1 | /* Look up a symbol in a shared object loaded by `dlopen'. |
2 | Copyright (C) 1995-2017 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <dlfcn.h> |
20 | #include <stddef.h> |
21 | |
22 | #include <ldsodefs.h> |
23 | |
24 | #if !defined SHARED && IS_IN (libdl) |
25 | |
26 | void * |
27 | dlsym (void *handle, const char *name) |
28 | { |
29 | return __dlsym (handle, name, RETURN_ADDRESS (0)); |
30 | } |
31 | |
32 | #else |
33 | |
34 | struct dlsym_args |
35 | { |
36 | /* The arguments to dlsym_doit. */ |
37 | void *handle; |
38 | const char *name; |
39 | void *who; |
40 | |
41 | /* The return value of dlsym_doit. */ |
42 | void *sym; |
43 | }; |
44 | |
45 | static void |
46 | dlsym_doit (void *a) |
47 | { |
48 | struct dlsym_args *args = (struct dlsym_args *) a; |
49 | |
50 | args->sym = _dl_sym (args->handle, args->name, args->who); |
51 | } |
52 | |
53 | |
54 | void * |
55 | __dlsym (void *handle, const char *name DL_CALLER_DECL) |
56 | { |
57 | # ifdef SHARED |
58 | if (__glibc_unlikely (_dlfcn_hook != NULL)) |
59 | return _dlfcn_hook->dlsym (handle, name, DL_CALLER); |
60 | # endif |
61 | |
62 | struct dlsym_args args; |
63 | args.who = DL_CALLER; |
64 | args.handle = handle; |
65 | args.name = name; |
66 | |
67 | /* Protect against concurrent loads and unloads. */ |
68 | __rtld_lock_lock_recursive (GL(dl_load_lock)); |
69 | |
70 | void *result = (_dlerror_run (dlsym_doit, &args) ? NULL : args.sym); |
71 | |
72 | __rtld_lock_unlock_recursive (GL(dl_load_lock)); |
73 | |
74 | return result; |
75 | } |
76 | # ifdef SHARED |
77 | strong_alias (__dlsym, dlsym) |
78 | # endif |
79 | #endif |
80 | |