1 files changed, 82 insertions, 0 deletions
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_win_weak_interception.cc b/compiler-rt/lib/sanitizer_common/sanitizer_win_weak_interception.cc
new file mode 100644
index 00000000000..3a26f87467e
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_win_weak_interception.cc
@@ -0,0 +1,82 @@
+//===-- sanitizer_win_weak_interception.cc --------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This module should be included in the sanitizer when it is implemented as a
+// shared library on Windows (dll), in order to delegate the calls of weak
+// functions to the implementation in the main executable when a strong
+// definition is provided.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+#if SANITIZER_WINDOWS && SANITIZER_DYNAMIC
+#include "sanitizer_win_weak_interception.h"
+#include "sanitizer_allocator_interface.h"
+#include "sanitizer_interface_internal.h"
+#include "sanitizer_win_defs.h"
+#include "interception/interception.h"
+
+extern "C" {
+void *WINAPI GetModuleHandleA(const char *module_name);
+void abort();
+}
+
+namespace __sanitizer {
+// Try to get a pointer to real_function in the main module and override
+// dll_function with that pointer. If the function isn't found, nothing changes.
+int interceptWhenPossible(uptr dll_function, const char *real_function) {
+  uptr real = __interception::InternalGetProcAddress(
+      (void *)GetModuleHandleA(0), real_function);
+  if (real && !__interception::OverrideFunction((uptr)dll_function, real, 0))
+    abort();
+  return 0;
+}
+} // namespace __sanitizer
+
+// Include Sanitizer Common interface.
+#define INTERFACE_FUNCTION(Name)
+#define INTERFACE_WEAK_FUNCTION(Name) INTERCEPT_SANITIZER_WEAK_FUNCTION(Name)
+#include "sanitizer_common_interface.inc"
+
+#pragma section(".WEAK$A", read)  // NOLINT
+#pragma section(".WEAK$Z", read)  // NOLINT
+
+typedef void (*InterceptCB)();
+extern "C" {
+__declspec(allocate(".WEAK$A")) InterceptCB __start_weak_list;
+__declspec(allocate(".WEAK$Z")) InterceptCB __stop_weak_list;
+}
+
+static int weak_intercept_init() {
+  static bool flag = false;
+  // weak_interception_init is expected to be called by only one thread.
+  if (flag) return 0;
+  flag = true;
+
+  for (InterceptCB *it = &__start_weak_list; it < &__stop_weak_list; ++it)
+    if (*it)
+      (*it)();
+
+  // In DLLs, the callbacks are expected to return 0,
+  // otherwise CRT initialization fails.
+  return 0;
+}
+
+#pragma section(".CRT$XIB", long, read)  // NOLINT
+__declspec(allocate(".CRT$XIB")) int (*__weak_intercept_preinit)() =
+    weak_intercept_init;
+
+static void WINAPI weak_intercept_thread_init(void *mod, unsigned long reason,
+                                              void *reserved) {
+  if (reason == /*DLL_PROCESS_ATTACH=*/1) weak_intercept_init();
+}
+
+#pragma section(".CRT$XLAB", long, read)  // NOLINT
+__declspec(allocate(".CRT$XLAB")) void(WINAPI *__weak_intercept_tls_init)(
+    void *, unsigned long, void *) = weak_intercept_thread_init;
+
+#endif // SANITIZER_WINDOWS && SANITIZER_DYNAMIC