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fix how SIGHUP is handled when ignored

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Working on a related problem caused me to notice that if a fish script
was run via `nohup` it would die when receiving SIGHUP. This fixes the
code to handle that correctly so that fish scripts can be nohup'd.

Fixes #4007
This commit is contained in:
Kurtis Rader 2017-05-03 20:29:01 -07:00
parent 084a820de3
commit fddd5fd045
1 changed files with 29 additions and 18 deletions
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43
src/signal.cpp
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@ -143,7 +143,7 @@ static const struct lookup_entry lookup[] = {
#ifdef SIGUNUSED
{SIGUNUSED, L"SIGUNUSED", N_(L"Unused signal")},
#endif
{0, 0, 0}};
{0, NULL, NULL}};
/// Test if \c name is a string describing the signal named \c canonical.
static int match_signal_name(const wchar_t *canonical, const wchar_t *name) {
@ -242,9 +242,8 @@ static void handle_chld(int sig, siginfo_t *info, void *context) {
default_handler(sig, info, context);
}
// We have a sigalarm handler that does nothing
// This is used in the signal torture test, to verify
// that we behave correctly when receiving lots of irrelevant signals
// We have a sigalarm handler that does nothing. This is used in the signal torture test, to verify
// that we behave correctly when receiving lots of irrelevant signals.
static void handle_sigalarm(int sig, siginfo_t *info, void *context) {
UNUSED(sig);
UNUSED(info);
@ -260,49 +259,57 @@ void signal_reset_handlers() {
act.sa_handler = SIG_DFL;
for (i = 0; lookup[i].desc; i++) {
sigaction(lookup[i].signal, &act, 0);
if (lookup[i].signal == SIGHUP) {
struct sigaction oact;
sigaction(SIGHUP, NULL, &oact);
if (oact.sa_handler == SIG_IGN) continue;
}
sigaction(lookup[i].signal, &act, NULL);
}
}
static void set_interactive_handlers() {
struct sigaction act;
struct sigaction act, oact;
sigemptyset(&act.sa_mask);
// Interactive mode. Ignore interactive signals. We are a shell, we know what is best for
// the user.
act.sa_handler = SIG_IGN;
sigaction(SIGINT, &act, 0);
sigaction(SIGQUIT, &act, 0);
sigaction(SIGTSTP, &act, 0);
sigaction(SIGTTOU, &act, 0);
sigaction(SIGINT, &act, NULL);
sigaction(SIGQUIT, &act, NULL);
sigaction(SIGTSTP, &act, NULL);
sigaction(SIGTTOU, &act, NULL);
// We don't ignore SIGTTIN because we might send it to ourself.
act.sa_sigaction = &default_handler;
act.sa_flags = SA_SIGINFO;
sigaction(SIGTTIN, &act, 0);
sigaction(SIGTTIN, &act, NULL);
act.sa_sigaction = &handle_int;
act.sa_flags = SA_SIGINFO;
sigaction(SIGINT, &act, 0);
sigaction(SIGINT, &act, NULL);
// SIGTERM restores the terminal controlling process before dying.
act.sa_sigaction = &handle_sigterm;
act.sa_flags = SA_SIGINFO;
sigaction(SIGTERM, &act, 0);
sigaction(SIGTERM, &act, NULL);
sigaction(SIGHUP, NULL, &oact);
if (oact.sa_handler == SIG_DFL) {
act.sa_sigaction = &handle_hup;
act.sa_flags = SA_SIGINFO;
sigaction(SIGHUP, &act, 0);
sigaction(SIGHUP, &act, NULL);
}
// SIGALARM as part of our signal torture test
act.sa_sigaction = &handle_sigalarm;
act.sa_flags = SA_SIGINFO;
sigaction(SIGALRM, &act, 0);
sigaction(SIGALRM, &act, NULL);
#ifdef SIGWINCH
act.sa_sigaction = &handle_winch;
act.sa_flags = SA_SIGINFO;
sigaction(SIGWINCH, &act, 0);
sigaction(SIGWINCH, &act, NULL);
#endif
}
@ -368,6 +375,10 @@ void get_signals_with_handlers(sigset_t *set) {
for (int i = 0; lookup[i].desc; i++) {
struct sigaction act = {};
sigaction(lookup[i].signal, NULL, &act);
// If SIGHUP is being ignored (e.g., because were were run via `nohup`) don't reset it.
// We don't special case other signals because if they're being ignored that shouldn't
// affect processes we spawn. They should get the default behavior for those signals.
if (lookup[i].signal == SIGHUP && act.sa_handler == SIG_IGN) continue;
if (act.sa_handler != SIG_DFL) sigaddset(set, lookup[i].signal);
}
}