void
MemoryProtectionExceptionHandler::uninstall()
{
if (sExceptionHandlerInstalled) {
MOZ_ASSERT(!sHandlingException);
// Restore the previous exception handler.
MOZ_ALWAYS_FALSE(sigaction(SIGSEGV, &sPrevSEGVHandler, nullptr));
sExceptionHandlerInstalled = false;
}
}
already_AddRefed<IDBTransaction>
IDBDatabase::Transaction(const StringOrStringSequence& aStoreNames,
IDBTransactionMode aMode,
ErrorResult& aRv)
{
AssertIsOnOwningThread();
aRv.MightThrowJSException();
if (aMode == IDBTransactionMode::Readwriteflush &&
!IndexedDatabaseManager::ExperimentalFeaturesEnabled()) {
// Pretend that this mode doesn't exist. We don't have a way to annotate
// certain enum values as depending on preferences so we just duplicate the
// normal exception generation here.
ThreadsafeAutoJSContext cx;
// Disable any automatic error reporting that might be set up so that we
// can grab the exception object.
AutoForceSetExceptionOnContext forceExn(cx);
MOZ_ALWAYS_FALSE(
ThrowErrorMessage(cx,
MSG_INVALID_ENUM_VALUE,
"Argument 2 of IDBDatabase.transaction",
"readwriteflush",
"IDBTransactionMode"));
MOZ_ASSERT(JS_IsExceptionPending(cx));
JS::Rooted<JS::Value> exception(cx);
MOZ_ALWAYS_TRUE(JS_GetPendingException(cx, &exception));
aRv.ThrowJSException(cx, exception);
return nullptr;
}
RefPtr<IDBTransaction> transaction;
aRv = Transaction(aStoreNames, aMode, getter_AddRefs(transaction));
if (NS_WARN_IF(aRv.Failed())) {
return nullptr;
}
return transaction.forget();
}
static void
UnixExceptionHandler(int signum, siginfo_t* info, void* context)
{
// Make absolutely sure we can only get here once.
if (sHandlingException.compareExchange(false, true)) {
// Restore the previous handler. We're going to forward to it
// anyway, and if we crash while doing so we don't want to hang.
MOZ_ALWAYS_FALSE(sigaction(SIGSEGV, &sPrevSEGVHandler, nullptr));
MOZ_ASSERT(signum == SIGSEGV && info->si_signo == SIGSEGV);
if (info->si_code == SEGV_ACCERR) {
// Get the address that the offending code tried to access.
uintptr_t address = uintptr_t(info->si_addr);
// If the faulting address is in one of our protected regions, we
// want to annotate the crash to make it stand out from the crowd.
if (sProtectedRegions.isProtected(address)) {
ReportCrashIfDebug("Hit MOZ_CRASH(Tried to access a protected region!)\n");
MOZ_CRASH_ANNOTATE("MOZ_CRASH(Tried to access a protected region!)");
}
}
}
// Forward to the previous handler which may be a debugger,
// the crash reporter or something else entirely.
if (sPrevSEGVHandler.sa_flags & SA_SIGINFO)
sPrevSEGVHandler.sa_sigaction(signum, info, context);
else if (sPrevSEGVHandler.sa_handler == SIG_DFL || sPrevSEGVHandler.sa_handler == SIG_IGN)
sigaction(SIGSEGV, &sPrevSEGVHandler, nullptr);
else
sPrevSEGVHandler.sa_handler(signum);
// If we reach here, we're returning to let the default signal handler deal
// with the exception. This is technically undefined behavior, but
// everything seems to do it, and it removes us from the crash stack.
}