binutils-gdb/bfd/elf-strtab.c

425 lines
10 KiB
C

/* 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;
};
/* 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))
{
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;
if (tab->size == tab->alloced)
{
bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *);
tab->alloced *= 2;
tab->array = 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 (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 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 (str, 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 (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;
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 (const void *a, const void *b)
{
const struct elf_strtab_hash_entry *A = a;
const struct elf_strtab_hash_entry *B = 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 (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 = 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;
void **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 = *p;
e->u.suffix = ent;
e->len = 0;
continue;
}
else
*p = 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);
}
}