1 //===- Signals.cpp - Signal Handling support --------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines some helpful functions for dealing with the possibility of
11 // Unix signals occurring while your program is running.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Support/Signals.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Config/llvm-config.h"
19 #include "llvm/Support/ErrorOr.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/FileUtilities.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/ManagedStatic.h"
24 #include "llvm/Support/MemoryBuffer.h"
25 #include "llvm/Support/Mutex.h"
26 #include "llvm/Support/Program.h"
27 #include "llvm/Support/StringSaver.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Support/Options.h"
32 //===----------------------------------------------------------------------===//
33 //=== WARNING: Implementation here must contain only TRULY operating system
34 //=== independent code.
35 //===----------------------------------------------------------------------===//
39 // Use explicit storage to avoid accessing cl::opt in a signal handler.
40 static bool DisableSymbolicationFlag = false;
41 static cl::opt<bool, true>
42 DisableSymbolication("disable-symbolication",
43 cl::desc("Disable symbolizing crash backtraces."),
44 cl::location(DisableSymbolicationFlag), cl::Hidden);
46 // Callbacks to run in signal handler must be lock-free because a signal handler
47 // could be running as we add new callbacks. We don't add unbounded numbers of
48 // callbacks, an array is therefore sufficient.
49 struct CallbackAndCookie {
50 sys::SignalHandlerCallback Callback;
52 enum class Status { Empty, Initializing, Initialized, Executing };
53 std::atomic<Status> Flag;
55 static constexpr size_t MaxSignalHandlerCallbacks = 8;
56 static CallbackAndCookie CallBacksToRun[MaxSignalHandlerCallbacks];
59 void sys::RunSignalHandlers() {
60 for (size_t I = 0; I < MaxSignalHandlerCallbacks; ++I) {
61 auto &RunMe = CallBacksToRun[I];
62 auto Expected = CallbackAndCookie::Status::Initialized;
63 auto Desired = CallbackAndCookie::Status::Executing;
64 if (!RunMe.Flag.compare_exchange_strong(Expected, Desired))
66 (*RunMe.Callback)(RunMe.Cookie);
67 RunMe.Callback = nullptr;
68 RunMe.Cookie = nullptr;
69 RunMe.Flag.store(CallbackAndCookie::Status::Empty);
74 static void insertSignalHandler(sys::SignalHandlerCallback FnPtr,
76 for (size_t I = 0; I < MaxSignalHandlerCallbacks; ++I) {
77 auto &SetMe = CallBacksToRun[I];
78 auto Expected = CallbackAndCookie::Status::Empty;
79 auto Desired = CallbackAndCookie::Status::Initializing;
80 if (!SetMe.Flag.compare_exchange_strong(Expected, Desired))
82 SetMe.Callback = FnPtr;
83 SetMe.Cookie = Cookie;
84 SetMe.Flag.store(CallbackAndCookie::Status::Initialized);
87 report_fatal_error("too many signal callbacks already registered");
90 static bool findModulesAndOffsets(void **StackTrace, int Depth,
91 const char **Modules, intptr_t *Offsets,
92 const char *MainExecutableName,
93 StringSaver &StrPool);
95 /// Format a pointer value as hexadecimal. Zero pad it out so its always the
97 static FormattedNumber format_ptr(void *PC) {
98 // Each byte is two hex digits plus 2 for the 0x prefix.
99 unsigned PtrWidth = 2 + 2 * sizeof(void *);
100 return format_hex((uint64_t)PC, PtrWidth);
103 /// Helper that launches llvm-symbolizer and symbolizes a backtrace.
105 static bool printSymbolizedStackTrace(StringRef Argv0, void **StackTrace,
106 int Depth, llvm::raw_ostream &OS) {
107 if (DisableSymbolicationFlag)
110 // Don't recursively invoke the llvm-symbolizer binary.
111 if (Argv0.find("llvm-symbolizer") != std::string::npos)
114 // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
115 // into actual instruction addresses.
116 // Use llvm-symbolizer tool to symbolize the stack traces. First look for it
117 // alongside our binary, then in $PATH.
118 ErrorOr<std::string> LLVMSymbolizerPathOrErr = std::error_code();
119 if (!Argv0.empty()) {
120 StringRef Parent = llvm::sys::path::parent_path(Argv0);
122 LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer", Parent);
124 if (!LLVMSymbolizerPathOrErr)
125 LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer");
126 if (!LLVMSymbolizerPathOrErr)
128 const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
130 // If we don't know argv0 or the address of main() at this point, try
131 // to guess it anyway (it's possible on some platforms).
132 std::string MainExecutableName =
133 Argv0.empty() ? sys::fs::getMainExecutable(nullptr, nullptr)
134 : (std::string)Argv0;
135 BumpPtrAllocator Allocator;
136 StringSaver StrPool(Allocator);
137 std::vector<const char *> Modules(Depth, nullptr);
138 std::vector<intptr_t> Offsets(Depth, 0);
139 if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
140 MainExecutableName.c_str(), StrPool))
143 SmallString<32> InputFile, OutputFile;
144 sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
145 sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
146 FileRemover InputRemover(InputFile.c_str());
147 FileRemover OutputRemover(OutputFile.c_str());
150 raw_fd_ostream Input(InputFD, true);
151 for (int i = 0; i < Depth; i++) {
153 Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
157 Optional<StringRef> Redirects[] = {StringRef(InputFile),
158 StringRef(OutputFile), llvm::None};
159 StringRef Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
161 // Pass --relative-address on Windows so that we don't
162 // have to add ImageBase from PE file.
163 // FIXME: Make this the default for llvm-symbolizer.
164 "--relative-address",
168 sys::ExecuteAndWait(LLVMSymbolizerPath, Args, None, Redirects);
172 // This report format is based on the sanitizer stack trace printer. See
173 // sanitizer_stacktrace_printer.cc in compiler-rt.
174 auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
177 StringRef Output = OutputBuf.get()->getBuffer();
178 SmallVector<StringRef, 32> Lines;
179 Output.split(Lines, "\n");
180 auto CurLine = Lines.begin();
182 for (int i = 0; i < Depth; i++) {
184 OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << '\n';
187 // Read pairs of lines (function name and file/line info) until we
188 // encounter empty line.
190 if (CurLine == Lines.end())
192 StringRef FunctionName = *CurLine++;
193 if (FunctionName.empty())
195 OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << ' ';
196 if (!FunctionName.startswith("??"))
197 OS << FunctionName << ' ';
198 if (CurLine == Lines.end())
200 StringRef FileLineInfo = *CurLine++;
201 if (!FileLineInfo.startswith("??"))
204 OS << "(" << Modules[i] << '+' << format_hex(Offsets[i], 0) << ")";
211 // Include the platform-specific parts of this class.
213 #include "Unix/Signals.inc"
216 #include "Windows/Signals.inc"