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32235d9095
There is no need to call bfd_write with 0 size. * elf-strtab.c (_bfd_elf_strtab_emit): Don't call bfd_write with 0 size.
473 lines
11 KiB
C
473 lines
11 KiB
C
/* ELF strtab with GC and suffix merging support.
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Copyright (C) 2001-2024 Free Software Foundation, Inc.
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Written by Jakub Jelinek <jakub@redhat.com>.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "sysdep.h"
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#include "bfd.h"
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#include "libbfd.h"
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#include "elf-bfd.h"
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#include "hashtab.h"
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#include "libiberty.h"
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/* An entry in the strtab hash table. */
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struct elf_strtab_hash_entry
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{
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struct bfd_hash_entry root;
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/* Length of this entry. This includes the zero terminator. */
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int len;
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unsigned int refcount;
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union {
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/* Index within the merged section. */
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bfd_size_type index;
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/* Entry this is a suffix of (if len < 0). */
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struct elf_strtab_hash_entry *suffix;
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} u;
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};
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/* The strtab hash table. */
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struct elf_strtab_hash
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{
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struct bfd_hash_table table;
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/* Next available index. */
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size_t size;
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/* Number of array entries alloced. */
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size_t alloced;
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/* Final strtab size. */
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bfd_size_type sec_size;
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/* Array of pointers to strtab entries. */
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struct elf_strtab_hash_entry **array;
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};
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/* Routine to create an entry in a section merge hashtab. */
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static struct bfd_hash_entry *
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elf_strtab_hash_newfunc (struct bfd_hash_entry *entry,
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struct bfd_hash_table *table,
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const char *string)
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{
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/* Allocate the structure if it has not already been allocated by a
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subclass. */
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if (entry == NULL)
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entry = (struct bfd_hash_entry *)
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bfd_hash_allocate (table, sizeof (struct elf_strtab_hash_entry));
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if (entry == NULL)
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return NULL;
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/* Call the allocation method of the superclass. */
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entry = bfd_hash_newfunc (entry, table, string);
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if (entry)
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{
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/* Initialize the local fields. */
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struct elf_strtab_hash_entry *ret;
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ret = (struct elf_strtab_hash_entry *) entry;
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ret->u.index = -1;
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ret->refcount = 0;
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ret->len = 0;
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}
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return entry;
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}
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/* Create a new hash table. */
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struct elf_strtab_hash *
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_bfd_elf_strtab_init (void)
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{
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struct elf_strtab_hash *table;
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size_t amt = sizeof (struct elf_strtab_hash);
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table = (struct elf_strtab_hash *) bfd_malloc (amt);
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if (table == NULL)
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return NULL;
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if (!bfd_hash_table_init (&table->table, elf_strtab_hash_newfunc,
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sizeof (struct elf_strtab_hash_entry)))
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{
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free (table);
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return NULL;
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}
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table->sec_size = 0;
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table->size = 1;
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table->alloced = 64;
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amt = sizeof (struct elf_strtab_hasn_entry *);
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table->array = ((struct elf_strtab_hash_entry **)
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bfd_malloc (table->alloced * amt));
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if (table->array == NULL)
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{
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bfd_hash_table_free (&table->table);
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free (table);
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return NULL;
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}
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table->array[0] = NULL;
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return table;
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}
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/* Free a strtab. */
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void
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_bfd_elf_strtab_free (struct elf_strtab_hash *tab)
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{
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bfd_hash_table_free (&tab->table);
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free (tab->array);
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free (tab);
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}
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/* Get the index of an entity in a hash table, adding it if it is not
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already present. */
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size_t
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_bfd_elf_strtab_add (struct elf_strtab_hash *tab,
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const char *str,
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bool copy)
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{
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register struct elf_strtab_hash_entry *entry;
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/* We handle this specially, since we don't want to do refcounting
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on it. */
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if (*str == '\0')
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return 0;
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BFD_ASSERT (tab->sec_size == 0);
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entry = (struct elf_strtab_hash_entry *)
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bfd_hash_lookup (&tab->table, str, true, copy);
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if (entry == NULL)
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return (size_t) -1;
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entry->refcount++;
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if (entry->len == 0)
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{
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entry->len = strlen (str) + 1;
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/* 2G strings lose. */
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BFD_ASSERT (entry->len > 0);
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if (tab->size == tab->alloced)
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{
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bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *);
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tab->alloced *= 2;
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tab->array = (struct elf_strtab_hash_entry **)
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bfd_realloc_or_free (tab->array, tab->alloced * amt);
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if (tab->array == NULL)
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return (size_t) -1;
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}
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entry->u.index = tab->size++;
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tab->array[entry->u.index] = entry;
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}
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return entry->u.index;
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}
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void
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_bfd_elf_strtab_addref (struct elf_strtab_hash *tab, size_t idx)
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{
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if (idx == 0 || idx == (size_t) -1)
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return;
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BFD_ASSERT (tab->sec_size == 0);
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BFD_ASSERT (idx < tab->size);
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++tab->array[idx]->refcount;
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}
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void
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_bfd_elf_strtab_delref (struct elf_strtab_hash *tab, size_t idx)
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{
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if (idx == 0 || idx == (size_t) -1)
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return;
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BFD_ASSERT (tab->sec_size == 0);
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BFD_ASSERT (idx < tab->size);
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BFD_ASSERT (tab->array[idx]->refcount > 0);
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--tab->array[idx]->refcount;
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}
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unsigned int
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_bfd_elf_strtab_refcount (struct elf_strtab_hash *tab, size_t idx)
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{
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return tab->array[idx]->refcount;
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}
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void
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_bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab)
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{
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size_t idx;
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for (idx = 1; idx < tab->size; idx++)
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tab->array[idx]->refcount = 0;
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}
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/* Save strtab refcounts prior to adding --as-needed library. */
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struct strtab_save
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{
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size_t size;
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unsigned int refcount[1];
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};
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void *
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_bfd_elf_strtab_save (struct elf_strtab_hash *tab)
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{
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struct strtab_save *save;
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size_t idx, size;
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size = sizeof (*save) + (tab->size - 1) * sizeof (save->refcount[0]);
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save = bfd_malloc (size);
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if (save == NULL)
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return save;
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save->size = tab->size;
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for (idx = 1; idx < tab->size; idx++)
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save->refcount[idx] = tab->array[idx]->refcount;
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return save;
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}
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/* Restore strtab refcounts on finding --as-needed library not needed. */
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void
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_bfd_elf_strtab_restore (struct elf_strtab_hash *tab, void *buf)
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{
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size_t idx, curr_size = tab->size, save_size;
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struct strtab_save *save = (struct strtab_save *) buf;
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BFD_ASSERT (tab->sec_size == 0);
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save_size = 1;
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if (save != NULL)
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save_size = save->size;
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BFD_ASSERT (save_size <= curr_size);
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tab->size = save_size;
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for (idx = 1; idx < save_size; ++idx)
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tab->array[idx]->refcount = save->refcount[idx];
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for (; idx < curr_size; ++idx)
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{
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/* We don't remove entries from the hash table, just set their
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REFCOUNT to zero. Setting LEN zero will result in the size
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growing if the entry is added again. See _bfd_elf_strtab_add. */
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tab->array[idx]->refcount = 0;
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tab->array[idx]->len = 0;
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}
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}
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bfd_size_type
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_bfd_elf_strtab_size (struct elf_strtab_hash *tab)
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{
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return tab->sec_size ? tab->sec_size : tab->size;
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}
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bfd_size_type
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_bfd_elf_strtab_len (struct elf_strtab_hash *tab)
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{
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return tab->size;
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}
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bfd_size_type
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_bfd_elf_strtab_offset (struct elf_strtab_hash *tab, size_t idx)
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{
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struct elf_strtab_hash_entry *entry;
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if (idx == 0)
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return 0;
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BFD_ASSERT (idx < tab->size);
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BFD_ASSERT (tab->sec_size);
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entry = tab->array[idx];
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BFD_ASSERT (entry->refcount > 0);
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entry->refcount--;
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return tab->array[idx]->u.index;
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}
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const char *
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_bfd_elf_strtab_str (struct elf_strtab_hash *tab, size_t idx,
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bfd_size_type *offset)
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{
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if (idx == 0)
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return NULL;
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BFD_ASSERT (idx < tab->size);
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BFD_ASSERT (tab->sec_size);
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if (tab->array[idx]->refcount == 0)
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return NULL;
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if (offset)
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*offset = tab->array[idx]->u.index;
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return tab->array[idx]->root.string;
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}
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bool
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_bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab)
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{
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bfd_size_type off = 1;
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size_t i;
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if (bfd_write ("", 1, abfd) != 1)
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return false;
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for (i = 1; i < tab->size; ++i)
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{
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register const char *str;
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register unsigned int len;
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BFD_ASSERT (tab->array[i]->refcount == 0);
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len = tab->array[i]->len;
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if ((int) len <= 0)
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continue;
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str = tab->array[i]->root.string;
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if (bfd_write (str, len, abfd) != len)
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return false;
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off += len;
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}
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BFD_ASSERT (off == tab->sec_size);
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return true;
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}
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/* Compare two elf_strtab_hash_entry structures. Called via qsort.
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Won't ever return zero as all entries differ, so there is no issue
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with qsort stability here. */
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static int
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strrevcmp (const void *a, const void *b)
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{
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struct elf_strtab_hash_entry *A = *(struct elf_strtab_hash_entry **) a;
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struct elf_strtab_hash_entry *B = *(struct elf_strtab_hash_entry **) b;
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unsigned int lenA = A->len;
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unsigned int lenB = B->len;
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const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
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const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
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int l = lenA < lenB ? lenA : lenB;
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while (l)
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{
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if (*s != *t)
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return (int) *s - (int) *t;
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s--;
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t--;
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l--;
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}
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return lenA - lenB;
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}
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static inline int
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is_suffix (const struct elf_strtab_hash_entry *A,
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const struct elf_strtab_hash_entry *B)
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{
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if (A->len <= B->len)
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/* B cannot be a suffix of A unless A is equal to B, which is guaranteed
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not to be equal by the hash table. */
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return 0;
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return memcmp (A->root.string + (A->len - B->len),
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B->root.string, B->len - 1) == 0;
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}
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/* This function assigns final string table offsets for used strings,
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merging strings matching suffixes of longer strings if possible. */
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void
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_bfd_elf_strtab_finalize (struct elf_strtab_hash *tab)
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{
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struct elf_strtab_hash_entry **array, **a, *e;
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bfd_size_type amt, sec_size;
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size_t size, i;
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/* Sort the strings by suffix and length. */
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amt = tab->size;
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amt *= sizeof (struct elf_strtab_hash_entry *);
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array = (struct elf_strtab_hash_entry **) bfd_malloc (amt);
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if (array == NULL)
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goto alloc_failure;
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for (i = 1, a = array; i < tab->size; ++i)
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{
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e = tab->array[i];
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if (e->refcount)
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{
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*a++ = e;
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/* Adjust the length to not include the zero terminator. */
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e->len -= 1;
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}
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else
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e->len = 0;
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}
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size = a - array;
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if (size != 0)
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{
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qsort (array, size, sizeof (struct elf_strtab_hash_entry *), strrevcmp);
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/* Loop over the sorted array and merge suffixes. Start from the
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end because we want eg.
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s1 -> "d"
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s2 -> "bcd"
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s3 -> "abcd"
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to end up as
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s3 -> "abcd"
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s2 _____^
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s1 _______^
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ie. we don't want s1 pointing into the old s2. */
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e = *--a;
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e->len += 1;
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while (--a >= array)
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{
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struct elf_strtab_hash_entry *cmp = *a;
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cmp->len += 1;
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if (is_suffix (e, cmp))
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{
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cmp->u.suffix = e;
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cmp->len = -cmp->len;
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}
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else
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e = cmp;
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}
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}
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alloc_failure:
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free (array);
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/* Assign positions to the strings we want to keep. */
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sec_size = 1;
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for (i = 1; i < tab->size; ++i)
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{
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e = tab->array[i];
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if (e->refcount && e->len > 0)
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{
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e->u.index = sec_size;
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sec_size += e->len;
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}
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}
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tab->sec_size = sec_size;
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/* Adjust the rest. */
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for (i = 1; i < tab->size; ++i)
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{
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e = tab->array[i];
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if (e->refcount && e->len < 0)
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e->u.index = e->u.suffix->u.index + (e->u.suffix->len + e->len);
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}
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}
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