From cfd20b04dfe495df80ad9c62949103d555f65f49 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Sat, 25 Mar 2023 02:08:52 +0000
Subject: ipc: retry sendmsg + recvmsg calls on EINTR

I'm not sure how this went undetected for so long, but EINTR
must be checked for when working with blocking sockets.  EINTR
shouldn't happen for non-blocking sockets, though, but it's
easier to just use the new wrapper in most of those places.

I don't know what I was smoking when I left out EINTR checks :x
---
 lib/PublicInbox/IPC.pm | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

(limited to 'lib/PublicInbox/IPC.pm')

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 548a72eb..7fa656d0 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -216,9 +216,27 @@ sub ipc_sibling_atfork_child {
 	$pid == $$ and die "BUG: $$ ipc_atfork_child called on itself";
 }
 
+sub send_cmd ($$$$) {
+	my ($s, $fds, $buf, $fl) = @_;
+	while (1) {
+		my $n = $send_cmd->($s, $fds, $buf, $fl);
+		next if !defined($n) && $!{EINTR};
+		return $n;
+	}
+}
+
+sub recv_cmd ($$$) {
+	my ($s, undef, $len) = @_; # $_[1] is $buf
+	while (1) {
+		my @fds = $recv_cmd->($s, $_[1], $len);
+		next if scalar(@fds) == 1 && !defined($fds[0]) && $!{EINTR};
+		return @fds;
+	}
+}
+
 sub recv_and_run {
 	my ($self, $s2, $len, $full_stream) = @_;
-	my @fds = $recv_cmd->($s2, my $buf, $len // $MY_MAX_ARG_STRLEN);
+	my @fds = recv_cmd($s2, my $buf, $len // $MY_MAX_ARG_STRLEN);
 	return if scalar(@fds) && !defined($fds[0]);
 	my $n = length($buf) or return 0;
 	my $nfd = 0;
@@ -278,15 +296,18 @@ sub stream_in_full ($$$) {
 	my ($s1, $fds, $buf) = @_;
 	socketpair(my $r, my $w, AF_UNIX, SOCK_STREAM, 0) or
 		croak "socketpair: $!";
-	my $n = $send_cmd->($s1, [ fileno($r) ],
+	my $n = send_cmd($s1, [ fileno($r) ],
 			ipc_freeze(['do_sock_stream', length($buf)]),
 			MSG_EOR) // croak "sendmsg: $!";
 	undef $r;
-	$n = $send_cmd->($w, $fds, $buf, 0) // croak "sendmsg: $!";
+	$n = send_cmd($w, $fds, $buf, 0) // croak "sendmsg: $!";
 	while ($n < length($buf)) {
-		my $x = syswrite($w, $buf, length($buf) - $n, $n) //
-				croak "syswrite: $!";
-		croak "syswrite wrote 0 bytes" if $x == 0;
+		my $x = syswrite($w, $buf, length($buf) - $n, $n);
+		if (!defined($n)) {
+			next if $!{EINTR};
+			croak "syswrite: $!";
+		}
+		$x or croak "syswrite wrote 0 bytes";
 		$n += $x;
 	}
 }
@@ -299,7 +320,7 @@ sub wq_io_do { # always async
 		if (length($buf) > $MY_MAX_ARG_STRLEN) {
 			stream_in_full($s1, $fds, $buf);
 		} else {
-			my $n = $send_cmd->($s1, $fds, $buf, MSG_EOR);
+			my $n = send_cmd $s1, $fds, $buf, MSG_EOR;
 			return if defined($n); # likely
 			$!{ETOOMANYREFS} and
 				croak "sendmsg: $! (check RLIMIT_NOFILE)";
-- 
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