1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
|
/* Load a shared object at runtime, relocate it, and run its initializer.
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 <dlfcn.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h> /* Check whether MAP_COPY is defined. */
#include <bits/libc-lock.h>
#include <elf/ldsodefs.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;
static size_t _dl_global_scope_alloc;
/* 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)
/* 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;
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;
/* 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. */
_dl_map_object_deps (new, NULL, 0, 0);
/* So far, so good. Now check the versions. */
(void) _dl_check_all_versions (new, 0);
/* 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,
(mode & RTLD_BINDING_MASK) == RTLD_LAZY, 0);
}
if (l == new)
break;
l = l->l_prev;
}
new->l_global = (mode & RTLD_GLOBAL) ? 1 : 0;
if (new->l_global)
{
struct link_map **new_global;
/* The symbols of the new object and its dependencies are to be
introduced into the global scope that will be used to resolve
references from other dynamically-loaded objects.
The global scope is the searchlist in the main link map. We
extend this list if necessary. There is one problem though:
since this structure was allocated very early (before the libc
is loaded) the memory it uses is allocated by the malloc()-stub
in the ld.so. When we come here these functions are not used
anymore. Instead the malloc() implementation of the libc is
used. But this means the block from the main map cannot be used
in an realloc() call. Therefore we allocate a completely new
array the first time we have to add something to the locale scope. */
if (_dl_global_scope_alloc == 0)
{
/* This is the first dynamic object given global scope. */
_dl_global_scope_alloc = _dl_main_searchlist->r_nlist + 8;
new_global = (struct link_map **)
malloc (_dl_global_scope_alloc * sizeof (struct link_map *));
if (new_global == NULL)
{
_dl_global_scope_alloc = 0;
nomem:
new->l_global = 0;
_dl_signal_error (ENOMEM, file, "cannot extend global scope");
}
/* Copy over the old entries. */
memcpy (new_global, _dl_main_searchlist->r_list,
(_dl_main_searchlist->r_nlist * sizeof (struct link_map *)));
_dl_main_searchlist->r_list = new_global;
}
else if (_dl_main_searchlist->r_nlist == _dl_global_scope_alloc)
{
/* We have to extend the existing array of link maps in the
main map. */
new_global = (struct link_map **)
malloc ((_dl_global_scope_alloc + 8) * sizeof (struct link_map *));
if (new_global == NULL)
goto nomem;
_dl_global_scope_alloc += 8;
_dl_main_searchlist->r_list = new_global;
}
/* Now add the new entry. */
_dl_main_searchlist->r_list[_dl_main_searchlist->r_nlist] = new;
/* XXX Do we have to add something to r_dupsearchlist??? --drepper */
}
/* 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);
if (new->l_global)
/* Now we can make the new map available in the global scope. */
++_dl_main_searchlist->r_nlist;
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)
{
struct dl_open_args args;
char *errstring;
int errcode;
/* Make sure we are alone. */
__libc_lock_lock (_dl_load_lock);
args.file = file;
args.mode = mode;
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;
}
|
