1/* Look up a symbol in a shared object loaded by `dlopen'.
2 Copyright (C) 1995-2020 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 <https://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
26void *
27dlsym (void *handle, const char *name)
28{
29 return __dlsym (handle, name, RETURN_ADDRESS (0));
30}
31
32#else
33
34struct 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
45static void
46dlsym_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
54void *
55__dlsym (void *handle, const char *name DL_CALLER_DECL)
56{
57# ifdef SHARED
58 if (!rtld_active ())
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
77strong_alias (__dlsym, dlsym)
78# endif
79#endif
80