lei: fix output race in client/daemon mode

The daemon needs to flush stdout before disconnecting or killing
clients, otherwise they may reread empty data on redirected
outputs.  We also don't want to unbuffer stdout too early in
case we have lots of small chunks of data to output.

The received ($self->{2}) will always have autoflush, matching normal
STDERR behavior.

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 3ad5e01a..6f21da35 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -236,6 +236,7 @@ my %CONFIG_KEYS = (
 
 sub x_it ($$) { # pronounced "exit"
         my ($self, $code) = @_;
+        $self->{1}->autoflush(1); # make sure client sees stdout before exit
         if (my $sig = ($code & 127)) {
                 kill($sig, $self->{pid} // $$);
         } else {
@@ -635,6 +636,7 @@ sub accept_dispatch { # Listener {post_accept} callback
                 say $sock "timed out waiting to recv FDs";
                 return;
         }
+        $self->{2}->autoflush(1); # keep stdout buffered until x_it|DESTROY
         # $ARGV_STR = join("]\0[", @ARGV);
         # $ENV_STR = join('', map { "$_=$ENV{$_}\0" } keys %ENV);
         # $line = "$$\0\0>$ARGV_STR\0\0>$ENV_STR\0\0";
@@ -773,4 +775,8 @@ sub oneshot {
         }, __PACKAGE__), @ARGV);
 }
 
+# ensures stdout hits the FS before sock disconnects so a client
+# can immediately reread it
+sub DESTROY { $_[0]->{1}->autoflush(1) }
+
 1;