#include "llvm/Support/CrashRecoveryContext.h"
#include "llvm/ADT/SmallString.h"
+#include "llvm/Config/config.h"
+#include "llvm/System/Mutex.h"
+#include "llvm/System/ThreadLocal.h"
#include <setjmp.h>
+#include <cstdio>
using namespace llvm;
namespace {
struct CrashRecoveryContextImpl;
+static sys::ThreadLocal<const CrashRecoveryContextImpl> CurrentContext;
+
struct CrashRecoveryContextImpl {
+ CrashRecoveryContext *CRC;
std::string Backtrace;
::jmp_buf JumpBuffer;
volatile unsigned Failed : 1;
public:
- CrashRecoveryContextImpl() : Failed(false) {}
+ CrashRecoveryContextImpl(CrashRecoveryContext *CRC) : CRC(CRC),
+ Failed(false) {
+ CurrentContext.set(this);
+ }
+ ~CrashRecoveryContextImpl() {
+ CurrentContext.erase();
+ }
void HandleCrash() {
+ // Eliminate the current context entry, to avoid re-entering in case the
+ // cleanup code crashes.
+ CurrentContext.erase();
+
assert(!Failed && "Crash recovery context already failed!");
Failed = true;
}
+static sys::Mutex gCrashRecoveryContexMutex;
static bool gCrashRecoveryEnabled = false;
CrashRecoveryContext::~CrashRecoveryContext() {
delete CRCI;
}
+CrashRecoveryContext *CrashRecoveryContext::GetCurrent() {
+ const CrashRecoveryContextImpl *CRCI = CurrentContext.get();
+ if (!CRCI)
+ return 0;
+
+ return CRCI->CRC;
+}
+
+#ifdef LLVM_ON_WIN32
+
+// FIXME: No real Win32 implementation currently.
+
void CrashRecoveryContext::Enable() {
+ sys::ScopedLock L(gCrashRecoveryContexMutex);
+
if (gCrashRecoveryEnabled)
return;
}
void CrashRecoveryContext::Disable() {
+ sys::ScopedLock L(gCrashRecoveryContexMutex);
+
if (!gCrashRecoveryEnabled)
return;
gCrashRecoveryEnabled = false;
}
+#else
+
+// Generic POSIX implementation.
+//
+// This implementation relies on synchronous signals being delivered to the
+// current thread. We use a thread local object to keep track of the active
+// crash recovery context, and install signal handlers to invoke HandleCrash on
+// the active object.
+//
+// This implementation does not to attempt to chain signal handlers in any
+// reliable fashion -- if we get a signal outside of a crash recovery context we
+// simply disable crash recovery and raise the signal again.
+
+#include <signal.h>
+
+static int Signals[] = { SIGABRT, SIGBUS, SIGFPE, SIGILL, SIGSEGV, SIGTRAP };
+static const unsigned NumSignals = sizeof(Signals) / sizeof(Signals[0]);
+static struct sigaction PrevActions[NumSignals];
+
+static void CrashRecoverySignalHandler(int Signal) {
+ // Lookup the current thread local recovery object.
+ const CrashRecoveryContextImpl *CRCI = CurrentContext.get();
+
+ if (!CRCI) {
+ // We didn't find a crash recovery context -- this means either we got a
+ // signal on a thread we didn't expect it on, the application got a signal
+ // outside of a crash recovery context, or something else went horribly
+ // wrong.
+ //
+ // Disable crash recovery and raise the signal again. The assumption here is
+ // that the enclosing application will terminate soon, and we won't want to
+ // attempt crash recovery again.
+ //
+ // This call of Disable isn't thread safe, but it doesn't actually matter.
+ CrashRecoveryContext::Disable();
+ raise(Signal);
+
+ // The signal will be thrown once the signal mask is restored.
+ return;
+ }
+
+ // Unblock the signal we received.
+ sigset_t SigMask;
+ sigemptyset(&SigMask);
+ sigaddset(&SigMask, Signal);
+ sigprocmask(SIG_UNBLOCK, &SigMask, 0);
+
+ if (CRCI)
+ const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
+}
+
+void CrashRecoveryContext::Enable() {
+ sys::ScopedLock L(gCrashRecoveryContexMutex);
+
+ if (gCrashRecoveryEnabled)
+ return;
+
+ gCrashRecoveryEnabled = true;
+
+ // Setup the signal handler.
+ struct sigaction Handler;
+ Handler.sa_handler = CrashRecoverySignalHandler;
+ Handler.sa_flags = 0;
+ sigemptyset(&Handler.sa_mask);
+
+ for (unsigned i = 0; i != NumSignals; ++i) {
+ sigaction(Signals[i], &Handler, &PrevActions[i]);
+ }
+}
+
+void CrashRecoveryContext::Disable() {
+ sys::ScopedLock L(gCrashRecoveryContexMutex);
+
+ if (!gCrashRecoveryEnabled)
+ return;
+
+ gCrashRecoveryEnabled = false;
+
+ // Restore the previous signal handlers.
+ for (unsigned i = 0; i != NumSignals; ++i)
+ sigaction(Signals[i], &PrevActions[i], 0);
+}
+
+#endif
+
bool CrashRecoveryContext::RunSafely(void (*Fn)(void*), void *UserData) {
// If crash recovery is disabled, do nothing.
if (gCrashRecoveryEnabled) {
assert(!Impl && "Crash recovery context already initialized!");
- CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl;
+ CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl(this);
Impl = CRCI;
if (setjmp(CRCI->JumpBuffer) != 0) {