/* ELF strtab with GC and suffix merging support.
Copyright (C) 2001-2015 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 = (struct bfd_hash_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 = (struct elf_strtab_hash *) 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)))
{
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)
{
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);
}
/* 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 = (struct elf_strtab_hash_entry **)
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;
}
unsigned int
_bfd_elf_strtab_refcount (struct elf_strtab_hash *tab, bfd_size_type idx)
{
return 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;
}
/* Downsizes strtab. Entries from IDX up to the current size are
removed from the array. */
void
_bfd_elf_strtab_restore_size (struct elf_strtab_hash *tab, bfd_size_type idx)
{
bfd_size_type curr_size = tab->size;
BFD_ASSERT (tab->sec_size == 0);
BFD_ASSERT (idx <= curr_size);
tab->size = idx;
for (; idx < curr_size; ++idx)
{
/* We don't remove entries from the hash table, just set their
REFCOUNT to zero. Setting LEN zero will result in the size
growing if the entry is added again. See _bfd_elf_strtab_add. */
tab->array[idx]->refcount = 0;
tab->array[idx]->len = 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 = (struct elf_strtab_hash_entry **) 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)
/* 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);
}
}