[PATCH 2 of 3] Tests: handling of EAGAIN from sysread() with IO::Socket::SSL

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1678424071 -10800
#      Fri Mar 10 07:54:31 2023 +0300
# Node ID 49d12f8c4cf69e1cbe7feccae3b0ea1ac2ca8c2f
# Parent  fdebeebd07b160f1d30e18d56e64dfb08570f8b1
Tests: handling of EAGAIN from sysread() with IO::Socket::SSL.

With IO::Socket::SSL, when select() reports that the socket is readable,
reading from it might still fail with EAGAIN, since no application data is
available in the socket.  In particular, this might happen with TLSv1.3
when a session ticket is received after the handshake.  Fix is to explicitly
check for EAGAIN errors.

diff --git a/lib/Test/Nginx/IMAP.pm b/lib/Test/Nginx/IMAP.pm
--- a/lib/Test/Nginx/IMAP.pm
+++ b/lib/Test/Nginx/IMAP.pm
@@ -68,7 +68,9 @@ sub getline {
 	while (IO::Select->new($socket)->can_read(8)) {
 		$socket->blocking(0);
 		my $n = $socket->sysread(my $buf, 1024);
+		my $again = !defined $n && $!{EAGAIN};
 		$socket->blocking(1);
+		next if $again;
 		last unless $n;
 
 		$self->{_read_buffer} .= $buf;
diff --git a/lib/Test/Nginx/POP3.pm b/lib/Test/Nginx/POP3.pm
--- a/lib/Test/Nginx/POP3.pm
+++ b/lib/Test/Nginx/POP3.pm
@@ -68,7 +68,9 @@ sub getline {
 	while (IO::Select->new($socket)->can_read(8)) {
 		$socket->blocking(0);
 		my $n = $socket->sysread(my $buf, 1024);
+		my $again = !defined $n && $!{EAGAIN};
 		$socket->blocking(1);
+		next if $again;
 		last unless $n;
 
 		$self->{_read_buffer} .= $buf;
diff --git a/lib/Test/Nginx/SMTP.pm b/lib/Test/Nginx/SMTP.pm
--- a/lib/Test/Nginx/SMTP.pm
+++ b/lib/Test/Nginx/SMTP.pm
@@ -68,7 +68,9 @@ sub getline {
 	while (IO::Select->new($socket)->can_read(8)) {
 		$socket->blocking(0);
 		my $n = $socket->sysread(my $buf, 1024);
+		my $again = !defined $n && $!{EAGAIN};
 		$socket->blocking(1);
+		next if $again;
 		last unless $n;
 
 		$self->{_read_buffer} .= $buf;
diff --git a/lib/Test/Nginx/Stream.pm b/lib/Test/Nginx/Stream.pm
--- a/lib/Test/Nginx/Stream.pm
+++ b/lib/Test/Nginx/Stream.pm
@@ -84,8 +84,10 @@ sub read {
 	$s = $self->{_socket};
 
 	$s->blocking(0);
-	if (IO::Select->new($s)->can_read($extra{read_timeout} || 8)) {
-		$s->sysread($buf, 1024);
+	while (IO::Select->new($s)->can_read($extra{read_timeout} || 8)) {
+		my $n = $s->sysread($buf, 1024);
+		next if !defined $n && $!{EAGAIN};
+		last;
 	}
 
 	log_in($buf);