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
|
/* 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 <link.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <errno.h>
#include <bits/libc-lock.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)
extern int __libc_multiple_libcs; /* Defined in init-first.c. */
extern int __libc_argc;
extern char **__libc_argv;
extern char **__environ;
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)
struct link_map *
_dl_open (const char *file, int mode)
{
struct link_map *new, *l;
ElfW(Addr) init;
struct r_debug *r;
/* Make sure we are alone. */
__libc_lock_lock (_dl_load_lock);
/* Load the named object. */
new = _dl_map_object (NULL, file, 0, lt_loaded, 0);
if (new->l_searchlist)
{
/* It was already open. */
__libc_lock_unlock (_dl_load_lock);
return new;
}
/* 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)
{
/* We use an indirect call call for _dl_relocate_object because
we must avoid using the PLT in the call. If our PLT entry for
_dl_relocate_object hasn't been used yet, then the dynamic
linker fixup routine will clobber _dl_global_scope during its
work. We must be sure that nothing will require a PLT fixup
between when _dl_object_relocation_scope returns and when we
enter the dynamic linker's code (_dl_relocate_object). */
__typeof (_dl_relocate_object) *reloc = &_dl_relocate_object;
/* GCC is very clever. If we wouldn't add some magic it would
simply optimize away our nice little variable `reloc' and we
would result in a not working binary. So let's swing the
magic ward. */
asm ("" : "=r" (reloc) : "0" (reloc));
(*reloc) (l, _dl_object_relocation_scope (l),
(mode & RTLD_BINDING_MASK) == RTLD_LAZY);
*_dl_global_scope_end = NULL;
}
if (l == new)
break;
l = l->l_prev;
}
new->l_global = (mode & RTLD_GLOBAL) ? 1 : 0;
if (new->l_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. */
if (_dl_global_scope_alloc == 0)
{
/* This is the first dynamic object given global scope. */
_dl_global_scope_alloc = 8;
_dl_global_scope = malloc (8 * sizeof (struct link_map *));
if (! _dl_global_scope)
{
_dl_global_scope = _dl_default_scope;
nomem:
_dl_close (new);
_dl_signal_error (ENOMEM, file, "cannot extend global scope");
}
_dl_global_scope[2] = _dl_default_scope[2];
_dl_global_scope[3] = new;
_dl_global_scope[4] = NULL;
_dl_global_scope[5] = NULL;
}
else
{
if (_dl_global_scope_alloc <
(size_t) (_dl_global_scope_end - _dl_global_scope + 2))
{
/* Must extend the list. */
struct link_map **new = realloc (_dl_global_scope,
_dl_global_scope_alloc * 2);
if (! new)
goto nomem;
_dl_global_scope_end = new + (_dl_global_scope_end -
_dl_global_scope);
_dl_global_scope = new;
_dl_global_scope_alloc *= 2;
}
/* Append the new object and re-terminate the list. */
*_dl_global_scope_end++ = new;
/* We keep the list double-terminated so the last element
can be filled in for symbol lookups. */
_dl_global_scope_end[0] = NULL;
_dl_global_scope_end[1] = NULL;
}
}
/* 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))
(*(void (*) (int, char **, char **)) init) (__libc_argc, __libc_argv,
__environ);
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;
/* Release the lock. */
__libc_lock_unlock (_dl_load_lock);
return new;
}
|
