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/* ELF strtab with GC and suffix merging support.

   Copyright 2001, 2002, 2003, 2005, 2006, 2007, 2008

   Free Software Foundation, Inc.

   Written by Jakub Jelinek <jakub@redhat.com>.

   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.  */

#include "sysdep.h"

#include "bfd.h"

#include "libbfd.h"

#include "elf-bfd.h"

#include "hashtab.h"

#include "libiberty.h"

/* An entry in the strtab hash table.  */

struct elf_strtab_hash_entry

{

  struct bfd_hash_entry root;

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

  int len;

  unsigned int refcount;

  union {

    /* Index within the merged section.  */

    bfd_size_type index;

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

    struct elf_strtab_hash_entry *suffix;

  } u;

};

/* The strtab hash table.  */

struct elf_strtab_hash

{

  struct bfd_hash_table table;

  /* Next available index.  */

  bfd_size_type size;

  /* Number of array entries alloced.  */

  bfd_size_type alloced;

  /* Final strtab size.  */

  bfd_size_type sec_size;

  /* Array of pointers to strtab entries.  */

  struct elf_strtab_hash_entry **array;

};

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

static struct bfd_hash_entry *

elf_strtab_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 = bfd_hash_allocate (table, sizeof (struct elf_strtab_hash_entry));

  if (entry == NULL)

    return NULL;

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

  entry = bfd_hash_newfunc (entry, table, string);

  if (entry)

    {

      /* Initialize the local fields.  */

      struct elf_strtab_hash_entry *ret;

      ret = (struct elf_strtab_hash_entry *) entry;

      ret->u.index = -1;

      ret->refcount = 0;

      ret->len = 0;

    }

  return entry;

}

/* Create a new hash table.  */

struct elf_strtab_hash *

_bfd_elf_strtab_init (void)

{

  struct elf_strtab_hash *table;

  bfd_size_type amt = sizeof (struct elf_strtab_hash);

  table = bfd_malloc (amt);

  if (table == NULL)

    return NULL;

  if (!bfd_hash_table_init (&table->table, elf_strtab_hash_newfunc,

                            sizeof (struct elf_strtab_hash_entry)))

    {

      free (table);

      return NULL;

    }

  table->sec_size = 0;

  table->size = 1;

  table->alloced = 64;

  amt = sizeof (struct elf_strtab_hasn_entry *);

  table->array = bfd_malloc (table->alloced * amt);

  if (table->array == NULL)

    {

      free (table);

      return NULL;

    }

  table->array[0] = NULL;

  return table;

}

/* Free a strtab.  */

void

_bfd_elf_strtab_free (struct elf_strtab_hash *tab)

{

  bfd_hash_table_free (&tab->table);

  free (tab->array);

  free (tab);

}

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

   already present.  */

bfd_size_type

_bfd_elf_strtab_add (struct elf_strtab_hash *tab,

                     const char *str,

                     bfd_boolean copy)

{

  register struct elf_strtab_hash_entry *entry;

  /* We handle this specially, since we don't want to do refcounting

     on it.  */

  if (*str == '\0')

    return 0;

  BFD_ASSERT (tab->sec_size == 0);

  entry = (struct elf_strtab_hash_entry *)

          bfd_hash_lookup (&tab->table, str, TRUE, copy);

  if (entry == NULL)

    return (bfd_size_type) -1;

  entry->refcount++;

  if (entry->len == 0)

    {

      entry->len = strlen (str) + 1;

      /* 2G strings lose.  */

      BFD_ASSERT (entry->len > 0);

      if (tab->size == tab->alloced)

        {

          bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *);

          tab->alloced *= 2;

          tab->array = bfd_realloc_or_free (tab->array, tab->alloced * amt);

          if (tab->array == NULL)

            return (bfd_size_type) -1;

        }

      entry->u.index = tab->size++;

      tab->array[entry->u.index] = entry;

    }

  return entry->u.index;

}

void

_bfd_elf_strtab_addref (struct elf_strtab_hash *tab, bfd_size_type idx)

{

  if (idx == 0 || idx == (bfd_size_type) -1)

    return;

  BFD_ASSERT (tab->sec_size == 0);

  BFD_ASSERT (idx < tab->size);

  ++tab->array[idx]->refcount;

}

void

_bfd_elf_strtab_delref (struct elf_strtab_hash *tab, bfd_size_type idx)

{

  if (idx == 0 || idx == (bfd_size_type) -1)

    return;

  BFD_ASSERT (tab->sec_size == 0);

  BFD_ASSERT (idx < tab->size);

  BFD_ASSERT (tab->array[idx]->refcount > 0);

  --tab->array[idx]->refcount;

}

void

_bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab)

{

  bfd_size_type idx;

  for (idx = 1; idx < tab->size; ++idx)

    tab->array[idx]->refcount = 0;

}

bfd_size_type

_bfd_elf_strtab_size (struct elf_strtab_hash *tab)

{

  return tab->sec_size ? tab->sec_size : tab->size;

}

bfd_size_type

_bfd_elf_strtab_offset (struct elf_strtab_hash *tab, bfd_size_type idx)

{

  struct elf_strtab_hash_entry *entry;

  if (idx == 0)

    return 0;

  BFD_ASSERT (idx < tab->size);

  BFD_ASSERT (tab->sec_size);

  entry = tab->array[idx];

  BFD_ASSERT (entry->refcount > 0);

  entry->refcount--;

  return tab->array[idx]->u.index;

}

bfd_boolean

_bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab)

{

  bfd_size_type off = 1, i;

  if (bfd_bwrite ("", 1, abfd) != 1)

    return FALSE;

  for (i = 1; i < tab->size; ++i)

    {

      register const char *str;

      register unsigned int len;

      BFD_ASSERT (tab->array[i]->refcount == 0);

      len = tab->array[i]->len;

      if ((int) len < 0)

        continue;

      str = tab->array[i]->root.string;

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

        return FALSE;

      off += len;

    }

  BFD_ASSERT (off == tab->sec_size);

  return TRUE;

}

/* Compare two elf_strtab_hash_entry structures.  Called via qsort.  */

static int

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

{

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

  struct elf_strtab_hash_entry *B = *(struct elf_strtab_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;

}

static inline int

is_suffix (const struct elf_strtab_hash_entry *A,

           const struct elf_strtab_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 - 1) == 0;

}

/* This function assigns final string table offsets for used strings,

   merging strings matching suffixes of longer strings if possible.  */

void

_bfd_elf_strtab_finalize (struct elf_strtab_hash *tab)

{

  struct elf_strtab_hash_entry **array, **a, *e;

  bfd_size_type size, amt;

  /* GCC 2.91.66 (egcs-1.1.2) on i386 miscompiles this function when i is

     a 64-bit bfd_size_type: a 64-bit target or --enable-64-bit-bfd.

     Besides, indexing with a long long wouldn't give anything but extra

     cycles.  */

  size_t i;

  /* Sort the strings by suffix and length.  */

  amt = tab->size * sizeof (struct elf_strtab_hash_entry *);

  array = bfd_malloc (amt);

  if (array == NULL)

    goto alloc_failure;

  for (i = 1, a = array; i < tab->size; ++i)

    {

      e = tab->array[i];

      if (e->refcount)

        {

          *a++ = e;

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

          e->len -= 1;

        }

      else

        e->len = 0;

    }

  size = a - array;

  if (size != 0)

    {

      qsort (array, size, sizeof (struct elf_strtab_hash_entry *), strrevcmp);

      /* Loop over the sorted array and merge suffixes.  Start from the

         end because we want eg.

         s1 -> "d"

         s2 -> "bcd"

         s3 -> "abcd"

         to end up as

         s3 -> "abcd"

         s2 _____^

         s1 _______^

         ie. we don't want s1 pointing into the old s2.  */

      e = *--a;

      e->len += 1;

      while (--a >= array)

        {

          struct elf_strtab_hash_entry *cmp = *a;

          cmp->len += 1;

          if (is_suffix (e, cmp))

            {

              cmp->u.suffix = e;

              cmp->len = -cmp->len;

            }

          else

            e = cmp;

        }

    }

alloc_failure:

  if (array)

    free (array);

  /* Assign positions to the strings we want to keep.  */

  size = 1;

  for (i = 1; i < tab->size; ++i)

    {

      e = tab->array[i];

      if (e->refcount && e->len > 0)

        {

          e->u.index = size;

          size += e->len;

        }

    }

  tab->sec_size = size;

  /* Adjust the rest.  */

  for (i = 1; i < tab->size; ++i)

    {

      e = tab->array[i];

      if (e->refcount && e->len < 0)

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

    }

}