1 //===- Signals.cpp - Generic Unix Signals Implementation -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines some helpful functions for dealing with the possibility of
11 // Unix signals occuring while your program is running.
13 //===----------------------------------------------------------------------===//
19 # include <execinfo.h> // For backtrace().
31 bool StackTraceRequested = false;
33 /// InterruptFunction - The function to call if ctrl-c is pressed.
34 void (*InterruptFunction)() = 0;
36 std::vector<sys::Path> *FilesToRemove = 0 ;
37 std::vector<sys::Path> *DirectoriesToRemove = 0;
39 // IntSigs - Signals that may interrupt the program at any time.
40 const int IntSigs[] = {
41 SIGHUP, SIGINT, SIGQUIT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
43 const int *IntSigsEnd = IntSigs + sizeof(IntSigs)/sizeof(IntSigs[0]);
45 // KillSigs - Signals that are synchronous with the program that will cause it
47 const int KillSigs[] = {
48 SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV, SIGSYS, SIGXCPU, SIGXFSZ
53 const int *KillSigsEnd = KillSigs + sizeof(KillSigs)/sizeof(KillSigs[0]);
56 void* StackTrace[256];
59 // PrintStackTrace - In the case of a program crash or fault, print out a stack
60 // trace so that the user has an indication of why and where we died.
62 // On glibc systems we have the 'backtrace' function, which works nicely, but
63 // doesn't demangle symbols. In order to backtrace symbols, we fork and exec a
64 // 'c++filt' process to do the demangling. This seems like the simplest and
65 // most robust solution when we can't allocate memory (such as in a signal
66 // handler). If we can't find 'c++filt', we fallback to printing mangled names.
68 void PrintStackTrace() {
70 // Use backtrace() to output a backtrace on Linux systems with glibc.
71 int depth = backtrace(StackTrace, sizeof(StackTrace)/sizeof(StackTrace[0]));
73 // Create a one-way unix pipe. The backtracing process writes to PipeFDs[1],
74 // the c++filt process reads from PipeFDs[0].
77 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
81 switch (pid_t ChildPID = fork()) {
82 case -1: // Error forking, print mangled stack trace
85 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
87 default: // backtracing process
88 close(PipeFDs[0]); // Close the reader side.
90 // Print the mangled backtrace into the pipe.
91 backtrace_symbols_fd(StackTrace, depth, PipeFDs[1]);
92 close(PipeFDs[1]); // We are done writing.
93 while (waitpid(ChildPID, 0, 0) == -1)
94 if (errno != EINTR) break;
97 case 0: // c++filt process
98 close(PipeFDs[1]); // Close the writer side.
99 dup2(PipeFDs[0], 0); // Read from standard input
100 close(PipeFDs[0]); // Close the old descriptor
101 dup2(2, 1); // Revector stdout -> stderr
103 // Try to run c++filt or gc++filt. If neither is found, call back on 'cat'
104 // to print the mangled stack trace. If we can't find cat, just exit.
105 execlp("c++filt", "c++filt", (char*)NULL);
106 execlp("gc++filt", "gc++filt", (char*)NULL);
107 execlp("cat", "cat", (char*)NULL);
108 execlp("/bin/cat", "cat", (char*)NULL);
114 // SignalHandler - The signal handler that runs...
115 RETSIGTYPE SignalHandler(int Sig) {
116 if (FilesToRemove != 0)
117 while (!FilesToRemove->empty()) {
118 FilesToRemove->back().eraseFromDisk(true);
119 FilesToRemove->pop_back();
122 if (DirectoriesToRemove != 0)
123 while (!DirectoriesToRemove->empty()) {
124 DirectoriesToRemove->back().eraseFromDisk(true);
125 DirectoriesToRemove->pop_back();
128 if (std::find(IntSigs, IntSigsEnd, Sig) != IntSigsEnd) {
129 if (InterruptFunction) {
130 void (*IF)() = InterruptFunction;
131 InterruptFunction = 0;
132 IF(); // run the interrupt function.
135 exit(1); // If this is an interrupt signal, exit the program
139 // Otherwise if it is a fault (like SEGV) output the stacktrace to
140 // STDERR (if we can) and reissue the signal to die...
141 if (StackTraceRequested)
143 signal(Sig, SIG_DFL);
147 void RegisterHandler(int Signal) {
148 signal(Signal, SignalHandler);
154 void sys::SetInterruptFunction(void (*IF)()) {
155 InterruptFunction = IF;
156 RegisterHandler(SIGINT);
159 // RemoveFileOnSignal - The public API
160 bool sys::RemoveFileOnSignal(const sys::Path &Filename, std::string* ErrMsg) {
161 if (FilesToRemove == 0)
162 FilesToRemove = new std::vector<sys::Path>;
164 FilesToRemove->push_back(Filename);
166 std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
167 std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
171 // RemoveDirectoryOnSignal - The public API
172 bool sys::RemoveDirectoryOnSignal(const sys::Path& path, std::string* ErrMsg) {
175 if (0 != stat(path.c_str(), &buf)) {
176 MakeErrMsg(ErrMsg, path.toString() + ": can't get status of file");
180 if (!S_ISDIR(buf.st_mode)) {
182 *ErrMsg = path.toString() + " is not a directory";
186 if (DirectoriesToRemove == 0)
187 DirectoriesToRemove = new std::vector<sys::Path>;
189 DirectoriesToRemove->push_back(path);
191 std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
192 std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
196 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIBABRT or
197 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
198 void sys::PrintStackTraceOnErrorSignal() {
199 StackTraceRequested = true;
200 std::for_each(KillSigs, KillSigsEnd, RegisterHandler);