207 lines
8.2 KiB
C++
207 lines
8.2 KiB
C++
//===-- interception.h ------------------------------------------*- C++ -*-===//
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of AddressSanitizer, an address sanity checker.
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//
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// Machinery for providing replacements/wrappers for system functions.
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//===----------------------------------------------------------------------===//
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#ifndef INTERCEPTION_H
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#define INTERCEPTION_H
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#if !defined(__linux__) && !defined(__APPLE__) && !defined(_WIN32)
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# error "Interception doesn't work on this operating system."
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#endif
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#include "sanitizer/common_interface_defs.h"
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// These typedefs should be used only in the interceptor definitions to replace
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// the standard system types (e.g. SSIZE_T instead of ssize_t)
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typedef __sanitizer::uptr SIZE_T;
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typedef __sanitizer::sptr SSIZE_T;
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typedef __sanitizer::sptr PTRDIFF_T;
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typedef __sanitizer::s64 INTMAX_T;
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typedef __sanitizer::u64 OFF_T;
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typedef __sanitizer::u64 OFF64_T;
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// How to use this library:
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// 1) Include this header to define your own interceptors
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// (see details below).
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// 2) Build all *.cc files and link against them.
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// On Mac you will also need to:
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// 3) Provide your own implementation for the following functions:
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// mach_error_t __interception::allocate_island(void **ptr,
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// size_t size,
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// void *hint);
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// mach_error_t __interception::deallocate_island(void *ptr);
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// See "interception_mac.h" for more details.
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// How to add an interceptor:
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// Suppose you need to wrap/replace system function (generally, from libc):
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// int foo(const char *bar, double baz);
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// You'll need to:
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// 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in
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// your source file.
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// 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo".
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// INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was
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// intercepted successfully.
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// You can access original function by calling REAL(foo)(bar, baz).
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// By default, REAL(foo) will be visible only inside your interceptor, and if
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// you want to use it in other parts of RTL, you'll need to:
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// 3a) add DECLARE_REAL(int, foo, const char*, double) to a
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// header file.
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// However, if the call "INTERCEPT_FUNCTION(foo)" and definition for
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// INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to:
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// 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double)
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// to a header file.
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// Notes: 1. Things may not work properly if macro INTERCEPT(...) {...} or
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// DECLARE_REAL(...) are located inside namespaces.
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// 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo);" to
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// effectively redirect calls from "foo" to "zoo". In this case
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// you aren't required to implement
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// INTERCEPTOR(int, foo, const char *bar, double baz) {...}
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// but instead you'll have to add
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// DEFINE_REAL(int, foo, const char *bar, double baz) in your
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// source file (to define a pointer to overriden function).
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// How it works:
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// To replace system functions on Linux we just need to declare functions
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// with same names in our library and then obtain the real function pointers
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// using dlsym().
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// There is one complication. A user may also intercept some of the functions
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// we intercept. To resolve this we declare our interceptors with __interceptor_
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// prefix, and then make actual interceptors weak aliases to __interceptor_
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// functions.
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// This is not so on Mac OS, where the two-level namespace makes
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// our replacement functions invisible to other libraries. This may be overcomed
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// using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared
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// libraries in Chromium were noticed when doing so. Instead we use
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// mach_override, a handy framework for patching functions at runtime.
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// To avoid possible name clashes, our replacement functions have
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// the "wrap_" prefix on Mac.
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// An alternative to function patching is to create a dylib containing a
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// __DATA,__interpose section that associates library functions with their
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// wrappers. When this dylib is preloaded before an executable using
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// DYLD_INSERT_LIBRARIES, it routes all the calls to interposed functions done
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// through stubs to the wrapper functions. Such a library is built with
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// -DMAC_INTERPOSE_FUNCTIONS=1.
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#if !defined(MAC_INTERPOSE_FUNCTIONS) || !defined(__APPLE__)
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# define MAC_INTERPOSE_FUNCTIONS 0
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#endif
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#if defined(__APPLE__)
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# define WRAP(x) wrap_##x
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# define WRAPPER_NAME(x) "wrap_"#x
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# define INTERCEPTOR_ATTRIBUTE
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# define DECLARE_WRAPPER(ret_type, func, ...)
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#elif defined(_WIN32)
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# if defined(_DLL) // DLL CRT
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# define WRAP(x) x
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# define WRAPPER_NAME(x) #x
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# define INTERCEPTOR_ATTRIBUTE
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# else // Static CRT
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# define WRAP(x) wrap_##x
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# define WRAPPER_NAME(x) "wrap_"#x
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# define INTERCEPTOR_ATTRIBUTE
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# endif
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# define DECLARE_WRAPPER(ret_type, func, ...)
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#else
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# define WRAP(x) __interceptor_ ## x
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# define WRAPPER_NAME(x) "__interceptor_" #x
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# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
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# define DECLARE_WRAPPER(ret_type, func, ...) \
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extern "C" ret_type func(__VA_ARGS__) \
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__attribute__((weak, alias("__interceptor_" #func), visibility("default")));
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#endif
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#if !MAC_INTERPOSE_FUNCTIONS
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# define PTR_TO_REAL(x) real_##x
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# define REAL(x) __interception::PTR_TO_REAL(x)
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# define FUNC_TYPE(x) x##_f
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# define DECLARE_REAL(ret_type, func, ...) \
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typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
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namespace __interception { \
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extern FUNC_TYPE(func) PTR_TO_REAL(func); \
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}
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#else // MAC_INTERPOSE_FUNCTIONS
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# define REAL(x) x
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# define DECLARE_REAL(ret_type, func, ...) \
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extern "C" ret_type func(__VA_ARGS__);
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#endif // MAC_INTERPOSE_FUNCTIONS
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#define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
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DECLARE_REAL(ret_type, func, __VA_ARGS__) \
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extern "C" ret_type WRAP(func)(__VA_ARGS__);
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// Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
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// macros does its job. In exceptional cases you may need to call REAL(foo)
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// without defining INTERCEPTOR(..., foo, ...). For example, if you override
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// foo with an interceptor for other function.
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#if !MAC_INTERPOSE_FUNCTIONS
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# define DEFINE_REAL(ret_type, func, ...) \
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typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
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namespace __interception { \
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FUNC_TYPE(func) PTR_TO_REAL(func); \
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}
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#else
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# define DEFINE_REAL(ret_type, func, ...)
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#endif
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#define INTERCEPTOR(ret_type, func, ...) \
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DEFINE_REAL(ret_type, func, __VA_ARGS__) \
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DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
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extern "C" \
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INTERCEPTOR_ATTRIBUTE \
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ret_type WRAP(func)(__VA_ARGS__)
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#if defined(_WIN32)
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# define INTERCEPTOR_WINAPI(ret_type, func, ...) \
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typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
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namespace __interception { \
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FUNC_TYPE(func) PTR_TO_REAL(func); \
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} \
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DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
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extern "C" \
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INTERCEPTOR_ATTRIBUTE \
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ret_type __stdcall WRAP(func)(__VA_ARGS__)
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#endif
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// ISO C++ forbids casting between pointer-to-function and pointer-to-object,
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// so we use casting via an integral type __interception::uptr,
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// assuming that system is POSIX-compliant. Using other hacks seem
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// challenging, as we don't even pass function type to
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// INTERCEPT_FUNCTION macro, only its name.
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namespace __interception {
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#if defined(_WIN64)
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typedef unsigned long long uptr; // NOLINT
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#else
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typedef unsigned long uptr; // NOLINT
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#endif // _WIN64
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} // namespace __interception
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#define INCLUDED_FROM_INTERCEPTION_LIB
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#if defined(__linux__)
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# include "interception_linux.h"
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# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func)
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#elif defined(__APPLE__)
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# include "interception_mac.h"
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# define OVERRIDE_FUNCTION(old_func, new_func) \
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OVERRIDE_FUNCTION_MAC(old_func, new_func)
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# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
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#else // defined(_WIN32)
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# include "interception_win.h"
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# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
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#endif
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#undef INCLUDED_FROM_INTERCEPTION_LIB
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#endif // INTERCEPTION_H
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