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//===- Signals.cpp - Generic Unix Signals Implementation -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines some helpful functions for dealing with the possibility of
// Unix signals occuring while your program is running.
//
//===----------------------------------------------------------------------===//
#include "Unix.h"
#include "llvm/ADT/STLExtras.h"
#include <vector>
#include <algorithm>
#if HAVE_EXECINFO_H
# include <execinfo.h> // For backtrace().
#endif
#if HAVE_SIGNAL_H
#include <signal.h>
#endif
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
using namespace llvm;
namespace {
bool StackTraceRequested = false;
/// InterruptFunction - The function to call if ctrl-c is pressed.
void (*InterruptFunction)() = 0;
std::vector<sys::Path> *FilesToRemove = 0 ;
std::vector<sys::Path> *DirectoriesToRemove = 0;
// IntSigs - Signals that may interrupt the program at any time.
const int IntSigs[] = {
SIGHUP, SIGINT, SIGQUIT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
};
const int *IntSigsEnd = array_endof(IntSigs);
// KillSigs - Signals that are synchronous with the program that will cause it
// to die.
const int KillSigs[] = {
SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV, SIGSYS, SIGXCPU, SIGXFSZ
#ifdef SIGEMT
, SIGEMT
#endif
};
const int *KillSigsEnd = array_endof(KillSigs);
#ifdef HAVE_BACKTRACE
void* StackTrace[256];
#endif
// PrintStackTrace - In the case of a program crash or fault, print out a stack
// trace so that the user has an indication of why and where we died.
//
// On glibc systems we have the 'backtrace' function, which works nicely, but
// doesn't demangle symbols. In order to backtrace symbols, we fork and exec a
// 'c++filt' process to do the demangling. This seems like the simplest and
// most robust solution when we can't allocate memory (such as in a signal
// handler). If we can't find 'c++filt', we fallback to printing mangled names.
//
void PrintStackTrace() {
#ifdef HAVE_BACKTRACE
// Use backtrace() to output a backtrace on Linux systems with glibc.
int depth = backtrace(StackTrace, array_lengthof(StackTrace));
// Create a one-way unix pipe. The backtracing process writes to PipeFDs[1],
// the c++filt process reads from PipeFDs[0].
int PipeFDs[2];
if (pipe(PipeFDs)) {
backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
return;
}
switch (pid_t ChildPID = fork()) {
case -1: // Error forking, print mangled stack trace
close(PipeFDs[0]);
close(PipeFDs[1]);
backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
return;
default: // backtracing process
close(PipeFDs[0]); // Close the reader side.
// Print the mangled backtrace into the pipe.
backtrace_symbols_fd(StackTrace, depth, PipeFDs[1]);
close(PipeFDs[1]); // We are done writing.
while (waitpid(ChildPID, 0, 0) == -1)
if (errno != EINTR) break;
return;
case 0: // c++filt process
close(PipeFDs[1]); // Close the writer side.
dup2(PipeFDs[0], 0); // Read from standard input
close(PipeFDs[0]); // Close the old descriptor
dup2(2, 1); // Revector stdout -> stderr
// Try to run c++filt or gc++filt. If neither is found, call back on 'cat'
// to print the mangled stack trace. If we can't find cat, just exit.
execlp("c++filt", "c++filt", (char*)NULL);
execlp("gc++filt", "gc++filt", (char*)NULL);
execlp("cat", "cat", (char*)NULL);
execlp("/bin/cat", "cat", (char*)NULL);
exit(0);
}
#endif
}
// SignalHandler - The signal handler that runs...
RETSIGTYPE SignalHandler(int Sig) {
if (FilesToRemove != 0)
while (!FilesToRemove->empty()) {
FilesToRemove->back().eraseFromDisk(true);
FilesToRemove->pop_back();
}
if (DirectoriesToRemove != 0)
while (!DirectoriesToRemove->empty()) {
DirectoriesToRemove->back().eraseFromDisk(true);
DirectoriesToRemove->pop_back();
}
if (std::find(IntSigs, IntSigsEnd, Sig) != IntSigsEnd) {
if (InterruptFunction) {
void (*IF)() = InterruptFunction;
InterruptFunction = 0;
IF(); // run the interrupt function.
return;
} else {
exit(1); // If this is an interrupt signal, exit the program
}
}
// Otherwise if it is a fault (like SEGV) output the stacktrace to
// STDERR (if we can) and reissue the signal to die...
if (StackTraceRequested)
PrintStackTrace();
signal(Sig, SIG_DFL);
}
// Just call signal
void RegisterHandler(int Signal) {
signal(Signal, SignalHandler);
}
}
void sys::SetInterruptFunction(void (*IF)()) {
InterruptFunction = IF;
RegisterHandler(SIGINT);
}
// RemoveFileOnSignal - The public API
bool sys::RemoveFileOnSignal(const sys::Path &Filename, std::string* ErrMsg) {
if (FilesToRemove == 0)
FilesToRemove = new std::vector<sys::Path>;
FilesToRemove->push_back(Filename);
std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
return false;
}
// RemoveDirectoryOnSignal - The public API
bool sys::RemoveDirectoryOnSignal(const sys::Path& path, std::string* ErrMsg) {
// Not a directory?
struct stat buf;
if (0 != stat(path.c_str(), &buf)) {
MakeErrMsg(ErrMsg, path.toString() + ": can't get status of file");
return true;
}
if (!S_ISDIR(buf.st_mode)) {
if (ErrMsg)
*ErrMsg = path.toString() + " is not a directory";
return true;
}
if (DirectoriesToRemove == 0)
DirectoriesToRemove = new std::vector<sys::Path>;
DirectoriesToRemove->push_back(path);
std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
return false;
}
/// PrintStackTraceOnErrorSignal - When an error signal (such as SIBABRT or
/// SIGSEGV) is delivered to the process, print a stack trace and then exit.
void sys::PrintStackTraceOnErrorSignal() {
StackTraceRequested = true;
std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
}
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