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 
34 namespace 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 
IsWrongLibUDevAbiVersion(rtc::DllHandle libudev_0)44 bool 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