1 //===-- interception.h ------------------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of AddressSanitizer, an address sanity checker. 11 // 12 // Machinery for providing replacements/wrappers for system functions. 13 //===----------------------------------------------------------------------===// 14 15 #ifndef INTERCEPTION_H 16 #define INTERCEPTION_H 17 18 #if !defined(__linux__) && !defined(__APPLE__) && !defined(_WIN32) 19 # error "Interception doesn't work on this operating system." 20 #endif 21 22 // How to use this library: 23 // 1) Include this header to define your own interceptors 24 // (see details below). 25 // 2) Build all *.cc files and link against them. 26 // On Mac you will also need to: 27 // 3) Provide your own implementation for the following functions: 28 // mach_error_t __interception::allocate_island(void **ptr, 29 // size_t size, 30 // void *hint); 31 // mach_error_t __interception::deallocate_island(void *ptr); 32 // See "interception_mac.h" for more details. 33 34 // How to add an interceptor: 35 // Suppose you need to wrap/replace system function (generally, from libc): 36 // int foo(const char *bar, double baz); 37 // You'll need to: 38 // 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in 39 // your source file. 40 // 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo". 41 // INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was 42 // intercepted successfully. 43 // You can access original function by calling REAL(foo)(bar, baz). 44 // By default, REAL(foo) will be visible only inside your interceptor, and if 45 // you want to use it in other parts of RTL, you'll need to: 46 // 3a) add DECLARE_REAL(int, foo, const char*, double); to a 47 // header file. 48 // However, if the call "INTERCEPT_FUNCTION(foo)" and definition for 49 // INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to: 50 // 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double); 51 // to a header file. 52 53 // Notes: 1. Things may not work properly if macro INTERCEPT(...) {...} or 54 // DECLARE_REAL(...); are located inside namespaces. 55 // 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo);" to 56 // effectively redirect calls from "foo" to "zoo". In this case 57 // you aren't required to implement 58 // INTERCEPTOR(int, foo, const char *bar, double baz); 59 // but instead you'll have to add 60 // DEFINE_REAL(int, foo, const char *bar, double baz); in your 61 // source file (to define a pointer to overriden function). 62 63 // How it works: 64 // To replace weak system functions on Linux we just need to declare functions 65 // with same names in our library and then obtain the real function pointers 66 // using dlsym(). This is not so on Mac OS, where the two-level namespace makes 67 // our replacement functions invisible to other libraries. This may be overcomed 68 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared 69 // libraries in Chromium were noticed when doing so. 70 // Instead we use mach_override, a handy framework for patching functions at 71 // runtime. To avoid possible name clashes, our replacement functions have 72 // the "wrap_" prefix on Mac. 73 74 #if defined(__APPLE__) 75 # define WRAP(x) wrap_##x 76 # define WRAPPER_NAME(x) "wrap_"#x 77 # define INTERCEPTOR_ATTRIBUTE 78 #elif defined(_WIN32) 79 # if defined(_DLL) // DLL CRT 80 # define WRAP(x) x 81 # define WRAPPER_NAME(x) #x 82 # define INTERCEPTOR_ATTRIBUTE 83 # else // Static CRT 84 # define WRAP(x) wrap_##x 85 # define WRAPPER_NAME(x) "wrap_"#x 86 # define INTERCEPTOR_ATTRIBUTE 87 # endif 88 #else 89 # define WRAP(x) x 90 # define WRAPPER_NAME(x) #x 91 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 92 #endif 93 94 #define PTR_TO_REAL(x) real_##x 95 #define REAL(x) __interception::PTR_TO_REAL(x) 96 #define FUNC_TYPE(x) x##_f 97 98 #define DECLARE_REAL(ret_type, func, ...); \ 99 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 100 namespace __interception { \ 101 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 102 } 103 104 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...); \ 105 DECLARE_REAL(ret_type, func, ##__VA_ARGS__); \ 106 extern "C" ret_type WRAP(func)(__VA_ARGS__); 107 108 // FIXME(timurrrr): We might need to add DECLARE_REAL_EX etc to support 109 // different calling conventions later. 110 111 #define DEFINE_REAL_EX(ret_type, convention, func, ...); \ 112 typedef ret_type (convention *FUNC_TYPE(func))(__VA_ARGS__); \ 113 namespace __interception { \ 114 FUNC_TYPE(func) PTR_TO_REAL(func); \ 115 } 116 117 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 118 // macros does its job. In exceptional cases you may need to call REAL(foo) 119 // without defining INTERCEPTOR(..., foo, ...). For example, if you override 120 // foo with an interceptor for other function. 121 #define DEFAULT_CONVENTION 122 123 #define DEFINE_REAL(ret_type, func, ...); \ 124 DEFINE_REAL_EX(ret_type, DEFAULT_CONVENTION, func, __VA_ARGS__); 125 126 #define INTERCEPTOR_EX(ret_type, convention, func, ...) \ 127 DEFINE_REAL_EX(ret_type, convention, func, __VA_ARGS__); \ 128 extern "C" \ 129 INTERCEPTOR_ATTRIBUTE \ 130 ret_type convention WRAP(func)(__VA_ARGS__) 131 132 #define INTERCEPTOR(ret_type, func, ...) \ 133 INTERCEPTOR_EX(ret_type, DEFAULT_CONVENTION, func, __VA_ARGS__) 134 135 #if defined(_WIN32) 136 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 137 INTERCEPTOR_EX(ret_type, __stdcall, func, __VA_ARGS__) 138 #endif 139 140 #define INCLUDED_FROM_INTERCEPTION_LIB 141 142 #if defined(__linux__) 143 # include "interception_linux.h" 144 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func) 145 #elif defined(__APPLE__) 146 # include "interception_mac.h" 147 # define OVERRIDE_FUNCTION(old_func, new_func) \ 148 OVERRIDE_FUNCTION_MAC(old_func, new_func) 149 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 150 #else // defined(_WIN32) 151 # include "interception_win.h" 152 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 153 #endif 154 155 #undef INCLUDED_FROM_INTERCEPTION_LIB 156 157 #endif // INTERCEPTION_H 158
