1// Copyright 2018 The Abseil Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// See "Retrieving Symbol Information by Address":
16// https://msdn.microsoft.com/en-us/library/windows/desktop/ms680578(v=vs.85).aspx
17
18#include <windows.h>
19
20// MSVC header dbghelp.h has a warning for an ignored typedef.
21#pragma warning(push)
22#pragma warning(disable:4091)
23#include <dbghelp.h>
24#pragma warning(pop)
25
26#pragma comment(lib, "dbghelp.lib")
27
28#include <algorithm>
29#include <cstring>
30
31#include "absl/base/internal/raw_logging.h"
32
33namespace absl {
34ABSL_NAMESPACE_BEGIN
35
36static HANDLE process = NULL;
37
38void InitializeSymbolizer(const char*) {
39  if (process != nullptr) {
40    return;
41  }
42  process = GetCurrentProcess();
43
44  // Symbols are not loaded until a reference is made requiring the
45  // symbols be loaded. This is the fastest, most efficient way to use
46  // the symbol handler.
47  SymSetOptions(SYMOPT_DEFERRED_LOADS | SYMOPT_UNDNAME);
48  if (!SymInitialize(process, nullptr, true)) {
49    // GetLastError() returns a Win32 DWORD, but we assign to
50    // unsigned long long to simplify the ABSL_RAW_LOG case below.  The uniform
51    // initialization guarantees this is not a narrowing conversion.
52    const unsigned long long error{GetLastError()};  // NOLINT(runtime/int)
53    ABSL_RAW_LOG(FATAL, "SymInitialize() failed: %llu", error);
54  }
55}
56
57bool Symbolize(const void* pc, char* out, int out_size) {
58  if (out_size <= 0) {
59    return false;
60  }
61  alignas(SYMBOL_INFO) char buf[sizeof(SYMBOL_INFO) + MAX_SYM_NAME];
62  SYMBOL_INFO* symbol = reinterpret_cast<SYMBOL_INFO*>(buf);
63  symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
64  symbol->MaxNameLen = MAX_SYM_NAME;
65  if (!SymFromAddr(process, reinterpret_cast<DWORD64>(pc), nullptr, symbol)) {
66    return false;
67  }
68  strncpy(out, symbol->Name, out_size);
69  if (out[out_size - 1] != '\0') {
70    // strncpy() does not '\0' terminate when it truncates.
71    static constexpr char kEllipsis[] = "...";
72    int ellipsis_size =
73        std::min<int>(sizeof(kEllipsis) - 1, out_size - 1);
74    memcpy(out + out_size - ellipsis_size - 1, kEllipsis, ellipsis_size);
75    out[out_size - 1] = '\0';
76  }
77  return true;
78}
79
80ABSL_NAMESPACE_END
81}  // namespace absl
82