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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/native_library.h"
      6 
      7 #include <windows.h>
      8 
      9 #include "base/file_util.h"
     10 #include "base/threading/thread_restrictions.h"
     11 #include "base/utf_string_conversions.h"
     12 
     13 namespace base {
     14 
     15 typedef HMODULE (WINAPI* LoadLibraryFunction)(const wchar_t* file_name);
     16 
     17 NativeLibrary LoadNativeLibraryHelper(const FilePath& library_path,
     18                                       LoadLibraryFunction load_library_api) {
     19   // LoadLibrary() opens the file off disk.
     20   base::ThreadRestrictions::AssertIOAllowed();
     21 
     22   // Switch the current directory to the library directory as the library
     23   // may have dependencies on DLLs in this directory.
     24   bool restore_directory = false;
     25   FilePath current_directory;
     26   if (file_util::GetCurrentDirectory(&current_directory)) {
     27     FilePath plugin_path = library_path.DirName();
     28     if (!plugin_path.empty()) {
     29       file_util::SetCurrentDirectory(plugin_path);
     30       restore_directory = true;
     31     }
     32   }
     33 
     34   HMODULE module = (*load_library_api)(library_path.value().c_str());
     35   if (restore_directory)
     36     file_util::SetCurrentDirectory(current_directory);
     37 
     38   return module;
     39 }
     40 
     41 // static
     42 NativeLibrary LoadNativeLibrary(const FilePath& library_path,
     43                                 std::string* error) {
     44   return LoadNativeLibraryHelper(library_path, LoadLibraryW);
     45 }
     46 
     47 NativeLibrary LoadNativeLibraryDynamically(const FilePath& library_path) {
     48   typedef HMODULE (WINAPI* LoadLibraryFunction)(const wchar_t* file_name);
     49 
     50   LoadLibraryFunction load_library;
     51   load_library = reinterpret_cast<LoadLibraryFunction>(
     52       GetProcAddress(GetModuleHandle(L"kernel32.dll"), "LoadLibraryW"));
     53 
     54   return LoadNativeLibraryHelper(library_path, load_library);
     55 }
     56 
     57 // static
     58 void UnloadNativeLibrary(NativeLibrary library) {
     59   FreeLibrary(library);
     60 }
     61 
     62 // static
     63 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
     64                                           const char* name) {
     65   return GetProcAddress(library, name);
     66 }
     67 
     68 // static
     69 string16 GetNativeLibraryName(const string16& name) {
     70   return name + ASCIIToUTF16(".dll");
     71 }
     72 
     73 }  // namespace base
     74