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FatalSignalHandler: remember the previous signal's handler 

And only restore those signals, instead of iterating over all possible
signals, instead of attempting to restore to SIG_DFL. Also, as a
consequence, we will install our handler even if there was already a
handler installed for the signal.

Pick-to: 6.3
Change-Id: I5ff8e16fcdcb4ffd9ab6fffd16eb756685f4e8b8
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
bb10
Thiago Macieira 2022-05-02 18:52:51 -07:00
parent c4600b2e25
commit 29dd43d5ab
1 changed files with 23 additions and 41 deletions
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64
src/testlib/qtestcase.cpp
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@ -1836,16 +1836,19 @@ using FatalSignalHandler = WindowsFaultHandler;
class FatalSignalHandler
{
public:
static constexpr std::array fatalSignals = {
SIGHUP, SIGINT, SIGQUIT, SIGILL, SIGBUS, SIGFPE, SIGSEGV, SIGPIPE, SIGTERM
};
using OldActionsArray = std::array<struct sigaction, fatalSignals.size()>;
FatalSignalHandler()
{
pauseOnCrash = qEnvironmentVariableIsSet("QTEST_PAUSE_ON_CRASH");
sigemptyset(&handledSignals);
const int fatalSignals[] = {
SIGHUP, SIGINT, SIGQUIT, SIGILL, SIGBUS, SIGFPE, SIGSEGV, SIGPIPE, SIGTERM };
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = SIG_DFL;
oldActions().fill(act);
// Remove the handler after it is invoked.
act.sa_flags = SA_RESETHAND;
@ -1882,39 +1885,14 @@ public:
for (int signal : fatalSignals)
sigaddset(&act.sa_mask, signal);
// The destructor can only restore SIG_DFL, so only register for signals
// that had default handling previously.
const auto isDefaultHandler = [](const struct sigaction &old) {
# ifdef SA_SIGINFO
// void sa_sigaction(int, siginfo_t *, void *) is never the default:
if (old.sa_flags & SA_SIGINFO)
return false;
# endif
// Otherwise, the handler is void sa_handler(int) but may be
// SIG_DFL (default action) or SIG_IGN (ignore signal):
return old.sa_handler == SIG_DFL;
};
struct sigaction oldact;
for (int signal : fatalSignals) {
// Registering reveals the existing handler:
if (sigaction(signal, &act, &oldact))
continue; // Failed to set our handler; nothing to restore.
if (isDefaultHandler(oldact))
sigaddset(&handledSignals, signal);
else // Restore non-default handler:
sigaction(signal, &oldact, nullptr);
}
for (size_t i = 0; i < fatalSignals.size(); ++i)
sigaction(fatalSignals[i], &act, &oldActions()[i]);
}
~FatalSignalHandler()
{
// Restore the default signal handler in place of ours.
// Restore the default signal handlers in place of ours.
// If ours has been replaced, leave the replacement alone.
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = SIG_DFL;
auto isOurs = [](const struct sigaction &old) {
# ifdef SA_SIGINFO
return (old.sa_flags & SA_SIGINFO) && old.sa_sigaction == FatalSignalHandler::actionHandler;
@ -1924,20 +1902,26 @@ public:
};
struct sigaction action;
for (int signum = 1; signum < 32; ++signum) {
if (!sigismember(&handledSignals, signum))
continue;
if (sigaction(signum, nullptr, &action))
for (size_t i = 0; i < fatalSignals.size(); ++i) {
struct sigaction &act = oldActions()[i];
if (act.sa_flags == 0 && act.sa_handler == SIG_DFL)
continue; // Already the default
if (sigaction(fatalSignals[i], nullptr, &action))
continue; // Failed to query present handler
if (isOurs(action))
sigaction(signum, &act, nullptr);
sigaction(fatalSignals[i], &act, nullptr);
}
}
private:
Q_DISABLE_COPY_MOVE(FatalSignalHandler)
static OldActionsArray &oldActions()
{
Q_CONSTINIT static OldActionsArray oldActions {};
return oldActions;
}
static void actionHandler(int signum, siginfo_t * /* info */, void * /* ucontext */)
{
const int msecsFunctionTime = qRound(QTestLog::msecsFunctionTime());
@ -1961,8 +1945,6 @@ private:
{
actionHandler(signum, nullptr, nullptr);
}
sigset_t handledSignals;
static bool pauseOnCrash;
};
bool FatalSignalHandler::pauseOnCrash = false;