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1 //===-- interception.h ------------------------------------------*- C++ -*-===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8 //
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9 // This file is a part of AddressSanitizer, an address sanity checker.
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10 //
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11 // Machinery for providing replacements/wrappers for system functions.
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12 //===----------------------------------------------------------------------===//
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13
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14 #ifndef INTERCEPTION_H
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15 #define INTERCEPTION_H
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16
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17 #include "sanitizer_common/sanitizer_internal_defs.h"
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18
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19 #if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \
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20 !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \
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21 !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS
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22 # error "Interception doesn't work on this operating system."
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23 #endif
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24
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25 // These typedefs should be used only in the interceptor definitions to replace
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26 // the standard system types (e.g. SSIZE_T instead of ssize_t)
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27 typedef __sanitizer::uptr SIZE_T;
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28 typedef __sanitizer::sptr SSIZE_T;
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29 typedef __sanitizer::sptr PTRDIFF_T;
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30 typedef __sanitizer::s64 INTMAX_T;
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31 typedef __sanitizer::u64 UINTMAX_T;
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32 typedef __sanitizer::OFF_T OFF_T;
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33 typedef __sanitizer::OFF64_T OFF64_T;
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34
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35 // How to add an interceptor:
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36 // Suppose you need to wrap/replace system function (generally, from libc):
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37 // int foo(const char *bar, double baz);
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38 // You'll need to:
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39 // 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in
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40 // your source file. See the notes below for cases when
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41 // INTERCEPTOR_WITH_SUFFIX(...) should be used instead.
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42 // 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo".
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43 // INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was
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44 // intercepted successfully.
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45 // You can access original function by calling REAL(foo)(bar, baz).
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46 // By default, REAL(foo) will be visible only inside your interceptor, and if
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47 // you want to use it in other parts of RTL, you'll need to:
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48 // 3a) add DECLARE_REAL(int, foo, const char*, double) to a
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49 // header file.
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50 // However, if the call "INTERCEPT_FUNCTION(foo)" and definition for
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51 // INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to:
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52 // 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double)
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53 // to a header file.
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54
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55 // Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or
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56 // DECLARE_REAL(...) are located inside namespaces.
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57 // 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to
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58 // effectively redirect calls from "foo" to "zoo". In this case
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59 // you aren't required to implement
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60 // INTERCEPTOR(int, foo, const char *bar, double baz) {...}
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61 // but instead you'll have to add
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62 // DECLARE_REAL(int, foo, const char *bar, double baz) in your
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63 // source file (to define a pointer to overriden function).
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64 // 3. Some Mac functions have symbol variants discriminated by
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65 // additional suffixes, e.g. _$UNIX2003 (see
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66 // https://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/index.html
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67 // for more details). To intercept such functions you need to use the
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68 // INTERCEPTOR_WITH_SUFFIX(...) macro.
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69
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70 // How it works:
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71 // To replace system functions on Linux we just need to declare functions
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72 // with same names in our library and then obtain the real function pointers
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73 // using dlsym().
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74 // There is one complication. A user may also intercept some of the functions
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75 // we intercept. To resolve this we declare our interceptors with __interceptor_
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76 // prefix, and then make actual interceptors weak aliases to __interceptor_
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77 // functions.
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78 //
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79 // This is not so on Mac OS, where the two-level namespace makes
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80 // our replacement functions invisible to other libraries. This may be overcomed
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81 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared
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82 // libraries in Chromium were noticed when doing so.
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83 // Instead we create a dylib containing a __DATA,__interpose section that
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84 // associates library functions with their wrappers. When this dylib is
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85 // preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all
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86 // the calls to interposed functions done through stubs to the wrapper
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87 // functions.
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88 // As it's decided at compile time which functions are to be intercepted on Mac,
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89 // INTERCEPT_FUNCTION() is effectively a no-op on this system.
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90
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91 #if SANITIZER_MAC
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92 #include <sys/cdefs.h> // For __DARWIN_ALIAS_C().
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93
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94 // Just a pair of pointers.
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95 struct interpose_substitution {
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96 const __sanitizer::uptr replacement;
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97 const __sanitizer::uptr original;
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98 };
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99
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100 // For a function foo() create a global pair of pointers { wrap_foo, foo } in
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101 // the __DATA,__interpose section.
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102 // As a result all the calls to foo() will be routed to wrap_foo() at runtime.
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103 #define INTERPOSER(func_name) __attribute__((used)) \
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104 const interpose_substitution substitution_##func_name[] \
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105 __attribute__((section("__DATA, __interpose"))) = { \
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106 { reinterpret_cast<const uptr>(WRAP(func_name)), \
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107 reinterpret_cast<const uptr>(func_name) } \
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108 }
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109
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110 // For a function foo() and a wrapper function bar() create a global pair
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111 // of pointers { bar, foo } in the __DATA,__interpose section.
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112 // As a result all the calls to foo() will be routed to bar() at runtime.
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113 #define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \
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114 const interpose_substitution substitution_##func_name[] \
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115 __attribute__((section("__DATA, __interpose"))) = { \
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116 { reinterpret_cast<const uptr>(wrapper_name), \
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117 reinterpret_cast<const uptr>(func_name) } \
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118 }
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119
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120 # define WRAP(x) wrap_##x
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121 # define WRAPPER_NAME(x) "wrap_"#x
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122 # define INTERCEPTOR_ATTRIBUTE
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123 # define DECLARE_WRAPPER(ret_type, func, ...)
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124
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125 #elif SANITIZER_WINDOWS
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126 # define WRAP(x) __asan_wrap_##x
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127 # define WRAPPER_NAME(x) "__asan_wrap_"#x
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128 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport)
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129 # define DECLARE_WRAPPER(ret_type, func, ...) \
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130 extern "C" ret_type func(__VA_ARGS__);
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131 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \
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132 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__);
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145
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133 #elif SANITIZER_RTEMS
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134 # define WRAP(x) x
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135 # define WRAPPER_NAME(x) #x
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136 # define INTERCEPTOR_ATTRIBUTE
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137 # define DECLARE_WRAPPER(ret_type, func, ...)
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138 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD
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139 # define WRAP(x) __interceptor_ ## x
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140 # define WRAPPER_NAME(x) "__interceptor_" #x
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141 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
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142 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher
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143 // priority than weak ones so weak aliases won't work for indirect calls
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144 // in position-independent (-fPIC / -fPIE) mode.
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145 # define DECLARE_WRAPPER(ret_type, func, ...) \
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146 extern "C" ret_type func(__VA_ARGS__) \
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147 __attribute__((alias("__interceptor_" #func), visibility("default")));
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145
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148 #elif !SANITIZER_FUCHSIA
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149 # define WRAP(x) __interceptor_ ## x
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150 # define WRAPPER_NAME(x) "__interceptor_" #x
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151 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
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152 # define DECLARE_WRAPPER(ret_type, func, ...) \
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153 extern "C" ret_type func(__VA_ARGS__) \
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154 __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
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155 #endif
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156
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157 #if SANITIZER_FUCHSIA
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158 // There is no general interception at all on Fuchsia.
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159 // Sanitizer runtimes just define functions directly to preempt them,
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160 // and have bespoke ways to access the underlying libc functions.
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161 # include <zircon/sanitizer.h>
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162 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
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163 # define REAL(x) __unsanitized_##x
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164 # define DECLARE_REAL(ret_type, func, ...)
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165 #elif SANITIZER_RTEMS
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166 # define REAL(x) __real_ ## x
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167 # define DECLARE_REAL(ret_type, func, ...) \
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168 extern "C" ret_type REAL(func)(__VA_ARGS__);
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169 #elif !SANITIZER_MAC
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170 # define PTR_TO_REAL(x) real_##x
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171 # define REAL(x) __interception::PTR_TO_REAL(x)
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172 # define FUNC_TYPE(x) x##_type
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173
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174 # define DECLARE_REAL(ret_type, func, ...) \
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175 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
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176 namespace __interception { \
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177 extern FUNC_TYPE(func) PTR_TO_REAL(func); \
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178 }
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179 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
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180 #else // SANITIZER_MAC
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181 # define REAL(x) x
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182 # define DECLARE_REAL(ret_type, func, ...) \
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183 extern "C" ret_type func(__VA_ARGS__);
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184 # define ASSIGN_REAL(x, y)
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185 #endif // SANITIZER_MAC
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186
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187 #if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
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188 # define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
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189 DECLARE_REAL(ret_type, func, __VA_ARGS__) \
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190 extern "C" ret_type WRAP(func)(__VA_ARGS__);
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191 // Declare an interceptor and its wrapper defined in a different translation
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192 // unit (ex. asm).
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193 # define DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(ret_type, func, ...) \
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194 extern "C" ret_type WRAP(func)(__VA_ARGS__); \
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195 extern "C" ret_type func(__VA_ARGS__);
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111
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196 #else
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197 # define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...)
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198 # define DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(ret_type, func, ...)
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199 #endif
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200
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201 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
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202 // macros does its job. In exceptional cases you may need to call REAL(foo)
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203 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
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204 // foo with an interceptor for other function.
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205 #if !SANITIZER_MAC && !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
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206 # define DEFINE_REAL(ret_type, func, ...) \
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207 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
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208 namespace __interception { \
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209 FUNC_TYPE(func) PTR_TO_REAL(func); \
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210 }
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211 #else
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212 # define DEFINE_REAL(ret_type, func, ...)
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213 #endif
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214
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215 #if SANITIZER_FUCHSIA
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216
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217 // We need to define the __interceptor_func name just to get
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218 // sanitizer_common/scripts/gen_dynamic_list.py to export func.
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219 // But we don't need to export __interceptor_func to get that.
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220 #define INTERCEPTOR(ret_type, func, ...) \
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221 extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \
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222 __interceptor_##func(__VA_ARGS__); \
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223 extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__)
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224
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225 #elif !SANITIZER_MAC
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226
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227 #define INTERCEPTOR(ret_type, func, ...) \
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228 DEFINE_REAL(ret_type, func, __VA_ARGS__) \
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229 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
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230 extern "C" \
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231 INTERCEPTOR_ATTRIBUTE \
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232 ret_type WRAP(func)(__VA_ARGS__)
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233
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234 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now.
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235 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
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236 INTERCEPTOR(ret_type, func, __VA_ARGS__)
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237
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238 #else // SANITIZER_MAC
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239
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240 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \
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241 extern "C" ret_type func(__VA_ARGS__) suffix; \
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242 extern "C" ret_type WRAP(func)(__VA_ARGS__); \
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243 INTERPOSER(func); \
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244 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__)
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245
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246 #define INTERCEPTOR(ret_type, func, ...) \
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247 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__)
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248
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249 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
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250 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__)
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251
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252 // Override |overridee| with |overrider|.
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253 #define OVERRIDE_FUNCTION(overridee, overrider) \
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254 INTERPOSER_2(overridee, WRAP(overrider))
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255 #endif
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256
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257 #if SANITIZER_WINDOWS
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258 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \
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259 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
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260 namespace __interception { \
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261 FUNC_TYPE(func) PTR_TO_REAL(func); \
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262 } \
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263 extern "C" \
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264 INTERCEPTOR_ATTRIBUTE \
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265 ret_type __stdcall WRAP(func)(__VA_ARGS__)
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266 #endif
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267
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268 // ISO C++ forbids casting between pointer-to-function and pointer-to-object,
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269 // so we use casting via an integral type __interception::uptr,
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270 // assuming that system is POSIX-compliant. Using other hacks seem
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271 // challenging, as we don't even pass function type to
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272 // INTERCEPT_FUNCTION macro, only its name.
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273 namespace __interception {
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274 #if defined(_WIN64)
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275 typedef unsigned long long uptr;
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111
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276 #else
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277 typedef unsigned long uptr;
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111
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278 #endif // _WIN64
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279 } // namespace __interception
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280
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281 #define INCLUDED_FROM_INTERCEPTION_LIB
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282
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145
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283 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
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284 SANITIZER_OPENBSD || SANITIZER_SOLARIS
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285
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111
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286 # include "interception_linux.h"
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287 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
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288 # define INTERCEPT_FUNCTION_VER(func, symver) \
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289 INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver)
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145
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290 #elif SANITIZER_MAC
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111
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291 # include "interception_mac.h"
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292 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
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293 # define INTERCEPT_FUNCTION_VER(func, symver) \
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294 INTERCEPT_FUNCTION_VER_MAC(func, symver)
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145
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295 #elif SANITIZER_WINDOWS
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111
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296 # include "interception_win.h"
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297 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
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298 # define INTERCEPT_FUNCTION_VER(func, symver) \
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299 INTERCEPT_FUNCTION_VER_WIN(func, symver)
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300 #endif
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301
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302 #undef INCLUDED_FROM_INTERCEPTION_LIB
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303
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304 #endif // INTERCEPTION_H
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