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glibc/elf/dl-open.c
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/* Load a shared object at runtime, relocate it, and run its initializer. | |
Copyright (C) 1996, 1997, 1998, 1999 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 <assert.h> | |
#include <dlfcn.h> | |
#include <errno.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <sys/mman.h> /* Check whether MAP_COPY is defined. */ | |
#include <sys/param.h> | |
#include <bits/libc-lock.h> | |
#include <elf/ldsodefs.h> | |
#include <dl-dst.h> | |
extern ElfW(Addr) _dl_sysdep_start (void **start_argptr, | |
void (*dl_main) (const ElfW(Phdr) *phdr, | |
ElfW(Word) phnum, | |
ElfW(Addr) *user_entry)); | |
weak_extern (_dl_sysdep_start) | |
/* This function is used to unload the cache file if necessary. */ | |
extern void _dl_unload_cache (void); | |
extern int __libc_multiple_libcs; /* Defined in init-first.c. */ | |
extern int __libc_argc; | |
extern char **__libc_argv; | |
extern char **__environ; | |
extern int _dl_lazy; /* Do we do lazy relocations? */ | |
/* Undefine the following for debugging. */ | |
/* #define SCOPE_DEBUG 1 */ | |
#ifdef SCOPE_DEBUG | |
static void show_scope (struct link_map *new); | |
#endif | |
/* During the program run we must not modify the global data of | |
loaded shared object simultanously in two threads. Therefore we | |
protect `_dl_open' and `_dl_close' in dl-close.c. | |
This must be a recursive lock since the initializer function of | |
the loaded object might as well require a call to this function. | |
At this time it is not anymore a problem to modify the tables. */ | |
__libc_lock_define_initialized_recursive (, _dl_load_lock) | |
extern size_t _dl_platformlen; | |
/* We must be carefull not to leave us in an inconsistent state. Thus we | |
catch any error and re-raise it after cleaning up. */ | |
struct dl_open_args | |
{ | |
const char *file; | |
int mode; | |
const void *caller; | |
struct link_map *map; | |
}; | |
static void | |
dl_open_worker (void *a) | |
{ | |
struct dl_open_args *args = a; | |
const char *file = args->file; | |
int mode = args->mode; | |
struct link_map *new, *l; | |
ElfW(Addr) init; | |
struct r_debug *r; | |
unsigned int global_add; | |
const char *dst; | |
int lazy; | |
/* Maybe we have to expand a DST. */ | |
dst = strchr (file, '$'); | |
if (dst != NULL) | |
{ | |
const void *caller = args->caller; | |
size_t len = strlen (file); | |
size_t required; | |
struct link_map *call_map; | |
char *new_file; | |
/* We have to find out from which object the caller is calling. | |
Find the highest-addressed object that ADDRESS is not below. */ | |
call_map = NULL; | |
for (l = _dl_loaded; l; l = l->l_next) | |
if (l->l_addr != 0 /* Make sure we do not currently set this map up | |
in this moment. */ | |
&& caller >= (const void *) l->l_addr | |
&& (call_map == NULL || call_map->l_addr < l->l_addr)) | |
call_map = l; | |
if (call_map == NULL) | |
/* In this case we assume this is the main application. */ | |
call_map = _dl_loaded; | |
/* Determine how much space we need. We have to allocate the | |
memory locally. */ | |
required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0)); | |
/* Get space for the new file name. */ | |
new_file = (char *) alloca (required + 1); | |
/* Generate the new file name. */ | |
DL_DST_SUBSTITUTE (call_map, file, new_file, 0); | |
/* If the substitution failed don't try to load. */ | |
if (*new_file == '\0') | |
_dl_signal_error (0, "dlopen", | |
"empty dynamics string token substitution"); | |
/* Now we have a new file name. */ | |
file = new_file; | |
} | |
/* Load the named object. */ | |
args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0); | |
if (new->l_searchlist.r_list) | |
/* It was already open. */ | |
return; | |
/* Load that object's dependencies. */ | |
global_add = _dl_map_object_deps (new, NULL, 0, 0, mode & RTLD_GLOBAL); | |
/* So far, so good. Now check the versions. */ | |
(void) _dl_check_all_versions (new, 0); | |
#ifdef SCOPE_DEBUG | |
show_scope (new); | |
#endif | |
/* Only do lazy relocation if `LD_BIND_NOW' is not set. */ | |
lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && _dl_lazy; | |
/* Relocate the objects loaded. We do this in reverse order so that copy | |
relocs of earlier objects overwrite the data written by later objects. */ | |
l = new; | |
while (l->l_next) | |
l = l->l_next; | |
while (1) | |
{ | |
if (! l->l_relocated) | |
{ | |
#ifdef PIC | |
if (_dl_profile != NULL) | |
{ | |
/* If this here is the shared object which we want to profile | |
make sure the profile is started. We can find out whether | |
this is necessary or not by observing the `_dl_profile_map' | |
variable. If was NULL but is not NULL afterwars we must | |
start the profiling. */ | |
struct link_map *old_profile_map = _dl_profile_map; | |
_dl_relocate_object (l, l->l_scope, 1, 1); | |
if (old_profile_map == NULL && _dl_profile_map != NULL) | |
/* We must prepare the profiling. */ | |
_dl_start_profile (_dl_profile_map, _dl_profile_output); | |
} | |
else | |
#endif | |
_dl_relocate_object (l, l->l_scope, lazy, 0); | |
} | |
if (l == new) | |
break; | |
l = l->l_prev; | |
} | |
/* Notify the debugger we have added some objects. We need to call | |
_dl_debug_initialize in a static program in case dynamic linking has | |
not been used before. */ | |
r = _dl_debug_initialize (0); | |
r->r_state = RT_ADD; | |
_dl_debug_state (); | |
/* Run the initializer functions of new objects. */ | |
while ((init = _dl_init_next (&new->l_searchlist))) | |
(*(void (*) (int, char **, char **)) init) (__libc_argc, __libc_argv, | |
__environ); | |
/* Now we can make the new map available in the global scope. */ | |
while (global_add-- > 0) | |
_dl_main_searchlist->r_list[_dl_main_searchlist->r_nlist++]->l_global = 1; | |
if (_dl_sysdep_start == NULL) | |
/* We must be the static _dl_open in libc.a. A static program that | |
has loaded a dynamic object now has competition. */ | |
__libc_multiple_libcs = 1; | |
} | |
struct link_map * | |
internal_function | |
_dl_open (const char *file, int mode, const void *caller) | |
{ | |
struct dl_open_args args; | |
char *errstring; | |
int errcode; | |
if ((mode & RTLD_BINDING_MASK) == 0) | |
/* One of the flags must be set. */ | |
_dl_signal_error (EINVAL, file, _("invalid mode for dlopen()")); | |
/* Make sure we are alone. */ | |
__libc_lock_lock (_dl_load_lock); | |
args.file = file; | |
args.mode = mode; | |
args.caller = caller; | |
args.map = NULL; | |
errcode = _dl_catch_error (&errstring, dl_open_worker, &args); | |
#ifndef MAP_COPY | |
/* We must munmap() the cache file. */ | |
_dl_unload_cache (); | |
#endif | |
/* Release the lock. */ | |
__libc_lock_unlock (_dl_load_lock); | |
if (errstring) | |
{ | |
/* Some error occured during loading. */ | |
char *local_errstring; | |
/* Remove the object from memory. It may be in an inconsistent | |
state if relocation failed, for example. */ | |
if (args.map) | |
_dl_close (args.map); | |
/* Make a local copy of the error string so that we can release the | |
memory allocated for it. */ | |
local_errstring = strdupa (errstring); | |
free (errstring); | |
/* Reraise the error. */ | |
_dl_signal_error (errcode, NULL, local_errstring); | |
} | |
return args.map; | |
} | |
#ifdef SCOPE_DEBUG | |
#include <unistd.h> | |
static void | |
show_scope (struct link_map *new) | |
{ | |
int scope_cnt; | |
for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt) | |
{ | |
char numbuf[2]; | |
unsigned int cnt; | |
numbuf[0] = '0' + scope_cnt; | |
numbuf[1] = '\0'; | |
_dl_sysdep_message ("scope ", numbuf, ":", NULL); | |
for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt) | |
if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name) | |
_dl_sysdep_message (" ", | |
new->l_scope[scope_cnt]->r_list[cnt]->l_name, | |
NULL); | |
else | |
_dl_sysdep_message (" <main>", NULL); | |
_dl_sysdep_message ("\n", NULL); | |
} | |
} | |
#endif |