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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/strings/stringprintf.h"
     11 #include "base/strings/utf_string_conversions.h"
     12 #include "base/threading/thread_restrictions.h"
     13 
     14 namespace base {
     15 
     16 typedef HMODULE (WINAPI* LoadLibraryFunction)(const wchar_t* file_name);
     17 
     18 namespace {
     19 
     20 NativeLibrary LoadNativeLibraryHelper(const FilePath& library_path,
     21                                       LoadLibraryFunction load_library_api,
     22                                       NativeLibraryLoadError* error) {
     23   // LoadLibrary() opens the file off disk.
     24   ThreadRestrictions::AssertIOAllowed();
     25 
     26   // Switch the current directory to the library directory as the library
     27   // may have dependencies on DLLs in this directory.
     28   bool restore_directory = false;
     29   FilePath current_directory;
     30   if (GetCurrentDirectory(&current_directory)) {
     31     FilePath plugin_path = library_path.DirName();
     32     if (!plugin_path.empty()) {
     33       SetCurrentDirectory(plugin_path);
     34       restore_directory = true;
     35     }
     36   }
     37 
     38   HMODULE module = (*load_library_api)(library_path.value().c_str());
     39   if (!module && error) {
     40     // GetLastError() needs to be called immediately after |load_library_api|.
     41     error->code = GetLastError();
     42   }
     43 
     44   if (restore_directory)
     45     SetCurrentDirectory(current_directory);
     46 
     47   return module;
     48 }
     49 
     50 }  // namespace
     51 
     52 std::string NativeLibraryLoadError::ToString() const {
     53   return StringPrintf("%u", code);
     54 }
     55 
     56 // static
     57 NativeLibrary LoadNativeLibrary(const FilePath& library_path,
     58                                 NativeLibraryLoadError* error) {
     59   return LoadNativeLibraryHelper(library_path, LoadLibraryW, error);
     60 }
     61 
     62 NativeLibrary LoadNativeLibraryDynamically(const FilePath& library_path) {
     63   typedef HMODULE (WINAPI* LoadLibraryFunction)(const wchar_t* file_name);
     64 
     65   LoadLibraryFunction load_library;
     66   load_library = reinterpret_cast<LoadLibraryFunction>(
     67       GetProcAddress(GetModuleHandle(L"kernel32.dll"), "LoadLibraryW"));
     68 
     69   return LoadNativeLibraryHelper(library_path, load_library, NULL);
     70 }
     71 
     72 // static
     73 void UnloadNativeLibrary(NativeLibrary library) {
     74   FreeLibrary(library);
     75 }
     76 
     77 // static
     78 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
     79                                           const char* name) {
     80   return GetProcAddress(library, name);
     81 }
     82 
     83 // static
     84 string16 GetNativeLibraryName(const string16& name) {
     85   return name + ASCIIToUTF16(".dll");
     86 }
     87 
     88 }  // namespace base
     89