lib/asan/interception/interception.h

   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 // TODO(timurrrr): we're likely to use something else later on Windows.
  80 # define WRAP(x) wrap_##x
  81 # define WRAPPER_NAME(x) #x
  82 # define INTERCEPTOR_ATTRIBUTE
  83 #else
  84 # define WRAP(x) x
  85 # define WRAPPER_NAME(x) #x
  86 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
  87 #endif
  88
  89 #define PTR_TO_REAL(x) real_##x
  90 #define REAL(x) __interception::PTR_TO_REAL(x)
  91 #define FUNC_TYPE(x) x##_f
  92
  93 #define DECLARE_REAL(ret_type, func, ...); \
  94   typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
  95   namespace __interception { \
  96     extern FUNC_TYPE(func) PTR_TO_REAL(func); \
  97   }
  98
  99 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...); \
 100   DECLARE_REAL(ret_type, func, ##__VA_ARGS__); \
 101   extern "C" ret_type WRAP(func)(__VA_ARGS__);
 102
 103 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
 104 // macros does its job. In exceptional cases you may need to call REAL(foo)
 105 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
 106 // foo with an interceptor for other function.
 107 #define DEFINE_REAL(ret_type, func, ...); \
 108   typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 109   namespace __interception { \
 110     FUNC_TYPE(func) PTR_TO_REAL(func); \
 111   }
 112
 113 #define INTERCEPTOR(ret_type, func, ...) \
 114   DEFINE_REAL(ret_type, func, __VA_ARGS__); \
 115   extern "C" \
 116   INTERCEPTOR_ATTRIBUTE \
 117   ret_type WRAP(func)(__VA_ARGS__)
 118
 119 #define INCLUDED_FROM_INTERCEPTION_LIB
 120
 121 #if defined(__linux__)
 122 # include "interception_linux.h"
 123 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func)
 124 #elif defined(__APPLE__)
 125 # include "interception_mac.h"
 126 # define OVERRIDE_FUNCTION(old_func, new_func) \
 127     OVERRIDE_FUNCTION_MAC(old_func, new_func)
 128 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
 129 #else  // defined(_WIN32)
 130   // FIXME: deal with interception on Win.
 131 # define INTERCEPT_FUNCTION(func) true
 132 #endif
 133
 134 #undef INCLUDED_FROM_INTERCEPTION_LIB
 135
 136 #endif  // INTERCEPTION_H