5 files changed, 125 insertions, 3 deletions
diff --git a/absl/debugging/BUILD.bazel b/absl/debugging/BUILD.bazel
index 8543200df87d..556bb38394c9 100644
--- a/absl/debugging/BUILD.bazel
+++ b/absl/debugging/BUILD.bazel
@@ -46,6 +46,7 @@ cc_library(
         "symbolize.cc",
         "symbolize_elf.inc",
         "symbolize_unimplemented.inc",
+        "symbolize_win32.inc",
     ],
     hdrs = [
         "internal/symbolize.h",
diff --git a/absl/debugging/CMakeLists.txt b/absl/debugging/CMakeLists.txt
index 8d2ec845d67b..456d07271b82 100644
--- a/absl/debugging/CMakeLists.txt
+++ b/absl/debugging/CMakeLists.txt
@@ -45,6 +45,7 @@ list(APPEND SYMBOLIZE_SRC
   "symbolize.cc"
   "symbolize_elf.inc"
   "symbolize_unimplemented.inc"
+  "symbolize_win32.inc"
   "internal/demangle.cc"
   ${DEBUGGING_PUBLIC_HEADERS}
   ${DEBUGGING_INTERNAL_HEADERS}
diff --git a/absl/debugging/symbolize.cc b/absl/debugging/symbolize.cc
index 355bf9ff9522..a35e24cc29a4 100644
--- a/absl/debugging/symbolize.cc
+++ b/absl/debugging/symbolize.cc
@@ -14,8 +14,15 @@
 
 #include "absl/debugging/symbolize.h"
 
-#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
+#if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE)
 #include "absl/debugging/symbolize_elf.inc"
+#elif defined(_WIN32) && defined(_DEBUG)
+// The Windows Symbolizer only works in debug mode. Note that _DEBUG
+// is the macro that defines whether or not MS C-Runtime debug info is
+// available. Note that the PDB files containing the debug info must
+// also be available to the program at runtime for the symbolizer to
+// work.
+#include "absl/debugging/symbolize_win32.inc"
 #else
 #include "absl/debugging/symbolize_unimplemented.inc"
 #endif
diff --git a/absl/debugging/symbolize_test.cc b/absl/debugging/symbolize_test.cc
index b23a8011990b..c1090b8dc437 100644
--- a/absl/debugging/symbolize_test.cc
+++ b/absl/debugging/symbolize_test.cc
@@ -90,8 +90,6 @@ static constexpr size_t kHpageSize = 1 << 21;
 const char kHpageTextPadding[kHpageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE(
     ".text") = "";
 
-#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
-
 static char try_symbolize_buffer[4096];
 
 // A wrapper function for absl::Symbolize() to make the unit test simple.  The
@@ -120,6 +118,8 @@ static const char *TrySymbolize(void *pc) {
   return TrySymbolizeWithLimit(pc, sizeof(try_symbolize_buffer));
 }
 
+#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
+
 TEST(Symbolize, Cached) {
   // Compilers should give us pointers to them.
   EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func)));
@@ -442,6 +442,45 @@ void ABSL_ATTRIBUTE_NOINLINE TestWithReturnAddress() {
 #endif
 }
 
+#elif defined(_WIN32) && defined(_DEBUG)
+
+TEST(Symbolize, Basics) {
+  EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func)));
+
+  // The name of an internal linkage symbol is not specified; allow either a
+  // mangled or an unmangled name here.
+  const char* static_func_symbol = TrySymbolize((void *)(&static_func));
+  ASSERT_TRUE(static_func_symbol != nullptr);
+  EXPECT_TRUE(strstr(static_func_symbol, "static_func") != nullptr);
+
+  EXPECT_TRUE(nullptr == TrySymbolize(nullptr));
+}
+
+TEST(Symbolize, Truncation) {
+  constexpr char kNonStaticFunc[] = "nonstatic_func";
+  EXPECT_STREQ("nonstatic_func",
+               TrySymbolizeWithLimit((void *)(&nonstatic_func),
+                                     strlen(kNonStaticFunc) + 1));
+  EXPECT_STREQ("nonstatic_...",
+               TrySymbolizeWithLimit((void *)(&nonstatic_func),
+                                     strlen(kNonStaticFunc) + 0));
+  EXPECT_STREQ("nonstatic...",
+               TrySymbolizeWithLimit((void *)(&nonstatic_func),
+                                     strlen(kNonStaticFunc) - 1));
+  EXPECT_STREQ("n...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 5));
+  EXPECT_STREQ("...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 4));
+  EXPECT_STREQ("..", TrySymbolizeWithLimit((void *)(&nonstatic_func), 3));
+  EXPECT_STREQ(".", TrySymbolizeWithLimit((void *)(&nonstatic_func), 2));
+  EXPECT_STREQ("", TrySymbolizeWithLimit((void *)(&nonstatic_func), 1));
+  EXPECT_EQ(nullptr, TrySymbolizeWithLimit((void *)(&nonstatic_func), 0));
+}
+
+TEST(Symbolize, SymbolizeWithDemangling) {
+  const char* result = TrySymbolize((void *)(&Foo::func));
+  ASSERT_TRUE(result != nullptr);
+  EXPECT_TRUE(strstr(result, "Foo::func") != nullptr) << result;
+}
+
 #else  // Symbolizer unimplemented
 
 TEST(Symbolize, Unimplemented) {
diff --git a/absl/debugging/symbolize_win32.inc b/absl/debugging/symbolize_win32.inc
new file mode 100644
index 000000000000..c300c50a4e2e
--- /dev/null
+++ b/absl/debugging/symbolize_win32.inc
@@ -0,0 +1,74 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// See "Retrieving Symbol Information by Address":
+// https://msdn.microsoft.com/en-us/library/windows/desktop/ms680578(v=vs.85).aspx
+
+#include <windows.h>
+#include <DbgHelp.h>
+#pragma comment(lib, "DbgHelp")
+
+#include <algorithm>
+#include <cstring>
+
+#include "absl/base/internal/raw_logging.h"
+
+namespace absl {
+
+static HANDLE process = NULL;
+
+void InitializeSymbolizer(const char *argv0) {
+  if (process != nullptr) {
+    return;
+  }
+  process = GetCurrentProcess();
+
+  // Symbols are not loaded until a reference is made requiring the
+  // symbols be loaded. This is the fastest, most efficient way to use
+  // the symbol handler.
+  SymSetOptions(SYMOPT_DEFERRED_LOADS | SYMOPT_UNDNAME);
+  if (!SymInitialize(process, nullptr, true)) {
+    // GetLastError() returns a Win32 DWORD, but we assign to
+    // unsigned long to simplify the ABSL_RAW_LOG case below.  The uniform
+    // initialization guarantees this is not a narrowing conversion.
+    const unsigned long long error{GetLastError()};  // NOLINT(runtime/int)
+    ABSL_RAW_LOG(FATAL, "SymInitialize() failed: %llu", error);
+  }
+}
+
+bool Symbolize(const void *pc, char *out, int out_size) {
+  if (out_size <= 0) {
+    return false;
+  }
+  std::aligned_storage<sizeof(SYMBOL_INFO) + MAX_SYM_NAME,
+                       alignof(SYMBOL_INFO)>::type buf;
+  SYMBOL_INFO *symbol = reinterpret_cast<SYMBOL_INFO *>(&buf);
+  symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
+  symbol->MaxNameLen = MAX_SYM_NAME;
+  if (!SymFromAddr(process, reinterpret_cast<DWORD64>(pc), nullptr, symbol)) {
+    return false;
+  }
+  strncpy(out, symbol->Name, out_size);
+  if (out[out_size - 1] != '\0') {
+    // strncpy() does not '\0' terminate when it truncates.
+    static constexpr char kEllipsis[] = "...";
+    int ellipsis_size =
+        std::min<int>(sizeof(kEllipsis) - 1, out_size - 1);
+    memcpy(out + out_size - ellipsis_size - 1, kEllipsis, ellipsis_size);
+    out[out_size - 1] = '\0';
+  }
+  return true;
+}
+
+}  // namespace absl