summary refs log tree commit diff
path: root/dlfcn/dlsym.c
blob: 285abaaa4e09b16f3bbd88e066c5c556f42236be (plain) (blame)
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
/* Look up a symbol in a shared object loaded by `dlopen'.
   Copyright (C) 1995-2018 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <dlfcn.h>
#include <stddef.h>

#include <ldsodefs.h>

#if !defined SHARED && IS_IN (libdl)

void *
dlsym (void *handle, const char *name)
{
  return __dlsym (handle, name, RETURN_ADDRESS (0));
}

#else

struct dlsym_args
{
  /* The arguments to dlsym_doit.  */
  void *handle;
  const char *name;
  void *who;

  /* The return value of dlsym_doit.  */
  void *sym;
};

static void
dlsym_doit (void *a)
{
  struct dlsym_args *args = (struct dlsym_args *) a;

  args->sym = _dl_sym (args->handle, args->name, args->who);
}


void *
__dlsym (void *handle, const char *name DL_CALLER_DECL)
{
# ifdef SHARED
  if (!rtld_active ())
    return _dlfcn_hook->dlsym (handle, name, DL_CALLER);
# endif

  struct dlsym_args args;
  args.who = DL_CALLER;
  args.handle = handle;
  args.name = name;

  /* Protect against concurrent loads and unloads.  */
  __rtld_lock_lock_recursive (GL(dl_load_lock));

  void *result = (_dlerror_run (dlsym_doit, &args) ? NULL : args.sym);

  __rtld_lock_unlock_recursive (GL(dl_load_lock));

  return result;
}
# ifdef SHARED
strong_alias (__dlsym, dlsym)
# endif
#endif