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      1 //===-- sanitizer_win_weak_interception.cpp -------------------------------===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 // This module should be included in the sanitizer when it is implemented as a
      9 // shared library on Windows (dll), in order to delegate the calls of weak
     10 // functions to the implementation in the main executable when a strong
     11 // definition is provided.
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "sanitizer_platform.h"
     15 #if SANITIZER_WINDOWS && SANITIZER_DYNAMIC
     16 #include "sanitizer_win_weak_interception.h"
     17 #include "sanitizer_allocator_interface.h"
     18 #include "sanitizer_interface_internal.h"
     19 #include "sanitizer_win_defs.h"
     20 #include "interception/interception.h"
     21 
     22 extern "C" {
     23 void *WINAPI GetModuleHandleA(const char *module_name);
     24 void abort();
     25 }
     26 
     27 namespace __sanitizer {
     28 // Try to get a pointer to real_function in the main module and override
     29 // dll_function with that pointer. If the function isn't found, nothing changes.
     30 int interceptWhenPossible(uptr dll_function, const char *real_function) {
     31   uptr real = __interception::InternalGetProcAddress(
     32       (void *)GetModuleHandleA(0), real_function);
     33   if (real && !__interception::OverrideFunction((uptr)dll_function, real, 0))
     34     abort();
     35   return 0;
     36 }
     37 } // namespace __sanitizer
     38 
     39 // Declare weak hooks.
     40 extern "C" {
     41 void __sanitizer_on_print(const char *str);
     42 void __sanitizer_weak_hook_memcmp(uptr called_pc, const void *s1,
     43                                   const void *s2, uptr n, int result);
     44 void __sanitizer_weak_hook_strcmp(uptr called_pc, const char *s1,
     45                                   const char *s2, int result);
     46 void __sanitizer_weak_hook_strncmp(uptr called_pc, const char *s1,
     47                                    const char *s2, uptr n, int result);
     48 void __sanitizer_weak_hook_strstr(uptr called_pc, const char *s1,
     49                                   const char *s2, char *result);
     50 }
     51 
     52 // Include Sanitizer Common interface.
     53 #define INTERFACE_FUNCTION(Name)
     54 #define INTERFACE_WEAK_FUNCTION(Name) INTERCEPT_SANITIZER_WEAK_FUNCTION(Name)
     55 #include "sanitizer_common_interface.inc"
     56 
     57 #pragma section(".WEAK$A", read)
     58 #pragma section(".WEAK$Z", read)
     59 
     60 typedef void (*InterceptCB)();
     61 extern "C" {
     62 __declspec(allocate(".WEAK$A")) InterceptCB __start_weak_list;
     63 __declspec(allocate(".WEAK$Z")) InterceptCB __stop_weak_list;
     64 }
     65 
     66 static int weak_intercept_init() {
     67   static bool flag = false;
     68   // weak_interception_init is expected to be called by only one thread.
     69   if (flag) return 0;
     70   flag = true;
     71 
     72   for (InterceptCB *it = &__start_weak_list; it < &__stop_weak_list; ++it)
     73     if (*it)
     74       (*it)();
     75 
     76   // In DLLs, the callbacks are expected to return 0,
     77   // otherwise CRT initialization fails.
     78   return 0;
     79 }
     80 
     81 #pragma section(".CRT$XIB", long, read)
     82 __declspec(allocate(".CRT$XIB")) int (*__weak_intercept_preinit)() =
     83     weak_intercept_init;
     84 
     85 static void WINAPI weak_intercept_thread_init(void *mod, unsigned long reason,
     86                                               void *reserved) {
     87   if (reason == /*DLL_PROCESS_ATTACH=*/1) weak_intercept_init();
     88 }
     89 
     90 #pragma section(".CRT$XLAB", long, read)
     91 __declspec(allocate(".CRT$XLAB")) void(WINAPI *__weak_intercept_tls_init)(
     92     void *, unsigned long, void *) = weak_intercept_thread_init;
     93 
     94 #endif // SANITIZER_WINDOWS && SANITIZER_DYNAMIC
     95