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fix(xcat-dep): block cancellation across the fork

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The handlers were installed after fork(), so a signal arriving in between killed
the wrapper under its inherited handler and left the new process group running.
INT, TERM and HUP are now blocked around the fork and delivered once the handler
is in place. The child restores the mask before exec, or the build would inherit
a blocked TERM and ignore the signal the forwarding depends on.
This commit is contained in:
Vinícius Ferrão
2026-09-06 02:44:58 -03:00
parent 796f7c174b
commit 88412a8a83
1 changed files with 14 additions and 1 deletions
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lib/XCAT/BuildUtils.pm
+14 -1
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@@ -235,10 +235,22 @@ sub run_bounded {
my $out = $a{out} || \*STDERR;
my $t0 = time;
# Block the handled signals across the fork. A cancellation landing between fork() and the
# handler below would kill this process under the inherited handler and leave the new process
# group running. A blocked signal stays pending and is delivered once the handler is in place.
# The child restores the mask before exec, or the build would inherit a blocked TERM.
my $handled = POSIX::SigSet->new(POSIX::SIGINT(), POSIX::SIGTERM(), POSIX::SIGHUP());
my $previous = POSIX::SigSet->new();
POSIX::sigprocmask(POSIX::SIG_BLOCK(), $handled, $previous);
my $pid = fork();
die "run_bounded: fork failed: $!\n" unless defined $pid;
unless (defined $pid) {
POSIX::sigprocmask(POSIX::SIG_SETMASK(), $previous);
die "run_bounded: fork failed: $!\n";
}
if ($pid == 0) {
POSIX::setpgid(0, 0);
POSIX::sigprocmask(POSIX::SIG_SETMASK(), $previous);
exec('bash', '-c', $cmd) or POSIX::_exit(127);
}
# setpgid from BOTH sides: whichever runs first wins, so the group exists before the first signal
@@ -267,6 +279,7 @@ sub run_bounded {
local $SIG{INT} = $forward;
local $SIG{TERM} = $forward;
local $SIG{HUP} = $forward;
POSIX::sigprocmask(POSIX::SIG_SETMASK(), $previous);
# An unbounded run still forks: it is the process group, not the deadline, that lets a signal
# to the orchestrator reach the build.