[PATCH 01/10] ds: don't block important signals we don't use

[Eric Wong]

Don't block SIGABRT, SIGBUS, SIGFPE, SIGILL nor SIGSEGV since
blocking them can hide real bugs in our code or 3rd-party
libraries and executables.

We'll also leave SIGXCPU and SIGXFSZ unblocked since users
may've setup RLIMIT_CPU and RLIMIT_FSIZE, respectively.
---
 lib/PublicInbox/DS.pm | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index e89dc430..97546016 100644
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -193,10 +193,16 @@ sub RunTimers {
 
 sub sig_setmask { sigprocmask(SIG_SETMASK, @_) or die "sigprocmask: $!" }
 
+our @UNBLOCKABLE = map { # ensure we detect bugs, HW problems and user rlimits
+       my $cb = POSIX->can("SIG$_");
+       my $num = $cb ? $cb->() : undef;
+       $num ? ($num) : ();
+} qw(ABRT BUS FPE ILL SEGV XCPU XFSZ);
+
 sub block_signals { # anything in @_ stays unblocked
        my $newset = POSIX::SigSet->new;
        $newset->fillset or die "fillset: $!";
-       $newset->delset($_) for @_;
+       for (@_, @UNBLOCKABLE) { $newset->delset($_) or die "delset($_): $!" }
        my $oldset = POSIX::SigSet->new;
        sig_setmask($newset, $oldset);
        $oldset;