185 lines
5.8 KiB
C
185 lines
5.8 KiB
C
/* Load a shared object at runtime, relocate it, and run its initializer.
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Copyright (C) 1996, 1997, 1998 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 <link.h>
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#include <dlfcn.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <bits/libc-lock.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 (_dl_sysdep_start)
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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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size_t _dl_global_scope_alloc;
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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_initialized_recursive (, _dl_load_lock)
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struct link_map *
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_dl_open (const char *file, int mode)
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{
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struct link_map *new, *l;
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ElfW(Addr) init;
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struct r_debug *r;
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/* Make sure we are alone. */
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__libc_lock_lock (_dl_load_lock);
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/* Load the named object. */
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new = _dl_map_object (NULL, file, lt_loaded, 0);
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if (new->l_searchlist)
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{
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/* It was already open. */
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__libc_lock_unlock (_dl_load_lock);
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return new;
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}
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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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(void) _dl_check_all_versions (new, 0);
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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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/* We use an indirect call call for _dl_relocate_object because
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we must avoid using the PLT in the call. If our PLT entry for
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_dl_relocate_object hasn't been used yet, then the dynamic
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linker fixup routine will clobber _dl_global_scope during its
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work. We must be sure that nothing will require a PLT fixup
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between when _dl_object_relocation_scope returns and when we
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enter the dynamic linker's code (_dl_relocate_object). */
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__typeof (_dl_relocate_object) *reloc = &_dl_relocate_object;
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/* GCC is very clever. If we wouldn't add some magic it would
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simply optimize away our nice little variable `reloc' and we
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would result in a not working binary. So let's swing the
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magic ward. */
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asm ("" : "=r" (reloc) : "0" (reloc));
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(*reloc) (l, _dl_object_relocation_scope (l),
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(mode & RTLD_BINDING_MASK) == RTLD_LAZY);
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*_dl_global_scope_end = NULL;
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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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new->l_global = (mode & RTLD_GLOBAL) ? 1 : 0;
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if (new->l_global)
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{
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/* The symbols of the new object 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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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 = 8;
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_dl_global_scope = malloc (8 * sizeof (struct link_map *));
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if (! _dl_global_scope)
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{
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_dl_global_scope = _dl_default_scope;
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nomem:
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_dl_close (new);
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_dl_signal_error (ENOMEM, file, "cannot extend global scope");
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}
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_dl_global_scope[2] = _dl_default_scope[2];
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_dl_global_scope[3] = new;
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_dl_global_scope[4] = NULL;
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_dl_global_scope[5] = NULL;
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}
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else
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{
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if (_dl_global_scope_alloc <
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(size_t) (_dl_global_scope_end - _dl_global_scope + 2))
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{
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/* Must extend the list. */
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struct link_map **new = realloc (_dl_global_scope,
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_dl_global_scope_alloc * 2);
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if (! new)
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goto nomem;
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_dl_global_scope_end = new + (_dl_global_scope_end -
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_dl_global_scope);
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_dl_global_scope = new;
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_dl_global_scope_alloc *= 2;
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}
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/* Append the new object and re-terminate the list. */
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*_dl_global_scope_end++ = new;
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/* We keep the list double-terminated so the last element
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can be filled in for symbol lookups. */
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_dl_global_scope_end[0] = NULL;
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_dl_global_scope_end[1] = NULL;
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}
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}
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/* Notify the debugger we have added some objects. We need to call
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_dl_debug_initialize in a static program in case dynamic linking has
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not been used before. */
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r = _dl_debug_initialize (0);
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r->r_state = RT_ADD;
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_dl_debug_state ();
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/* Run the initializer functions of new objects. */
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while (init = _dl_init_next (new))
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(*(void (*) (int, char **, char **)) init) (__libc_argc, __libc_argv,
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__environ);
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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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/* Release the lock. */
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__libc_lock_unlock (_dl_load_lock);
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return new;
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}
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