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| 1 // Copyright (c) 2010 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 #ifndef APP_WIN_IAT_PATCH_FUNCTION_H_ | |
| 6 #define APP_WIN_IAT_PATCH_FUNCTION_H_ | |
| 7 #pragma once | |
| 8 | |
| 9 #include <windows.h> | |
| 10 | |
| 11 #include "base/basictypes.h" | |
| 12 | |
| 13 namespace app { | |
| 14 namespace win { | |
| 15 | |
| 16 // A class that encapsulates Import Address Table patching helpers and restores | |
| 17 // the original function in the destructor. | |
| 18 // | |
| 19 // It will intercept functions for a specific DLL imported from another DLL. | |
| 20 // This is the case when, for example, we want to intercept | |
| 21 // CertDuplicateCertificateContext function (exported from crypt32.dll) called | |
| 22 // by wininet.dll. | |
| 23 class IATPatchFunction { | |
| 24 public: | |
| 25 IATPatchFunction(); | |
| 26 ~IATPatchFunction(); | |
| 27 | |
| 28 // Intercept a function in an import table of a specific | |
| 29 // module. Save the original function and the import | |
| 30 // table address. These values will be used later | |
| 31 // during Unpatch | |
| 32 // | |
| 33 // Arguments: | |
| 34 // module Module to be intercepted | |
| 35 // imported_from_module Module that exports the 'function_name' | |
| 36 // function_name Name of the API to be intercepted | |
| 37 // | |
| 38 // Returns: Windows error code (winerror.h). NO_ERROR if successful | |
| 39 // | |
| 40 // Note: Patching a function will make the IAT patch take some "ownership" on | |
| 41 // |module|. It will LoadLibrary(module) to keep the DLL alive until a call | |
| 42 // to Unpatch(), which will call FreeLibrary() and allow the module to be | |
| 43 // unloaded. The idea is to help prevent the DLL from going away while a | |
| 44 // patch is still active. | |
| 45 DWORD Patch(const wchar_t* module, | |
| 46 const char* imported_from_module, | |
| 47 const char* function_name, | |
| 48 void* new_function); | |
| 49 | |
| 50 // Unpatch the IAT entry using internally saved original | |
| 51 // function. | |
| 52 // | |
| 53 // Returns: Windows error code (winerror.h). NO_ERROR if successful | |
| 54 DWORD Unpatch(); | |
| 55 | |
| 56 bool is_patched() const { | |
| 57 return (NULL != intercept_function_); | |
| 58 } | |
| 59 | |
| 60 private: | |
| 61 HMODULE module_handle_; | |
| 62 void* intercept_function_; | |
| 63 void* original_function_; | |
| 64 IMAGE_THUNK_DATA* iat_thunk_; | |
| 65 | |
| 66 DISALLOW_COPY_AND_ASSIGN(IATPatchFunction); | |
| 67 }; | |
| 68 | |
| 69 } // namespace win | |
| 70 } // namespace app | |
| 71 | |
| 72 #endif // APP_WIN_IAT_PATCH_FUNCTION_H_ | |
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