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/*

 * wrjpgcom.c

 *

 * Copyright (C) 1994-1997, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains a very simple stand-alone application that inserts

 * user-supplied text as a COM (comment) marker in a JFIF file.

 * This may be useful as an example of the minimum logic needed to parse

 * JPEG markers.

 */

#define JPEG_CJPEG_DJPEG	/* to get the command-line config symbols */

#include "jinclude.h"		/* get auto-config symbols,  */

#ifndef HAVE_STDLIB_H		/*  should declare malloc() */

extern void * malloc ();

#endif

#include 		/* to declare isupper(), tolower() */

#ifdef USE_SETMODE

#include 		/* to declare setmode()'s parameter macros */

/* If you have setmode() but not , just delete this line: */

#include 			/* to declare setmode() */

#endif

#ifdef USE_CCOMMAND		/* command-line reader for Macintosh */

#ifdef __MWERKS__

#include               /* Metrowerks needs this */

#include 		/* ... and this */

#endif

#ifdef THINK_C

#include 		/* Think declares it here */

#endif

#endif

#ifdef DONT_USE_B_MODE		/* define mode parameters for fopen() */

#define READ_BINARY	"r"

#define WRITE_BINARY	"w"

#else

#ifdef VMS			/* VMS is very nonstandard */

#define READ_BINARY	"rb", "ctx=stm"

#define WRITE_BINARY	"wb", "ctx=stm"

#else				/* standard ANSI-compliant case */

#define READ_BINARY	"rb"

#define WRITE_BINARY	"wb"

#endif

#endif

#ifndef EXIT_FAILURE		/* define exit() codes if not provided */

#define EXIT_FAILURE  1

#endif

#ifndef EXIT_SUCCESS

#ifdef VMS

#define EXIT_SUCCESS  1		/* VMS is very nonstandard */

#else

#define EXIT_SUCCESS  0

#endif

#endif

/* Reduce this value if your malloc() can't allocate blocks up to 64K.

 * On DOS, compiling in large model is usually a better solution.

 */

#ifndef MAX_COM_LENGTH

#define MAX_COM_LENGTH 65000L	/* must be <= 65533 in any case */

#endif

/*

 * These macros are used to read the input file and write the output file.

 * To reuse this code in another application, you might need to change these.

 */

static FILE * infile;		/* input JPEG file */

/* Return next input byte, or EOF if no more */

#define NEXTBYTE()  getc(infile)

static FILE * outfile;		/* output JPEG file */

/* Emit an output byte */

#define PUTBYTE(x)  putc((x), outfile)

/* Error exit handler */

#define ERREXIT(msg)  (fprintf(stderr, "%s\n", msg), exit(EXIT_FAILURE))

/* Read one byte, testing for EOF */

static int

read_1_byte (void)

{

  int c;

  c = NEXTBYTE();

  if (c == EOF)

    ERREXIT("Premature EOF in JPEG file");

  return c;

}

/* Read 2 bytes, convert to unsigned int */

/* All 2-byte quantities in JPEG markers are MSB first */

static unsigned int

read_2_bytes (void)

{

  int c1, c2;

  c1 = NEXTBYTE();

  if (c1 == EOF)

    ERREXIT("Premature EOF in JPEG file");

  c2 = NEXTBYTE();

  if (c2 == EOF)

    ERREXIT("Premature EOF in JPEG file");

  return (((unsigned int) c1) << 8) + ((unsigned int) c2);

}

/* Routines to write data to output file */

static void

write_1_byte (int c)

{

  PUTBYTE(c);

}

static void

write_2_bytes (unsigned int val)

{

  PUTBYTE((val >> 8) & 0xFF);

  PUTBYTE(val & 0xFF);

}

static void

write_marker (int marker)

{

  PUTBYTE(0xFF);

  PUTBYTE(marker);

}

static void

copy_rest_of_file (void)

{

  int c;

  while ((c = NEXTBYTE()) != EOF)

    PUTBYTE(c);

}

/*

 * JPEG markers consist of one or more 0xFF bytes, followed by a marker

 * code byte (which is not an FF).  Here are the marker codes of interest

 * in this program.  (See jdmarker.c for a more complete list.)

 */

#define M_SOF0  0xC0		/* Start Of Frame N */

#define M_SOF1  0xC1		/* N indicates which compression process */

#define M_SOF2  0xC2		/* Only SOF0-SOF2 are now in common use */

#define M_SOF3  0xC3

#define M_SOF5  0xC5		/* NB: codes C4 and CC are NOT SOF markers */

#define M_SOF6  0xC6

#define M_SOF7  0xC7

#define M_SOF9  0xC9

#define M_SOF10 0xCA

#define M_SOF11 0xCB

#define M_SOF13 0xCD

#define M_SOF14 0xCE

#define M_SOF15 0xCF

#define M_SOI   0xD8		/* Start Of Image (beginning of datastream) */

#define M_EOI   0xD9		/* End Of Image (end of datastream) */

#define M_SOS   0xDA		/* Start Of Scan (begins compressed data) */

#define M_COM   0xFE		/* COMment */

/*

 * Find the next JPEG marker and return its marker code.

 * We expect at least one FF byte, possibly more if the compressor used FFs

 * to pad the file.  (Padding FFs will NOT be replicated in the output file.)

 * There could also be non-FF garbage between markers.  The treatment of such

 * garbage is unspecified; we choose to skip over it but emit a warning msg.

 * NB: this routine must not be used after seeing SOS marker, since it will

 * not deal correctly with FF/00 sequences in the compressed image data...

 */

static int

next_marker (void)

{

  int c;

  int discarded_bytes = 0;

  /* Find 0xFF byte; count and skip any non-FFs. */

  c = read_1_byte();

  while (c != 0xFF) {

    discarded_bytes++;

    c = read_1_byte();

  }

  /* Get marker code byte, swallowing any duplicate FF bytes.  Extra FFs

   * are legal as pad bytes, so don't count them in discarded_bytes.

   */

  do {

    c = read_1_byte();

  } while (c == 0xFF);

  if (discarded_bytes != 0) {

    fprintf(stderr, "Warning: garbage data found in JPEG file\n");

  }

  return c;

}

/*

 * Read the initial marker, which should be SOI.

 * For a JFIF file, the first two bytes of the file should be literally

 * 0xFF M_SOI.  To be more general, we could use next_marker, but if the

 * input file weren't actually JPEG at all, next_marker might read the whole

 * file and then return a misleading error message...

 */

static int

first_marker (void)

{

  int c1, c2;

  c1 = NEXTBYTE();

  c2 = NEXTBYTE();

  if (c1 != 0xFF || c2 != M_SOI)

    ERREXIT("Not a JPEG file");

  return c2;

}

/*

 * Most types of marker are followed by a variable-length parameter segment.

 * This routine skips over the parameters for any marker we don't otherwise

 * want to process.

 * Note that we MUST skip the parameter segment explicitly in order not to

 * be fooled by 0xFF bytes that might appear within the parameter segment;

 * such bytes do NOT introduce new markers.

 */

static void

copy_variable (void)

/* Copy an unknown or uninteresting variable-length marker */

{

  unsigned int length;

  /* Get the marker parameter length count */

  length = read_2_bytes();

  write_2_bytes(length);

  /* Length includes itself, so must be at least 2 */

  if (length < 2)

    ERREXIT("Erroneous JPEG marker length");

  length -= 2;

  /* Skip over the remaining bytes */

  while (length > 0) {

    write_1_byte(read_1_byte());

    length--;

  }

}

static void

skip_variable (void)

/* Skip over an unknown or uninteresting variable-length marker */

{

  unsigned int length;

  /* Get the marker parameter length count */

  length = read_2_bytes();

  /* Length includes itself, so must be at least 2 */

  if (length < 2)

    ERREXIT("Erroneous JPEG marker length");

  length -= 2;

  /* Skip over the remaining bytes */

  while (length > 0) {

    (void) read_1_byte();

    length--;

  }

}

/*

 * Parse the marker stream until SOFn or EOI is seen;

 * copy data to output, but discard COM markers unless keep_COM is true.

 */

static int

scan_JPEG_header (int keep_COM)

{

  int marker;

  /* Expect SOI at start of file */

  if (first_marker() != M_SOI)

    ERREXIT("Expected SOI marker first");

  write_marker(M_SOI);

  /* Scan miscellaneous markers until we reach SOFn. */

  for (;;) {

    marker = next_marker();

    switch (marker) {

      /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,

       * treated as SOFn.  C4 in particular is actually DHT.

       */

    case M_SOF0:		/* Baseline */

    case M_SOF1:		/* Extended sequential, Huffman */

    case M_SOF2:		/* Progressive, Huffman */

    case M_SOF3:		/* Lossless, Huffman */

    case M_SOF5:		/* Differential sequential, Huffman */

    case M_SOF6:		/* Differential progressive, Huffman */

    case M_SOF7:		/* Differential lossless, Huffman */

    case M_SOF9:		/* Extended sequential, arithmetic */

    case M_SOF10:		/* Progressive, arithmetic */

    case M_SOF11:		/* Lossless, arithmetic */

    case M_SOF13:		/* Differential sequential, arithmetic */

    case M_SOF14:		/* Differential progressive, arithmetic */

    case M_SOF15:		/* Differential lossless, arithmetic */

      return marker;

    case M_SOS:			/* should not see compressed data before SOF */

      ERREXIT("SOS without prior SOFn");

      break;

    case M_EOI:			/* in case it's a tables-only JPEG stream */

      return marker;

    case M_COM:			/* Existing COM: conditionally discard */

      if (keep_COM) {

	write_marker(marker);

	copy_variable();

      } else {

	skip_variable();

      }

      break;

    default:			/* Anything else just gets copied */

      write_marker(marker);

      copy_variable();		/* we assume it has a parameter count... */

      break;

    }

  } /* end loop */

}

/* Command line parsing code */

static const char * progname;	/* program name for error messages */

static void

usage (void)

/* complain about bad command line */

{

  fprintf(stderr, "wrjpgcom inserts a textual comment in a JPEG file.\n");

  fprintf(stderr, "You can add to or replace any existing comment(s).\n");

  fprintf(stderr, "Usage: %s [switches] ", progname);

#ifdef TWO_FILE_COMMANDLINE

  fprintf(stderr, "inputfile outputfile\n");

#else

  fprintf(stderr, "[inputfile]\n");

#endif

  fprintf(stderr, "Switches (names may be abbreviated):\n");

  fprintf(stderr, "  -replace         Delete any existing comments\n");

  fprintf(stderr, "  -comment \"text\"  Insert comment with given text\n");

  fprintf(stderr, "  -cfile name      Read comment from named file\n");

  fprintf(stderr, "Notice that you must put quotes around the comment text\n");

  fprintf(stderr, "when you use -comment.\n");

  fprintf(stderr, "If you do not give either -comment or -cfile on the command line,\n");

  fprintf(stderr, "then the comment text is read from standard input.\n");

  fprintf(stderr, "It can be multiple lines, up to %u characters total.\n",

	  (unsigned int) MAX_COM_LENGTH);

#ifndef TWO_FILE_COMMANDLINE

  fprintf(stderr, "You must specify an input JPEG file name when supplying\n");

  fprintf(stderr, "comment text from standard input.\n");

#endif

  exit(EXIT_FAILURE);

}

static int

keymatch (char * arg, const char * keyword, int minchars)

/* Case-insensitive matching of (possibly abbreviated) keyword switches. */

/* keyword is the constant keyword (must be lower case already), */

/* minchars is length of minimum legal abbreviation. */

{

  register int ca, ck;

  register int nmatched = 0;

  while ((ca = *arg++) != '\0') {

    if ((ck = *keyword++) == '\0')

      return 0;			/* arg longer than keyword, no good */

    if (isupper(ca))		/* force arg to lcase (assume ck is already) */

      ca = tolower(ca);

    if (ca != ck)

      return 0;			/* no good */

    nmatched++;			/* count matched characters */

  }

  /* reached end of argument; fail if it's too short for unique abbrev */

  if (nmatched < minchars)

    return 0;

  return 1;			/* A-OK */

}

/*

 * The main program.

 */

int

main (int argc, char **argv)

{

  int argn;

  char * arg;

  int keep_COM = 1;

  char * comment_arg = NULL;

  FILE * comment_file = NULL;

  unsigned int comment_length = 0;

  int marker;

  /* On Mac, fetch a command line. */

#ifdef USE_CCOMMAND

  argc = ccommand(&argv);

#endif

  progname = argv[0];

  if (progname == NULL || progname[0] == 0)

    progname = "wrjpgcom";	/* in case C library doesn't provide it */

  /* Parse switches, if any */

  for (argn = 1; argn < argc; argn++) {

    arg = argv[argn];

    if (arg[0] != '-')

      break;			/* not switch, must be file name */

    arg++;			/* advance over '-' */

    if (keymatch(arg, "replace", 1)) {

      keep_COM = 0;

    } else if (keymatch(arg, "cfile", 2)) {

      if (++argn >= argc) usage();

      if ((comment_file = fopen(argv[argn], "r")) == NULL) {

	fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);

	exit(EXIT_FAILURE);

      }

    } else if (keymatch(arg, "comment", 1)) {

      if (++argn >= argc) usage();

      comment_arg = argv[argn];

      /* If the comment text starts with '"', then we are probably running

       * under MS-DOG and must parse out the quoted string ourselves.  Sigh.

       */

      if (comment_arg[0] == '"') {

	comment_arg = (char *) malloc((size_t) MAX_COM_LENGTH);

	if (comment_arg == NULL)

	  ERREXIT("Insufficient memory");

	strcpy(comment_arg, argv[argn]+1);

	for (;;) {

	  comment_length = (unsigned int) strlen(comment_arg);

	  if (comment_length > 0 && comment_arg[comment_length-1] == '"') {

	    comment_arg[comment_length-1] = '\0'; /* zap terminating quote */

	    break;

	  }

	  if (++argn >= argc)

	    ERREXIT("Missing ending quote mark");

	  strcat(comment_arg, " ");

	  strcat(comment_arg, argv[argn]);

	}

      }

      comment_length = (unsigned int) strlen(comment_arg);

    } else

      usage();

  }

  /* Cannot use both -comment and -cfile. */

  if (comment_arg != NULL && comment_file != NULL)

    usage();

  /* If there is neither -comment nor -cfile, we will read the comment text

   * from stdin; in this case there MUST be an input JPEG file name.

   */

  if (comment_arg == NULL && comment_file == NULL && argn >= argc)

    usage();

  /* Open the input file. */

  if (argn < argc) {

    if ((infile = fopen(argv[argn], READ_BINARY)) == NULL) {

      fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);

      exit(EXIT_FAILURE);

    }

  } else {

    /* default input file is stdin */

#ifdef USE_SETMODE		/* need to hack file mode? */

    setmode(fileno(stdin), O_BINARY);

#endif

#ifdef USE_FDOPEN		/* need to re-open in binary mode? */

    if ((infile = fdopen(fileno(stdin), READ_BINARY)) == NULL) {

      fprintf(stderr, "%s: can't open stdin\n", progname);

      exit(EXIT_FAILURE);

    }

#else

    infile = stdin;

#endif

  }

  /* Open the output file. */

#ifdef TWO_FILE_COMMANDLINE

  /* Must have explicit output file name */

  if (argn != argc-2) {

    fprintf(stderr, "%s: must name one input and one output file\n",

	    progname);

    usage();

  }

  if ((outfile = fopen(argv[argn+1], WRITE_BINARY)) == NULL) {

    fprintf(stderr, "%s: can't open %s\n", progname, argv[argn+1]);

    exit(EXIT_FAILURE);

  }

#else

  /* Unix style: expect zero or one file name */

  if (argn < argc-1) {

    fprintf(stderr, "%s: only one input file\n", progname);

    usage();

  }

  /* default output file is stdout */

#ifdef USE_SETMODE		/* need to hack file mode? */

  setmode(fileno(stdout), O_BINARY);

#endif

#ifdef USE_FDOPEN		/* need to re-open in binary mode? */

  if ((outfile = fdopen(fileno(stdout), WRITE_BINARY)) == NULL) {

    fprintf(stderr, "%s: can't open stdout\n", progname);

    exit(EXIT_FAILURE);

  }

#else

  outfile = stdout;

#endif

#endif /* TWO_FILE_COMMANDLINE */

  /* Collect comment text from comment_file or stdin, if necessary */

  if (comment_arg == NULL) {

    FILE * src_file;

    int c;

    comment_arg = (char *) malloc((size_t) MAX_COM_LENGTH);

    if (comment_arg == NULL)

      ERREXIT("Insufficient memory");

    comment_length = 0;

    src_file = (comment_file != NULL ? comment_file : stdin);

    while ((c = getc(src_file)) != EOF) {

      if (comment_length >= (unsigned int) MAX_COM_LENGTH) {

	fprintf(stderr, "Comment text may not exceed %u bytes\n",

		(unsigned int) MAX_COM_LENGTH);

	exit(EXIT_FAILURE);

      }

      comment_arg[comment_length++] = (char) c;

    }

    if (comment_file != NULL)

      fclose(comment_file);

  }

  /* Copy JPEG headers until SOFn marker;

   * we will insert the new comment marker just before SOFn.

   * This (a) causes the new comment to appear after, rather than before,

   * existing comments; and (b) ensures that comments come after any JFIF

   * or JFXX markers, as required by the JFIF specification.

   */

  marker = scan_JPEG_header(keep_COM);

  /* Insert the new COM marker, but only if nonempty text has been supplied */

  if (comment_length > 0) {

    write_marker(M_COM);

    write_2_bytes(comment_length + 2);

    while (comment_length > 0) {

      write_1_byte(*comment_arg++);

      comment_length--;

    }

  }

  /* Duplicate the remainder of the source file.

   * Note that any COM markers occuring after SOF will not be touched.

   */

  write_marker(marker);

  copy_rest_of_file();

  /* All done. */

  exit(EXIT_SUCCESS);

  return 0;			/* suppress no-return-value warnings */

}