1/*
2 * libjingle
3 * Copyright 2004 Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include "talk/media/devices/libudevsymboltable.h"
29
30#include <dlfcn.h>
31
32#include "webrtc/base/logging.h"
33
34namespace cricket {
35
36#define LATE_BINDING_SYMBOL_TABLE_CLASS_NAME LIBUDEV_SYMBOLS_CLASS_NAME
37#define LATE_BINDING_SYMBOL_TABLE_SYMBOLS_LIST LIBUDEV_SYMBOLS_LIST
38#define LATE_BINDING_SYMBOL_TABLE_DLL_NAME "libudev.so.0"
39#include "webrtc/base/latebindingsymboltable.cc.def"
40#undef LATE_BINDING_SYMBOL_TABLE_CLASS_NAME
41#undef LATE_BINDING_SYMBOL_TABLE_SYMBOLS_LIST
42#undef LATE_BINDING_SYMBOL_TABLE_DLL_NAME
43
44bool IsWrongLibUDevAbiVersion(rtc::DllHandle libudev_0) {
45  rtc::DllHandle libudev_1 = dlopen("libudev.so.1",
46                                          RTLD_NOW|RTLD_LOCAL|RTLD_NOLOAD);
47  bool unsafe_symlink = (libudev_0 == libudev_1);
48  if (unsafe_symlink) {
49    // .0 and .1 are distinct ABIs, so if they point to the same thing then one
50    // of them must be wrong. Probably the old has been symlinked to the new in
51    // a misguided attempt at backwards compatibility.
52    LOG(LS_ERROR) << "libudev.so.0 and libudev.so.1 unsafely point to the"
53                     " same thing; not using libudev";
54  } else if (libudev_1) {
55    // If libudev.so.1 is resident but distinct from libudev.so.0, then some
56    // system library loaded the new ABI separately. This is not a problem for
57    // LateBindingSymbolTable because its symbol look-ups are restricted to its
58    // DllHandle, but having libudev.so.0 resident may cause problems for that
59    // system library because symbol names are not namespaced by DLL. (Although
60    // our use of RTLD_LOCAL should avoid most problems.)
61    LOG(LS_WARNING)
62        << "libudev.so.1 is resident but distinct from libudev.so.0";
63  }
64  if (libudev_1) {
65    // Release the refcount that we acquired above. (Does not unload the DLL;
66    // whoever loaded it still needs it.)
67    dlclose(libudev_1);
68  }
69  return unsafe_symlink;
70}
71
72}  // namespace cricket
73