390 lines
11 KiB
C
390 lines
11 KiB
C
/* Load a shared object at runtime, relocate it, and run its initializer.
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Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <assert.h>
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#include <dlfcn.h>
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#include <errno.h>
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#include <libintl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mman.h> /* Check whether MAP_COPY is defined. */
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#include <sys/param.h>
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#include <bits/libc-lock.h>
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#include <ldsodefs.h>
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#include <bp-sym.h>
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#include <dl-dst.h>
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extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
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void (*dl_main) (const ElfW(Phdr) *phdr,
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ElfW(Word) phnum,
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ElfW(Addr) *user_entry));
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weak_extern (BP_SYM (_dl_sysdep_start))
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/* This function is used to unload the cache file if necessary. */
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extern void _dl_unload_cache (void);
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extern int __libc_multiple_libcs; /* Defined in init-first.c. */
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extern int __libc_argc;
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extern char **__libc_argv;
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extern char **__environ;
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extern int _dl_lazy; /* Do we do lazy relocations? */
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/* Undefine the following for debugging. */
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/* #define SCOPE_DEBUG 1 */
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#ifdef SCOPE_DEBUG
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static void show_scope (struct link_map *new);
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#endif
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/* During the program run we must not modify the global data of
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loaded shared object simultanously in two threads. Therefore we
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protect `_dl_open' and `_dl_close' in dl-close.c.
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This must be a recursive lock since the initializer function of
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the loaded object might as well require a call to this function.
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At this time it is not anymore a problem to modify the tables. */
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__libc_lock_define (extern, _dl_load_lock)
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extern size_t _dl_platformlen;
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/* We must be carefull not to leave us in an inconsistent state. Thus we
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catch any error and re-raise it after cleaning up. */
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struct dl_open_args
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{
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const char *file;
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int mode;
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const void *caller;
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struct link_map *map;
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};
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static void
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dl_open_worker (void *a)
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{
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struct dl_open_args *args = a;
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const char *file = args->file;
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int mode = args->mode;
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struct link_map *new, *l;
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const char *dst;
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int lazy;
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unsigned int i;
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/* Maybe we have to expand a DST. */
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dst = strchr (file, '$');
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if (dst != NULL)
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{
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const void *caller = args->caller;
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size_t len = strlen (file);
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size_t required;
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struct link_map *call_map;
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char *new_file;
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/* DSTs must not appear in SUID/SGID programs. */
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if (__libc_enable_secure)
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/* This is an error. */
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_dl_signal_error (0, "dlopen",
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N_("DST not allowed in SUID/SGID programs"));
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/* We have to find out from which object the caller is calling.
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Find the highest-addressed object that ADDRESS is not below. */
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call_map = NULL;
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for (l = _dl_loaded; l; l = l->l_next)
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if (l->l_addr != 0 /* Make sure we do not currently set this map up
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in this moment. */
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&& caller >= (const void *) l->l_map_start
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&& caller < (const void *) l->l_map_end)
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{
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/* There must be exactly one DSO for the range of the virtual
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memory. Otherwise something is really broken. */
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call_map = l;
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break;
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}
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if (call_map == NULL)
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/* In this case we assume this is the main application. */
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call_map = _dl_loaded;
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/* Determine how much space we need. We have to allocate the
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memory locally. */
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required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
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/* Get space for the new file name. */
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new_file = (char *) alloca (required + 1);
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/* Generate the new file name. */
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DL_DST_SUBSTITUTE (call_map, file, new_file, 0);
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/* If the substitution failed don't try to load. */
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if (*new_file == '\0')
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_dl_signal_error (0, "dlopen",
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N_("empty dynamic string token substitution"));
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/* Now we have a new file name. */
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file = new_file;
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}
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/* Load the named object. */
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args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0,
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mode);
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/* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
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set and the object is not already loaded. */
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if (new == NULL)
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{
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assert (mode & RTLD_NOLOAD);
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return;
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}
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if (new->l_searchlist.r_list)
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/* It was already open. */
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return;
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/* Load that object's dependencies. */
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_dl_map_object_deps (new, NULL, 0, 0);
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/* So far, so good. Now check the versions. */
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for (i = 0; i < new->l_searchlist.r_nlist; ++i)
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if (new->l_searchlist.r_list[i]->l_versions == NULL)
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(void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
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#ifdef SCOPE_DEBUG
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show_scope (new);
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#endif
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/* Only do lazy relocation if `LD_BIND_NOW' is not set. */
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lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && _dl_lazy;
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/* Relocate the objects loaded. We do this in reverse order so that copy
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relocs of earlier objects overwrite the data written by later objects. */
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l = new;
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while (l->l_next)
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l = l->l_next;
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while (1)
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{
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if (! l->l_relocated)
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{
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#ifdef SHARED
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if (_dl_profile != NULL)
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{
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/* If this here is the shared object which we want to profile
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make sure the profile is started. We can find out whether
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this is necessary or not by observing the `_dl_profile_map'
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variable. If was NULL but is not NULL afterwars we must
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start the profiling. */
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struct link_map *old_profile_map = _dl_profile_map;
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_dl_relocate_object (l, l->l_scope, 1, 1);
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if (old_profile_map == NULL && _dl_profile_map != NULL)
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/* We must prepare the profiling. */
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_dl_start_profile (_dl_profile_map, _dl_profile_output);
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}
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else
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#endif
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_dl_relocate_object (l, l->l_scope, lazy, 0);
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}
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if (l == new)
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break;
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l = l->l_prev;
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}
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/* Run the initializer functions of new objects. */
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_dl_init (new, __libc_argc, __libc_argv, __environ);
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/* Now we can make the new map available in the global scope. */
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if (mode & RTLD_GLOBAL)
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{
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struct link_map **new_global;
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unsigned int to_add = 0;
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unsigned int cnt;
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/* Count the objects we have to put in the global scope. */
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for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
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if (new->l_searchlist.r_list[cnt]->l_global == 0)
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++to_add;
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/* The symbols of the new objects and its dependencies are to be
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introduced into the global scope that will be used to resolve
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references from other dynamically-loaded objects.
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The global scope is the searchlist in the main link map. We
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extend this list if necessary. There is one problem though:
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since this structure was allocated very early (before the libc
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is loaded) the memory it uses is allocated by the malloc()-stub
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in the ld.so. When we come here these functions are not used
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anymore. Instead the malloc() implementation of the libc is
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used. But this means the block from the main map cannot be used
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in an realloc() call. Therefore we allocate a completely new
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array the first time we have to add something to the locale scope. */
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if (_dl_global_scope_alloc == 0)
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{
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/* This is the first dynamic object given global scope. */
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_dl_global_scope_alloc = _dl_main_searchlist->r_nlist + to_add + 8;
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new_global = (struct link_map **)
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malloc (_dl_global_scope_alloc * sizeof (struct link_map *));
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if (new_global == NULL)
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{
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_dl_global_scope_alloc = 0;
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nomem:
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_dl_signal_error (ENOMEM, new->l_libname->name,
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N_("cannot extend global scope"));
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return;
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}
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/* Copy over the old entries. */
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memcpy (new_global, _dl_main_searchlist->r_list,
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(_dl_main_searchlist->r_nlist * sizeof (struct link_map *)));
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_dl_main_searchlist->r_list = new_global;
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}
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else if (_dl_main_searchlist->r_nlist + to_add > _dl_global_scope_alloc)
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{
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/* We have to extend the existing array of link maps in the
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main map. */
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new_global = (struct link_map **)
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realloc (_dl_main_searchlist->r_list,
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((_dl_global_scope_alloc + to_add + 8)
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* sizeof (struct link_map *)));
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if (new_global == NULL)
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goto nomem;
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_dl_global_scope_alloc += to_add + 8;
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_dl_main_searchlist->r_list = new_global;
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}
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/* Now add the new entries. */
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for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
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{
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struct link_map *map = new->l_searchlist.r_list[cnt];
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if (map->l_global == 0)
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{
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map->l_global = 1;
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_dl_main_searchlist->r_list[_dl_main_searchlist->r_nlist] = map;
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++_dl_main_searchlist->r_nlist;
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}
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}
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/* XXX Do we have to add something to r_dupsearchlist??? --drepper */
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}
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/* Mark the object as not deletable if the RTLD_NODELETE flags was
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passed. */
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if (__builtin_expect (mode & RTLD_NODELETE, 0))
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new->l_flags_1 |= DF_1_NODELETE;
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if (_dl_sysdep_start == NULL)
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/* We must be the static _dl_open in libc.a. A static program that
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has loaded a dynamic object now has competition. */
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__libc_multiple_libcs = 1;
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}
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void *
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internal_function
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_dl_open (const char *file, int mode, const void *caller)
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{
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struct dl_open_args args;
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const char *objname;
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const char *errstring;
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int errcode;
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if ((mode & RTLD_BINDING_MASK) == 0)
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/* One of the flags must be set. */
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_dl_signal_error (EINVAL, file, N_("invalid mode for dlopen()"));
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/* Make sure we are alone. */
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__libc_lock_lock (_dl_load_lock);
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args.file = file;
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args.mode = mode;
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args.caller = caller;
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args.map = NULL;
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errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
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#ifndef MAP_COPY
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/* We must munmap() the cache file. */
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_dl_unload_cache ();
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#endif
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/* Release the lock. */
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__libc_lock_unlock (_dl_load_lock);
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if (errstring)
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{
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/* Some error occurred during loading. */
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char *local_errstring;
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/* Remove the object from memory. It may be in an inconsistent
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state if relocation failed, for example. */
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if (args.map)
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_dl_close (args.map);
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/* Make a local copy of the error string so that we can release the
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memory allocated for it. */
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local_errstring = strdupa (errstring);
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if (errstring != _dl_out_of_memory)
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free ((char *) errstring);
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/* Reraise the error. */
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_dl_signal_error (errcode, objname, local_errstring);
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}
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return args.map;
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}
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#ifdef SCOPE_DEBUG
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#include <unistd.h>
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static void
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show_scope (struct link_map *new)
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{
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int scope_cnt;
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for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
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{
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char numbuf[2];
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unsigned int cnt;
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numbuf[0] = '0' + scope_cnt;
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numbuf[1] = '\0';
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_dl_sysdep_message ("scope ", numbuf, ":", NULL);
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for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
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if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
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_dl_sysdep_message (" ",
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new->l_scope[scope_cnt]->r_list[cnt]->l_name,
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NULL);
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else
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_dl_sysdep_message (" <main>", NULL);
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_dl_sysdep_message ("\n", NULL);
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}
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}
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#endif
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