text[prefix_size + *newlength] = 0;
+                        if (prefix_size > 0)
+                           memcpy(text, png_ptr->read_buffer, prefix_size);
+                        {
+                           png_bytep old_ptr = png_ptr->read_buffer;
+                           png_ptr->read_buffer = text;
+                           png_ptr->read_buffer_size = buffer_size;
+                           text = old_ptr; /* freed below */
             }
+                     }
-            png_warning(png_ptr, "png_inflate logic error");
+                     else
+                     {
+                        /* The size changed on the second read, there can be no
+                         * guarantee that anything is correct at this point.
+                         * The 'msg' pointer has been set to "unexpected end of
+                         * LZ stream", which is fine, but return an error code
+                         * that the caller won't accept.
+                         */
+                        ret = PNG_UNEXPECTED_ZLIB_RETURN;
+                     }
+                  }
+                  else if (ret == Z_OK)
+                     ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
+                  /* Free the text pointer (this is the old read_buffer on
+                   * success)
+                   */
             png_free(png_ptr, text);
+                  /* This really is very benign, but it's still an error because
+                   * the extra space may otherwise be used as a Trojan Horse.
+                   */
+                  if (ret == Z_STREAM_END &&
+                     chunklength - prefix_size != lzsize)
+                     png_chunk_benign_error(png_ptr, "extra compressed data");
          }
          else
-            png_warning(png_ptr, "Not enough memory to decompress chunk");
+               {
+                  /* Out of memory allocating the buffer */
+                  ret = Z_MEM_ERROR;
+                  png_zstream_error(png_ptr, Z_MEM_ERROR);
       }
    }
-   else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
+            else
    {
-#ifdef PNG_STDIO_SUPPORTED
-      char umsg[50];
+               /* inflateReset failed, store the error message */
+               png_zstream_error(png_ptr, ret);
-      png_snprintf(umsg, sizeof umsg,
-          "Unknown zTXt compression type %d", comp_type);
-      png_warning(png_ptr, umsg);
-#else
-      png_warning(png_ptr, "Unknown zTXt compression type");
-#endif
+               if (ret == Z_STREAM_END)
+                  ret = PNG_UNEXPECTED_ZLIB_RETURN;
+            }
+         }
-      /* The recovery is to simply drop the data. */
+         else if (ret == Z_OK)
+            ret = PNG_UNEXPECTED_ZLIB_RETURN;
+         /* Release the claimed stream */
+         png_ptr->zowner = 0;
    }
-   /* Generic error return - leave the prefix, delete the compressed
-    * data, reallocate the chunkdata to remove the potentially large
-    * amount of compressed data.
+      else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
+         ret = PNG_UNEXPECTED_ZLIB_RETURN;
+      return ret;
+   }
+   else
+   {
+      /* Application/configuration limits exceeded */
+      png_zstream_error(png_ptr, Z_MEM_ERROR);
+      return Z_MEM_ERROR;
+   }
+}
+#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
+#ifdef PNG_READ_iCCP_SUPPORTED
+/* Perform a partial read and decompress, producing 'avail_out' bytes and
+ * reading from the current chunk as required.
     */
+static int
+png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
+   png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
+   int finish)
    {
-      png_charp text = png_malloc_warn(png_ptr, prefix_size + 1);
+   if (png_ptr->zowner == png_ptr->chunk_name)
+   {
+      int ret;
-      if (text != NULL)
+      /* next_in and avail_in must have been initialized by the caller. */
+      png_ptr->zstream.next_out = next_out;
+      png_ptr->zstream.avail_out = 0; /* set in the loop */
+      do
       {
-         if (prefix_size > 0)
-            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+         if (png_ptr->zstream.avail_in == 0)
+         {
+            if (read_size > *chunk_bytes)
+               read_size = (uInt)*chunk_bytes;
+            *chunk_bytes -= read_size;
-         png_free(png_ptr, png_ptr->chunkdata);
-         png_ptr->chunkdata = text;
+            if (read_size > 0)
+               png_crc_read(png_ptr, read_buffer, read_size);
-         /* This is an extra zero in the 'uncompressed' part. */
-         *(png_ptr->chunkdata + prefix_size) = 0x00;
+            png_ptr->zstream.next_in = read_buffer;
+            png_ptr->zstream.avail_in = read_size;
       }
-      /* Ignore a malloc error here - it is safe. */
+         if (png_ptr->zstream.avail_out == 0)
+         {
+            uInt avail = ZLIB_IO_MAX;
+            if (avail > *out_size)
+               avail = (uInt)*out_size;
+            *out_size -= avail;
+            png_ptr->zstream.avail_out = avail;
    }
-   *newlength = prefix_size;
+         /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
+          * the available output is produced; this allows reading of truncated
+          * streams.
+          */
+         ret = inflate(&png_ptr->zstream,
+            *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
 }
+      while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
+      *out_size += png_ptr->zstream.avail_out;
+      png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
+      /* Ensure the error message pointer is always set: */
+      png_zstream_error(png_ptr, ret);
+      return ret;
+   }
+   else
+   {
+      png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
+      return Z_STREAM_ERROR;
+   }
+}
 #endif
 /* Read and check the IDHR chunk */
 void /* PRIVATE */
-png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[13];
    png_uint_32 width, height;
 ,11 → 802,11
    png_debug(1, "in png_handle_IHDR");
    if (png_ptr->mode & PNG_HAVE_IHDR)
-      png_error(png_ptr, "Out of place IHDR");
+      png_chunk_error(png_ptr, "out of place");
    /* Check the length */
    if (length != 13)
-      png_error(png_ptr, "Invalid IHDR chunk");
+      png_chunk_error(png_ptr, "invalid");
    png_ptr->mode |= PNG_HAVE_IHDR;
 ,7 → 867,7
 /* Read and check the palette */
 void /* PRIVATE */
-png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_color palette[PNG_MAX_PALETTE_LENGTH];
    int num, i;
 ,25 → 878,32
    png_debug(1, "in png_handle_PLTE");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before PLTE");
+      png_chunk_error(png_ptr, "missing IHDR");
+   /* Moved to before the 'after IDAT' check below because otherwise duplicate
+    * PLTE chunks are potentially ignored (the spec says there shall not be more
+    * than one PLTE, the error is not treated as benign, so this check trumps
+    * the requirement that PLTE appears before IDAT.)
+    */
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      png_chunk_error(png_ptr, "duplicate");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid PLTE after IDAT");
+      /* This is benign because the non-benign error happened before, when an
+       * IDAT was encountered in a color-mapped image with no PLTE.
+       */
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      png_error(png_ptr, "Duplicate PLTE chunk");
    png_ptr->mode |= PNG_HAVE_PLTE;
    if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
    {
-      png_warning(png_ptr,
-          "Ignoring PLTE chunk in grayscale PNG");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
       return;
    }
 ,19 → 917,18
    if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
    {
-      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
-      {
-         png_warning(png_ptr, "Invalid palette chunk");
          png_crc_finish(png_ptr, length);
-         return;
-      }
+      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+         png_chunk_benign_error(png_ptr, "invalid");
       else
-      {
-         png_error(png_ptr, "Invalid palette chunk");
+         png_chunk_error(png_ptr, "invalid");
+      return;
       }
-   }
+   /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
    num = (int)length / 3;
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
 ,6 → 973,10
        * we have two options: an error abort, or a warning and we
        * ignore the data in this chunk (which should be OK, since
        * it's considered ancillary for a RGB or RGBA image).
+       *
+       * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
+       * chunk type to determine whether to check the ancillary or the critical
+       * flags.
        */
       if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
       {
 ,55 → 1000,74
    }
 #endif
+   /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
+    * own copy of the palette.  This has the side effect that when png_start_row
+    * is called (this happens after any call to png_read_update_info) the
+    * info_ptr palette gets changed.  This is extremely unexpected and
+    * confusing.
+    *
+    * Fix this by not sharing the palette in this way.
+    */
    png_set_PLTE(png_ptr, info_ptr, palette, num);
+   /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
+    * IDAT.  Prior to 1.6.0 this was not checked; instead the code merely
+    * checked the apparent validity of a tRNS chunk inserted before PLTE on a
+    * palette PNG.  1.6.0 attempts to rigorously follow the standard and
+    * therefore does a benign error if the erroneous condition is detected *and*
+    * cancels the tRNS if the benign error returns.  The alternative is to
+    * amend the standard since it would be rather hypocritical of the standards
+    * maintainers to ignore it.
+    */
 #ifdef PNG_READ_tRNS_SUPPORTED
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   if (png_ptr->num_trans > 0 ||
+      (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
    {
-      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
-      {
-         if (png_ptr->num_trans > (png_uint_16)num)
-         {
-            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
-            png_ptr->num_trans = (png_uint_16)num;
-         }
+      /* Cancel this because otherwise it would be used if the transforms
+       * require it.  Don't cancel the 'valid' flag because this would prevent
+       * detection of duplicate chunks.
+       */
+      png_ptr->num_trans = 0;
-         if (info_ptr->num_trans > (png_uint_16)num)
-         {
-            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
-            info_ptr->num_trans = (png_uint_16)num;
+      if (info_ptr != NULL)
+         info_ptr->num_trans = 0;
+      png_chunk_benign_error(png_ptr, "tRNS must be after");
          }
-      }
-   }
 #endif
+#ifdef PNG_READ_hIST_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
+      png_chunk_benign_error(png_ptr, "hIST must be after");
+#endif
+#ifdef PNG_READ_bKGD_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
+      png_chunk_benign_error(png_ptr, "bKGD must be after");
+#endif
 }
 void /* PRIVATE */
-png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_debug(1, "in png_handle_IEND");
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
-   {
-      png_error(png_ptr, "No image in file");
-   }
+      png_chunk_error(png_ptr, "out of place");
    png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
+   png_crc_finish(png_ptr, length);
    if (length != 0)
-   {
-      png_warning(png_ptr, "Incorrect IEND chunk length");
-   }
+      png_chunk_benign_error(png_ptr, "invalid");
-   png_crc_finish(png_ptr, length);
-   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
+   PNG_UNUSED(info_ptr)
 }
 #ifdef PNG_READ_gAMA_SUPPORTED
 void /* PRIVATE */
-png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_fixed_point igamma;
    png_byte buf[4];
 ,34 → 1075,19
    png_debug(1, "in png_handle_gAMA");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before gAMA");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
    {
-      png_warning(png_ptr, "Invalid gAMA after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place gAMA chunk");
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
-#ifdef PNG_READ_sRGB_SUPPORTED
-       && !(info_ptr->valid & PNG_INFO_sRGB)
-#endif
-       )
-   {
-      png_warning(png_ptr, "Duplicate gAMA chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
    if (length != 4)
    {
-      png_warning(png_ptr, "Incorrect gAMA chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,45 → 1098,16
    igamma = png_get_fixed_point(NULL, buf);
-   /* Check for zero gamma or an error. */
-   if (igamma <= 0)
-   {
-      png_warning(png_ptr,
-          "Ignoring gAMA chunk with out of range gamma");
-      return;
+   png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
+   png_colorspace_sync(png_ptr, info_ptr);
    }
-#  ifdef PNG_READ_sRGB_SUPPORTED
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
-   {
-      if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
-      {
-         png_warning(png_ptr,
-             "Ignoring incorrect gAMA value when sRGB is also present");
-#    ifdef PNG_CONSOLE_IO_SUPPORTED
-         fprintf(stderr, "gamma = (%d/100000)", (int)igamma);
 #    endif
-         return;
-      }
-   }
-#  endif /* PNG_READ_sRGB_SUPPORTED */
-#  ifdef PNG_READ_GAMMA_SUPPORTED
-   /* Gamma correction on read is supported. */
-   png_ptr->gamma = igamma;
-#  endif
-   /* And set the 'info' structure members. */
-   png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
-}
-#endif
 #ifdef PNG_READ_sBIT_SUPPORTED
 void /* PRIVATE */
-png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_size_t truelen;
+   unsigned int truelen;
    png_byte buf[4];
    png_debug(1, "in png_handle_sBIT");
 ,25 → 1115,19
    buf[0] = buf[1] = buf[2] = buf[3] = 0;
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sBIT");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
    {
-      png_warning(png_ptr, "Invalid sBIT after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-   {
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place sBIT chunk");
-   }
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
    {
-      png_warning(png_ptr, "Duplicate sBIT chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 ,11 → 1135,11
       truelen = 3;
    else
-      truelen = (png_size_t)png_ptr->channels;
+      truelen = png_ptr->channels;
    if (length != truelen || length > 4)
    {
-      png_warning(png_ptr, "Incorrect sBIT chunk length");
+      png_chunk_benign_error(png_ptr, "invalid");
       png_crc_finish(png_ptr, length);
       return;
    }
 ,43 → 1172,27
 #ifdef PNG_READ_cHRM_SUPPORTED
 void /* PRIVATE */
-png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[32];
-   png_fixed_point x_white, y_white, x_red, y_red, x_green, y_green, x_blue,
-      y_blue;
+   png_xy xy;
    png_debug(1, "in png_handle_cHRM");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before cHRM");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
    {
-      png_warning(png_ptr, "Invalid cHRM after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Missing PLTE before cHRM");
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
-#  ifdef PNG_READ_sRGB_SUPPORTED
-       && !(info_ptr->valid & PNG_INFO_sRGB)
-#  endif
-      )
-   {
-      png_warning(png_ptr, "Duplicate cHRM chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
    if (length != 32)
    {
-      png_warning(png_ptr, "Incorrect cHRM chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,302 → 1201,381
    if (png_crc_finish(png_ptr, 0))
       return;
-   x_white = png_get_fixed_point(NULL, buf);
-   y_white = png_get_fixed_point(NULL, buf + 4);
-   x_red   = png_get_fixed_point(NULL, buf + 8);
-   y_red   = png_get_fixed_point(NULL, buf + 12);
-   x_green = png_get_fixed_point(NULL, buf + 16);
-   y_green = png_get_fixed_point(NULL, buf + 20);
-   x_blue  = png_get_fixed_point(NULL, buf + 24);
-   y_blue  = png_get_fixed_point(NULL, buf + 28);
+   xy.whitex = png_get_fixed_point(NULL, buf);
+   xy.whitey = png_get_fixed_point(NULL, buf + 4);
+   xy.redx   = png_get_fixed_point(NULL, buf + 8);
+   xy.redy   = png_get_fixed_point(NULL, buf + 12);
+   xy.greenx = png_get_fixed_point(NULL, buf + 16);
+   xy.greeny = png_get_fixed_point(NULL, buf + 20);
+   xy.bluex  = png_get_fixed_point(NULL, buf + 24);
+   xy.bluey  = png_get_fixed_point(NULL, buf + 28);
-   if (x_white == PNG_FIXED_ERROR ||
-       y_white == PNG_FIXED_ERROR ||
-       x_red   == PNG_FIXED_ERROR ||
-       y_red   == PNG_FIXED_ERROR ||
-       x_green == PNG_FIXED_ERROR ||
-       y_green == PNG_FIXED_ERROR ||
-       x_blue  == PNG_FIXED_ERROR ||
-       y_blue  == PNG_FIXED_ERROR)
+   if (xy.whitex == PNG_FIXED_ERROR ||
+       xy.whitey == PNG_FIXED_ERROR ||
+       xy.redx   == PNG_FIXED_ERROR ||
+       xy.redy   == PNG_FIXED_ERROR ||
+       xy.greenx == PNG_FIXED_ERROR ||
+       xy.greeny == PNG_FIXED_ERROR ||
+       xy.bluex  == PNG_FIXED_ERROR ||
+       xy.bluey  == PNG_FIXED_ERROR)
    {
-      png_warning(png_ptr, "Ignoring cHRM chunk with negative chromaticities");
+      png_chunk_benign_error(png_ptr, "invalid values");
       return;
    }
-#ifdef PNG_READ_sRGB_SUPPORTED
-   if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
+   /* If a colorspace error has already been output skip this chunk */
+   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+      return;
+   if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
    {
-      if (PNG_OUT_OF_RANGE(x_white, 31270,  1000) ||
-          PNG_OUT_OF_RANGE(y_white, 32900,  1000) ||
-          PNG_OUT_OF_RANGE(x_red,   64000L, 1000) ||
-          PNG_OUT_OF_RANGE(y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(y_green, 60000L, 1000) ||
-          PNG_OUT_OF_RANGE(x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(y_blue,   6000,  1000))
-      {
-         png_warning(png_ptr,
-             "Ignoring incorrect cHRM value when sRGB is also present");
-#ifdef PNG_CONSOLE_IO_SUPPORTED
-         fprintf(stderr, "wx=%d, wy=%d, rx=%d, ry=%d\n",
-             x_white, y_white, x_red, y_red);
-         fprintf(stderr, "gx=%d, gy=%d, bx=%d, by=%d\n",
-             x_green, y_green, x_blue, y_blue);
-#endif /* PNG_CONSOLE_IO_SUPPORTED */
-      }
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+      png_colorspace_sync(png_ptr, info_ptr);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
-#endif /* PNG_READ_sRGB_SUPPORTED */
-   png_set_cHRM_fixed(png_ptr, info_ptr, x_white, y_white, x_red, y_red,
-      x_green, y_green, x_blue, y_blue);
+   png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
+   (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
+/*prefer cHRM values*/);
+   png_colorspace_sync(png_ptr, info_ptr);
 }
 #endif
 #ifdef PNG_READ_sRGB_SUPPORTED
 void /* PRIVATE */
-png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   int intent;
-   png_byte buf[1];
+   png_byte intent;
    png_debug(1, "in png_handle_sRGB");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sRGB");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
    {
-      png_warning(png_ptr, "Invalid sRGB after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place sRGB chunk");
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
-   {
-      png_warning(png_ptr, "Duplicate sRGB chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
    if (length != 1)
    {
-      png_warning(png_ptr, "Incorrect sRGB chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
-   png_crc_read(png_ptr, buf, 1);
+   png_crc_read(png_ptr, &intent, 1);
    if (png_crc_finish(png_ptr, 0))
       return;
-   intent = buf[0];
+   /* If a colorspace error has already been output skip this chunk */
+   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+      return;
-   /* Check for bad intent */
-   if (intent >= PNG_sRGB_INTENT_LAST)
+   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
+    * this.
+    */
+   if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
    {
-      png_warning(png_ptr, "Unknown sRGB intent");
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+      png_colorspace_sync(png_ptr, info_ptr);
+      png_chunk_benign_error(png_ptr, "too many profiles");
       return;
    }
-#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
-   {
-      if (PNG_OUT_OF_RANGE(info_ptr->gamma, 45500L, 500))
-      {
-         png_warning(png_ptr,
-             "Ignoring incorrect gAMA value when sRGB is also present");
-#ifdef PNG_CONSOLE_IO_SUPPORTED
-         fprintf(stderr, "incorrect gamma=(%d/100000)\n", info_ptr->gamma);
-#endif
+   (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
+   png_colorspace_sync(png_ptr, info_ptr);
       }
-   }
-#endif /* PNG_READ_gAMA_SUPPORTED */
-#ifdef PNG_READ_cHRM_SUPPORTED
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
-      if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_white, 32900,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->x_red,   64000L, 1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_green, 60000L, 1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_blue,   6000,  1000))
-      {
-         png_warning(png_ptr,
-             "Ignoring incorrect cHRM value when sRGB is also present");
-      }
-#endif /* PNG_READ_cHRM_SUPPORTED */
-   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
-}
 #endif /* PNG_READ_sRGB_SUPPORTED */
 #ifdef PNG_READ_iCCP_SUPPORTED
 void /* PRIVATE */
-png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-/* Note: this does not properly handle chunks that are > 64K under DOS */
+png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+/* Note: this does not properly handle profiles that are > 64K under DOS */
 {
-   png_byte compression_type;
-   png_bytep pC;
-   png_charp profile;
-   png_uint_32 skip = 0;
-   png_uint_32 profile_size;
-   png_alloc_size_t profile_length;
-   png_size_t slength, prefix_length, data_length;
+   png_const_charp errmsg = NULL; /* error message output, or no error */
+   int finished = 0; /* crc checked */
    png_debug(1, "in png_handle_iCCP");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before iCCP");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
    {
-      png_warning(png_ptr, "Invalid iCCP after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place iCCP chunk");
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP))
+   /* Consistent with all the above colorspace handling an obviously *invalid*
+    * chunk is just ignored, so does not invalidate the color space.  An
+    * alternative is to set the 'invalid' flags at the start of this routine
+    * and only clear them in they were not set before and all the tests pass.
+    * The minimum 'deflate' stream is assumed to be just the 2 byte header and 4
+    * byte checksum.  The keyword must be one character and there is a
+    * terminator (0) byte and the compression method.
+    */
+   if (length < 9)
    {
-      png_warning(png_ptr, "Duplicate iCCP chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "too short");
       return;
    }
-#ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
+   /* If a colorspace error has already been output skip this chunk */
+   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
    {
-      png_warning(png_ptr, "iCCP chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
+      png_crc_finish(png_ptr, length);
+      return;
    }
-#endif
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
+    * this.
+    */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
+   {
+      uInt read_length, keyword_length;
+      char keyword[81];
-   if (png_crc_finish(png_ptr, skip))
+      /* Find the keyword; the keyword plus separator and compression method
+       * bytes can be at most 81 characters long.
+       */
+      read_length = 81; /* maximum */
+      if (read_length > length)
+         read_length = (uInt)length;
+      png_crc_read(png_ptr, (png_bytep)keyword, read_length);
+      length -= read_length;
+      keyword_length = 0;
+      while (keyword_length < 80 && keyword_length < read_length &&
+         keyword[keyword_length] != 0)
+         ++keyword_length;
+      /* TODO: make the keyword checking common */
+      if (keyword_length >= 1 && keyword_length <= 79)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+         /* We only understand '0' compression - deflate - so if we get a
+          * different value we can't safely decode the chunk.
+          */
+         if (keyword_length+1 < read_length &&
+            keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
+         {
+            read_length -= keyword_length+2;
-   png_ptr->chunkdata[slength] = 0x00;
+            if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
+            {
+               Byte profile_header[132];
+               Byte local_buffer[PNG_INFLATE_BUF_SIZE];
+               png_alloc_size_t size = (sizeof profile_header);
-   for (profile = png_ptr->chunkdata; *profile; profile++)
-      /* Empty loop to find end of name */ ;
+               png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
+               png_ptr->zstream.avail_in = read_length;
+               (void)png_inflate_read(png_ptr, local_buffer,
+                  (sizeof local_buffer), &length, profile_header, &size,
+/*finish: don't, because the output is too small*/);
-   ++profile;
+               if (size == 0)
+               {
+                  /* We have the ICC profile header; do the basic header checks.
+                   */
+                  const png_uint_32 profile_length =
+                     png_get_uint_32(profile_header);
-   /* There should be at least one zero (the compression type byte)
-    * following the separator, and we should be on it
+                  if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
+                     keyword, profile_length))
+                  {
+                     /* The length is apparently ok, so we can check the 132
+                      * byte header.
     */
-   if (profile >= png_ptr->chunkdata + slength - 1)
+                     if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
+                        keyword, profile_length, profile_header,
+                        png_ptr->color_type))
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Malformed iCCP chunk");
-      return;
-   }
+                        /* Now read the tag table; a variable size buffer is
+                         * needed at this point, allocate one for the whole
+                         * profile.  The header check has already validated
+                         * that none of these stuff will overflow.
+                         */
+                        const png_uint_32 tag_count = png_get_uint_32(
+                           profile_header+128);
+                        png_bytep profile = png_read_buffer(png_ptr,
+                           profile_length, 2/*silent*/);
-   /* Compression_type should always be zero */
-   compression_type = *profile++;
+                        if (profile != NULL)
+                        {
+                           memcpy(profile, profile_header,
+                              (sizeof profile_header));
-   if (compression_type)
+                           size = 12 * tag_count;
+                           (void)png_inflate_read(png_ptr, local_buffer,
+                              (sizeof local_buffer), &length,
+                              profile + (sizeof profile_header), &size, 0);
+                           /* Still expect a a buffer error because we expect
+                            * there to be some tag data!
+                            */
+                           if (size == 0)
    {
-      png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
-      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
-                                 wrote nonzero) */
-   }
+                              if (png_icc_check_tag_table(png_ptr,
+                                 &png_ptr->colorspace, keyword, profile_length,
+                                 profile))
+                              {
+                                 /* The profile has been validated for basic
+                                  * security issues, so read the whole thing in.
+                                  */
+                                 size = profile_length - (sizeof profile_header)
+                                    - 12 * tag_count;
-   prefix_length = profile - png_ptr->chunkdata;
-   png_decompress_chunk(png_ptr, compression_type,
-       slength, prefix_length, &data_length);
+                                 (void)png_inflate_read(png_ptr, local_buffer,
+                                    (sizeof local_buffer), &length,
+                                    profile + (sizeof profile_header) +
+* tag_count, &size, 1/*finish*/);
-   profile_length = data_length - prefix_length;
+                                 if (length > 0 && !(png_ptr->flags &
+                                       PNG_FLAG_BENIGN_ERRORS_WARN))
+                                    errmsg = "extra compressed data";
-   if (prefix_length > data_length || profile_length < 4)
+                                 /* But otherwise allow extra data: */
+                                 else if (size == 0)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Profile size field missing from iCCP chunk");
-      return;
+                                    if (length > 0)
+                                    {
+                                       /* This can be handled completely, so
+                                        * keep going.
+                                        */
+                                       png_chunk_warning(png_ptr,
+                                          "extra compressed data");
    }
-   /* Check the profile_size recorded in the first 32 bits of the ICC profile */
-   pC = (png_bytep)(png_ptr->chunkdata + prefix_length);
-   profile_size = ((*(pC    )) << 24) |
-                  ((*(pC + 1)) << 16) |
-                  ((*(pC + 2)) <<  8) |
-                  ((*(pC + 3))      );
+                                    png_crc_finish(png_ptr, length);
+                                    finished = 1;
-   /* NOTE: the following guarantees that 'profile_length' fits into 32 bits,
-    * because profile_size is a 32 bit value.
-    */
-   if (profile_size < profile_length)
-      profile_length = profile_size;
+#                                   ifdef PNG_sRGB_SUPPORTED
+                                       /* Check for a match against sRGB */
+                                       png_icc_set_sRGB(png_ptr,
+                                          &png_ptr->colorspace, profile,
+                                          png_ptr->zstream.adler);
+#                                   endif
-   /* And the following guarantees that profile_size == profile_length. */
-   if (profile_size > profile_length)
+                                    /* Steal the profile for info_ptr. */
+                                    if (info_ptr != NULL)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-#ifdef PNG_STDIO_SUPPORTED
+                                       png_free_data(png_ptr, info_ptr,
+                                          PNG_FREE_ICCP, 0);
+                                       info_ptr->iccp_name = png_voidcast(char*,
+                                          png_malloc_base(png_ptr,
+                                          keyword_length+1));
+                                       if (info_ptr->iccp_name != NULL)
       {
-         char umsg[80];
+                                          memcpy(info_ptr->iccp_name, keyword,
+                                             keyword_length+1);
+                                          info_ptr->iccp_proflen =
+                                             profile_length;
+                                          info_ptr->iccp_profile = profile;
+                                          png_ptr->read_buffer = NULL; /*steal*/
+                                          info_ptr->free_me |= PNG_FREE_ICCP;
+                                          info_ptr->valid |= PNG_INFO_iCCP;
+                                       }
-         png_snprintf2(umsg, 80,
-             "Ignoring iCCP chunk with declared size = %u "
-              "and actual length = %u",
-              (unsigned int) profile_size,
-              (unsigned int) profile_length);
-         png_warning(png_ptr, umsg);
+                                       else
+                                       {
+                                          png_ptr->colorspace.flags |=
+                                             PNG_COLORSPACE_INVALID;
+                                          errmsg = "out of memory";
       }
-#else
-      png_warning(png_ptr,
-         "Ignoring iCCP chunk with uncompressed size mismatch");
-#endif
+                                    }
+                                    /* else the profile remains in the read
+                                     * buffer which gets reused for subsequent
+                                     * chunks.
+                                     */
+                                    if (info_ptr != NULL)
+                                       png_colorspace_sync(png_ptr, info_ptr);
+                                    if (errmsg == NULL)
+                                    {
+                                       png_ptr->zowner = 0;
       return;
    }
+                                 }
-   png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,
-       compression_type, (png_bytep)png_ptr->chunkdata + prefix_length,
-       profile_size);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
+                                 else if (size > 0)
+                                    errmsg = "truncated";
+                                 else
+                                    errmsg = png_ptr->zstream.msg;
 }
+                              /* else png_icc_check_tag_table output an error */
+                           }
+                           else /* profile truncated */
+                              errmsg = png_ptr->zstream.msg;
+                        }
+                        else
+                           errmsg = "out of memory";
+                     }
+                     /* else png_icc_check_header output an error */
+                  }
+                  /* else png_icc_check_length output an error */
+               }
+               else /* profile truncated */
+                  errmsg = png_ptr->zstream.msg;
+               /* Release the stream */
+               png_ptr->zowner = 0;
+            }
+            else /* png_inflate_claim failed */
+               errmsg = png_ptr->zstream.msg;
+         }
+         else
+            errmsg = "bad compression method"; /* or missing */
+      }
+      else
+         errmsg = "bad keyword";
+   }
+   else
+      errmsg = "too many profiles";
+   /* Failure: the reason is in 'errmsg' */
+   if (!finished)
+      png_crc_finish(png_ptr, length);
+   png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+   png_colorspace_sync(png_ptr, info_ptr);
+   if (errmsg != NULL) /* else already output */
+      png_chunk_benign_error(png_ptr, errmsg);
+}
 #endif /* PNG_READ_iCCP_SUPPORTED */
 #ifdef PNG_READ_sPLT_SUPPORTED
 void /* PRIVATE */
-png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 {
-   png_bytep entry_start;
+   png_bytep entry_start, buffer;
    png_sPLT_t new_palette;
-#ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_sPLT_entryp pp;
-#endif
    png_uint_32 data_length;
    int entry_size, i;
    png_uint_32 skip = 0;
-   png_size_t slength;
    png_uint_32 dl;
    png_size_t max_dl;
 ,7 → 1582,6
    png_debug(1, "in png_handle_sPLT");
 #ifdef PNG_USER_LIMITS_SUPPORTED
    if (png_ptr->user_chunk_cache_max != 0)
    {
       if (png_ptr->user_chunk_cache_max == 1)
 ,54 → 1600,52
 #endif
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sPLT");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid sPLT after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
+   if (length > 65535U)
    {
-      png_warning(png_ptr, "sPLT chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "too large to fit in memory");
+      return;
    }
 #endif
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+   if (buffer == NULL)
+   {
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
+      return;
+   }
    /* WARNING: this may break if size_t is less than 32 bits; it is assumed
     * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
     * potential breakage point if the types in pngconf.h aren't exactly right.
     */
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
    if (png_crc_finish(png_ptr, skip))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       return;
-   }
-   png_ptr->chunkdata[slength] = 0x00;
+   buffer[length] = 0;
-   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;
-       entry_start++)
+   for (entry_start = buffer; *entry_start; entry_start++)
       /* Empty loop to find end of name */ ;
    ++entry_start;
    /* A sample depth should follow the separator, and we should be on it  */
-   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
+   if (entry_start > buffer + length - 2)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "malformed sPLT chunk");
       return;
    }
 ,23 → 1653,19
    new_palette.depth = *entry_start++;
    entry_size = (new_palette.depth == 8 ? 6 : 10);
    /* This must fit in a png_uint_32 because it is derived from the original
-    * chunk data length (and use 'length', not 'slength' here for clarity -
-    * they are guaranteed to be the same, see the tests above.)
+    * chunk data length.
     */
-   data_length = length - (png_uint_32)(entry_start -
-      (png_bytep)png_ptr->chunkdata);
+   data_length = length - (png_uint_32)(entry_start - buffer);
    /* Integrity-check the data length */
    if (data_length % entry_size)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "sPLT chunk has bad length");
       return;
    }
    dl = (png_int_32)(data_length / entry_size);
-   max_dl = PNG_SIZE_MAX / png_sizeof(png_sPLT_entry);
+   max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
    if (dl > max_dl)
    {
 ,7 → 1676,7
    new_palette.nentries = (png_int_32)(data_length / entry_size);
    new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
-       png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));
+       png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
    if (new_palette.entries == NULL)
    {
 ,17 → 1729,15
          pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
       }
-      pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
+      pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
    }
 #endif
    /* Discard all chunk data except the name and stash that */
-   new_palette.name = png_ptr->chunkdata;
+   new_palette.name = (png_charp)buffer;
    png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
    png_free(png_ptr, new_palette.entries);
 }
 #endif /* PNG_READ_sPLT_SUPPORTED */
 ,7 → 1744,7
 #ifdef PNG_READ_tRNS_SUPPORTED
 void /* PRIVATE */
-png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
 ,19 → 1751,19
    png_debug(1, "in png_handle_tRNS");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before tRNS");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid tRNS after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
    {
-      png_warning(png_ptr, "Duplicate tRNS chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 ,8 → 1773,8
       if (length != 2)
       {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
 ,12 → 1789,12
       if (length != 6)
       {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
-      png_crc_read(png_ptr, buf, (png_size_t)length);
+      png_crc_read(png_ptr, buf, length);
       png_ptr->num_trans = 1;
       png_ptr->trans_color.red = png_get_uint_16(buf);
       png_ptr->trans_color.green = png_get_uint_16(buf + 2);
 ,33 → 1805,28
    {
       if (!(png_ptr->mode & PNG_HAVE_PLTE))
       {
-         /* Should be an error, but we can cope with it. */
-         png_warning(png_ptr, "Missing PLTE before tRNS");
-      }
-      if (length > (png_uint_32)png_ptr->num_palette ||
-          length > PNG_MAX_PALETTE_LENGTH)
-      {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
+         /* TODO: is this actually an error in the ISO spec? */
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "out of place");
          return;
       }
-      if (length == 0)
+      if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
+         length == 0)
       {
-         png_warning(png_ptr, "Zero length tRNS chunk");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
-      png_crc_read(png_ptr, readbuf, (png_size_t)length);
+      png_crc_read(png_ptr, readbuf, length);
       png_ptr->num_trans = (png_uint_16)length;
    }
    else
    {
-      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid with alpha channel");
       return;
    }
 ,6 → 1836,10
       return;
    }
+   /* TODO: this is a horrible side effect in the palette case because the
+    * png_struct ends up with a pointer to the tRNS buffer owned by the
+    * png_info.  Fix this.
+    */
    png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
        &(png_ptr->trans_color));
 }
 ,35 → 1847,30
 #ifdef PNG_READ_bKGD_SUPPORTED
 void /* PRIVATE */
-png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_size_t truelen;
+   unsigned int truelen;
    png_byte buf[6];
+   png_color_16 background;
    png_debug(1, "in png_handle_bKGD");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before bKGD");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
+      (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+       !(png_ptr->mode & PNG_HAVE_PLTE)))
    {
-      png_warning(png_ptr, "Invalid bKGD after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-       !(png_ptr->mode & PNG_HAVE_PLTE))
-   {
-      png_warning(png_ptr, "Missing PLTE before bKGD");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
    {
-      png_warning(png_ptr, "Duplicate bKGD chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 ,8 → 1885,8
    if (length != truelen)
    {
-      png_warning(png_ptr, "Incorrect bKGD chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,49 → 1902,52
     */
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
-      png_ptr->background.index = buf[0];
+      background.index = buf[0];
       if (info_ptr && info_ptr->num_palette)
       {
          if (buf[0] >= info_ptr->num_palette)
          {
-            png_warning(png_ptr, "Incorrect bKGD chunk index value");
+            png_chunk_benign_error(png_ptr, "invalid index");
             return;
          }
-         png_ptr->background.red =
-             (png_uint_16)png_ptr->palette[buf[0]].red;
+         background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
+         background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
+         background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
+      }
-         png_ptr->background.green =
-             (png_uint_16)png_ptr->palette[buf[0]].green;
+      else
+         background.red = background.green = background.blue = 0;
-         png_ptr->background.blue =
-             (png_uint_16)png_ptr->palette[buf[0]].blue;
+      background.gray = 0;
       }
-   }
    else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
    {
-      png_ptr->background.red =
-      png_ptr->background.green =
-      png_ptr->background.blue =
-      png_ptr->background.gray = png_get_uint_16(buf);
+      background.index = 0;
+      background.red =
+      background.green =
+      background.blue =
+      background.gray = png_get_uint_16(buf);
    }
    else
    {
-      png_ptr->background.red = png_get_uint_16(buf);
-      png_ptr->background.green = png_get_uint_16(buf + 2);
-      png_ptr->background.blue = png_get_uint_16(buf + 4);
+      background.index = 0;
+      background.red = png_get_uint_16(buf);
+      background.green = png_get_uint_16(buf + 2);
+      background.blue = png_get_uint_16(buf + 4);
+      background.gray = 0;
    }
-   png_set_bKGD(png_ptr, info_ptr, &(png_ptr->background));
+   png_set_bKGD(png_ptr, info_ptr, &background);
 }
 #endif
 #ifdef PNG_READ_hIST_SUPPORTED
 void /* PRIVATE */
-png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    unsigned int num, i;
    png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
 ,36 → 1955,28
    png_debug(1, "in png_handle_hIST");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before hIST");
+      png_chunk_error(png_ptr, "missing IHDR");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
    {
-      png_warning(png_ptr, "Invalid hIST after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-   else if (!(png_ptr->mode & PNG_HAVE_PLTE))
-   {
-      png_warning(png_ptr, "Missing PLTE before hIST");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
    {
-      png_warning(png_ptr, "Duplicate hIST chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
    num = length / 2 ;
-   if (num != (unsigned int)png_ptr->num_palette || num >
-       (unsigned int)PNG_MAX_PALETTE_LENGTH)
+   if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
    {
-      png_warning(png_ptr, "Incorrect hIST chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,7 → 1997,7
 #ifdef PNG_READ_pHYs_SUPPORTED
 void /* PRIVATE */
-png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[9];
    png_uint_32 res_x, res_y;
 ,26 → 2006,26
    png_debug(1, "in png_handle_pHYs");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before pHYs");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid pHYs after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
    {
-      png_warning(png_ptr, "Duplicate pHYs chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
    if (length != 9)
    {
-      png_warning(png_ptr, "Incorrect pHYs chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,7 → 2043,7
 #ifdef PNG_READ_oFFs_SUPPORTED
 void /* PRIVATE */
-png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[9];
    png_int_32 offset_x, offset_y;
 ,26 → 2052,26
    png_debug(1, "in png_handle_oFFs");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before oFFs");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid oFFs after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
-      png_warning(png_ptr, "Duplicate oFFs chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
    if (length != 9)
    {
-      png_warning(png_ptr, "Incorrect oFFs chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,62 → 2090,57
 #ifdef PNG_READ_pCAL_SUPPORTED
 /* Read the pCAL chunk (described in the PNG Extensions document) */
 void /* PRIVATE */
-png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_int_32 X0, X1;
    png_byte type, nparams;
-   png_charp buf, units, endptr;
+   png_bytep buffer, buf, units, endptr;
    png_charpp params;
-   png_size_t slength;
    int i;
    png_debug(1, "in png_handle_pCAL");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before pCAL");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid pCAL after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
    {
-      png_warning(png_ptr, "Duplicate pCAL chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
    png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
        length + 1);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (png_ptr->chunkdata == NULL)
+   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "No memory for pCAL purpose");
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
    if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       return;
-   }
-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
+   buffer[length] = 0; /* Null terminate the last string */
    png_debug(3, "Finding end of pCAL purpose string");
-   for (buf = png_ptr->chunkdata; *buf; buf++)
+   for (buf = buffer; *buf; buf++)
       /* Empty loop */ ;
-   endptr = png_ptr->chunkdata + slength;
+   endptr = buffer + length;
    /* We need to have at least 12 bytes after the purpose string
     * in order to get the parameter information.
 ,9 → 2147,7
     */
    if (endptr <= buf + 12)
    {
-      png_warning(png_ptr, "Invalid pCAL data");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,15 → 2167,13
        (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
        (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
    {
-      png_warning(png_ptr, "Invalid pCAL parameters for equation type");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+      png_chunk_benign_error(png_ptr, "invalid parameter count");
       return;
    }
    else if (type >= PNG_EQUATION_LAST)
    {
-      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
+      png_chunk_benign_error(png_ptr, "unrecognized equation type");
    }
    for (buf = units; *buf; buf++)
 ,43 → 2181,37
    png_debug(3, "Allocating pCAL parameters array");
-   params = (png_charpp)png_malloc_warn(png_ptr,
-       (png_size_t)(nparams * png_sizeof(png_charp)));
+   params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
+       nparams * (sizeof (png_charp))));
    if (params == NULL)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "No memory for pCAL params");
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
    /* Get pointers to the start of each parameter string. */
-   for (i = 0; i < (int)nparams; i++)
+   for (i = 0; i < nparams; i++)
    {
       buf++; /* Skip the null string terminator from previous parameter. */
       png_debug1(3, "Reading pCAL parameter %d", i);
-      for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)
+      for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
          /* Empty loop to move past each parameter string */ ;
       /* Make sure we haven't run out of data yet */
       if (buf > endptr)
       {
-         png_warning(png_ptr, "Invalid pCAL data");
-         png_free(png_ptr, png_ptr->chunkdata);
-         png_ptr->chunkdata = NULL;
          png_free(png_ptr, params);
+         png_chunk_benign_error(png_ptr, "invalid data");
          return;
       }
    }
-   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,
-      units, params);
+   png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
+      (png_charp)units, params);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
    png_free(png_ptr, params);
 }
 #endif
 ,59 → 2219,61
 #ifdef PNG_READ_sCAL_SUPPORTED
 /* Read the sCAL chunk */
 void /* PRIVATE */
-png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_size_t slength, i;
+   png_bytep buffer;
+   png_size_t i;
    int state;
    png_debug(1, "in png_handle_sCAL");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sCAL");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      png_warning(png_ptr, "Invalid sCAL after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
    {
-      png_warning(png_ptr, "Duplicate sCAL chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
+   /* Need unit type, width, \0, height: minimum 4 bytes */
+   else if (length < 4)
+   {
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
+      return;
+   }
    png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
       length + 1);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
-   if (png_ptr->chunkdata == NULL)
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "Out of memory while processing sCAL chunk");
+      png_chunk_benign_error(png_ptr, "out of memory");
       png_crc_finish(png_ptr, length);
       return;
    }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
+   png_crc_read(png_ptr, buffer, length);
+   buffer[length] = 0; /* Null terminate the last string */
    if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       return;
-   }
    /* Validate the unit. */
-   if (png_ptr->chunkdata[0] != 1 && png_ptr->chunkdata[0] != 2)
+   if (buffer[0] != 1 && buffer[0] != 2)
    {
-      png_warning(png_ptr, "Invalid sCAL ignored: invalid unit");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+      png_chunk_benign_error(png_ptr, "invalid unit");
       return;
    }
 ,38 → 2280,39
    /* Validate the ASCII numbers, need two ASCII numbers separated by
     * a '\0' and they need to fit exactly in the chunk data.
     */
-   i = 0;
+   i = 1;
    state = 0;
-   if (png_ptr->chunkdata[1] == 45 /* negative width */ ||
-       !png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||
-       i >= slength || png_ptr->chunkdata[i++] != 0)
-      png_warning(png_ptr, "Invalid sCAL chunk ignored: bad width format");
+   if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
+       i >= length || buffer[i++] != 0)
+      png_chunk_benign_error(png_ptr, "bad width format");
+   else if (!PNG_FP_IS_POSITIVE(state))
+      png_chunk_benign_error(png_ptr, "non-positive width");
    else
    {
       png_size_t heighti = i;
-      if (png_ptr->chunkdata[i] == 45 /* negative height */ ||
-          !png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||
-          i != slength)
-         png_warning(png_ptr, "Invalid sCAL chunk ignored: bad height format");
+      state = 0;
+      if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
+         i != length)
+         png_chunk_benign_error(png_ptr, "bad height format");
+      else if (!PNG_FP_IS_POSITIVE(state))
+         png_chunk_benign_error(png_ptr, "non-positive height");
       else
          /* This is the (only) success case. */
-         png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0],
-            png_ptr->chunkdata+1, png_ptr->chunkdata+heighti);
+         png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
+            (png_charp)buffer+1, (png_charp)buffer+heighti);
    }
-   /* Clean up - just free the temporarily allocated buffer. */
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
 }
 #endif
 #ifdef PNG_READ_tIME_SUPPORTED
 void /* PRIVATE */
-png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[7];
    png_time mod_time;
 ,12 → 2320,12
    png_debug(1, "in png_handle_tIME");
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Out of place tIME chunk");
+      png_chunk_error(png_ptr, "missing IHDR");
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
    {
-      png_warning(png_ptr, "Duplicate tIME chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 ,8 → 2334,8
    if (length != 7)
    {
-      png_warning(png_ptr, "Incorrect tIME chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 ,14 → 2358,13
 #ifdef PNG_READ_tEXt_SUPPORTED
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_textp text_ptr;
+   png_text  text_info;
+   png_bytep buffer;
    png_charp key;
    png_charp text;
    png_uint_32 skip = 0;
-   png_size_t slength;
-   int ret;
    png_debug(1, "in png_handle_tEXt");
 ,8 → 2379,8
       if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_warning(png_ptr, "No space in chunk cache for tEXt");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 ,76 → 2387,51
 #endif
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before tEXt");
+      png_chunk_error(png_ptr, "missing IHDR");
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
+   if (length > 65535U)
    {
-      png_warning(png_ptr, "tEXt chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "too large to fit in memory");
+      return;
    }
 #endif
-   png_free(png_ptr, png_ptr->chunkdata);
+   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (png_ptr->chunkdata == NULL)
+   if (buffer == NULL)
    {
-     png_warning(png_ptr, "No memory to process text chunk");
+     png_chunk_benign_error(png_ptr, "out of memory");
      return;
    }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
    if (png_crc_finish(png_ptr, skip))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       return;
-   }
-   key = png_ptr->chunkdata;
+   key = (png_charp)buffer;
+   key[length] = 0;
-   key[slength] = 0x00;
    for (text = key; *text; text++)
       /* Empty loop to find end of key */ ;
-   if (text != key + slength)
+   if (text != key + length)
       text++;
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-       png_sizeof(png_text));
+   text_info.compression = PNG_TEXT_COMPRESSION_NONE;
+   text_info.key = key;
+   text_info.lang = NULL;
+   text_info.lang_key = NULL;
+   text_info.itxt_length = 0;
+   text_info.text = text;
+   text_info.text_length = strlen(text);
-   if (text_ptr == NULL)
-   {
-      png_warning(png_ptr, "Not enough memory to process text chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-   text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
-   text_ptr->key = key;
-   text_ptr->lang = NULL;
-   text_ptr->lang_key = NULL;
-   text_ptr->itxt_length = 0;
-   text_ptr->text = text;
-   text_ptr->text_length = png_strlen(text);
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   png_free(png_ptr, text_ptr);
-   if (ret)
+   if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
       png_warning(png_ptr, "Insufficient memory to process text chunk");
 }
 #endif
 ,13 → 2439,11
 #ifdef PNG_READ_zTXt_SUPPORTED
 /* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_textp text_ptr;
-   png_charp text;
-   int comp_type;
-   int ret;
-   png_size_t slength, prefix_len, data_len;
+   png_const_charp errmsg = NULL;
+   png_bytep       buffer;
+   png_uint_32     keyword_length;
    png_debug(1, "in png_handle_zTXt");
 ,8 → 2458,8
       if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_warning(png_ptr, "No space in chunk cache for zTXt");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 ,101 → 2466,82
 #endif
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before zTXt");
+      png_chunk_error(png_ptr, "missing IHDR");
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
-#ifdef PNG_MAX_MALLOC_64K
-   /* We will no doubt have problems with chunks even half this size, but
-    * there is no hard and fast rule to tell us where to stop.
-    */
-   if (length > (png_uint_32)65535L)
+   buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "zTXt chunk too large to fit in memory");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
-#endif
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   png_crc_read(png_ptr, buffer, length);
-   if (png_ptr->chunkdata == NULL)
-   {
-      png_warning(png_ptr, "Out of memory processing zTXt chunk");
+   if (png_crc_finish(png_ptr, 0))
       return;
-   }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   /* TODO: also check that the keyword contents match the spec! */
+   for (keyword_length = 0;
+      keyword_length < length && buffer[keyword_length] != 0;
+      ++keyword_length)
+      /* Empty loop to find end of name */ ;
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+   if (keyword_length > 79 || keyword_length < 1)
+      errmsg = "bad keyword";
-   png_ptr->chunkdata[slength] = 0x00;
+   /* zTXt must have some LZ data after the keyword, although it may expand to
+    * zero bytes; we need a '\0' at the end of the keyword, the compression type
+    * then the LZ data:
+    */
+   else if (keyword_length + 3 > length)
+      errmsg = "truncated";
-   for (text = png_ptr->chunkdata; *text; text++)
-      /* Empty loop */ ;
+   else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
+      errmsg = "unknown compression type";
-   /* zTXt must have some text after the chunkdataword */
-   if (text >= png_ptr->chunkdata + slength - 2)
-   {
-      png_warning(png_ptr, "Truncated zTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
    else
    {
-       comp_type = *(++text);
+      png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
-       if (comp_type != PNG_TEXT_COMPRESSION_zTXt)
+      /* TODO: at present png_decompress_chunk imposes a single application
+       * level memory limit, this should be split to different values for iCCP
+       * and text chunks.
+       */
+      if (png_decompress_chunk(png_ptr, length, keyword_length+2,
+         &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
        {
-          png_warning(png_ptr, "Unknown compression type in zTXt chunk");
-          comp_type = PNG_TEXT_COMPRESSION_zTXt;
-       }
+         png_text text;
-       text++;        /* Skip the compression_method byte */
-   }
+         /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
+          * for the extra compression type byte and the fact that it isn't
+          * necessarily '\0' terminated.
+          */
+         buffer = png_ptr->read_buffer;
+         buffer[uncompressed_length+(keyword_length+2)] = 0;
-   prefix_len = text - png_ptr->chunkdata;
+         text.compression = PNG_TEXT_COMPRESSION_zTXt;
+         text.key = (png_charp)buffer;
+         text.text = (png_charp)(buffer + keyword_length+2);
+         text.text_length = uncompressed_length;
+         text.itxt_length = 0;
+         text.lang = NULL;
+         text.lang_key = NULL;
-   png_decompress_chunk(png_ptr, comp_type,
-       (png_size_t)length, prefix_len, &data_len);
+         if (png_set_text_2(png_ptr, info_ptr, &text, 1))
+            errmsg = "insufficient memory";
+      }
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-       png_sizeof(png_text));
-   if (text_ptr == NULL)
-   {
-      png_warning(png_ptr, "Not enough memory to process zTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
+      else
+         errmsg = png_ptr->zstream.msg;
    }
-   text_ptr->compression = comp_type;
-   text_ptr->key = png_ptr->chunkdata;
-   text_ptr->lang = NULL;
-   text_ptr->lang_key = NULL;
-   text_ptr->itxt_length = 0;
-   text_ptr->text = png_ptr->chunkdata + prefix_len;
-   text_ptr->text_length = data_len;
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-   png_free(png_ptr, text_ptr);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   if (ret)
-      png_error(png_ptr, "Insufficient memory to store zTXt chunk");
+   if (errmsg != NULL)
+      png_chunk_benign_error(png_ptr, errmsg);
 }
 #endif
 ,14 → 2548,11
 #ifdef PNG_READ_iTXt_SUPPORTED
 /* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_textp text_ptr;
-   png_charp key, lang, text, lang_key;
-   int comp_flag;
-   int comp_type = 0;
-   int ret;
-   png_size_t slength, prefix_len, data_len;
+   png_const_charp errmsg = NULL;
+   png_bytep buffer;
+   png_uint_32 prefix_length;
    png_debug(1, "in png_handle_iTXt");
 ,8 → 2567,8
       if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_warning(png_ptr, "No space in chunk cache for iTXt");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 ,266 → 2575,384
 #endif
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before iTXt");
+      png_chunk_error(png_ptr, "missing IHDR");
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
-#ifdef PNG_MAX_MALLOC_64K
-   /* We will no doubt have problems with chunks even half this size, but
-    * there is no hard and fast rule to tell us where to stop.
-    */
-   if (length > (png_uint_32)65535L)
+   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "iTXt chunk too large to fit in memory");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
-#endif
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   png_crc_read(png_ptr, buffer, length);
-   if (png_ptr->chunkdata == NULL)
-   {
-      png_warning(png_ptr, "No memory to process iTXt chunk");
-      return;
-   }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
    if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       return;
-   }
-   png_ptr->chunkdata[slength] = 0x00;
-   for (lang = png_ptr->chunkdata; *lang; lang++)
+   /* First the keyword. */
+   for (prefix_length=0;
+      prefix_length < length && buffer[prefix_length] != 0;
+      ++prefix_length)
       /* Empty loop */ ;
-   lang++;        /* Skip NUL separator */
+   /* Perform a basic check on the keyword length here. */
+   if (prefix_length > 79 || prefix_length < 1)
+      errmsg = "bad keyword";
-   /* iTXt must have a language tag (possibly empty), two compression bytes,
-    * translated keyword (possibly empty), and possibly some text after the
-    * keyword
+   /* Expect keyword, compression flag, compression type, language, translated
+    * keyword (both may be empty but are 0 terminated) then the text, which may
+    * be empty.
     */
+   else if (prefix_length + 5 > length)
+      errmsg = "truncated";
-   if (lang >= png_ptr->chunkdata + slength - 3)
+   else if (buffer[prefix_length+1] == 0 ||
+      (buffer[prefix_length+1] == 1 &&
+      buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
    {
-      png_warning(png_ptr, "Truncated iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+      int compressed = buffer[prefix_length+1] != 0;
+      png_uint_32 language_offset, translated_keyword_offset;
+      png_alloc_size_t uncompressed_length = 0;
-   else
-   {
-      comp_flag = *lang++;
-      comp_type = *lang++;
-   }
+      /* Now the language tag */
+      prefix_length += 3;
+      language_offset = prefix_length;
-   for (lang_key = lang; *lang_key; lang_key++)
+      for (; prefix_length < length && buffer[prefix_length] != 0;
+         ++prefix_length)
       /* Empty loop */ ;
-   lang_key++;        /* Skip NUL separator */
+      /* WARNING: the length may be invalid here, this is checked below. */
+      translated_keyword_offset = ++prefix_length;
-   if (lang_key >= png_ptr->chunkdata + slength)
-   {
-      png_warning(png_ptr, "Truncated iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-   for (text = lang_key; *text; text++)
+      for (; prefix_length < length && buffer[prefix_length] != 0;
+         ++prefix_length)
       /* Empty loop */ ;
-   text++;        /* Skip NUL separator */
+      /* prefix_length should now be at the trailing '\0' of the translated
+       * keyword, but it may already be over the end.  None of this arithmetic
+       * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
+       * systems the available allocaton may overflow.
+       */
+      ++prefix_length;
-   if (text >= png_ptr->chunkdata + slength)
+      if (!compressed && prefix_length <= length)
+         uncompressed_length = length - prefix_length;
+      else if (compressed && prefix_length < length)
    {
-      png_warning(png_ptr, "Malformed iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
+         uncompressed_length = PNG_SIZE_MAX;
+         /* TODO: at present png_decompress_chunk imposes a single application
+          * level memory limit, this should be split to different values for
+          * iCCP and text chunks.
+          */
+         if (png_decompress_chunk(png_ptr, length, prefix_length,
+            &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+            buffer = png_ptr->read_buffer;
+         else
+            errmsg = png_ptr->zstream.msg;
    }
-   prefix_len = text - png_ptr->chunkdata;
+      else
+         errmsg = "truncated";
-   key=png_ptr->chunkdata;
+      if (errmsg == NULL)
+      {
+         png_text text;
-   if (comp_flag)
-      png_decompress_chunk(png_ptr, comp_type,
-          (size_t)length, prefix_len, &data_len);
+         buffer[uncompressed_length+prefix_length] = 0;
+         if (compressed)
+            text.compression = PNG_ITXT_COMPRESSION_NONE;
    else
-      data_len = png_strlen(png_ptr->chunkdata + prefix_len);
+            text.compression = PNG_ITXT_COMPRESSION_zTXt;
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-       png_sizeof(png_text));
+         text.key = (png_charp)buffer;
+         text.lang = (png_charp)buffer + language_offset;
+         text.lang_key = (png_charp)buffer + translated_keyword_offset;
+         text.text = (png_charp)buffer + prefix_length;
+         text.text_length = 0;
+         text.itxt_length = uncompressed_length;
-   if (text_ptr == NULL)
-   {
-      png_warning(png_ptr, "Not enough memory to process iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
+         if (png_set_text_2(png_ptr, info_ptr, &text, 1))
+            errmsg = "insufficient memory";
    }
+   }
-   text_ptr->compression = (int)comp_flag + 1;
-   text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);
-   text_ptr->lang = png_ptr->chunkdata + (lang - key);
-   text_ptr->itxt_length = data_len;
-   text_ptr->text_length = 0;
-   text_ptr->key = png_ptr->chunkdata;
-   text_ptr->text = png_ptr->chunkdata + prefix_len;
+   else
+      errmsg = "bad compression info";
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+   if (errmsg != NULL)
+      png_chunk_benign_error(png_ptr, errmsg);
+}
+#endif
-   png_free(png_ptr, text_ptr);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+/* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
+static int
+png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
+{
+   png_alloc_size_t limit = PNG_SIZE_MAX;
-   if (ret)
-      png_error(png_ptr, "Insufficient memory to store iTXt chunk");
+   if (png_ptr->unknown_chunk.data != NULL)
+   {
+      png_free(png_ptr, png_ptr->unknown_chunk.data);
+      png_ptr->unknown_chunk.data = NULL;
 }
+#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max > 0 &&
+         png_ptr->user_chunk_malloc_max < limit)
+         limit = png_ptr->user_chunk_malloc_max;
+#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
+      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+         limit = PNG_USER_CHUNK_MALLOC_MAX;
 #endif
-/* This function is called when we haven't found a handler for a
- * chunk.  If there isn't a problem with the chunk itself (ie bad
- * chunk name, CRC, or a critical chunk), the chunk is silently ignored
- * -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
- * case it will be saved away to be written out later.
- */
-void /* PRIVATE */
-png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+   if (length <= limit)
 {
-   png_uint_32 skip = 0;
+      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
+      /* The following is safe because of the PNG_SIZE_MAX init above */
+      png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
+      /* 'mode' is a flag array, only the bottom four bits matter here */
+      png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
-   png_debug(1, "in png_handle_unknown");
+      if (length == 0)
+         png_ptr->unknown_chunk.data = NULL;
-#ifdef PNG_USER_LIMITS_SUPPORTED
-   if (png_ptr->user_chunk_cache_max != 0)
+      else
    {
-      if (png_ptr->user_chunk_cache_max == 1)
+         /* Do a 'warn' here - it is handled below. */
+         png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
+            png_malloc_warn(png_ptr, length));
+      }
+   }
+   if (png_ptr->unknown_chunk.data == NULL && length > 0)
       {
+      /* This is benign because we clean up correctly */
          png_crc_finish(png_ptr, length);
-         return;
+      png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
+      return 0;
       }
-      if (--png_ptr->user_chunk_cache_max == 1)
+   else
       {
-         png_warning(png_ptr, "No space in chunk cache for unknown chunk");
-         png_crc_finish(png_ptr, length);
-         return;
+      if (length > 0)
+         png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
+      png_crc_finish(png_ptr, 0);
+      return 1;
       }
    }
-#endif
+#endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
-   if (png_ptr->mode & PNG_HAVE_IDAT)
+/* Handle an unknown, or known but disabled, chunk */
+void /* PRIVATE */
+png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
+   png_uint_32 length, int keep)
    {
-      PNG_IDAT;
+   int handled = 0; /* the chunk was handled */
-      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* Not an IDAT */
-         png_ptr->mode |= PNG_AFTER_IDAT;
-   }
+   png_debug(1, "in png_handle_unknown");
-   if (!(png_ptr->chunk_name[0] & 0x20))
-   {
+   /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
+    * the bug which meant that setting a non-default behavior for a specific
+    * chunk would be ignored (the default was always used unless a user
+    * callback was installed).
+    *
+    * 'keep' is the value from the png_chunk_unknown_handling, the setting for
+    * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
+    * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
+    * This is just an optimization to avoid multiple calls to the lookup
+    * function.
+    */
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-      if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
-          PNG_HANDLE_CHUNK_ALWAYS
-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-          && png_ptr->read_user_chunk_fn == NULL
+   keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
 #endif
-          )
-#endif
-         png_chunk_error(png_ptr, "unknown critical chunk");
-   }
+   /* One of the following methods will read the chunk or skip it (at least one
+    * of these is always defined because this is the only way to switch on
+    * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
+    */
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
-   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-       || (png_ptr->read_user_chunk_fn != NULL)
-#endif
-       )
+      /* The user callback takes precedence over the chunk keep value, but the
+       * keep value is still required to validate a save of a critical chunk.
+       */
+      if (png_ptr->read_user_chunk_fn != NULL)
    {
-#ifdef PNG_MAX_MALLOC_64K
-      if (length > (png_uint_32)65535L)
+         if (png_cache_unknown_chunk(png_ptr, length))
       {
-         png_warning(png_ptr, "unknown chunk too large to fit in memory");
-         skip = length - (png_uint_32)65535L;
-         length = (png_uint_32)65535L;
+            /* Callback to user unknown chunk handler */
+            int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
+               &png_ptr->unknown_chunk);
+            /* ret is:
+             * negative: An error occured, png_chunk_error will be called.
+             *     zero: The chunk was not handled, the chunk will be discarded
+             *           unless png_set_keep_unknown_chunks has been used to set
+             *           a 'keep' behavior for this particular chunk, in which
+             *           case that will be used.  A critical chunk will cause an
+             *           error at this point unless it is to be saved.
+             * positive: The chunk was handled, libpng will ignore/discard it.
+             */
+            if (ret < 0)
+               png_chunk_error(png_ptr, "error in user chunk");
+            else if (ret == 0)
+            {
+               /* If the keep value is 'default' or 'never' override it, but
+                * still error out on critical chunks unless the keep value is
+                * 'always'  While this is weird it is the behavior in 1.4.12.
+                * A possible improvement would be to obey the value set for the
+                * chunk, but this would be an API change that would probably
+                * damage some applications.
+                *
+                * The png_app_warning below catches the case that matters, where
+                * the application has not set specific save or ignore for this
+                * chunk or global save or ignore.
+                */
+               if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
+               {
+#                 ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+                     if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
+                     {
+                        png_chunk_warning(png_ptr, "Saving unknown chunk:");
+                        png_app_warning(png_ptr,
+                           "forcing save of an unhandled chunk;"
+                           " please call png_set_keep_unknown_chunks");
+                           /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
       }
 #endif
+                  keep = PNG_HANDLE_CHUNK_IF_SAFE;
+               }
+            }
-      png_memcpy((png_charp)png_ptr->unknown_chunk.name,
-          (png_charp)png_ptr->chunk_name,
-          png_sizeof(png_ptr->unknown_chunk.name));
+            else /* chunk was handled */
+            {
+               handled = 1;
+               /* Critical chunks can be safely discarded at this point. */
+               keep = PNG_HANDLE_CHUNK_NEVER;
+            }
+         }
-      png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name)-1]
-          = '\0';
+         else
+            keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
+      }
-      png_ptr->unknown_chunk.size = (png_size_t)length;
+      else
+         /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
+#  endif /* PNG_READ_USER_CHUNKS_SUPPORTED */
-      if (length == 0)
-         png_ptr->unknown_chunk.data = NULL;
+#  ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+      {
+         /* keep is currently just the per-chunk setting, if there was no
+          * setting change it to the global default now (not that this may
+          * still be AS_DEFAULT) then obtain the cache of the chunk if required,
+          * if not simply skip the chunk.
+          */
+         if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
+            keep = png_ptr->unknown_default;
-      else
+         if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
+            (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
+             PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
       {
-         png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
-         png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
+            if (!png_cache_unknown_chunk(png_ptr, length))
+               keep = PNG_HANDLE_CHUNK_NEVER;
       }
-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-      if (png_ptr->read_user_chunk_fn != NULL)
+         else
+            png_crc_finish(png_ptr, length);
+      }
+#  else
+#     ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+#        error no method to support READ_UNKNOWN_CHUNKS
+#     endif
       {
-         /* Callback to user unknown chunk handler */
-         int ret;
+         /* If here there is no read callback pointer set and no support is
+          * compiled in to just save the unknown chunks, so simply skip this
+          * chunk.  If 'keep' is something other than AS_DEFAULT or NEVER then
+          * the app has erroneously asked for unknown chunk saving when there
+          * is no support.
+          */
+         if (keep > PNG_HANDLE_CHUNK_NEVER)
+            png_app_error(png_ptr, "no unknown chunk support available");
-         ret = (*(png_ptr->read_user_chunk_fn))
-             (png_ptr, &png_ptr->unknown_chunk);
+         png_crc_finish(png_ptr, length);
+      }
+#  endif /* PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED */
-         if (ret < 0)
-            png_chunk_error(png_ptr, "error in user chunk");
-         if (ret == 0)
+#  ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+      /* Now store the chunk in the chunk list if appropriate, and if the limits
+       * permit it.
+       */
+      if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
+         (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
+          PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
          {
-            if (!(png_ptr->chunk_name[0] & 0x20))
+#     ifdef PNG_USER_LIMITS_SUPPORTED
+         switch (png_ptr->user_chunk_cache_max)
             {
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-               if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
-                   PNG_HANDLE_CHUNK_ALWAYS)
-#endif
-                  png_chunk_error(png_ptr, "unknown critical chunk");
-            }
+            case 2:
+               png_ptr->user_chunk_cache_max = 1;
+               png_chunk_benign_error(png_ptr, "no space in chunk cache");
+               /* FALL THROUGH */
+            case 1:
+               /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
+                * chunk being skipped, now there will be a hard error below.
+                */
+               break;
+            default: /* not at limit */
+               --(png_ptr->user_chunk_cache_max);
+               /* FALL THROUGH */
+            case 0: /* no limit */
+#     endif /* PNG_USER_LIMITS_SUPPORTED */
+               /* Here when the limit isn't reached or when limits are compiled
+                * out; store the chunk.
+                */
             png_set_unknown_chunks(png_ptr, info_ptr,
                 &png_ptr->unknown_chunk, 1);
+               handled = 1;
+#     ifdef PNG_USER_LIMITS_SUPPORTED
+               break;
          }
+#     endif
       }
-      else
+#  else /* no store support! */
+      PNG_UNUSED(info_ptr)
+#     error untested code (reading unknown chunks with no store support)
 #endif
-         png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+   /* Regardless of the error handling below the cached data (if any) can be
+    * freed now.  Notice that the data is not freed if there is a png_error, but
+    * it will be freed by destroy_read_struct.
+    */
+   if (png_ptr->unknown_chunk.data != NULL)
       png_free(png_ptr, png_ptr->unknown_chunk.data);
       png_ptr->unknown_chunk.data = NULL;
-   }
-   else
-#endif
-      skip = length;
+#else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
+   /* There is no support to read an unknown chunk, so just skip it. */
+   png_crc_finish(png_ptr, length);
+   PNG_UNUSED(info_ptr)
+   PNG_UNUSED(keep)
+#endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
-   png_crc_finish(png_ptr, skip);
-#ifndef PNG_READ_USER_CHUNKS_SUPPORTED
-   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
-#endif
+   /* Check for unhandled critical chunks */
+   if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+      png_chunk_error(png_ptr, "unhandled critical chunk");
 }
 /* This function is called to verify that a chunk name is valid.
 ,259 → 2962,525
  * the chunk name itself is valid.
  */
-#define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
+/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
+ *
+ * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
+ */
 void /* PRIVATE */
-png_check_chunk_name(png_structp png_ptr, png_const_bytep chunk_name)
+png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
 {
+   int i;
    png_debug(1, "in png_check_chunk_name");
-   if (isnonalpha(chunk_name[0]) || isnonalpha(chunk_name[1]) ||
-       isnonalpha(chunk_name[2]) || isnonalpha(chunk_name[3]))
+   for (i=1; i<=4; ++i)
    {
+      int c = chunk_name & 0xff;
+      if (c < 65 || c > 122 || (c > 90 && c < 97))
       png_chunk_error(png_ptr, "invalid chunk type");
+      chunk_name >>= 8;
    }
 }
-/* Combines the row recently read in with the existing pixels in the
- * row.  This routine takes care of alpha and transparency if requested.
- * This routine also handles the two methods of progressive display
- * of interlaced images, depending on the mask value.
- * The mask value describes which pixels are to be combined with
- * the row.  The pattern always repeats every 8 pixels, so just 8
- * bits are needed.  A one indicates the pixel is to be combined,
- * a zero indicates the pixel is to be skipped.  This is in addition
- * to any alpha or transparency value associated with the pixel.  If
- * you want all pixels to be combined, pass 0xff (255) in mask.
+/* Combines the row recently read in with the existing pixels in the row.  This
+ * routine takes care of alpha and transparency if requested.  This routine also
+ * handles the two methods of progressive display of interlaced images,
+ * depending on the 'display' value; if 'display' is true then the whole row
+ * (dp) is filled from the start by replicating the available pixels.  If
+ * 'display' is false only those pixels present in the pass are filled in.
  */
 void /* PRIVATE */
-png_combine_row(png_structp png_ptr, png_bytep row, int mask)
+png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
 {
+   unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
+   png_const_bytep sp = png_ptr->row_buf + 1;
+   png_uint_32 row_width = png_ptr->width;
+   unsigned int pass = png_ptr->pass;
+   png_bytep end_ptr = 0;
+   png_byte end_byte = 0;
+   unsigned int end_mask;
    png_debug(1, "in png_combine_row");
-   if (mask == 0xff)
+   /* Added in 1.5.6: it should not be possible to enter this routine until at
+    * least one row has been read from the PNG data and transformed.
+    */
+   if (pixel_depth == 0)
+      png_error(png_ptr, "internal row logic error");
+   /* Added in 1.5.4: the pixel depth should match the information returned by
+    * any call to png_read_update_info at this point.  Do not continue if we got
+    * this wrong.
+    */
+   if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
+          PNG_ROWBYTES(pixel_depth, row_width))
+      png_error(png_ptr, "internal row size calculation error");
+   /* Don't expect this to ever happen: */
+   if (row_width == 0)
+      png_error(png_ptr, "internal row width error");
+   /* Preserve the last byte in cases where only part of it will be overwritten,
+    * the multiply below may overflow, we don't care because ANSI-C guarantees
+    * we get the low bits.
+    */
+   end_mask = (pixel_depth * row_width) & 7;
+   if (end_mask != 0)
    {
-      png_memcpy(row, png_ptr->row_buf + 1,
-          PNG_ROWBYTES(png_ptr->row_info.pixel_depth, png_ptr->width));
+      /* end_ptr == NULL is a flag to say do nothing */
+      end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
+      end_byte = *end_ptr;
+#     ifdef PNG_READ_PACKSWAP_SUPPORTED
+         if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
+            end_mask = 0xff << end_mask;
+         else /* big-endian byte */
+#     endif
+         end_mask = 0xff >> end_mask;
+      /* end_mask is now the bits to *keep* from the destination row */
    }
-   else
+   /* For non-interlaced images this reduces to a memcpy(). A memcpy()
+    * will also happen if interlacing isn't supported or if the application
+    * does not call png_set_interlace_handling().  In the latter cases the
+    * caller just gets a sequence of the unexpanded rows from each interlace
+    * pass.
+    */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
+      pass < 6 && (display == 0 ||
+      /* The following copies everything for 'display' on passes 0, 2 and 4. */
+      (display == 1 && (pass & 1) != 0)))
    {
-      switch (png_ptr->row_info.pixel_depth)
+      /* Narrow images may have no bits in a pass; the caller should handle
+       * this, but this test is cheap:
+       */
+      if (row_width <= PNG_PASS_START_COL(pass))
+         return;
+      if (pixel_depth < 8)
       {
-         case 1:
+         /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
+          * into 32 bits, then a single loop over the bytes using the four byte
+          * values in the 32-bit mask can be used.  For the 'display' option the
+          * expanded mask may also not require any masking within a byte.  To
+          * make this work the PACKSWAP option must be taken into account - it
+          * simply requires the pixels to be reversed in each byte.
+          *
+          * The 'regular' case requires a mask for each of the first 6 passes,
+          * the 'display' case does a copy for the even passes in the range
+          * 0..6.  This has already been handled in the test above.
+          *
+          * The masks are arranged as four bytes with the first byte to use in
+          * the lowest bits (little-endian) regardless of the order (PACKSWAP or
+          * not) of the pixels in each byte.
+          *
+          * NOTE: the whole of this logic depends on the caller of this function
+          * only calling it on rows appropriate to the pass.  This function only
+          * understands the 'x' logic; the 'y' logic is handled by the caller.
+          *
+          * The following defines allow generation of compile time constant bit
+          * masks for each pixel depth and each possibility of swapped or not
+          * swapped bytes.  Pass 'p' is in the range 0..6; 'x', a pixel index,
+          * is in the range 0..7; and the result is 1 if the pixel is to be
+          * copied in the pass, 0 if not.  'S' is for the sparkle method, 'B'
+          * for the block method.
+          *
+          * With some compilers a compile time expression of the general form:
+          *
+          *    (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
+          *
+          * Produces warnings with values of 'shift' in the range 33 to 63
+          * because the right hand side of the ?: expression is evaluated by
+          * the compiler even though it isn't used.  Microsoft Visual C (various
+          * versions) and the Intel C compiler are known to do this.  To avoid
+          * this the following macros are used in 1.5.6.  This is a temporary
+          * solution to avoid destabilizing the code during the release process.
+          */
+#        if PNG_USE_COMPILE_TIME_MASKS
+#           define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
+#           define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
+#        else
+#           define PNG_LSR(x,s) ((x)>>(s))
+#           define PNG_LSL(x,s) ((x)<<(s))
+#        endif
+#        define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
+           PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
+#        define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
+           PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
+         /* Return a mask for pass 'p' pixel 'x' at depth 'd'.  The mask is
+          * little endian - the first pixel is at bit 0 - however the extra
+          * parameter 's' can be set to cause the mask position to be swapped
+          * within each byte, to match the PNG format.  This is done by XOR of
+          * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
+          */
+#        define PIXEL_MASK(p,x,d,s) \
+            (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
+         /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
+          */
+#        define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
+#        define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
+         /* Combine 8 of these to get the full mask.  For the 1-bpp and 2-bpp
+          * cases the result needs replicating, for the 4-bpp case the above
+          * generates a full 32 bits.
+          */
+#        define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
+#        define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
+            S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
+            S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
+#        define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
+            B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
+            B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
+#if PNG_USE_COMPILE_TIME_MASKS
+         /* Utility macros to construct all the masks for a depth/swap
+          * combination.  The 's' parameter says whether the format is PNG
+          * (big endian bytes) or not.  Only the three odd-numbered passes are
+          * required for the display/block algorithm.
+          */
+#        define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
+            S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
+#        define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
+#        define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
+         /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
+          * then pass:
+          */
+         static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
          {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            int s_inc, s_start, s_end;
-            int m = 0x80;
-            int shift;
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
+            /* Little-endian byte masks for PACKSWAP */
+            { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
+            /* Normal (big-endian byte) masks - PNG format */
+            { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
+         };
+         /* display_mask has only three entries for the odd passes, so index by
+          * pass>>1.
+          */
+         static PNG_CONST png_uint_32 display_mask[2][3][3] =
+         {
+            /* Little-endian byte masks for PACKSWAP */
+            { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
+            /* Normal (big-endian byte) masks - PNG format */
+            { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
+         };
+#        define MASK(pass,depth,display,png)\
+            ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
+               row_mask[png][DEPTH_INDEX(depth)][pass])
+#else /* !PNG_USE_COMPILE_TIME_MASKS */
+         /* This is the runtime alternative: it seems unlikely that this will
+          * ever be either smaller or faster than the compile time approach.
+          */
+#        define MASK(pass,depth,display,png)\
+            ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
+#endif /* !PNG_USE_COMPILE_TIME_MASKS */
+         /* Use the appropriate mask to copy the required bits.  In some cases
+          * the byte mask will be 0 or 0xff, optimize these cases.  row_width is
+          * the number of pixels, but the code copies bytes, so it is necessary
+          * to special case the end.
+          */
+         png_uint_32 pixels_per_byte = 8 / pixel_depth;
+         png_uint_32 mask;
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (png_ptr->transformations & PNG_PACKSWAP)
-            {
-                s_start = 0;
-                s_end = 7;
-                s_inc = 1;
-            }
+               mask = MASK(pass, pixel_depth, display, 0);
             else
 #endif
-            {
-                s_start = 7;
-                s_end = 0;
-                s_inc = -1;
-            }
+            mask = MASK(pass, pixel_depth, display, 1);
-            shift = s_start;
-            for (i = 0; i < row_width; i++)
+         for (;;)
             {
-               if (m & mask)
-               {
-                  int value;
+            png_uint_32 m;
-                  value = (*sp >> shift) & 0x01;
-                  *dp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
-                  *dp |= (png_byte)(value << shift);
-               }
+            /* It doesn't matter in the following if png_uint_32 has more than
+             * 32 bits because the high bits always match those in m<<24; it is,
+             * however, essential to use OR here, not +, because of this.
+             */
+            m = mask;
+            mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
+            m &= 0xff;
-               if (shift == s_end)
+            if (m != 0) /* something to copy */
                {
-                  shift = s_start;
-                  sp++;
-                  dp++;
+               if (m != 0xff)
+                  *dp = (png_byte)((*dp & ~m) | (*sp & m));
+               else
+                  *dp = *sp;
                }
-               else
-                  shift += s_inc;
+            /* NOTE: this may overwrite the last byte with garbage if the image
+             * is not an exact number of bytes wide; libpng has always done
+             * this.
+             */
+            if (row_width <= pixels_per_byte)
+               break; /* May need to restore part of the last byte */
-               if (m == 1)
-                  m = 0x80;
-               else
-                  m >>= 1;
+            row_width -= pixels_per_byte;
+            ++dp;
+            ++sp;
             }
-            break;
          }
-         case 2:
+      else /* pixel_depth >= 8 */
          {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            int s_start, s_end, s_inc;
-            int m = 0x80;
-            int shift;
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-            int value;
+         unsigned int bytes_to_copy, bytes_to_jump;
-#ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (png_ptr->transformations & PNG_PACKSWAP)
+         /* Validate the depth - it must be a multiple of 8 */
+         if (pixel_depth & 7)
+            png_error(png_ptr, "invalid user transform pixel depth");
+         pixel_depth >>= 3; /* now in bytes */
+         row_width *= pixel_depth;
+         /* Regardless of pass number the Adam 7 interlace always results in a
+          * fixed number of pixels to copy then to skip.  There may be a
+          * different number of pixels to skip at the start though.
+          */
             {
-               s_start = 0;
-               s_end = 6;
-               s_inc = 2;
+            unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
+            row_width -= offset;
+            dp += offset;
+            sp += offset;
             }
-            else
-#endif
+         /* Work out the bytes to copy. */
+         if (display)
             {
-               s_start = 6;
-               s_end = 0;
-               s_inc = -2;
+            /* When doing the 'block' algorithm the pixel in the pass gets
+             * replicated to adjacent pixels.  This is why the even (0,2,4,6)
+             * passes are skipped above - the entire expanded row is copied.
+             */
+            bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
+            /* But don't allow this number to exceed the actual row width. */
+            if (bytes_to_copy > row_width)
+               bytes_to_copy = row_width;
             }
-            shift = s_start;
+         else /* normal row; Adam7 only ever gives us one pixel to copy. */
+            bytes_to_copy = pixel_depth;
-            for (i = 0; i < row_width; i++)
+         /* In Adam7 there is a constant offset between where the pixels go. */
+         bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
+         /* And simply copy these bytes.  Some optimization is possible here,
+          * depending on the value of 'bytes_to_copy'.  Special case the low
+          * byte counts, which we know to be frequent.
+          *
+          * Notice that these cases all 'return' rather than 'break' - this
+          * avoids an unnecessary test on whether to restore the last byte
+          * below.
+          */
+         switch (bytes_to_copy)
             {
-               if (m & mask)
+            case 1:
+               for (;;)
                {
-                  value = (*sp >> shift) & 0x03;
-                  *dp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
-                  *dp |= (png_byte)(value << shift);
+                  *dp = *sp;
+                  if (row_width <= bytes_to_jump)
+                     return;
+                  dp += bytes_to_jump;
+                  sp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
                }
-               if (shift == s_end)
+            case 2:
+               /* There is a possibility of a partial copy at the end here; this
+                * slows the code down somewhat.
+                */
+               do
                {
-                  shift = s_start;
-                  sp++;
-                  dp++;
-               }
+                  dp[0] = sp[0], dp[1] = sp[1];
-               else
-                  shift += s_inc;
+                  if (row_width <= bytes_to_jump)
+                     return;
-               if (m == 1)
-                  m = 0x80;
-               else
-                  m >>= 1;
+                  sp += bytes_to_jump;
+                  dp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
             }
-            break;
-         }
+               while (row_width > 1);
-         case 4:
-         {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            int s_start, s_end, s_inc;
-            int m = 0x80;
-            int shift;
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-            int value;
+               /* And there can only be one byte left at this point: */
+               *dp = *sp;
+               return;
-#ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (png_ptr->transformations & PNG_PACKSWAP)
+            case 3:
+               /* This can only be the RGB case, so each copy is exactly one
+                * pixel and it is not necessary to check for a partial copy.
+                */
+               for(;;)
             {
-               s_start = 0;
-               s_end = 4;
-               s_inc = 4;
-            }
+                  dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
-            else
-#endif
-            {
-               s_start = 4;
-               s_end = 0;
-               s_inc = -4;
+                  if (row_width <= bytes_to_jump)
+                     return;
+                  sp += bytes_to_jump;
+                  dp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
             }
-            shift = s_start;
-            for (i = 0; i < row_width; i++)
+            default:
+#if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
+               /* Check for double byte alignment and, if possible, use a
+                * 16-bit copy.  Don't attempt this for narrow images - ones that
+                * are less than an interlace panel wide.  Don't attempt it for
+                * wide bytes_to_copy either - use the memcpy there.
+                */
+               if (bytes_to_copy < 16 /*else use memcpy*/ &&
+                  png_isaligned(dp, png_uint_16) &&
+                  png_isaligned(sp, png_uint_16) &&
+                  bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
+                  bytes_to_jump % (sizeof (png_uint_16)) == 0)
             {
-               if (m & mask)
+                  /* Everything is aligned for png_uint_16 copies, but try for
+                   * png_uint_32 first.
+                   */
+                  if (png_isaligned(dp, png_uint_32) &&
+                     png_isaligned(sp, png_uint_32) &&
+                     bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
+                     bytes_to_jump % (sizeof (png_uint_32)) == 0)
                {
-                  value = (*sp >> shift) & 0xf;
-                  *dp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
-                  *dp |= (png_byte)(value << shift);
-               }
+                     png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
+                     png_const_uint_32p sp32 = png_aligncastconst(
+                        png_const_uint_32p, sp);
+                     size_t skip = (bytes_to_jump-bytes_to_copy) /
+                        (sizeof (png_uint_32));
-               if (shift == s_end)
+                     do
                {
-                  shift = s_start;
-                  sp++;
-                  dp++;
+                        size_t c = bytes_to_copy;
+                        do
+                        {
+                           *dp32++ = *sp32++;
+                           c -= (sizeof (png_uint_32));
                }
+                        while (c > 0);
-               else
-                  shift += s_inc;
+                        if (row_width <= bytes_to_jump)
+                           return;
-               if (m == 1)
-                  m = 0x80;
+                        dp32 += skip;
+                        sp32 += skip;
+                        row_width -= bytes_to_jump;
+                     }
+                     while (bytes_to_copy <= row_width);
-               else
-                  m >>= 1;
+                     /* Get to here when the row_width truncates the final copy.
+                      * There will be 1-3 bytes left to copy, so don't try the
+                      * 16-bit loop below.
+                      */
+                     dp = (png_bytep)dp32;
+                     sp = (png_const_bytep)sp32;
+                     do
+                        *dp++ = *sp++;
+                     while (--row_width > 0);
+                     return;
             }
-            break;
-         }
-         default:
+                  /* Else do it in 16-bit quantities, but only if the size is
+                   * not too large.
+                   */
+                  else
          {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            png_size_t pixel_bytes = (png_ptr->row_info.pixel_depth >> 3);
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-            png_byte m = 0x80;
+                     png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
+                     png_const_uint_16p sp16 = png_aligncastconst(
+                        png_const_uint_16p, sp);
+                     size_t skip = (bytes_to_jump-bytes_to_copy) /
+                        (sizeof (png_uint_16));
-            for (i = 0; i < row_width; i++)
+                     do
             {
-               if (m & mask)
+                        size_t c = bytes_to_copy;
+                        do
                {
-                  png_memcpy(dp, sp, pixel_bytes);
+                           *dp16++ = *sp16++;
+                           c -= (sizeof (png_uint_16));
                }
+                        while (c > 0);
-               sp += pixel_bytes;
-               dp += pixel_bytes;
+                        if (row_width <= bytes_to_jump)
+                           return;
-               if (m == 1)
-                  m = 0x80;
+                        dp16 += skip;
+                        sp16 += skip;
+                        row_width -= bytes_to_jump;
+                     }
+                     while (bytes_to_copy <= row_width);
-               else
-                  m >>= 1;
+                     /* End of row - 1 byte left, bytes_to_copy > row_width: */
+                     dp = (png_bytep)dp16;
+                     sp = (png_const_bytep)sp16;
+                     do
+                        *dp++ = *sp++;
+                     while (--row_width > 0);
+                     return;
             }
-            break;
          }
+#endif /* PNG_ALIGN_ code */
+               /* The true default - use a memcpy: */
+               for (;;)
+               {
+                  memcpy(dp, sp, bytes_to_copy);
+                  if (row_width <= bytes_to_jump)
+                     return;
+                  sp += bytes_to_jump;
+                  dp += bytes_to_jump;
+                  row_width -= bytes_to_jump;
+                  if (bytes_to_copy > row_width)
+                     bytes_to_copy = row_width;
       }
    }
+         /* NOT REACHED*/
+      } /* pixel_depth >= 8 */
+      /* Here if pixel_depth < 8 to check 'end_ptr' below. */
 }
+   else
+#endif
+   /* If here then the switch above wasn't used so just memcpy the whole row
+    * from the temporary row buffer (notice that this overwrites the end of the
+    * destination row if it is a partial byte.)
+    */
+   memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
+   /* Restore the overwritten bits from the last byte if necessary. */
+   if (end_ptr != NULL)
+      *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
+}
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 void /* PRIVATE */
-png_do_read_interlace(png_structp png_ptr)
+png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
+   png_uint_32 transformations /* Because these may affect the byte layout */)
 {
-   png_row_infop row_info = &(png_ptr->row_info);
-   png_bytep row = png_ptr->row_buf + 1;
-   int pass = png_ptr->pass;
-   png_uint_32 transformations = png_ptr->transformations;
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
    /* Offset to next interlace block */
-   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
    png_debug(1, "in png_do_read_interlace");
    if (row != NULL && row_info != NULL)
 ,8 → 3527,9
                v = (png_byte)((*sp >> sshift) & 0x01);
                for (j = 0; j < jstop; j++)
                {
-                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
+                  unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
+                  tmp |= v << dshift;
+                  *dp = (png_byte)(tmp & 0xff);
                   if (dshift == s_end)
                   {
 ,8 → 3590,9
                v = (png_byte)((*sp >> sshift) & 0x03);
                for (j = 0; j < jstop; j++)
                {
-                  *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
+                  unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
+                  tmp |= v << dshift;
+                  *dp = (png_byte)(tmp & 0xff);
                   if (dshift == s_end)
                   {
 ,13 → 3647,14
             for (i = 0; i < row_info->width; i++)
             {
-               png_byte v = (png_byte)((*sp >> sshift) & 0xf);
+               png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
                int j;
                for (j = 0; j < jstop; j++)
                {
-                  *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
+                  unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
+                  tmp |= v << dshift;
+                  *dp = (png_byte)(tmp & 0xff);
                   if (dshift == s_end)
                   {
 ,6 → 3677,7
             }
             break;
          }
          default:
          {
             png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
 ,14 → 3692,14
             for (i = 0; i < row_info->width; i++)
             {
-               png_byte v[8];
+               png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
                int j;
-               png_memcpy(v, sp, pixel_bytes);
+               memcpy(v, sp, pixel_bytes);
                for (j = 0; j < jstop; j++)
                {
-                  png_memcpy(dp, v, pixel_bytes);
+                  memcpy(dp, v, pixel_bytes);
                   dp -= pixel_bytes;
                }
 ,6 → 3708,7
             break;
          }
       }
       row_info->width = final_width;
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
 ,33 → 3718,27
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
-void /* PRIVATE */
-png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
-    png_const_bytep prev_row, int filter)
+static void
+png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
 {
-   png_debug(1, "in png_read_filter_row");
-   png_debug2(2, "row = %u, filter = %d", png_ptr->row_number, filter);
-   switch (filter)
-   {
-      case PNG_FILTER_VALUE_NONE:
-         break;
-      case PNG_FILTER_VALUE_SUB:
-      {
          png_size_t i;
          png_size_t istop = row_info->rowbytes;
          unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
          png_bytep rp = row + bpp;
-         png_bytep lp = row;
+   PNG_UNUSED(prev_row)
          for (i = bpp; i < istop; i++)
          {
-            *rp = (png_byte)(((int)(*rp) + (int)(*lp++)) & 0xff);
+      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
             rp++;
          }
-         break;
       }
-      case PNG_FILTER_VALUE_UP:
+static void
+png_read_filter_row_up(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
       {
          png_size_t i;
          png_size_t istop = row_info->rowbytes;
 ,14 → 3750,15
             *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
             rp++;
          }
-         break;
       }
-      case PNG_FILTER_VALUE_AVG:
+static void
+png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
       {
          png_size_t i;
          png_bytep rp = row;
          png_const_bytep pp = prev_row;
-         png_bytep lp = row;
          unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
          png_size_t istop = row_info->rowbytes - bpp;
 ,35 → 3773,86
          for (i = 0; i < istop; i++)
          {
             *rp = (png_byte)(((int)(*rp) +
-                (int)(*pp++ + *lp++) / 2 ) & 0xff);
+         (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
             rp++;
          }
-         break;
       }
-      case PNG_FILTER_VALUE_PAETH:
+static void
+png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
       {
-         png_size_t i;
-         png_bytep rp = row;
-         png_const_bytep pp = prev_row;
-         png_bytep lp = row;
-         png_const_bytep cp = prev_row;
-         unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
-         png_size_t istop=row_info->rowbytes - bpp;
+   png_bytep rp_end = row + row_info->rowbytes;
+   int a, c;
-         for (i = 0; i < bpp; i++)
+   /* First pixel/byte */
+   c = *prev_row++;
+   a = *row + c;
+   *row++ = (png_byte)a;
+   /* Remainder */
+   while (row < rp_end)
          {
-            *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
-            rp++;
+      int b, pa, pb, pc, p;
+      a &= 0xff; /* From previous iteration or start */
+      b = *prev_row++;
+      p = b - c;
+      pc = a - c;
+#     ifdef PNG_USE_ABS
+         pa = abs(p);
+         pb = abs(pc);
+         pc = abs(p + pc);
+#     else
+         pa = p < 0 ? -p : p;
+         pb = pc < 0 ? -pc : pc;
+         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#     endif
+      /* Find the best predictor, the least of pa, pb, pc favoring the earlier
+       * ones in the case of a tie.
+       */
+      if (pb < pa) pa = pb, a = b;
+      if (pc < pa) a = c;
+      /* Calculate the current pixel in a, and move the previous row pixel to c
+       * for the next time round the loop
+       */
+      c = b;
+      a += *row;
+      *row++ = (png_byte)a;
          }
+}
-         for (i = 0; i < istop; i++)   /* Use leftover rp,pp */
+static void
+png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row)
          {
+   int bpp = (row_info->pixel_depth + 7) >> 3;
+   png_bytep rp_end = row + bpp;
+   /* Process the first pixel in the row completely (this is the same as 'up'
+    * because there is only one candidate predictor for the first row).
+    */
+   while (row < rp_end)
+   {
+      int a = *row + *prev_row++;
+      *row++ = (png_byte)a;
+   }
+   /* Remainder */
+   rp_end += row_info->rowbytes - bpp;
+   while (row < rp_end)
+   {
             int a, b, c, pa, pb, pc, p;
-            a = *lp++;
-            b = *pp++;
-            c = *cp++;
+      c = *(prev_row - bpp);
+      a = *(row - bpp);
+      b = *prev_row++;
             p = b - c;
             pc = a - c;
 ,49 → 3867,264
             pc = (p + pc) < 0 ? -(p + pc) : p + pc;
 #endif
-            /*
-               if (pa <= pb && pa <= pc)
-                  p = a;
+      if (pb < pa) pa = pb, a = b;
+      if (pc < pa) a = c;
-               else if (pb <= pc)
-                  p = b;
+      c = b;
+      a += *row;
+      *row++ = (png_byte)a;
+   }
+}
+static void
+png_init_filter_functions(png_structrp pp)
+   /* This function is called once for every PNG image (except for PNG images
+    * that only use PNG_FILTER_VALUE_NONE for all rows) to set the
+    * implementations required to reverse the filtering of PNG rows.  Reversing
+    * the filter is the first transformation performed on the row data.  It is
+    * performed in place, therefore an implementation can be selected based on
+    * the image pixel format.  If the implementation depends on image width then
+    * take care to ensure that it works correctly if the image is interlaced -
+    * interlacing causes the actual row width to vary.
+    */
+{
+   unsigned int bpp = (pp->pixel_depth + 7) >> 3;
+   pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
+   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
+   pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
+   if (bpp == 1)
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+         png_read_filter_row_paeth_1byte_pixel;
                else
-                  p = c;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+         png_read_filter_row_paeth_multibyte_pixel;
+#ifdef PNG_FILTER_OPTIMIZATIONS
+   /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
+    * call to install hardware optimizations for the above functions; simply
+    * replace whatever elements of the pp->read_filter[] array with a hardware
+    * specific (or, for that matter, generic) optimization.
+    *
+    * To see an example of this examine what configure.ac does when
+    * --enable-arm-neon is specified on the command line.
              */
+   PNG_FILTER_OPTIMIZATIONS(pp, bpp);
+#endif
+}
-            p = (pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c;
+void /* PRIVATE */
+png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
+   png_const_bytep prev_row, int filter)
+{
+   /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
+    * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
+    * implementations.  See png_init_filter_functions above.
+    */
+   if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
+   {
+      if (pp->read_filter[0] == NULL)
+         png_init_filter_functions(pp);
-            *rp = (png_byte)(((int)(*rp) + p) & 0xff);
-            rp++;
+      pp->read_filter[filter-1](row_info, row, prev_row);
          }
-         break;
       }
-      default:
-         png_error(png_ptr, "Ignoring bad adaptive filter type");
-         /*NOT REACHED */
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+void /* PRIVATE */
+png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
+   png_alloc_size_t avail_out)
+{
+   /* Loop reading IDATs and decompressing the result into output[avail_out] */
+   png_ptr->zstream.next_out = output;
+   png_ptr->zstream.avail_out = 0; /* safety: set below */
+   if (output == NULL)
+      avail_out = 0;
+   do
+   {
+      int ret;
+      png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
+      if (png_ptr->zstream.avail_in == 0)
+      {
+         uInt avail_in;
+         png_bytep buffer;
+         while (png_ptr->idat_size == 0)
+         {
+            png_crc_finish(png_ptr, 0);
+            png_ptr->idat_size = png_read_chunk_header(png_ptr);
+            /* This is an error even in the 'check' case because the code just
+             * consumed a non-IDAT header.
+             */
+            if (png_ptr->chunk_name != png_IDAT)
+               png_error(png_ptr, "Not enough image data");
+         }
+         avail_in = png_ptr->IDAT_read_size;
+         if (avail_in > png_ptr->idat_size)
+            avail_in = (uInt)png_ptr->idat_size;
+         /* A PNG with a gradually increasing IDAT size will defeat this attempt
+          * to minimize memory usage by causing lots of re-allocs, but
+          * realistically doing IDAT_read_size re-allocs is not likely to be a
+          * big problem.
+          */
+         buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
+         png_crc_read(png_ptr, buffer, avail_in);
+         png_ptr->idat_size -= avail_in;
+         png_ptr->zstream.next_in = buffer;
+         png_ptr->zstream.avail_in = avail_in;
+      }
+      /* And set up the output side. */
+      if (output != NULL) /* standard read */
+      {
+         uInt out = ZLIB_IO_MAX;
+         if (out > avail_out)
+            out = (uInt)avail_out;
+         avail_out -= out;
+         png_ptr->zstream.avail_out = out;
+      }
+      else /* after last row, checking for end */
+      {
+         png_ptr->zstream.next_out = tmpbuf;
+         png_ptr->zstream.avail_out = (sizeof tmpbuf);
+      }
+      /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
+       * process.  If the LZ stream is truncated the sequential reader will
+       * terminally damage the stream, above, by reading the chunk header of the
+       * following chunk (it then exits with png_error).
+       *
+       * TODO: deal more elegantly with truncated IDAT lists.
+       */
+      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+      /* Take the unconsumed output back. */
+      if (output != NULL)
+         avail_out += png_ptr->zstream.avail_out;
+      else /* avail_out counts the extra bytes */
+         avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
+      png_ptr->zstream.avail_out = 0;
+      if (ret == Z_STREAM_END)
+      {
+         /* Do this for safety; we won't read any more into this row. */
+         png_ptr->zstream.next_out = NULL;
+         png_ptr->mode |= PNG_AFTER_IDAT;
+         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+         if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
+            png_chunk_benign_error(png_ptr, "Extra compressed data");
          break;
    }
+      if (ret != Z_OK)
+      {
+         png_zstream_error(png_ptr, ret);
+         if (output != NULL)
+            png_chunk_error(png_ptr, png_ptr->zstream.msg);
+         else /* checking */
+         {
+            png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
+            return;
 }
+      }
+   } while (avail_out > 0);
-#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+   if (avail_out > 0)
+   {
+      /* The stream ended before the image; this is the same as too few IDATs so
+       * should be handled the same way.
+       */
+      if (output != NULL)
+         png_error(png_ptr, "Not enough image data");
+      else /* the deflate stream contained extra data */
+         png_chunk_benign_error(png_ptr, "Too much image data");
+   }
+}
 void /* PRIVATE */
-png_read_finish_row(png_structp png_ptr)
+png_read_finish_IDAT(png_structrp png_ptr)
 {
+   /* We don't need any more data and the stream should have ended, however the
+    * LZ end code may actually not have been processed.  In this case we must
+    * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
+    * may still remain to be consumed.
+    */
+   if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+   {
+      /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
+       * the compressed stream, but the stream may be damaged too, so even after
+       * this call we may need to terminate the zstream ownership.
+       */
+      png_read_IDAT_data(png_ptr, NULL, 0);
+      png_ptr->zstream.next_out = NULL; /* safety */
+      /* Now clear everything out for safety; the following may not have been
+       * done.
+       */
+      if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+      {
+         png_ptr->mode |= PNG_AFTER_IDAT;
+         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+      }
+   }
+   /* If the zstream has not been released do it now *and* terminate the reading
+    * of the final IDAT chunk.
+    */
+   if (png_ptr->zowner == png_IDAT)
+   {
+      /* Always do this; the pointers otherwise point into the read buffer. */
+      png_ptr->zstream.next_in = NULL;
+      png_ptr->zstream.avail_in = 0;
+      /* Now we no longer own the zstream. */
+      png_ptr->zowner = 0;
+      /* The slightly weird semantics of the sequential IDAT reading is that we
+       * are always in or at the end of an IDAT chunk, so we always need to do a
+       * crc_finish here.  If idat_size is non-zero we also need to read the
+       * spurious bytes at the end of the chunk now.
+       */
+      (void)png_crc_finish(png_ptr, png_ptr->idat_size);
+   }
+}
+void /* PRIVATE */
+png_read_finish_row(png_structrp png_ptr)
+{
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
    /* Start of interlace block */
-   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
    /* Offset to next interlace block */
-   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
    /* Start of interlace block in the y direction */
-   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
    /* Offset to next interlace block in the y direction */
-   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
    png_debug(1, "in png_read_finish_row");
 ,7 → 4137,10
    {
       png_ptr->row_number = 0;
-      png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+      /* TO DO: don't do this if prev_row isn't needed (requires
+       * read-ahead of the next row's filter byte.
+       */
+      memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
       do
       {
 ,92 → 4172,28
    }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
-   {
-      PNG_IDAT;
-      char extra;
-      int ret;
-      png_ptr->zstream.next_out = (Byte *)&extra;
-      png_ptr->zstream.avail_out = (uInt)1;
-      for (;;)
-      {
-         if (!(png_ptr->zstream.avail_in))
-         {
-            while (!png_ptr->idat_size)
-            {
-               png_crc_finish(png_ptr, 0);
-               png_ptr->idat_size = png_read_chunk_header(png_ptr);
-               if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
-                  png_error(png_ptr, "Not enough image data");
+   /* Here after at the end of the last row of the last pass. */
+   png_read_finish_IDAT(png_ptr);
             }
-            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
-            png_ptr->zstream.next_in = png_ptr->zbuf;
-            if (png_ptr->zbuf_size > png_ptr->idat_size)
-               png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
-            png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);
-            png_ptr->idat_size -= png_ptr->zstream.avail_in;
-         }
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-         if (ret == Z_STREAM_END)
-         {
-            if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||
-                png_ptr->idat_size)
-               png_warning(png_ptr, "Extra compressed data");
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-         if (ret != Z_OK)
-            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
-                "Decompression Error");
-         if (!(png_ptr->zstream.avail_out))
-         {
-            png_warning(png_ptr, "Extra compressed data");
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-      }
-      png_ptr->zstream.avail_out = 0;
-   }
-   if (png_ptr->idat_size || png_ptr->zstream.avail_in)
-      png_warning(png_ptr, "Extra compression data");
-   inflateReset(&png_ptr->zstream);
-   png_ptr->mode |= PNG_AFTER_IDAT;
-}
 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 void /* PRIVATE */
-png_read_start_row(png_structp png_ptr)
+png_read_start_row(png_structrp png_ptr)
 {
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
    /* Start of interlace block */
-   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
    /* Offset to next interlace block */
-   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
    /* Start of interlace block in the y direction */
-   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
    /* Offset to next interlace block in the y direction */
-   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
    int max_pixel_depth;
 ,8 → 4200,10
    png_size_t row_bytes;
    png_debug(1, "in png_read_start_row");
-   png_ptr->zstream.avail_in = 0;
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
    png_init_read_transformations(png_ptr);
+#endif
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
 ,6 → 4229,16
    max_pixel_depth = png_ptr->pixel_depth;
+   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
+    * calculations to calculate the final pixel depth, then
+    * png_do_read_transforms actually does the transforms.  This means that the
+    * code which effectively calculates this value is actually repeated in three
+    * separate places.  They must all match.  Innocent changes to the order of
+    * transformations can and will break libpng in a way that causes memory
+    * overwrites.
+    *
+    * TODO: fix this.
+    */
 #ifdef PNG_READ_PACK_SUPPORTED
    if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
       max_pixel_depth = 8;
 ,13 → 4276,28
    }
 #endif
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+   if (png_ptr->transformations & PNG_EXPAND_16)
+   {
+#     ifdef PNG_READ_EXPAND_SUPPORTED
+         /* In fact it is an error if it isn't supported, but checking is
+          * the safe way.
+          */
+         if (png_ptr->transformations & PNG_EXPAND)
+         {
+            if (png_ptr->bit_depth < 16)
+               max_pixel_depth *= 2;
+         }
+         else
+#     endif
+         png_ptr->transformations &= ~PNG_EXPAND_16;
+   }
+#endif
 #ifdef PNG_READ_FILLER_SUPPORTED
    if (png_ptr->transformations & (PNG_FILLER))
    {
-      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-         max_pixel_depth = 32;
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+      if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
       {
          if (max_pixel_depth <= 8)
             max_pixel_depth = 16;
 ,7 → 4306,8
             max_pixel_depth = 32;
       }
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
+         png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
          if (max_pixel_depth <= 32)
             max_pixel_depth = 32;
 ,6 → 4369,12
    }
 #endif
+   /* This value is stored in png_struct and double checked in the row read
+    * code.
+    */
+   png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
+   png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
    /* Align the width on the next larger 8 pixels.  Mainly used
     * for interlacing
     */
 ,6 → 4393,7
    if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
    {
      png_free(png_ptr, png_ptr->big_row_buf);
+     png_free(png_ptr, png_ptr->big_prev_row);
      if (png_ptr->interlaced)
         png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
 ,22 → 4400,32
             row_bytes + 48);
      else
-        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr,
-            row_bytes + 48);
+        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
-     png_ptr->old_big_row_buf_size = row_bytes + 48;
+     png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
 #ifdef PNG_ALIGNED_MEMORY_SUPPORTED
      /* Use 16-byte aligned memory for row_buf with at least 16 bytes
-      * of padding before and after row_buf.
+      * of padding before and after row_buf; treat prev_row similarly.
+      * NOTE: the alignment is to the start of the pixels, one beyond the start
+      * of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this
+      * was incorrect; the filter byte was aligned, which had the exact
+      * opposite effect of that intended.
       */
-     png_ptr->row_buf = png_ptr->big_row_buf + 32 -
-         (((png_alloc_size_t)png_ptr->big_row_buf + 15) & 0x0F);
+     {
+        png_bytep temp = png_ptr->big_row_buf + 32;
+        int extra = (int)((temp - (png_bytep)0) & 0x0f);
+        png_ptr->row_buf = temp - extra - 1/*filter byte*/;
-     png_ptr->old_big_row_buf_size = row_bytes + 48;
+        temp = png_ptr->big_prev_row + 32;
+        extra = (int)((temp - (png_bytep)0) & 0x0f);
+        png_ptr->prev_row = temp - extra - 1/*filter byte*/;
+     }
 #else
-     /* Use 32 bytes of padding before and 16 bytes after row_buf. */
-     png_ptr->row_buf = png_ptr->big_row_buf + 32;
+     /* Use 31 bytes of padding before and 17 bytes after row_buf. */
+     png_ptr->row_buf = png_ptr->big_row_buf + 31;
+     png_ptr->prev_row = png_ptr->big_prev_row + 31;
 #endif
      png_ptr->old_big_row_buf_size = row_bytes + 48;
    }
 ,17 → 4438,8
    if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
       png_error(png_ptr, "Row has too many bytes to allocate in memory");
-   if (png_ptr->rowbytes + 1 > png_ptr->old_prev_row_size)
-   {
-      png_free(png_ptr, png_ptr->prev_row);
+   memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
-      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
-      png_ptr->old_prev_row_size = png_ptr->rowbytes + 1;
-   }
-   png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
    png_debug1(3, "width = %u,", png_ptr->width);
    png_debug1(3, "height = %u,", png_ptr->height);
    png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
 ,6 → 4448,27
    png_debug1(3, "irowbytes = %lu",
        (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
+   /* The sequential reader needs a buffer for IDAT, but the progressive reader
+    * does not, so free the read buffer now regardless; the sequential reader
+    * reallocates it on demand.
+    */
+   if (png_ptr->read_buffer)
+   {
+      png_bytep buffer = png_ptr->read_buffer;
+      png_ptr->read_buffer_size = 0;
+      png_ptr->read_buffer = NULL;
+      png_free(png_ptr, buffer);
+   }
+   /* Finally claim the zstream for the inflate of the IDAT data, use the bits
+    * value from the stream (note that this will result in a fatal error if the
+    * IDAT stream has a bogus deflate header window_bits value, but this should
+    * not be happening any longer!)
+    */
+   if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
+      png_error(png_ptr, png_ptr->zstream.msg);
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
 #endif /* PNG_READ_SUPPORTED */

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Regard whitespace Rev 1897 → Rev 3928