[PATCH] EOFpipe: avoid uninitialized variables in lei tests

[PATCH] EOFpipe: avoid uninitialized variables in lei tests

[Eric Wong]

From: Eric Wong <e@yhbt.net>

EINTR can happen due to spurious wakeups and lead to
uninitialized variable warnings when comparing the result of
->do_read to a numeric value.  Thus avoid EINTR by making the
pipe non-blocking on initialization.

Furthermore, our ->do_read API is overkill and not appropriate
for only detecting EOF on a pipe since it is designed for
parsing network protocols.  Relying on level-triggering makes
more sense here, since we only want to detect EOF and don't have
to worry about event loop monopolization.
---
 lib/PublicInbox/EOFpipe.pm | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/lib/PublicInbox/EOFpipe.pm b/lib/PublicInbox/EOFpipe.pm
index 77b699a2..3eaa0e4e 100644
--- a/lib/PublicInbox/EOFpipe.pm
+++ b/lib/PublicInbox/EOFpipe.pm
@@ -4,21 +4,29 @@
 package PublicInbox::EOFpipe;
 use v5.12;
 use parent qw(PublicInbox::DS);
-use PublicInbox::Syscall qw(EPOLLIN EPOLLONESHOT $F_SETPIPE_SZ);
+use PublicInbox::Syscall qw(EPOLLIN $F_SETPIPE_SZ);
+use Errno qw(EAGAIN);
 
 sub new {
 	my (undef, $rd, @cb_args) = @_;
 	my $self = bless { cb_args => \@cb_args }, __PACKAGE__;
 	# 4096: page size
 	fcntl($rd, $F_SETPIPE_SZ, 4096) if $F_SETPIPE_SZ;
-	$self->SUPER::new($rd, EPOLLIN|EPOLLONESHOT);
+	$rd->blocking(0); # avoid EINTR
+	$self->SUPER::new($rd, EPOLLIN); # level trigger for spurious wakeup
 }
 
 sub event_step {
 	my ($self) = @_;
-	if ($self->do_read(my $buf, 1) == 0) { # auto-closed
+	my $r = sysread $self->{sock}, my $buf, 1;
+	if (!defined $r) {
+		warn "W: EOFpipe read: $!\n" if $! != EAGAIN;
+	} elsif ($r == 0) {
+		$self->close;
 		my ($cb, @args) = @{delete $self->{cb_args}};
 		$cb->(@args);
+	} else {
+		warn "BUG? EOFpipe read $r bytes, expected 0\n";
 	}
 }