linux: don't always print dlopen errors from LoadNativeLibrary

webkit/plugins/npapi/plugin_lib_posix.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/plugins/npapi/plugin_lib.h"
 
 #include <dlfcn.h>
 #if defined(OS_OPENBSD)
 #include <sys/exec_elf.h>
 #else
 #include <elf.h>
@@ skipping 97 matching lines @@
     path_end = info->path + sizeof(info->path);
   FilePath path = FilePath(std::string(info->path, path_end - info->path));
 
   if (!ELFMatchesCurrentArchitecture(path)) {
     LOG(WARNING) << path.value() << " is nspluginwrapper wrapping a "
                  << "plugin for a different architecture; it will "
                  << "work better if you instead use a native plugin.";
     return;
   }
 
-  void* newdl = base::LoadNativeLibrary(path);
+  std::string error;
+  void* newdl = base::LoadNativeLibrary(path, &error);
   if (!newdl) {
     // We couldn't load the unwrapped plugin for some reason, despite
     // being able to load the wrapped one.  Just use the wrapped one.
     LOG_IF(ERROR, PluginList::DebugPluginLoading())
         << "Could not use unwrapped nspluginwrapper plugin "
-        << unwrapped_path->value() << ", using the wrapped one.";
+        << unwrapped_path->value() << " (" << error << "), "
+        << "using the wrapped one.";
     return;
   }
 
   // Unload the wrapped plugin, and use the wrapped plugin instead.
   LOG_IF(ERROR, PluginList::DebugPluginLoading())
       << "Using unwrapped version " << unwrapped_path->value()
       << " of nspluginwrapper-wrapped plugin.";
   base::UnloadNativeLibrary(*dl);
   *dl = newdl;
   *unwrapped_path = path;
 }
 
 }  // namespace
 
 bool PluginLib::ReadWebPluginInfo(const FilePath& filename,
                                   WebPluginInfo* info) {
   // The file to reference is:
   // http://mxr.mozilla.org/firefox/source/modules/plugin/base/src/nsPluginsDirUnix.cpp
 
   // Skip files that aren't appropriate for our architecture.
   if (!ELFMatchesCurrentArchitecture(filename)) {
     LOG_IF(ERROR, PluginList::DebugPluginLoading())
         << "Skipping plugin " << filename.value()
         << " because it doesn't match the current architecture.";
     return false;
   }
 
-  void* dl = base::LoadNativeLibrary(filename);
+  std::string error;
+  void* dl = base::LoadNativeLibrary(filename, &error);
   if (!dl) {
     LOG_IF(ERROR, PluginList::DebugPluginLoading())
         << "While reading plugin info, unable to load library "
-        << filename.value() << ", skipping.";
+        << filename.value() << " (" << error << "), skipping.";
     return false;
   }
 
   info->path = filename;
   info->enabled = WebPluginInfo::USER_ENABLED;
 
   // Attempt to swap in the wrapped plugin if this is nspluginwrapper.
   UnwrapNSPluginWrapper(&dl, &info->path);
 
   // See comments in plugin_lib_mac regarding this symbol.
@@ skipping 119 matching lines @@
       break;
     }
   }
   if (!version.empty()) {
     info->version = UTF8ToUTF16(version);
   }
 }
 
 }  // namespace npapi
 }  // namespace webkit