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      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 
     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