lei: support /dev/fd/[0-2] inputs and outputs in daemon

Since lei-daemon won't have the same FDs as the client, we
need to special-case thse mappings and won't be able to open
arbitrary, non-standard FDs.

We also won't attempt to support /proc/self/fd/[0-2] since
that's a Linux-ism.  /dev/fd/[0-2] and /dev/std{in,out,err}
are portable to FreeBSD, at least.  mawk(1) also supports
/dev/std{out,err}, as does gawk(1) (which supports everything
we can support, and arbitrary /dev/fd/$FD).

1 files changed, 7 insertions, 6 deletions

diff --git a/lib/PublicInbox/LeiOverview.pm b/lib/PublicInbox/LeiOverview.pm
index 96bfff24..8e26cba4 100644
--- a/lib/PublicInbox/LeiOverview.pm
+++ b/lib/PublicInbox/LeiOverview.pm
@@ -71,8 +71,9 @@ sub new {
 --$ofmt_key=$fmt and --output=$ofmt conflict
 
         }
-        $fmt //= 'json' if $dst eq '/dev/stdout';
-        $fmt //= detect_fmt($lei, $dst) or return;
+
+        my $devfd = $lei->path_to_fd($dst) // return;
+        $fmt //= $devfd >= 0 ? 'json' : (detect_fmt($lei, $dst) or return);
 
         if (index($dst, '://') < 0) { # not a URL, so assume path
                  $dst = File::Spec->canonpath($dst);
@@ -84,11 +85,11 @@ sub new {
         if ($fmt =~ /\A($JSONL|(?:concat)?json)\z/) {
                 $json = $self->{json} = ref(PublicInbox::Config->json);
         }
-        if ($dst eq '/dev/stdout') {
-                my $isatty = $lei->{need_pager} = -t $lei->{1};
+        if ($devfd >= 0) {
+                my $isatty = $lei->{need_pager} = -t $lei->{$devfd};
                 $opt->{pretty} //= $isatty;
                 if (!$isatty && -f _) {
-                        my $fl = fcntl($lei->{1}, F_GETFL, 0) //
+                        my $fl = fcntl($lei->{$devfd}, F_GETFL, 0) //
                                 return $lei->fail("fcntl(stdout): $!");
                         ovv_out_lk_init($self) unless ($fl & O_APPEND);
                 } else {
@@ -101,7 +102,7 @@ sub new {
                 $lei->{dedupe} //= PublicInbox::LeiDedupe->new($lei);
         } else {
                 # default to the cheapest sort since MUA usually resorts
-                $opt->{'sort'} //= 'docid' if $dst ne '/dev/stdout';
+                $opt->{'sort'} //= 'docid' if $devfd < 0;
                 $lei->{l2m} = eval { PublicInbox::LeiToMail->new($lei) };
                 return $lei->fail($@) if $@;
                 if ($opt->{mua} && $lei->{l2m}->lock_free) {