interception.h revision b4fefa713da3dabda1cd83ae4182c71f1683f02c 
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 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().
67// There is one complication. A user may also intercept some of the functions
68// we intercept. To resolve this we declare our interceptors with __interceptor_
69// prefix, and then make actual interceptors weak aliases to __interceptor_
70// functions.
71// This is not so on Mac OS, where the two-level namespace makes
72// our replacement functions invisible to other libraries. This may be overcomed
73// using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared
74// libraries in Chromium were noticed when doing so. Instead we use
75// mach_override, a handy framework for patching functions at runtime.
76// To avoid possible name clashes, our replacement functions have
77// the "wrap_" prefix on Mac.
78
79#if defined(__APPLE__)
80# define WRAP(x) wrap_##x
81# define WRAPPER_NAME(x) "wrap_"#x
82# define INTERCEPTOR_ATTRIBUTE
83# define DECLARE_WRAPPER(ret_type, convention, func, ...)
84#elif defined(_WIN32)
85# if defined(_DLL)  // DLL CRT
86#  define WRAP(x) x
87#  define WRAPPER_NAME(x) #x
88#  define INTERCEPTOR_ATTRIBUTE
89# else  // Static CRT
90#  define WRAP(x) wrap_##x
91#  define WRAPPER_NAME(x) "wrap_"#x
92#  define INTERCEPTOR_ATTRIBUTE
93# endif
94# define DECLARE_WRAPPER(ret_type, convention, func, ...)
95#else
96# define WRAP(x) __interceptor_ ## x
97# define WRAPPER_NAME(x) "__interceptor_" #x
98# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
99# define DECLARE_WRAPPER(ret_type, convention, func, ...) \
100    extern "C" ret_type convention func(__VA_ARGS__) \
101    __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
102#endif
103
104#define PTR_TO_REAL(x) real_##x
105#define REAL(x) __interception::PTR_TO_REAL(x)
106#define FUNC_TYPE(x) x##_f
107
108#define DECLARE_REAL(ret_type, func, ...) \
109  typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
110  namespace __interception { \
111    extern FUNC_TYPE(func) PTR_TO_REAL(func); \
112  }
113
114#define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
115  DECLARE_REAL(ret_type, func, ##__VA_ARGS__) \
116  extern "C" ret_type WRAP(func)(__VA_ARGS__);
117
118// FIXME(timurrrr): We might need to add DECLARE_REAL_EX etc to support
119// different calling conventions later.
120
121#define DEFINE_REAL_EX(ret_type, convention, func, ...) \
122  typedef ret_type (convention *FUNC_TYPE(func))(__VA_ARGS__); \
123  namespace __interception { \
124    FUNC_TYPE(func) PTR_TO_REAL(func); \
125  }
126
127// Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
128// macros does its job. In exceptional cases you may need to call REAL(foo)
129// without defining INTERCEPTOR(..., foo, ...). For example, if you override
130// foo with an interceptor for other function.
131#define DEFAULT_CONVENTION
132
133#define DEFINE_REAL(ret_type, func, ...) \
134  DEFINE_REAL_EX(ret_type, DEFAULT_CONVENTION, func, __VA_ARGS__)
135
136#define INTERCEPTOR_EX(ret_type, convention, func, ...) \
137  DEFINE_REAL_EX(ret_type, convention, func, __VA_ARGS__) \
138  DECLARE_WRAPPER(ret_type, convention, func, __VA_ARGS__) \
139  extern "C" \
140  INTERCEPTOR_ATTRIBUTE \
141  ret_type convention WRAP(func)(__VA_ARGS__)
142
143#define INTERCEPTOR(ret_type, func, ...) \
144  INTERCEPTOR_EX(ret_type, DEFAULT_CONVENTION, func, __VA_ARGS__)
145
146#if defined(_WIN32)
147# define INTERCEPTOR_WINAPI(ret_type, func, ...) \
148  INTERCEPTOR_EX(ret_type, __stdcall, func, __VA_ARGS__)
149#endif
150
151#define INCLUDED_FROM_INTERCEPTION_LIB
152
153#if defined(__linux__)
154# include "interception_linux.h"
155# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func)
156#elif defined(__APPLE__)
157# include "interception_mac.h"
158# define OVERRIDE_FUNCTION(old_func, new_func) \
159    OVERRIDE_FUNCTION_MAC(old_func, new_func)
160# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
161#else  // defined(_WIN32)
162# include "interception_win.h"
163# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
164#endif
165
166#undef INCLUDED_FROM_INTERCEPTION_LIB
167
168#endif  // INTERCEPTION_H
169