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Perform proper cleanup for signals with 'Term' action (#3057) 

Issue #3049 describes a case where terminating i3 by means of SIGTERM
causes it to leak the runtime directory and all its contents. There are
multiple issues at play: first, any cleanup handlers registered via
atexit are never invoked when a signal terminates the program (see
atexit(3)). Hence, the log SHM log cleanup performed in i3_exit is not
invoked in that case. Second, compared to the shutdown path for the
'exit' command, we do not unlink the UNIX domain socket we create,
causing it to be leaked as well. Third, a handler for SIGTERM is not
registered at all despite handle_signal claiming to be the handler for
all 'Term' signals.
This change addresses all three problems and results in a graceful exit
including cleanup to happen when we receive a signal with the default
action 'Term'. It addresses issue #3049.
This commit is contained in:
Daniel Mueller 2017-11-28 23:29:47 -08:00 committed by Michael Stapelberg
parent e4d6458cc3
commit 3e34122de4
3 changed files with 135 additions and 21 deletions
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74
src/main.c
View File

@ -174,19 +174,62 @@ static void i3_exit(void) {
fflush(stderr);
shm_unlink(shmlogname);
}
ipc_shutdown(SHUTDOWN_REASON_EXIT);
unlink(config.ipc_socket_path);
}
/*
* (One-shot) Handler for all signals with default action "Core", see signal(7)
*
* Unlinks the SHM log and re-raises the signal.
*
*/
static void handle_core_signal(int sig, siginfo_t *info, void *data) {
if (*shmlogname != '\0') {
shm_unlink(shmlogname);
}
raise(sig);
}
/*
* (One-shot) Handler for all signals with default action "Term", see signal(7)
*
* Unlinks the SHM log and re-raises the signal.
* Exits the program gracefully.
*
*/
static void handle_signal(int sig, siginfo_t *info, void *data) {
if (*shmlogname != '\0') {
shm_unlink(shmlogname);
static void handle_term_signal(struct ev_loop *loop, ev_signal *signal, int revents) {
/* We exit gracefully here in the sense that cleanup handlers
* installed via atexit are invoked. */
exit(128 + signal->signum);
}
/*
* Set up handlers for all signals with default action "Term", see signal(7)
*
*/
static void setup_term_handlers(void) {
static struct ev_signal signal_watchers[6];
size_t num_watchers = sizeof(signal_watchers) / sizeof(signal_watchers[0]);
/* We have to rely on libev functionality here and should not use
* sigaction handlers because we need to invoke the exit handlers
* and cannot do so from an asynchronous signal handling context as
* not all code triggered during exit is signal safe (and exiting
* the main loop from said handler is not easily possible). libev's
* signal handlers does not impose such a constraint on us. */
ev_signal_init(&signal_watchers[0], handle_term_signal, SIGHUP);
ev_signal_init(&signal_watchers[1], handle_term_signal, SIGINT);
ev_signal_init(&signal_watchers[2], handle_term_signal, SIGALRM);
ev_signal_init(&signal_watchers[3], handle_term_signal, SIGTERM);
ev_signal_init(&signal_watchers[4], handle_term_signal, SIGUSR1);
ev_signal_init(&signal_watchers[5], handle_term_signal, SIGUSR1);
for (size_t i = 0; i < num_watchers; i++) {
ev_signal_start(main_loop, &signal_watchers[i]);
/* The signal handlers should not block ev_run from returning
* and so none of the signal handlers should hold a reference to
* the main loop. */
ev_unref(main_loop);
}
raise(sig);
}
int main(int argc, char *argv[]) {
@ -853,15 +896,15 @@ int main(int argc, char *argv[]) {
err(EXIT_FAILURE, "pledge");
#endif
struct sigaction action;
action.sa_sigaction = handle_signal;
action.sa_flags = SA_NODEFER | SA_RESETHAND | SA_SIGINFO;
sigemptyset(&action.sa_mask);
if (!disable_signalhandler)
setup_signal_handler();
else {
struct sigaction action;
action.sa_sigaction = handle_core_signal;
action.sa_flags = SA_NODEFER | SA_RESETHAND | SA_SIGINFO;
sigemptyset(&action.sa_mask);
/* Catch all signals with default action "Core", see signal(7) */
if (sigaction(SIGQUIT, &action, NULL) == -1 ||
sigaction(SIGILL, &action, NULL) == -1 ||
@ -871,14 +914,7 @@ int main(int argc, char *argv[]) {
ELOG("Could not setup signal handler.\n");
}
/* Catch all signals with default action "Term", see signal(7) */
if (sigaction(SIGHUP, &action, NULL) == -1 ||
sigaction(SIGINT, &action, NULL) == -1 ||
sigaction(SIGALRM, &action, NULL) == -1 ||
sigaction(SIGUSR1, &action, NULL) == -1 ||
sigaction(SIGUSR2, &action, NULL) == -1)
ELOG("Could not setup signal handler.\n");
setup_term_handlers();
/* Ignore SIGPIPE to survive errors when an IPC client disconnects
* while we are sending them a message */
signal(SIGPIPE, SIG_IGN);

47
testcases/lib/i3test.pm.in
View File

@ -12,6 +12,7 @@ use AnyEvent::I3;
use List::Util qw(first);
use Time::HiRes qw(sleep);
use Cwd qw(abs_path);
use POSIX ':sys_wait_h';
use Scalar::Util qw(blessed);
use SocketActivation;
use i3test::Util qw(slurp);
@ -37,6 +38,7 @@ our @EXPORT = qw(
cmd
sync_with_i3
exit_gracefully
exit_forcefully
workspace_exists
focused_ws
get_socket_path
@ -123,7 +125,7 @@ END {
} else {
kill(-9, $i3_pid)
or $tester->BAIL_OUT("could not kill i3");
or $tester->BAIL_OUT("could not kill i3: $!");
waitpid $i3_pid, 0;
}
@ -759,7 +761,7 @@ sub exit_gracefully {
if (!$exited) {
kill(9, $pid)
or $tester->BAIL_OUT("could not kill i3");
or $tester->BAIL_OUT("could not kill i3: $!");
}
if ($socketpath =~ m,^/tmp/i3-test-socket-,) {
@ -770,6 +772,47 @@ sub exit_gracefully {
undef $i3_pid;
}
=head2 exit_forcefully($pid, [ $signal ])
Tries to exit i3 forcefully by sending a signal (defaults to SIGTERM).
You only need to use this function if you want to test signal handling
(in which case you must have launched i3 on your own with
C<launch_with_config>).
use i3test i3_autostart => 0;
my $pid = launch_with_config($config);
# …
exit_forcefully($pid);
=cut
sub exit_forcefully {
my ($pid, $signal) = @_;
$signal ||= 'TERM';
# Send the given signal to the i3 instance and wait for up to 10s
# for it to terminate.
kill($signal, $pid)
or $tester->BAIL_OUT("could not kill i3: $!");
my $status;
my $timeout = 10;
do {
$status = waitpid $pid, WNOHANG;
if ($status <= 0) {
sleep(1);
$timeout--;
}
} while ($status <= 0 && $timeout > 0);
if ($status <= 0) {
kill('KILL', $pid)
or $tester->BAIL_OUT("could not kill i3: $!");
waitpid $pid, 0;
}
undef $i3_pid;
}
=head2 get_socket_path([ $cache ])
Gets the socket path from the C<I3_SOCKET_PATH> atom stored on the X11 root

35
testcases/t/540-sigterm-cleanup.t Normal file
View File

@ -0,0 +1,35 @@
#!perl
# vim:ts=4:sw=4:expandtab
#
# Please read the following documents before working on tests:
# • https://build.i3wm.org/docs/testsuite.html
# (or docs/testsuite)
#
# • https://build.i3wm.org/docs/lib-i3test.html
# (alternatively: perldoc ./testcases/lib/i3test.pm)
#
# • https://build.i3wm.org/docs/ipc.html
# (or docs/ipc)
#
# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
# (unless you are already familiar with Perl)
#
# Tests that the socket file is cleaned up properly after gracefully
# shutting down i3 via SIGTERM.
# Ticket: #3049
use i3test i3_autostart => 0;
my $config = <<EOT;
# i3 config file (v4)
font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
EOT
my $pid = launch_with_config($config, dont_add_socket_path => 1);
my $socket = get_socket_path();
ok(-S $socket, "socket $socket exists");
exit_forcefully($pid, 'TERM');
ok(!-e $socket, "socket $socket no longer exists");
done_testing;