1 //===--- CrashRecoveryContext.cpp - Crash Recovery ------------------------===//
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 #include "llvm/Support/CrashRecoveryContext.h"
11 #include "llvm/ADT/SmallString.h"
12 #include "llvm/Config/config.h"
13 #include "llvm/System/ThreadLocal.h"
20 struct CrashRecoveryContextImpl;
22 static sys::ThreadLocal<const CrashRecoveryContextImpl> CurrentContext;
24 struct CrashRecoveryContextImpl {
25 std::string Backtrace;
27 volatile unsigned Failed : 1;
30 CrashRecoveryContextImpl() : Failed(false) {
31 CurrentContext.set(this);
33 ~CrashRecoveryContextImpl() {
34 CurrentContext.set(0);
38 assert(!Failed && "Crash recovery context already failed!");
41 // FIXME: Stash the backtrace.
43 // Jump back to the RunSafely we were called under.
44 longjmp(JumpBuffer, 1);
50 static bool gCrashRecoveryEnabled = false;
52 CrashRecoveryContext::~CrashRecoveryContext() {
53 CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
59 // FIXME: No real Win32 implementation currently.
61 void CrashRecoveryContext::Enable() {
62 if (gCrashRecoveryEnabled)
65 gCrashRecoveryEnabled = true;
68 void CrashRecoveryContext::Disable() {
69 if (!gCrashRecoveryEnabled)
72 gCrashRecoveryEnabled = false;
77 // Generic POSIX implementation.
79 // This implementation relies on synchronous signals being delivered to the
80 // current thread. We use a thread local object to keep track of the active
81 // crash recovery context, and install signal handlers to invoke HandleCrash on
84 // This implementation does not to attempt to chain signal handlers in any
85 // reliable fashion -- if we get a signal outside of a crash recovery context we
86 // simply disable crash recovery and raise the signal again.
92 struct sigaction PrevAction;
101 static const unsigned NumSignals = sizeof(SignalInfo) / sizeof(SignalInfo[0]);
103 static void CrashRecoverySignalHandler(int Signal) {
104 // Lookup the current thread local recovery object.
105 const CrashRecoveryContextImpl *CRCI = CurrentContext.get();
108 // We didn't find a crash recovery context -- this means either we got a
109 // signal on a thread we didn't expect it on, the application got a signal
110 // outside of a crash recovery context, or something else went horribly
113 // Disable crash recovery and raise the signal again. The assumption here is
114 // that the enclosing application will terminate soon, and we won't want to
115 // attempt crash recovery again.
117 // This call of Disable isn't thread safe, but it doesn't actually matter.
118 CrashRecoveryContext::Disable();
122 // Unblock the signal we received.
124 sigemptyset(&SigMask);
125 sigaddset(&SigMask, Signal);
126 sigprocmask(SIG_UNBLOCK, &SigMask, 0);
129 const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
132 void CrashRecoveryContext::Enable() {
133 if (gCrashRecoveryEnabled)
136 gCrashRecoveryEnabled = true;
138 // Setup the signal handler.
139 struct sigaction Handler;
140 Handler.sa_handler = CrashRecoverySignalHandler;
141 Handler.sa_flags = 0;
142 sigemptyset(&Handler.sa_mask);
144 for (unsigned i = 0; i != NumSignals; ++i) {
145 sigaction(SignalInfo[i].Signal, &Handler,
146 &SignalInfo[i].PrevAction);
150 void CrashRecoveryContext::Disable() {
151 if (!gCrashRecoveryEnabled)
154 gCrashRecoveryEnabled = false;
156 // Restore the previous signal handlers.
157 for (unsigned i = 0; i != NumSignals; ++i)
158 sigaction(SignalInfo[i].Signal, &SignalInfo[i].PrevAction, 0);
163 bool CrashRecoveryContext::RunSafely(void (*Fn)(void*), void *UserData) {
164 // If crash recovery is disabled, do nothing.
165 if (gCrashRecoveryEnabled) {
166 assert(!Impl && "Crash recovery context already initialized!");
167 CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl;
170 if (setjmp(CRCI->JumpBuffer) != 0) {
179 void CrashRecoveryContext::HandleCrash() {
180 CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
181 assert(CRCI && "Crash recovery context never initialized!");
185 const std::string &CrashRecoveryContext::getBacktrace() const {
186 CrashRecoveryContextImpl *CRC = (CrashRecoveryContextImpl *) Impl;
187 assert(CRC && "Crash recovery context never initialized!");
188 assert(CRC->Failed && "No crash was detected!");
189 return CRC->Backtrace;