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      1 //===-- sanitizer_win_dll_thunk.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 file defines a family of thunks that should be statically linked into
      9 // the DLLs that have instrumentation in order to delegate the calls to the
     10 // shared runtime that lives in the main binary.
     11 // See https://github.com/google/sanitizers/issues/209 for the details.
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifdef SANITIZER_DLL_THUNK
     15 #include "sanitizer_win_defs.h"
     16 #include "sanitizer_win_dll_thunk.h"
     17 #include "interception/interception.h"
     18 
     19 extern "C" {
     20 void *WINAPI GetModuleHandleA(const char *module_name);
     21 void abort();
     22 }
     23 
     24 namespace __sanitizer {
     25 uptr dllThunkGetRealAddrOrDie(const char *name) {
     26   uptr ret =
     27       __interception::InternalGetProcAddress((void *)GetModuleHandleA(0), name);
     28   if (!ret)
     29     abort();
     30   return ret;
     31 }
     32 
     33 int dllThunkIntercept(const char* main_function, uptr dll_function) {
     34   uptr wrapper = dllThunkGetRealAddrOrDie(main_function);
     35   if (!__interception::OverrideFunction(dll_function, wrapper, 0))
     36     abort();
     37   return 0;
     38 }
     39 
     40 int dllThunkInterceptWhenPossible(const char* main_function,
     41     const char* default_function, uptr dll_function) {
     42   uptr wrapper = __interception::InternalGetProcAddress(
     43     (void *)GetModuleHandleA(0), main_function);
     44   if (!wrapper)
     45     wrapper = dllThunkGetRealAddrOrDie(default_function);
     46   if (!__interception::OverrideFunction(dll_function, wrapper, 0))
     47     abort();
     48   return 0;
     49 }
     50 } // namespace __sanitizer
     51 
     52 // Include Sanitizer Common interface.
     53 #define INTERFACE_FUNCTION(Name) INTERCEPT_SANITIZER_FUNCTION(Name)
     54 #define INTERFACE_WEAK_FUNCTION(Name) INTERCEPT_SANITIZER_WEAK_FUNCTION(Name)
     55 #include "sanitizer_common_interface.inc"
     56 
     57 #pragma section(".DLLTH$A", read)
     58 #pragma section(".DLLTH$Z", read)
     59 
     60 typedef void (*DllThunkCB)();
     61 extern "C" {
     62 __declspec(allocate(".DLLTH$A")) DllThunkCB __start_dll_thunk;
     63 __declspec(allocate(".DLLTH$Z")) DllThunkCB __stop_dll_thunk;
     64 }
     65 
     66 // Disable compiler warnings that show up if we declare our own version
     67 // of a compiler intrinsic (e.g. strlen).
     68 #pragma warning(disable: 4391)
     69 #pragma warning(disable: 4392)
     70 
     71 extern "C" int __dll_thunk_init() {
     72   static bool flag = false;
     73   // __dll_thunk_init is expected to be called by only one thread.
     74   if (flag) return 0;
     75   flag = true;
     76 
     77   for (DllThunkCB *it = &__start_dll_thunk; it < &__stop_dll_thunk; ++it)
     78     if (*it)
     79       (*it)();
     80 
     81   // In DLLs, the callbacks are expected to return 0,
     82   // otherwise CRT initialization fails.
     83   return 0;
     84 }
     85 
     86 // We want to call dll_thunk_init before C/C++ initializers / constructors are
     87 // executed, otherwise functions like memset might be invoked.
     88 #pragma section(".CRT$XIB", long, read)
     89 __declspec(allocate(".CRT$XIB")) int (*__dll_thunk_preinit)() =
     90     __dll_thunk_init;
     91 
     92 static void WINAPI dll_thunk_thread_init(void *mod, unsigned long reason,
     93                                          void *reserved) {
     94   if (reason == /*DLL_PROCESS_ATTACH=*/1) __dll_thunk_init();
     95 }
     96 
     97 #pragma section(".CRT$XLAB", long, read)
     98 __declspec(allocate(".CRT$XLAB")) void (WINAPI *__dll_thunk_tls_init)(void *,
     99     unsigned long, void *) = dll_thunk_thread_init;
    100 
    101 #endif // SANITIZER_DLL_THUNK
    102