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/* ELF strtab with GC and suffix merging support.

   Copyright 2001, 2002 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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "bfd.h"

#include "sysdep.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.  */

  unsigned int len;

  unsigned int refcount;

  union {

    /* Index within the merged section.  */

    bfd_size_type index;

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

    struct elf_strtab_hash_entry *suffix;

    struct elf_strtab_hash_entry *next;

  } 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;

};

static struct bfd_hash_entry *elf_strtab_hash_newfunc

  PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));

static int cmplengthentry PARAMS ((const PTR, const PTR));

static int last4_eq PARAMS ((const PTR, const PTR));

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

static struct bfd_hash_entry *

elf_strtab_hash_newfunc (entry, table, string)

     struct bfd_hash_entry *entry;

     struct bfd_hash_table *table;

     const char *string;

{

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

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

     subclass.  */

  if (ret == (struct elf_strtab_hash_entry *) NULL)

    ret = ((struct elf_strtab_hash_entry *)

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

  if (ret == (struct elf_strtab_hash_entry *) NULL)

    return NULL;

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

  ret = ((struct elf_strtab_hash_entry *)

         bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));

  if (ret)

    {

      /* Initialize the local fields.  */

      ret->u.index = -1;

      ret->refcount = 0;

      ret->len = 0;

    }

  return (struct bfd_hash_entry *)ret;

}

/* Create a new hash table.  */

struct elf_strtab_hash *

_bfd_elf_strtab_init ()

{

  struct elf_strtab_hash *table;

  bfd_size_type amt = sizeof (struct elf_strtab_hash);

  table = (struct elf_strtab_hash *) bfd_malloc (amt);

  if (table == NULL)

    return NULL;

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

    {

      free (table);

      return NULL;

    }

  table->sec_size = 0;

  table->size = 1;

  table->alloced = 64;

  amt = sizeof (struct elf_strtab_hasn_entry *);

  table->array = (struct elf_strtab_hash_entry **)

                 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 (tab)

     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 (tab, str, copy)

     struct elf_strtab_hash *tab;

     const char *str;

     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;

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

        {

          bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *);

          tab->alloced *= 2;

          tab->array = (struct elf_strtab_hash_entry **)

                       bfd_realloc (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 (tab, idx)

     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 (tab, idx)

     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 (tab)

     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 (tab)

     struct elf_strtab_hash *tab;

{

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

}

bfd_size_type

_bfd_elf_strtab_offset (tab, idx)

     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;

}

boolean

_bfd_elf_strtab_emit (abfd, tab)

     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 size_t len;

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

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

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

      if (len == 0)

        continue;

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

        return false;

      off += len;

    }

  BFD_ASSERT (off == tab->sec_size);

  return true;

}

/* Compare two elf_strtab_hash_entry structures.  This is called via qsort.  */

static int

cmplengthentry (a, b)

     const PTR a;

     const PTR 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;

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

    return 1;

  else if (A->len > B->len)

    return -1;

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

}

static int

last4_eq (a, b)

     const PTR a;

     const PTR 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;

  if (memcmp (A->root.string + A->len - 5, B->root.string + B->len - 5, 4)

      != 0)

    /* This was a hashtable collision.  */

    return 0;

  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 - 5) == 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 (tab)

     struct elf_strtab_hash *tab;

{

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

  htab_t last4tab = NULL;

  bfd_size_type size, amt;

  struct elf_strtab_hash_entry *last[256], **last_ptr[256];

  /* 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;

  /* Now sort the strings by length, longest first.  */

  array = NULL;

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

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

  if (array == NULL)

    goto alloc_failure;

  memset (last, 0, sizeof (last));

  for (i = 0; i < 256; ++i)

    last_ptr[i] = &last[i];

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

    if (tab->array[i]->refcount)

      *a++ = tab->array[i];

    else

      tab->array[i]->len = 0;

  size = a - array;

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

  last4tab = htab_create_alloc (size * 4, NULL, last4_eq, NULL, calloc, free);

  if (last4tab == NULL)

    goto alloc_failure;

  /* Now insert the strings into hash tables (strings with last 4 characters

     and strings with last character equal), look for longer strings which

     we're suffix of.  */

  for (a = array, end = array + size; a < end; a++)

    {

      register hashval_t hash;

      unsigned int c;

      unsigned int j;

      const unsigned char *s;

      PTR *p;

      e = *a;

      if (e->len > 4)

        {

          s = e->root.string + e->len - 1;

          hash = 0;

          for (j = 0; j < 4; j++)

            {

              c = *--s;

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

              hash ^= hash >> 2;

            }

          p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);

          if (p == NULL)

            goto alloc_failure;

          if (*p)

            {

              struct elf_strtab_hash_entry *ent;

              ent = (struct elf_strtab_hash_entry *) *p;

              e->u.suffix = ent;

              e->len = 0;

              continue;

            }

          else

            *p = (PTR) e;

        }

      else

        {

          struct elf_strtab_hash_entry *tem;

          c = e->root.string[e->len - 2] & 0xff;

          for (tem = last[c]; tem; tem = tem->u.next)

            if (tem->len > e->len

                && memcmp (tem->root.string + (tem->len - e->len),

                           e->root.string, e->len - 1) == 0)

              break;

          if (tem)

            {

              e->u.suffix = tem;

              e->len = 0;

              continue;

            }

        }

      c = e->root.string[e->len - 2] & 0xff;

      /* Put longest strings first.  */

      *last_ptr[c] = e;

      last_ptr[c] = &e->u.next;

      e->u.next = NULL;

    }

alloc_failure:

  if (array)

    free (array);

  if (last4tab)

    htab_delete (last4tab);

  /* Now 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)

        {

          e->u.index = size;

          size += e->len;

        }

    }

  tab->sec_size = size;

  /* And now adjust the rest.  */

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

    {

      e = tab->array[i];

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

        e->u.index = e->u.suffix->u.index

                     + (e->u.suffix->len - strlen (e->root.string) - 1);

    }

}