/* 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 <libintl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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;
/* DSTs must not appear in SUID/SGID programs. */
if (__libc_enable_secure)
/* This is an error. */
_dl_signal_error (0, "dlopen",
"DST not allowed in SUID/SGID programs");
/* 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 dynamic 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;
}
void *
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