1//===-- sanitizer_win_weak_interception.cc --------------------------------===//
2//
3// This file is distributed under the University of Illinois Open Source
4// License. See LICENSE.TXT for details.
5//
6//===----------------------------------------------------------------------===//
7// This module should be included in the sanitizer when it is implemented as a
8// shared library on Windows (dll), in order to delegate the calls of weak
9// functions to the implementation in the main executable when a strong
10// definition is provided.
11//===----------------------------------------------------------------------===//
12
13#include "sanitizer_platform.h"
14#if SANITIZER_WINDOWS && SANITIZER_DYNAMIC
15#include "sanitizer_win_weak_interception.h"
16#include "sanitizer_allocator_interface.h"
17#include "sanitizer_interface_internal.h"
18#include "sanitizer_win_defs.h"
19#include "interception/interception.h"
20
21extern "C" {
22void *WINAPI GetModuleHandleA(const char *module_name);
23void abort();
24}
25
26namespace __sanitizer {
27// Try to get a pointer to real_function in the main module and override
28// dll_function with that pointer. If the function isn't found, nothing changes.
29int interceptWhenPossible(uptr dll_function, const char *real_function) {
30  uptr real = __interception::InternalGetProcAddress(
31      (void *)GetModuleHandleA(0), real_function);
32  if (real && !__interception::OverrideFunction((uptr)dll_function, real, 0))
33    abort();
34  return 0;
35}
36} // namespace __sanitizer
37
38// Declare weak hooks.
39extern "C" {
40void __sanitizer_weak_hook_memcmp(uptr called_pc, const void *s1,
41                                  const void *s2, uptr n, int result);
42void __sanitizer_weak_hook_strcmp(uptr called_pc, const char *s1,
43                                  const char *s2, int result);
44void __sanitizer_weak_hook_strncmp(uptr called_pc, const char *s1,
45                                   const char *s2, uptr n, int result);
46void __sanitizer_weak_hook_strstr(uptr called_pc, const char *s1,
47                                  const char *s2, char *result);
48}
49
50// Include Sanitizer Common interface.
51#define INTERFACE_FUNCTION(Name)
52#define INTERFACE_WEAK_FUNCTION(Name) INTERCEPT_SANITIZER_WEAK_FUNCTION(Name)
53#include "sanitizer_common_interface.inc"
54
55#pragma section(".WEAK$A", read)  // NOLINT
56#pragma section(".WEAK$Z", read)  // NOLINT
57
58typedef void (*InterceptCB)();
59extern "C" {
60__declspec(allocate(".WEAK$A")) InterceptCB __start_weak_list;
61__declspec(allocate(".WEAK$Z")) InterceptCB __stop_weak_list;
62}
63
64static int weak_intercept_init() {
65  static bool flag = false;
66  // weak_interception_init is expected to be called by only one thread.
67  if (flag) return 0;
68  flag = true;
69
70  for (InterceptCB *it = &__start_weak_list; it < &__stop_weak_list; ++it)
71    if (*it)
72      (*it)();
73
74  // In DLLs, the callbacks are expected to return 0,
75  // otherwise CRT initialization fails.
76  return 0;
77}
78
79#pragma section(".CRT$XIB", long, read)  // NOLINT
80__declspec(allocate(".CRT$XIB")) int (*__weak_intercept_preinit)() =
81    weak_intercept_init;
82
83static void WINAPI weak_intercept_thread_init(void *mod, unsigned long reason,
84                                              void *reserved) {
85  if (reason == /*DLL_PROCESS_ATTACH=*/1) weak_intercept_init();
86}
87
88#pragma section(".CRT$XLAB", long, read)  // NOLINT
89__declspec(allocate(".CRT$XLAB")) void(WINAPI *__weak_intercept_tls_init)(
90    void *, unsigned long, void *) = weak_intercept_thread_init;
91
92#endif // SANITIZER_WINDOWS && SANITIZER_DYNAMIC
93