asan_interceptors.h revision c695a47beeac6ab4ce48e4b33b2ba04869ef0269 
1//===-- asan_interceptors.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// ASan-private header for asan_interceptors.cc
13//===----------------------------------------------------------------------===//
14#ifndef ASAN_INTERCEPTORS_H
15#define ASAN_INTERCEPTORS_H
16
17#include "asan_internal.h"
18
19// To replace weak system functions on Linux we just need to declare functions
20// with same names in our library and then obtain the real function pointers
21// using dlsym(). This is not so on Mac OS, where the two-level namespace makes
22// our replacement functions invisible to other libraries. This may be overcomed
23// using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared
24// libraries in Chromium were noticed when doing so.
25// Instead we use mach_override, a handy framework for patching functions at
26// runtime. To avoid possible name clashes, our replacement functions have
27// the "wrap_" prefix on Mac.
28//
29// After interception, the calls to system functions will be substituted by
30// calls to our interceptors. We store pointers to system function f()
31// in __asan::real_f().
32//
33// TODO(glider): mach_override_ptr() tends to spend too much time
34// in allocateBranchIsland(). This should be ok for real-word
35// application, but slows down our tests which fork too many children.
36#ifdef __APPLE__
37#include "mach_override/mach_override.h"
38#define WRAP(x) wrap_##x
39#define WRAPPER_NAME(x) "wrap_"#x
40
41#define OVERRIDE_FUNCTION(oldfunc, newfunc)                             \
42  CHECK(0 == __asan_mach_override_ptr((void*)(oldfunc),                        \
43                                      (void*)(newfunc),                        \
44                                      (void**)&real_##oldfunc));               \
45  CHECK(real_##oldfunc != NULL);
46
47#define OVERRIDE_FUNCTION_IF_EXISTS(oldfunc, newfunc)                   \
48  do { __asan_mach_override_ptr((void*)(oldfunc),                              \
49                                (void*)(newfunc),                              \
50                                (void**)&real_##oldfunc); } while (0)
51
52#define INTERCEPT_FUNCTION(func)                                        \
53  OVERRIDE_FUNCTION(func, WRAP(func))
54
55#define INTERCEPT_FUNCTION_IF_EXISTS(func)                              \
56  OVERRIDE_FUNCTION_IF_EXISTS(func, WRAP(func))
57
58#else  // __linux__
59#define WRAP(x) x
60#define WRAPPER_NAME(x) #x
61
62#define INTERCEPT_FUNCTION(func)                                        \
63  CHECK((real_##func = (func##_f)dlsym(RTLD_NEXT, #func)));
64
65#define INTERCEPT_FUNCTION_IF_EXISTS(func)                              \
66  do { real_##func = (func##_f)dlsym(RTLD_NEXT, #func); } while (0)
67#endif
68
69#ifdef __APPLE__
70void *WRAP(memcpy)(void *to, const void *from, size_t size);
71void *WRAP(memmove)(void *to, const void *from, size_t size);
72void *WRAP(memset)(void *block, int c, size_t size);
73char *WRAP(strchr)(const char *string, int c);
74int WRAP(strcmp)(const char *s1, const char *s2);
75char *WRAP(strcpy)(char *to, const char *from);  // NOLINT
76char *WRAP(strdup)(const char *s);
77size_t WRAP(strlen)(const char *s);
78int WRAP(strncmp)(const char *s1, const char *s2, size_t size);
79char *WRAP(strncpy)(char *to, const char *from, size_t size);
80#endif
81
82namespace __asan {
83
84typedef void* (*index_f)(const char *string, int c);
85typedef void* (*memcpy_f)(void *to, const void *from, size_t size);
86typedef void* (*memmove_f)(void *to, const void *from, size_t size);
87typedef void* (*memset_f)(void *block, int c, size_t size);
88typedef char* (*strchr_f)(const char *str, int c);
89typedef int (*strcmp_f)(const char *s1, const char *s2);
90typedef char* (*strcpy_f)(char *to, const char *from);
91typedef char* (*strdup_f)(const char *s);
92typedef size_t (*strlen_f)(const char *s);
93typedef int (*strncmp_f)(const char *s1, const char *s2, size_t size);
94typedef char* (*strncpy_f)(char *to, const char *from, size_t size);
95typedef size_t (*strnlen_f)(const char *s, size_t maxlen);
96
97// __asan::real_X() holds pointer to library implementation of X().
98extern index_f          real_index;
99extern memcpy_f         real_memcpy;
100extern memmove_f        real_memmove;
101extern memset_f         real_memset;
102extern strchr_f         real_strchr;
103extern strcmp_f         real_strcmp;
104extern strcpy_f         real_strcpy;
105extern strdup_f         real_strdup;
106extern strlen_f         real_strlen;
107extern strncmp_f        real_strncmp;
108extern strncpy_f        real_strncpy;
109extern strnlen_f        real_strnlen;
110
111// __asan::internal_X() is the implementation of X() for use in RTL.
112size_t internal_strlen(const char *s);
113size_t internal_strnlen(const char *s, size_t maxlen);
114
115// Initializes pointers to str*/mem* functions.
116void InitializeAsanInterceptors();
117
118}  // namespace __asan
119
120#endif  // ASAN_INTERCEPTORS_H
121