Initial platform independent implementation of operating system concept

of "Signals" (cleanup after fatal errors).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16085 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 169 insertions, 0 deletions

diff --git a/lib/System/Unix/Signals.cpp b/lib/System/Unix/Signals.cpp
new file mode 100644
index 0000000000..445fec74f7
--- /dev/null
+++ b/lib/System/Unix/Signals.cpp
@@ -0,0 +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