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      1 /*
      2  * libjingle
      3  * Copyright 2004--2010, 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/base/latebindingsymboltable.h"
     29 
     30 #ifdef LINUX
     31 #include <dlfcn.h>
     32 #endif
     33 
     34 #include "talk/base/logging.h"
     35 
     36 namespace talk_base {
     37 
     38 inline static const char *GetDllError() {
     39 #ifdef LINUX
     40   char *err = dlerror();
     41   if (err) {
     42     return err;
     43   } else {
     44     return "No error";
     45   }
     46 #else
     47 #error Not implemented
     48 #endif
     49 }
     50 
     51 DllHandle InternalLoadDll(const char dll_name[]) {
     52 #ifdef LINUX
     53   DllHandle handle = dlopen(dll_name, RTLD_NOW);
     54 #else
     55 #error Not implemented
     56 #endif
     57   if (handle == kInvalidDllHandle) {
     58     LOG(LS_WARNING) << "Can't load " << dll_name << ": " << GetDllError();
     59   }
     60   return handle;
     61 }
     62 
     63 void InternalUnloadDll(DllHandle handle) {
     64 #ifdef LINUX
     65   if (dlclose(handle) != 0) {
     66     LOG(LS_ERROR) << GetDllError();
     67   }
     68 #else
     69 #error Not implemented
     70 #endif
     71 }
     72 
     73 static bool LoadSymbol(DllHandle handle,
     74                        const char *symbol_name,
     75                        void **symbol) {
     76 #ifdef LINUX
     77   *symbol = dlsym(handle, symbol_name);
     78   char *err = dlerror();
     79   if (err) {
     80     LOG(LS_ERROR) << "Error loading symbol " << symbol_name << ": " << err;
     81     return false;
     82   } else if (!*symbol) {
     83     LOG(LS_ERROR) << "Symbol " << symbol_name << " is NULL";
     84     return false;
     85   }
     86   return true;
     87 #else
     88 #error Not implemented
     89 #endif
     90 }
     91 
     92 // This routine MUST assign SOME value for every symbol, even if that value is
     93 // NULL, or else some symbols may be left with uninitialized data that the
     94 // caller may later interpret as a valid address.
     95 bool InternalLoadSymbols(DllHandle handle,
     96                          int num_symbols,
     97                          const char *const symbol_names[],
     98                          void *symbols[]) {
     99 #ifdef LINUX
    100   // Clear any old errors.
    101   dlerror();
    102 #endif
    103   for (int i = 0; i < num_symbols; ++i) {
    104     if (!LoadSymbol(handle, symbol_names[i], &symbols[i])) {
    105       return false;
    106     }
    107   }
    108   return true;
    109 }
    110 
    111 }  // namespace talk_base
    112