| // Copyright 2017 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 | |
| // | |
| // https://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. | |
| // | |
| // Produces a stack trace for Windows. Normally, one could use | |
| // stacktrace_x86-inl.h or stacktrace_x86_64-inl.h -- and indeed, that | |
| // should work for binaries compiled using MSVC in "debug" mode. | |
| // However, in "release" mode, Windows uses frame-pointer | |
| // optimization, which makes getting a stack trace very difficult. | |
| // | |
| // There are several approaches one can take. One is to use Windows | |
| // intrinsics like StackWalk64. These can work, but have restrictions | |
| // on how successful they can be. Another attempt is to write a | |
| // version of stacktrace_x86-inl.h that has heuristic support for | |
| // dealing with FPO, similar to what WinDbg does (see | |
| // http://www.nynaeve.net/?p=97). There are (non-working) examples of | |
| // these approaches, complete with TODOs, in stacktrace_win32-inl.h#1 | |
| // | |
| // The solution we've ended up doing is to call the undocumented | |
| // windows function RtlCaptureStackBackTrace, which probably doesn't | |
| // work with FPO but at least is fast, and doesn't require a symbol | |
| // server. | |
| // | |
| // This code is inspired by a patch from David Vitek: | |
| // https://code.google.com/p/google-perftools/issues/detail?id=83 | |
| typedef USHORT NTAPI RtlCaptureStackBackTrace_Function( | |
| IN ULONG frames_to_skip, | |
| IN ULONG frames_to_capture, | |
| OUT PVOID *backtrace, | |
| OUT PULONG backtrace_hash); | |
| // It is not possible to load RtlCaptureStackBackTrace at static init time in | |
| // UWP. CaptureStackBackTrace is the public version of RtlCaptureStackBackTrace | |
| static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn = | |
| &::CaptureStackBackTrace; | |
| // Load the function we need at static init time, where we don't have | |
| // to worry about someone else holding the loader's lock. | |
| static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn = | |
| (RtlCaptureStackBackTrace_Function*)GetProcAddress( | |
| GetModuleHandleA("ntdll.dll"), "RtlCaptureStackBackTrace"); | |
| template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT> | |
| static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count, | |
| const void*, int* min_dropped_frames) { | |
| USHORT n = 0; | |
| if (!RtlCaptureStackBackTrace_fn || skip_count < 0 || max_depth < 0) { | |
| // can't get a stacktrace with no function/invalid args | |
| } else { | |
| n = RtlCaptureStackBackTrace_fn(static_cast<ULONG>(skip_count) + 2, | |
| static_cast<ULONG>(max_depth), result, 0); | |
| } | |
| if (IS_STACK_FRAMES) { | |
| // No implementation for finding out the stack frame sizes yet. | |
| memset(sizes, 0, sizeof(*sizes) * n); | |
| } | |
| if (min_dropped_frames != nullptr) { | |
| // Not implemented. | |
| *min_dropped_frames = 0; | |
| } | |
| return n; | |
| } | |
| namespace absl { | |
| ABSL_NAMESPACE_BEGIN | |
| namespace debugging_internal { | |
| bool StackTraceWorksForTest() { | |
| return false; | |
| } | |
| } // namespace debugging_internal | |
| ABSL_NAMESPACE_END | |
| } // namespace absl | |