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/* Support for reading /etc/ld.so.cache files written by Linux ldconfig.
Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <link.h>
#include <unistd.h>
#include <sys/mman.h>
/* System-dependent function to read a file's whole contents
in the most convenient manner available. */
extern void *_dl_sysdep_read_whole_file (const char *filename,
size_t *filesize_ptr,
int mmap_prot);
#ifndef LD_SO_CACHE
# define LD_SO_CACHE "/etc/ld.so.cache"
#endif
#define CACHEMAGIC "ld.so-1.7.0"
struct cache_file
{
char magic[sizeof CACHEMAGIC - 1];
unsigned int nlibs;
struct
{
int flags; /* This is 1 for an ELF library. */
unsigned int key, value; /* String table indices. */
} libs[0];
};
/* Look up NAME in ld.so.cache and return the file name stored there,
or null if none is found. */
const char *
_dl_load_cache_lookup (const char *name)
{
static struct cache_file *cache;
static size_t cachesize;
unsigned int i;
const char *best;
/* Print a message if the loading of libs is traced. */
if (_dl_debug_libs)
_dl_sysdep_message ("\t search cache=", LD_SO_CACHE, "\n", NULL);
if (cache == NULL)
{
/* Read the contents of the file. */
void *file = _dl_sysdep_read_whole_file (LD_SO_CACHE, &cachesize,
PROT_READ);
if (file && cachesize > sizeof *cache &&
!memcmp (file, CACHEMAGIC, sizeof CACHEMAGIC - 1))
/* Looks ok. */
cache = file;
else
{
if (file)
__munmap (file, cachesize);
cache = (void *) -1;
return NULL;
}
}
if (cache == (void *) -1)
/* Previously looked for the cache file and didn't find it. */
return NULL;
best = NULL;
for (i = 0; i < cache->nlibs; ++i)
if ((cache->libs[i].flags == 1 ||
cache->libs[i].flags == 3) && /* ELF library entry. */
/* Make sure string table indices are not bogus before using them. */
cache->libs[i].key < cachesize - sizeof *cache &&
cache->libs[i].value < cachesize - sizeof *cache &&
/* Does the name match? */
! strcmp (name, ((const char *) &cache->libs[cache->nlibs] +
cache->libs[i].key)))
{
if ((best == NULL) || (cache->libs[i].flags == 3))
{
best = ((const char *) &cache->libs[cache->nlibs]
+ cache->libs[i].value);
if (cache->libs[i].flags == 3)
/* We've found an exact match for the shared object and no
general `ELF' release. Stop searching. */
break;
}
}
/* Print our result if wanted. */
if (_dl_debug_libs && best != NULL)
_dl_sysdep_message ("\t trying file=", best, "\n", NULL);
return best;
}
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