spawn_pp: cleanup, error checks and descriptive errors

[public-inbox.git] / lib / PublicInbox / SpawnPP.pm

diff --git a/lib/PublicInbox/SpawnPP.pm b/lib/PublicInbox/SpawnPP.pm
index 2c5edef62efc55acbf48e2e0f4cc6efa6ac852d2..7a5793f621ea710cf8c7fbc0b4f7cb37e8a2e087 100644 (file)
--- a/lib/PublicInbox/SpawnPP.pm
+++ b/lib/PublicInbox/SpawnPP.pm
@@ -1,11 +1,10 @@
-# Copyright (C) 2016-2021 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 
 # Pure-Perl implementation of "spawn".  This can't take advantage
 # of vfork, so no speedups under Linux for spawning from large processes.
 package PublicInbox::SpawnPP;
-use strict;
-use v5.10.1;
+use v5.12;
 use POSIX qw(dup2 _exit setpgid :signal_h);
 
 # Pure Perl implementation for folks that do not use Inline::C
@@ -13,16 +12,18 @@ sub pi_fork_exec ($$$$$$$) {
        my ($redir, $f, $cmd, $env, $rlim, $cd, $pgid) = @_;
        my $old = POSIX::SigSet->new();
        my $set = POSIX::SigSet->new();
-       $set->fillset or die "fillset failed: $!";
-       sigprocmask(SIG_SETMASK, $set, $old) or die "can't block signals: $!";
+       $set->fillset or die "sigfillset: $!";
+       sigprocmask(SIG_SETMASK, $set, $old) or die "SIG_SETMASK(set): $!";
        my $syserr;
-       my $pid = fork;
-       unless (defined $pid) { # compat with Inline::C version
-               $syserr = $!;
-               $pid = -1;
-       }
+       pipe(my ($r, $w)) or die "pipe: $!";
+       my $pid = fork // die "fork (+exec) @$cmd: $!\n";
        if ($pid == 0) {
-               $SIG{__DIE__} = sub { warn @_; _exit 1 };
+               close $r;
+               $SIG{__DIE__} = sub {
+                       warn(@_);
+                       syswrite($w, my $num = $! + 0);
+                       _exit(1);
+               };
                for my $child_fd (0..$#$redir) {
                        my $parent_fd = $redir->[$child_fd];
                        next if $parent_fd == $child_fd;
@@ -32,7 +33,7 @@ sub pi_fork_exec ($$$$$$$) {
                if ($pgid >= 0 && !defined(setpgid(0, $pgid))) {
                        die "setpgid(0, $pgid): $!";
                }
-               $SIG{$_} = 'DEFAULT' for keys %SIG;
+               $SIG{$_} = 'DEFAULT' for grep(!/\A__/, keys %SIG);
                if ($cd ne '') {
                        chdir $cd or die "chdir $cd: $!";
                }
@@ -41,19 +42,23 @@ sub pi_fork_exec ($$$$$$$) {
                        BSD::Resource::setrlimit($r, $soft, $hard) or
                                die "setrlimit($r=[$soft,$hard]: $!)";
                }
-               $old->delset(POSIX::SIGCHLD) or die "delset SIGCHLD: $!";
-               sigprocmask(SIG_SETMASK, $old) or die "SETMASK: ~SIGCHLD: $!";
+               $old->delset(POSIX::SIGCHLD) or die "sigdelset CHLD: $!";
+               sigprocmask(SIG_SETMASK, $old) or die "SIG_SETMASK ~CHLD: $!";
                $cmd->[0] = $f;
                if ($ENV{MOD_PERL}) {
                        @$cmd = (which('env'), '-i', @$env, @$cmd);
                } else {
                        %ENV = map { split(/=/, $_, 2) } @$env;
                }
-               exec @$cmd;
+               exec { $f } @$cmd;
                die "exec @$cmd failed: $!";
        }
-       sigprocmask(SIG_SETMASK, $old) or die "can't unblock signals: $!";
-       $! = $syserr;
+       close $w;
+       sigprocmask(SIG_SETMASK, $old) or die "SIG_SETMASK(old): $!";
+       if (my $cerrnum = do { local $/, <$r> }) {
+               $! = $cerrnum;
+               die "forked child $@: $!";
+       }
        $pid;
 }