From a7cbcde7518e2f95673ec5ddba32b7ea6e0b84bb Mon Sep 17 00:00:00 2001
From: Daniel Gustafsson <daniel@yesql.se>
Date: Fri, 16 Mar 2018 21:32:32 +0100
Subject: [PATCH] Add test for ensuring WAL segment is zeroed out

Switch to a new WAL file and ensure the last segment in the now
switched-away-from file is completely zeroed out.

This adds a mode to check_pg_config() where the match from the
regexp can be returned, not just the literal count of matches.
Only one match is returned (the first), but given the structure
of pg_config.h that's likely to be enough.
---
 src/test/perl/TestLib.pm             | 18 ++++++++++++++++--
 src/test/recovery/t/002_archiving.pl | 20 +++++++++++++++++++-
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/test/perl/TestLib.pm b/src/test/perl/TestLib.pm
index 7d017d49bd..8b9796c4f6 100644
--- a/src/test/perl/TestLib.pm
+++ b/src/test/perl/TestLib.pm
@@ -227,15 +227,29 @@ sub append_to_file
 # that.
 sub check_pg_config
 {
-	my ($regexp) = @_;
+	my ($regexp, $value) = @_;
 	my ($stdout, $stderr);
+	my $match;
 	my $result = IPC::Run::run [ 'pg_config', '--includedir' ], '>',
 	  \$stdout, '2>', \$stderr
 	  or die "could not execute pg_config";
 	chomp($stdout);
 
 	open my $pg_config_h, '<', "$stdout/pg_config.h" or die "$!";
-	my $match = (grep {/^$regexp/} <$pg_config_h>);
+	if (defined $value)
+	{
+		while (<$pg_config_h>)
+		{
+			$_ =~ m/^$regexp/;
+			next unless defined $1;
+			$match = $1;
+			last;
+		}
+	}
+	else
+	{
+		$match = (grep {/^$regexp/} <$pg_config_h>);
+	}
 	close $pg_config_h;
 	return $match;
 }
diff --git a/src/test/recovery/t/002_archiving.pl b/src/test/recovery/t/002_archiving.pl
index e1bd3c95cc..c235e98904 100644
--- a/src/test/recovery/t/002_archiving.pl
+++ b/src/test/recovery/t/002_archiving.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 1;
+use Test::More tests => 2;
 use File::Copy;
 
 # Initialize master node, doing archives
@@ -49,3 +49,21 @@ $node_standby->poll_query_until('postgres', $caughtup_query)
 my $result =
   $node_standby->safe_psql('postgres', "SELECT count(*) FROM tab_int");
 is($result, qq(1000), 'check content from archives');
+
+# Add some content, switch WAL file and read the last segment of the WAL
+# file which should be zeroed out
+my $current_file = $node_master->safe_psql('postgres',
+	"SELECT pg_walfile_name(pg_current_wal_lsn())");
+$node_master->safe_psql('postgres', "INSERT INTO tab_int VALUES (1)");
+$node_master->safe_psql('postgres', "SELECT pg_switch_wal()");
+
+my $xlog_blcksz = check_pg_config('#define XLOG_BLCKSZ (\d+)', 1);
+
+open my $fh, '<:raw', $node_master->data_dir . '/pg_wal/' . $current_file;
+# SEEK_END is defined as 2, but is not allowed when using strict mode
+seek $fh, ($xlog_blcksz * -1), 2;
+my $len = read($fh, my $bytes, $xlog_blcksz);
+close $fh;
+
+my ($wal_segment) = unpack 'N' . $xlog_blcksz, $bytes;
+is($wal_segment, 0, 'make sure wal segment is zeroed');
-- 
2.14.1.145.gb3622a4ee