httpd: avoid crash on cgit -> coderepo 404 fallback

A trickled cgit response can cause HTTPD::Async->event_step to
fire an extra time after header parsing.  We need to account for
the lack of async_pass call populating ->{fh} and ->{http} in
that case and avoid calling $self->{fh}->write when there's
no {fh}.

diff --git a/lib/PublicInbox/GitHTTPBackend.pm b/lib/PublicInbox/GitHTTPBackend.pm
index 1eb51f2704e1f2f06414d7f8db78b9c08ef743fc..974a1831340c3581a3fc55a5e0b335b7055c22f3 100644 (file)
--- a/lib/PublicInbox/GitHTTPBackend.pm
+++ b/lib/PublicInbox/GitHTTPBackend.pm
@@ -128,7 +128,7 @@ sub input_prepare {
        { 0 => $in };
 }
 
-sub parse_cgi_headers {
+sub parse_cgi_headers { # {parse_hdr} for Qspawn
        my ($r, $bref, $ctx) = @_;
        return r(500) unless defined $r && $r >= 0;
        $$bref =~ s/\A(.*?)\r?\n\r?\n//s or return $r == 0 ? r(500) : undef;
@@ -145,7 +145,9 @@ sub parse_cgi_headers {
        }
 
        # fallback to WwwCoderepo if cgit 404s.  Duplicating $ctx prevents
-       # ->finalize from the current Qspawn from using qspawn.wcb
+       # ->finalize from the current Qspawn from using qspawn.wcb.
+       # This makes qspawn skip ->async_pass and causes
+       # PublicInbox::HTTPD::Async::event_step to close shortly after
        if ($code == 404 && $ctx->{www} && !$ctx->{_coderepo_tried}++) {
                my %ctx = %$ctx;
                $ctx{env} = +{ %{$ctx->{env}} };

diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index cb76cfab4a83317284ed25456ec9dd346ea80db1..9e592f47412bf4f7aa1c32555196ee92b13a06de 100644 (file)
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -48,7 +48,8 @@ sub event_step {
                # this may call async_pass when headers are done
                $cb->(my $refcnt_guard = delete $self->{arg});
        } elsif (my $sock = $self->{sock}) {
-               my $http = $self->{http};
+               # $http may be undef if discarding body output from cgit on 404
+               my $http = $self->{http} or return $self->close;
                # $self->{sock} is a read pipe for git-http-backend or cgit
                # and 65536 is the default Linux pipe size
                my $r = sysread($sock, my $buf, 65536);