230 lines
8.6 KiB
C++
230 lines
8.6 KiB
C++
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//===- Signals.cpp - Signal Handling support --------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines some helpful functions for dealing with the possibility of
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// Unix signals occurring while your program is running.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/Signals.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/FileUtilities.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/FormatAdapters.h"
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#include "llvm/Support/FormatVariadic.h"
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#include "llvm/Support/ManagedStatic.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/Mutex.h"
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#include "llvm/Support/Program.h"
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#include "llvm/Support/StringSaver.h"
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#include "llvm/Support/raw_ostream.h"
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#include <vector>
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//===----------------------------------------------------------------------===//
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//=== WARNING: Implementation here must contain only TRULY operating system
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//=== independent code.
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//===----------------------------------------------------------------------===//
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using namespace llvm;
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// Use explicit storage to avoid accessing cl::opt in a signal handler.
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static bool DisableSymbolicationFlag = false;
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static cl::opt<bool, true>
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DisableSymbolication("disable-symbolication",
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cl::desc("Disable symbolizing crash backtraces."),
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cl::location(DisableSymbolicationFlag), cl::Hidden);
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constexpr char DisableSymbolizationEnv[] = "LLVM_DISABLE_SYMBOLIZATION";
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constexpr char LLVMSymbolizerPathEnv[] = "LLVM_SYMBOLIZER_PATH";
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// Callbacks to run in signal handler must be lock-free because a signal handler
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// could be running as we add new callbacks. We don't add unbounded numbers of
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// callbacks, an array is therefore sufficient.
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struct CallbackAndCookie {
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sys::SignalHandlerCallback Callback;
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void *Cookie;
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enum class Status { Empty, Initializing, Initialized, Executing };
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std::atomic<Status> Flag;
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};
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static constexpr size_t MaxSignalHandlerCallbacks = 8;
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static CallbackAndCookie CallBacksToRun[MaxSignalHandlerCallbacks];
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// Signal-safe.
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void sys::RunSignalHandlers() {
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for (size_t I = 0; I < MaxSignalHandlerCallbacks; ++I) {
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auto &RunMe = CallBacksToRun[I];
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auto Expected = CallbackAndCookie::Status::Initialized;
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auto Desired = CallbackAndCookie::Status::Executing;
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if (!RunMe.Flag.compare_exchange_strong(Expected, Desired))
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continue;
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(*RunMe.Callback)(RunMe.Cookie);
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RunMe.Callback = nullptr;
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RunMe.Cookie = nullptr;
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RunMe.Flag.store(CallbackAndCookie::Status::Empty);
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}
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}
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// Signal-safe.
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static void insertSignalHandler(sys::SignalHandlerCallback FnPtr,
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void *Cookie) {
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for (size_t I = 0; I < MaxSignalHandlerCallbacks; ++I) {
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auto &SetMe = CallBacksToRun[I];
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auto Expected = CallbackAndCookie::Status::Empty;
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auto Desired = CallbackAndCookie::Status::Initializing;
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if (!SetMe.Flag.compare_exchange_strong(Expected, Desired))
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continue;
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SetMe.Callback = FnPtr;
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SetMe.Cookie = Cookie;
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SetMe.Flag.store(CallbackAndCookie::Status::Initialized);
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return;
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}
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report_fatal_error("too many signal callbacks already registered");
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}
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static bool findModulesAndOffsets(void **StackTrace, int Depth,
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const char **Modules, intptr_t *Offsets,
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const char *MainExecutableName,
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StringSaver &StrPool);
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/// Format a pointer value as hexadecimal. Zero pad it out so its always the
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/// same width.
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static FormattedNumber format_ptr(void *PC) {
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// Each byte is two hex digits plus 2 for the 0x prefix.
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unsigned PtrWidth = 2 + 2 * sizeof(void *);
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return format_hex((uint64_t)PC, PtrWidth);
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}
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/// Helper that launches llvm-symbolizer and symbolizes a backtrace.
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LLVM_ATTRIBUTE_USED
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static bool printSymbolizedStackTrace(StringRef Argv0, void **StackTrace,
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int Depth, llvm::raw_ostream &OS) {
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if (DisableSymbolicationFlag || getenv(DisableSymbolizationEnv))
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return false;
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// Don't recursively invoke the llvm-symbolizer binary.
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if (Argv0.find("llvm-symbolizer") != std::string::npos)
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return false;
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// FIXME: Subtract necessary number from StackTrace entries to turn return addresses
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// into actual instruction addresses.
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// Use llvm-symbolizer tool to symbolize the stack traces. First look for it
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// alongside our binary, then in $PATH.
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ErrorOr<std::string> LLVMSymbolizerPathOrErr = std::error_code();
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if (const char *Path = getenv(LLVMSymbolizerPathEnv)) {
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LLVMSymbolizerPathOrErr = sys::findProgramByName(Path);
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} else if (!Argv0.empty()) {
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StringRef Parent = llvm::sys::path::parent_path(Argv0);
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if (!Parent.empty())
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LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer", Parent);
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}
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if (!LLVMSymbolizerPathOrErr)
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LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer");
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if (!LLVMSymbolizerPathOrErr)
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return false;
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const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
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// If we don't know argv0 or the address of main() at this point, try
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// to guess it anyway (it's possible on some platforms).
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std::string MainExecutableName =
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sys::fs::exists(Argv0) ? (std::string)std::string(Argv0)
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: sys::fs::getMainExecutable(nullptr, nullptr);
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BumpPtrAllocator Allocator;
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StringSaver StrPool(Allocator);
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std::vector<const char *> Modules(Depth, nullptr);
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std::vector<intptr_t> Offsets(Depth, 0);
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if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
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MainExecutableName.c_str(), StrPool))
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return false;
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int InputFD;
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SmallString<32> InputFile, OutputFile;
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sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
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sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
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FileRemover InputRemover(InputFile.c_str());
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FileRemover OutputRemover(OutputFile.c_str());
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{
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raw_fd_ostream Input(InputFD, true);
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for (int i = 0; i < Depth; i++) {
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if (Modules[i])
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Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
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}
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}
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Optional<StringRef> Redirects[] = {StringRef(InputFile),
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StringRef(OutputFile), StringRef("")};
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StringRef Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
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#ifdef _WIN32
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// Pass --relative-address on Windows so that we don't
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// have to add ImageBase from PE file.
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// FIXME: Make this the default for llvm-symbolizer.
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"--relative-address",
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#endif
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"--demangle"};
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int RunResult =
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sys::ExecuteAndWait(LLVMSymbolizerPath, Args, None, Redirects);
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if (RunResult != 0)
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return false;
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// This report format is based on the sanitizer stack trace printer. See
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// sanitizer_stacktrace_printer.cc in compiler-rt.
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auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
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if (!OutputBuf)
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return false;
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StringRef Output = OutputBuf.get()->getBuffer();
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SmallVector<StringRef, 32> Lines;
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Output.split(Lines, "\n");
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auto CurLine = Lines.begin();
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int frame_no = 0;
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for (int i = 0; i < Depth; i++) {
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auto PrintLineHeader = [&]() {
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OS << right_justify(formatv("#{0}", frame_no++).str(),
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std::log10(Depth) + 2)
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<< ' ' << format_ptr(StackTrace[i]) << ' ';
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};
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if (!Modules[i]) {
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PrintLineHeader();
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OS << '\n';
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continue;
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}
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// Read pairs of lines (function name and file/line info) until we
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// encounter empty line.
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for (;;) {
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if (CurLine == Lines.end())
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return false;
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StringRef FunctionName = *CurLine++;
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if (FunctionName.empty())
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break;
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PrintLineHeader();
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if (!FunctionName.startswith("??"))
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OS << FunctionName << ' ';
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if (CurLine == Lines.end())
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return false;
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StringRef FileLineInfo = *CurLine++;
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if (!FileLineInfo.startswith("??"))
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OS << FileLineInfo;
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else
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OS << "(" << Modules[i] << '+' << format_hex(Offsets[i], 0) << ")";
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OS << "\n";
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}
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}
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return true;
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}
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// Include the platform-specific parts of this class.
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#ifdef LLVM_ON_UNIX
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#include "Unix/Signals.inc"
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#endif
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#ifdef _WIN32
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#include "Windows/Signals.inc"
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#endif
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