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