[llvm-commits] CVS: llvm/lib/System/Unix/Signals.cpp

[Reid Spencer]

Changes in directory llvm/lib/System/Unix:

Signals.cpp added (r1.1)
---
Log message:

Initial platform independent implementation of operating system concept
of "Signals" (cleanup after fatal errors).


---
Diffs of the changes:  (+169 -0)

Index: llvm/lib/System/Unix/Signals.cpp
diff -c /dev/null llvm/lib/System/Unix/Signals.cpp:1.1
*** /dev/null	Sun Aug 29 14:22:58 2004
--- llvm/lib/System/Unix/Signals.cpp	Sun Aug 29 14:22:48 2004
***************
*** 0 ****
--- 1,169 ----
+ //===- Signals.cpp - Generic Unix Signals Implementation -----*- C++ -*-===//
+ // 
+ //                     The LLVM Compiler Infrastructure
+ //
+ // This file was developed by the LLVM research group and 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 <vector>
+ #include <algorithm>
+ #ifdef HAVE_EXECINFO_H
+ # include <execinfo.h>         // For backtrace().
+ #endif
+ #include <sys/wait.h>
+ #include <signal.h>
+ 
+ namespace {
+ 
+ std::vector<std::string> *FilesToRemove = 0 ;
+ std::vector<llvm::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 = IntSigs + sizeof(IntSigs)/sizeof(IntSigs[0]);
+ 
+ // 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 = KillSigs + sizeof(KillSigs)/sizeof(KillSigs[0]);
+ 
+ #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, sizeof(StackTrace)/sizeof(StackTrace[0]));
+   
+   // 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", 0);
+     execlp("gc++filt", "gc++filt", 0);
+     execlp("cat", "cat", 0);
+     execlp("/bin/cat", "cat", 0);
+     exit(0);
+   }
+ #endif
+ }
+ 
+ // SignalHandler - The signal handler that runs...
+ RETSIGTYPE SignalHandler(int Sig) {
+   if (FilesToRemove != 0)
+     while (!FilesToRemove->empty()) {
+       std::remove(FilesToRemove->back().c_str());
+       FilesToRemove->pop_back();
+     }
+ 
+   if (DirectoriesToRemove != 0)
+     while (!DirectoriesToRemove->empty()) {
+       DirectoriesToRemove->back().destroy_directory(true);
+       DirectoriesToRemove->pop_back();
+     }
+ 
+   if (std::find(IntSigs, IntSigsEnd, Sig) != IntSigsEnd)
+     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...
+   PrintStackTrace();
+   signal(Sig, SIG_DFL);
+ }
+ 
+ // Just call signal
+ void RegisterHandler(int Signal) { 
+   signal(Signal, SignalHandler); 
+ }
+ 
+ }
+ 
+ namespace llvm {
+ 
+ // RemoveFileOnSignal - The public API
+ void sys::RemoveFileOnSignal(const std::string &Filename) {
+   if (FilesToRemove == 0)
+     FilesToRemove = new std::vector<std::string>;
+ 
+   FilesToRemove->push_back(Filename);
+ 
+   std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
+   std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
+ }
+ 
+ // RemoveDirectoryOnSignal - The public API
+ void sys::RemoveDirectoryOnSignal(const llvm::sys::Path& path) {
+   if (!path.is_directory())
+     return;
+ 
+   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);
+ }
+ 
+ /// 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() {
+   std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
+ }
+ 
+ }
+ 
+ // vim: sw=2 smartindent smarttab tw=80 autoindent expandtab