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/* SEC_MERGE support.

   Copyright (C) 2001-2015 Free Software Foundation, Inc.

   Written by Jakub Jelinek .

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

   MA 02110-1301, USA.  */

/* This file contains support for merging duplicate entities within sections,

   as used in ELF SHF_MERGE.  */

#include "sysdep.h"

#include "bfd.h"

#include "elf-bfd.h"

#include "libbfd.h"

#include "hashtab.h"

#include "libiberty.h"

struct sec_merge_sec_info;

/* An entry in the section merge hash table.  */

struct sec_merge_hash_entry

{

  struct bfd_hash_entry root;

  /* Length of this entry.  This includes the zero terminator.  */

  unsigned int len;

  /* Start of this string needs to be aligned to

     alignment octets (not 1 << align).  */

  unsigned int alignment;

  union

  {

    /* Index within the merged section.  */

    bfd_size_type index;

    /* Entry this is a suffix of (if alignment is 0).  */

    struct sec_merge_hash_entry *suffix;

  } u;

  /* Which section is it in.  */

  struct sec_merge_sec_info *secinfo;

  /* Next entity in the hash table.  */

  struct sec_merge_hash_entry *next;

};

/* The section merge hash table.  */

struct sec_merge_hash

{

  struct bfd_hash_table table;

  /* Next available index.  */

  bfd_size_type size;

  /* First entity in the SEC_MERGE sections of this type.  */

  struct sec_merge_hash_entry *first;

  /* Last entity in the SEC_MERGE sections of this type.  */

  struct sec_merge_hash_entry *last;

  /* Entity size.  */

  unsigned int entsize;

  /* Are entries fixed size or zero terminated strings?  */

  bfd_boolean strings;

};

struct sec_merge_info

{

  /* Chain of sec_merge_infos.  */

  struct sec_merge_info *next;

  /* Chain of sec_merge_sec_infos.  */

  struct sec_merge_sec_info *chain;

  /* A hash table used to hold section content.  */

  struct sec_merge_hash *htab;

};

struct sec_merge_sec_info

{

  /* Chain of sec_merge_sec_infos.  */

  struct sec_merge_sec_info *next;

  /* The corresponding section.  */

  asection *sec;

  /* Pointer to merge_info pointing to us.  */

  void **psecinfo;

  /* A hash table used to hold section content.  */

  struct sec_merge_hash *htab;

  /* First string in this section.  */

  struct sec_merge_hash_entry *first_str;

  /* Original section content.  */

  unsigned char contents[1];

};

/* Routine to create an entry in a section merge hashtab.  */

static struct bfd_hash_entry *

sec_merge_hash_newfunc (struct bfd_hash_entry *entry,

			struct bfd_hash_table *table, const char *string)

{

  /* Allocate the structure if it has not already been allocated by a

     subclass.  */

  if (entry == NULL)

    entry = (struct bfd_hash_entry *)

        bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));

  if (entry == NULL)

    return NULL;

  /* Call the allocation method of the superclass.  */

  entry = bfd_hash_newfunc (entry, table, string);

  if (entry != NULL)

    {

      /* Initialize the local fields.  */

      struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;

      ret->u.suffix = NULL;

      ret->alignment = 0;

      ret->secinfo = NULL;

      ret->next = NULL;

    }

  return entry;

}

/* Look up an entry in a section merge hash table.  */

static struct sec_merge_hash_entry *

sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,

		       unsigned int alignment, bfd_boolean create)

{

  const unsigned char *s;

  unsigned long hash;

  unsigned int c;

  struct sec_merge_hash_entry *hashp;

  unsigned int len, i;

  unsigned int _index;

  hash = 0;

  len = 0;

  s = (const unsigned char *) string;

  if (table->strings)

    {

      if (table->entsize == 1)

	{

	  while ((c = *s++) != '\0')

	    {

	      hash += c + (c << 17);

	      hash ^= hash >> 2;

	      ++len;

	    }

	  hash += len + (len << 17);

	}

      else

	{

	  for (;;)

	    {

	      for (i = 0; i < table->entsize; ++i)

		if (s[i] != '\0')

		  break;

	      if (i == table->entsize)

		break;

	      for (i = 0; i < table->entsize; ++i)

		{

		  c = *s++;

		  hash += c + (c << 17);

		  hash ^= hash >> 2;

		}

	      ++len;

	    }

	  hash += len + (len << 17);

	  len *= table->entsize;

	}

      hash ^= hash >> 2;

      len += table->entsize;

    }

  else

    {

      for (i = 0; i < table->entsize; ++i)

	{

	  c = *s++;

	  hash += c + (c << 17);

	  hash ^= hash >> 2;

	}

      len = table->entsize;

    }

  _index = hash % table->table.size;

  for (hashp = (struct sec_merge_hash_entry *) table->table.table[_index];

       hashp != NULL;

       hashp = (struct sec_merge_hash_entry *) hashp->root.next)

    {

      if (hashp->root.hash == hash

	  && len == hashp->len

	  && memcmp (hashp->root.string, string, len) == 0)

	{

	  /* If the string we found does not have at least the required

	     alignment, we need to insert another copy.  */

	  if (hashp->alignment < alignment)

	    {

	      if (create)

		{

		  /*  Mark the less aligned copy as deleted.  */

		  hashp->len = 0;

		  hashp->alignment = 0;

		}

	      break;

	    }

	  return hashp;

	}

    }

  if (! create)

    return NULL;

  hashp = ((struct sec_merge_hash_entry *)

	   bfd_hash_insert (&table->table, string, hash));

  if (hashp == NULL)

    return NULL;

  hashp->len = len;

  hashp->alignment = alignment;

  return hashp;

}

/* Create a new hash table.  */

static struct sec_merge_hash *

sec_merge_init (unsigned int entsize, bfd_boolean strings)

{

  struct sec_merge_hash *table;

  table = (struct sec_merge_hash *) bfd_malloc (sizeof (struct sec_merge_hash));

  if (table == NULL)

    return NULL;

  if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,

			       sizeof (struct sec_merge_hash_entry), 16699))

    {

      free (table);

      return NULL;

    }

  table->size = 0;

  table->first = NULL;

  table->last = NULL;

  table->entsize = entsize;

  table->strings = strings;

  return table;

}

/* Get the index of an entity in a hash table, adding it if it is not

   already present.  */

static struct sec_merge_hash_entry *

sec_merge_add (struct sec_merge_hash *tab, const char *str,

	       unsigned int alignment, struct sec_merge_sec_info *secinfo)

{

  struct sec_merge_hash_entry *entry;

  entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);

  if (entry == NULL)

    return NULL;

  if (entry->secinfo == NULL)

    {

      tab->size++;

      entry->secinfo = secinfo;

      if (tab->first == NULL)

	tab->first = entry;

      else

	tab->last->next = entry;

      tab->last = entry;

    }

  return entry;

}

static bfd_boolean

sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry,

		unsigned char *contents, file_ptr offset)

{

  struct sec_merge_sec_info *secinfo = entry->secinfo;

  asection *sec = secinfo->sec;

  char *pad = NULL;

  bfd_size_type off = 0;

  int alignment_power = sec->output_section->alignment_power;

  if (alignment_power)

    {

      pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);

      if (pad == NULL)

	return FALSE;

    }

  for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)

    {

      const char *str;

      bfd_size_type len;

      len = -off & (entry->alignment - 1);

      if (len != 0)

	{

	  if (contents)

	    {

	      memcpy (contents + offset, pad, len);

	      offset += len;

	    }

	  else if (bfd_bwrite (pad, len, abfd) != len)

	    goto err;

	  off += len;

	}

      str = entry->root.string;

      len = entry->len;

      if (contents)

	{

	  memcpy (contents + offset, str, len);

	  offset += len;

	}

      else if (bfd_bwrite (str, len, abfd) != len)

	goto err;

      off += len;

    }

  /* Trailing alignment needed?  */

  off = sec->size - off;

  if (off != 0)

    {

      if (contents)

	memcpy (contents + offset, pad, off);

      else if (bfd_bwrite (pad, off, abfd) != off)

    goto err;

    }

  if (pad != NULL)

    free (pad);

  return TRUE;

 err:

  if (pad != NULL)

    free (pad);

  return FALSE;

}

/* Register a SEC_MERGE section as a candidate for merging.

   This function is called for all non-dynamic SEC_MERGE input sections.  */

bfd_boolean

_bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,

			void **psecinfo)

{

  struct sec_merge_info *sinfo;

  struct sec_merge_sec_info *secinfo;

  unsigned int align;

  bfd_size_type amt;

  bfd_byte *contents;

  if ((abfd->flags & DYNAMIC) != 0

      || (sec->flags & SEC_MERGE) == 0)

    abort ();

  if (sec->size == 0

      || (sec->flags & SEC_EXCLUDE) != 0

      || sec->entsize == 0)

    return TRUE;

  if ((sec->flags & SEC_RELOC) != 0)

    {

      /* We aren't prepared to handle relocations in merged sections.  */

      return TRUE;

    }

  align = sec->alignment_power;

  if ((sec->entsize < (unsigned) 1 << align

       && ((sec->entsize & (sec->entsize - 1))

	   || !(sec->flags & SEC_STRINGS)))

      || (sec->entsize > (unsigned) 1 << align

	  && (sec->entsize & (((unsigned) 1 << align) - 1))))

    {

      /* Sanity check.  If string character size is smaller than

	 alignment, then we require character size to be a power

	 of 2, otherwise character size must be integer multiple

	 of alignment.  For non-string constants, alignment must

	 be smaller than or equal to entity size and entity size

	 must be integer multiple of alignment.  */

      return TRUE;

    }

  for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)

    if ((secinfo = sinfo->chain)

	&& ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))

	&& secinfo->sec->entsize == sec->entsize

	&& secinfo->sec->alignment_power == sec->alignment_power

	&& secinfo->sec->output_section == sec->output_section)

      break;

  if (sinfo == NULL)

    {

      /* Initialize the information we need to keep track of.  */

      sinfo = (struct sec_merge_info *)

          bfd_alloc (abfd, sizeof (struct sec_merge_info));

      if (sinfo == NULL)

	goto error_return;

      sinfo->next = (struct sec_merge_info *) *psinfo;

      sinfo->chain = NULL;

      *psinfo = sinfo;

      sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));

      if (sinfo->htab == NULL)

	goto error_return;

    }

  /* Read the section from abfd.  */

  amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;

  if (sec->flags & SEC_STRINGS)

    /* Some versions of gcc may emit a string without a zero terminator.

       See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html

       Allocate space for an extra zero.  */

    amt += sec->entsize;

  *psecinfo = bfd_alloc (abfd, amt);

  if (*psecinfo == NULL)

    goto error_return;

  secinfo = (struct sec_merge_sec_info *) *psecinfo;

  if (sinfo->chain)

    {

      secinfo->next = sinfo->chain->next;

      sinfo->chain->next = secinfo;

    }

  else

    secinfo->next = secinfo;

  sinfo->chain = secinfo;

  secinfo->sec = sec;

  secinfo->psecinfo = psecinfo;

  secinfo->htab = sinfo->htab;

  secinfo->first_str = NULL;

  sec->rawsize = sec->size;

  if (sec->flags & SEC_STRINGS)

    memset (secinfo->contents + sec->size, 0, sec->entsize);

  contents = secinfo->contents;

  if (! bfd_get_full_section_contents (sec->owner, sec, &contents))

    goto error_return;

  return TRUE;

 error_return:

  *psecinfo = NULL;

  return FALSE;

}

/* Record one section into the hash table.  */

static bfd_boolean

record_section (struct sec_merge_info *sinfo,

		struct sec_merge_sec_info *secinfo)

{

  asection *sec = secinfo->sec;

  struct sec_merge_hash_entry *entry;

  bfd_boolean nul;

  unsigned char *p, *end;

  bfd_vma mask, eltalign;

  unsigned int align, i;

  align = sec->alignment_power;

  end = secinfo->contents + sec->size;

  nul = FALSE;

  mask = ((bfd_vma) 1 << align) - 1;

  if (sec->flags & SEC_STRINGS)

    {

      for (p = secinfo->contents; p < end; )

	{

	  eltalign = p - secinfo->contents;

	  eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;

	  if (!eltalign || eltalign > mask)

	    eltalign = mask + 1;

	  entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,

				 secinfo);

	  if (! entry)

	    goto error_return;

	  p += entry->len;

	  if (sec->entsize == 1)

	    {

	      while (p < end && *p == 0)

		{

		  if (!nul && !((p - secinfo->contents) & mask))

		    {

		      nul = TRUE;

		      entry = sec_merge_add (sinfo->htab, "",

					     (unsigned) mask + 1, secinfo);

		      if (! entry)

			goto error_return;

		    }

		  p++;

		}

	    }

	  else

	    {

	      while (p < end)

		{

		  for (i = 0; i < sec->entsize; i++)

		    if (p[i] != '\0')

		      break;

		  if (i != sec->entsize)

		    break;

		  if (!nul && !((p - secinfo->contents) & mask))

		    {

		      nul = TRUE;

		      entry = sec_merge_add (sinfo->htab, (char *) p,

					     (unsigned) mask + 1, secinfo);

		      if (! entry)

			goto error_return;

		    }

		  p += sec->entsize;

		}

	    }

	}

    }

  else

    {

      for (p = secinfo->contents; p < end; p += sec->entsize)

	{

	  entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);

	  if (! entry)

	    goto error_return;

	}

    }

  return TRUE;

error_return:

  for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)

    *secinfo->psecinfo = NULL;

  return FALSE;

}

static int

strrevcmp (const void *a, const void *b)

{

  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;

  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;

  unsigned int lenA = A->len;

  unsigned int lenB = B->len;

  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;

  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;

  int l = lenA < lenB ? lenA : lenB;

  while (l)

    {

      if (*s != *t)

	return (int) *s - (int) *t;

      s--;

      t--;

      l--;

    }

  return lenA - lenB;

}

/* Like strrevcmp, but for the case where all strings have the same

   alignment > entsize.  */

static int

strrevcmp_align (const void *a, const void *b)

{

  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;

  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;

  unsigned int lenA = A->len;

  unsigned int lenB = B->len;

  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;

  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;

  int l = lenA < lenB ? lenA : lenB;

  int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));

  if (tail_align != 0)

    return tail_align;

  while (l)

    {

      if (*s != *t)

	return (int) *s - (int) *t;

      s--;

      t--;

      l--;

    }

  return lenA - lenB;

}

static inline int

is_suffix (const struct sec_merge_hash_entry *A,

	   const struct sec_merge_hash_entry *B)

{

  if (A->len <= B->len)

    /* B cannot be a suffix of A unless A is equal to B, which is guaranteed

       not to be equal by the hash table.  */

    return 0;

  return memcmp (A->root.string + (A->len - B->len),

		 B->root.string, B->len) == 0;

}

/* This is a helper function for _bfd_merge_sections.  It attempts to

   merge strings matching suffixes of longer strings.  */

static void

merge_strings (struct sec_merge_info *sinfo)

{

  struct sec_merge_hash_entry **array, **a, *e;

  struct sec_merge_sec_info *secinfo;

  bfd_size_type size, amt;

  unsigned int alignment = 0;

  /* Now sort the strings */

  amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);

  array = (struct sec_merge_hash_entry **) bfd_malloc (amt);

  if (array == NULL)

    goto alloc_failure;

  for (e = sinfo->htab->first, a = array; e; e = e->next)

    if (e->alignment)

      {

	*a++ = e;

	/* Adjust the length to not include the zero terminator.  */

	e->len -= sinfo->htab->entsize;

	if (alignment != e->alignment)

	  {

	    if (alignment == 0)

	      alignment = e->alignment;

	    else

	      alignment = (unsigned) -1;

	  }

      }

  sinfo->htab->size = a - array;

  if (sinfo->htab->size != 0)

    {

      qsort (array, (size_t) sinfo->htab->size,

	     sizeof (struct sec_merge_hash_entry *),

	     (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize

	      ? strrevcmp_align : strrevcmp));

      /* Loop over the sorted array and merge suffixes */

      e = *--a;

      e->len += sinfo->htab->entsize;

      while (--a >= array)

	{

	  struct sec_merge_hash_entry *cmp = *a;

	  cmp->len += sinfo->htab->entsize;

	  if (e->alignment >= cmp->alignment

	      && !((e->len - cmp->len) & (cmp->alignment - 1))

	      && is_suffix (e, cmp))

	    {

	      cmp->u.suffix = e;

	      cmp->alignment = 0;

	    }

	  else

	    e = cmp;

	}

    }

alloc_failure:

  if (array)

    free (array);

  /* Now assign positions to the strings we want to keep.  */

  size = 0;

  secinfo = sinfo->htab->first->secinfo;

  for (e = sinfo->htab->first; e; e = e->next)

    {

      if (e->secinfo != secinfo)

	{

	  secinfo->sec->size = size;

	  secinfo = e->secinfo;

	}

      if (e->alignment)

	{

	  if (e->secinfo->first_str == NULL)

	    {

	      e->secinfo->first_str = e;

	      size = 0;

	    }

	  size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);

	  e->u.index = size;

	  size += e->len;

	}

    }

  secinfo->sec->size = size;

  if (secinfo->sec->alignment_power != 0)

    {

      bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;

      secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;

    }

  /* And now adjust the rest, removing them from the chain (but not hashtable)

     at the same time.  */

  for (a = &sinfo->htab->first, e = *a; e; e = e->next)

    if (e->alignment)

      a = &e->next;

    else

      {

	*a = e->next;

	if (e->len)

	  {

	    e->secinfo = e->u.suffix->secinfo;

	    e->alignment = e->u.suffix->alignment;

	    e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);

	  }

      }

}

/* This function is called once after all SEC_MERGE sections are registered

   with _bfd_merge_section.  */

bfd_boolean

_bfd_merge_sections (bfd *abfd,

		     struct bfd_link_info *info ATTRIBUTE_UNUSED,

		     void *xsinfo,

		     void (*remove_hook) (bfd *, asection *))

{

  struct sec_merge_info *sinfo;

  for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)

    {

      struct sec_merge_sec_info * secinfo;

      if (! sinfo->chain)

	continue;

      /* Move sinfo->chain to head of the chain, terminate it.  */

      secinfo = sinfo->chain;

      sinfo->chain = secinfo->next;

      secinfo->next = NULL;

      /* Record the sections into the hash table.  */

      for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)

	if (secinfo->sec->flags & SEC_EXCLUDE)

	  {

	    *secinfo->psecinfo = NULL;

	    if (remove_hook)

	      (*remove_hook) (abfd, secinfo->sec);

	  }

	else if (! record_section (sinfo, secinfo))

	  break;

      if (secinfo)

	continue;

      if (sinfo->htab->first == NULL)

	continue;

      if (sinfo->htab->strings)

	merge_strings (sinfo);

      else

	{

	  struct sec_merge_hash_entry *e;

	  bfd_size_type size = 0;

	  /* Things are much simpler for non-strings.

	     Just assign them slots in the section.  */

	  secinfo = NULL;

	  for (e = sinfo->htab->first; e; e = e->next)

	    {

	      if (e->secinfo->first_str == NULL)

		{

		  if (secinfo)

		    secinfo->sec->size = size;

		  e->secinfo->first_str = e;

		  size = 0;

		}

	      size = (size + e->alignment - 1)

		     & ~((bfd_vma) e->alignment - 1);

	      e->u.index = size;

	      size += e->len;

	      secinfo = e->secinfo;

	    }

	  secinfo->sec->size = size;

	}

	/* Finally remove all input sections which have not made it into

	   the hash table at all.  */

	for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)

	  if (secinfo->first_str == NULL)

	    secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;

    }

  return TRUE;

}

/* Write out the merged section.  */

bfd_boolean

_bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)

{

  struct sec_merge_sec_info *secinfo;

  file_ptr pos;

  unsigned char *contents;

  Elf_Internal_Shdr *hdr;

  secinfo = (struct sec_merge_sec_info *) psecinfo;

  if (!secinfo)

    return FALSE;

  if (secinfo->first_str == NULL)

    return TRUE;

  /* FIXME: octets_per_byte.  */

  hdr = &elf_section_data (sec->output_section)->this_hdr;

  if (hdr->sh_offset == (file_ptr) -1)

    {

      /* We must compress this section.  Write output to the

	 buffer.  */

      contents = hdr->contents;

      if ((sec->output_section->flags & SEC_ELF_COMPRESS) == 0

	  || contents == NULL)

	abort ();

    }

  else

    {

      contents = NULL;

  pos = sec->output_section->filepos + sec->output_offset;

  if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)

    return FALSE;

    }

  if (! sec_merge_emit (output_bfd, secinfo->first_str, contents,

			sec->output_offset))

    return FALSE;

  return TRUE;

}

/* Adjust an address in the SEC_MERGE section.  Given OFFSET within

   *PSEC, this returns the new offset in the adjusted SEC_MERGE

   section and writes the new section back into *PSEC.  */

bfd_vma

_bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,

			    void *psecinfo, bfd_vma offset)

{

  struct sec_merge_sec_info *secinfo;

  struct sec_merge_hash_entry *entry;

  unsigned char *p;

  asection *sec = *psec;

  secinfo = (struct sec_merge_sec_info *) psecinfo;

  if (!secinfo)

    return offset;

  if (offset >= sec->rawsize)

    {

      if (offset > sec->rawsize)

	{

	  (*_bfd_error_handler)

	    (_("%s: access beyond end of merged section (%ld)"),

	     bfd_get_filename (sec->owner), (long) offset);

	}

      return secinfo->first_str ? sec->size : 0;

    }

  if (secinfo->htab->strings)

    {

      if (sec->entsize == 1)

	{

	  p = secinfo->contents + offset - 1;

	  while (p >= secinfo->contents && *p)

	    --p;

	  ++p;

	}

      else

	{

	  p = secinfo->contents + (offset / sec->entsize) * sec->entsize;

	  p -= sec->entsize;

	  while (p >= secinfo->contents)

	    {

	      unsigned int i;

	      for (i = 0; i < sec->entsize; ++i)

		if (p[i] != '\0')

		  break;

	      if (i == sec->entsize)

		break;

	      p -= sec->entsize;

	    }

	  p += sec->entsize;

	}

    }

  else

    {

      p = secinfo->contents + (offset / sec->entsize) * sec->entsize;

    }

  entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);

  if (!entry)

    {

      if (! secinfo->htab->strings)

	abort ();

      /* This should only happen if somebody points into the padding

	 after a NUL character but before next entity.  */

      if (*p)

	abort ();

      if (! secinfo->htab->first)

	abort ();

      entry = secinfo->htab->first;

      p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize

	   - entry->len);

    }

  *psec = entry->secinfo->sec;

  return entry->u.index + (secinfo->contents + offset - p);

}

/* Tidy up when done.  */

void

_bfd_merge_sections_free (void *xsinfo)

{

  struct sec_merge_info *sinfo;

  for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)

    {

      bfd_hash_table_free (&sinfo->htab->table);

      free (sinfo->htab);

    }

}