Allow using Unix-domain sockets on Windows in tests

The test suites currently don't use Unix-domain sockets on Windows.
This optionally allows enabling that by setting the environment
variable PG_TEST_USE_UNIX_SOCKETS.

This should currently be considered experimental.  In particular,
pg_regress.c contains some comments that the cleanup code for
Unix-domain sockets doesn't work correctly under Windows, which hasn't
been an problem until now.  But it's good enough for locally
supervised testing of the functionality.
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/54bde68c-d134-4eb8-5bd3-8af33b72a010@2ndquadrant.com

src/bin/pg_ctl/t/001_start_stop.pl

@@ -29,7 +29,7 @@ print $conf "port = $node_port\n";
 print $conf TestLib::slurp_file($ENV{TEMP_CONFIG})
   if defined $ENV{TEMP_CONFIG};
 
-if (!$windows_os)
+if ($use_unix_sockets)
 {
 	print $conf "listen_addresses = ''\n";
 	print $conf "unix_socket_directories = '$tempdir_short'\n";

src/test/authentication/t/001_password.pl

@@ -3,17 +3,16 @@
 # - Plain
 # - MD5-encrypted
 # - SCRAM-encrypted
-# This test cannot run on Windows as Postgres cannot be set up with Unix
-# sockets and needs to go through SSPI.
+# This test can only run with Unix-domain sockets.
 
 use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
 use Test::More;
-if ($windows_os)
+if (!$use_unix_sockets)
 {
-	plan skip_all => "authentication tests cannot run on Windows";
+	plan skip_all => "authentication tests cannot run without Unix-domain sockets";
 }
 else
 {

src/test/authentication/t/002_saslprep.pl

 # Test password normalization in SCRAM.
 #
-# This test cannot run on Windows as Postgres cannot be set up with Unix
-# sockets and needs to go through SSPI.
+# This test can only run with Unix-domain sockets.
 
 use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
 use Test::More;
-if ($windows_os)
+if (!$use_unix_sockets)
 {
-	plan skip_all => "authentication tests cannot run on Windows";
+	plan skip_all => "authentication tests cannot run without Unix-domain sockets";
 }
 else
 {

src/test/perl/PostgresNode.pm

@@ -116,7 +116,7 @@ INIT
 
 	# Set PGHOST for backward compatibility.  This doesn't work for own_host
 	# nodes, so prefer to not rely on this when writing new tests.
-	$use_tcp            = $TestLib::windows_os;
+	$use_tcp            = !$TestLib::use_unix_sockets;
 	$test_localhost     = "127.0.0.1";
 	$last_host_assigned = 1;
 	$test_pghost        = $use_tcp ? $test_localhost : TestLib::tempdir_short;
@@ -387,7 +387,7 @@ sub set_replication_conf
 
 	open my $hba, '>>', "$pgdata/pg_hba.conf";
 	print $hba "\n# Allow replication (set up by PostgresNode.pm)\n";
-	if ($TestLib::windows_os)
+	if ($TestLib::windows_os && !$TestLib::use_unix_sockets)
 	{
 		print $hba
 		  "host replication all $test_localhost/32 sspi include_realm=1 map=regress\n";

src/test/perl/TestLib.pm

@@ -83,9 +83,10 @@ our @EXPORT = qw(
   command_checks_all
 
   $windows_os
+  $use_unix_sockets
 );
 
-our ($windows_os, $tmp_check, $log_path, $test_logfile);
+our ($windows_os, $use_unix_sockets, $tmp_check, $log_path, $test_logfile);
 
 BEGIN
 {
@@ -117,6 +118,11 @@ BEGIN
 		require Win32API::File;
 		Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle));
 	}
+
+	# Specifies whether to use Unix sockets for test setups.  On
+	# Windows we don't use them by default since it's not universally
+	# supported, but it can be overridden if desired.
+	$use_unix_sockets = (!$windows_os || defined $ENV{PG_TEST_USE_UNIX_SOCKETS});
 }
 
 =pod

src/test/regress/pg_regress.c

@@ -292,7 +292,7 @@ stop_postmaster(void)
  * remove the directory.  Ignore errors; leaking a temporary directory is
  * unimportant.  This can run from a signal handler.  The code is not
  * acceptable in a Windows signal handler (see initdb.c:trapsig()), but
- * on Windows, pg_regress does not use Unix sockets.
+ * on Windows, pg_regress does not use Unix sockets by default.
  */
 static void
 remove_temp(void)
@@ -2106,6 +2106,7 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 		{NULL, 0, NULL, 0}
 	};
 
+	bool		use_unix_sockets;
 	_stringlist *sl;
 	int			c;
 	int			i;
@@ -2121,15 +2122,23 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 
 	atexit(stop_postmaster);
 
-#if !defined(HAVE_UNIX_SOCKETS) || defined(WIN32)
+#if !defined(HAVE_UNIX_SOCKETS)
+	use_unix_sockets = false;
+#elif defined(WIN32)
+
 	/*
-	 * No Unix-domain sockets available, so change default.  For now, we also
-	 * don't use them on Windows, even if the build supports them.  (See
-	 * comment at remove_temp() for a reason.)
+	 * We don't use Unix-domain sockets on Windows by default, even if the
+	 * build supports them.  (See comment at remove_temp() for a reason.)
+	 * Override at your own risk.
 	 */
-	hostname = "localhost";
+	use_unix_sockets = getenv("PG_TEST_USE_UNIX_SOCKETS") ? true : false;
+#else
+	use_unix_sockets = true;
 #endif
 
+	if (!use_unix_sockets)
+		hostname = "localhost";
+
 	/*
 	 * We call the initialization function here because that way we can set
 	 * default parameters and let them be overwritten by the commandline.
@@ -2243,6 +2252,7 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 	if (config_auth_datadir)
 	{
 #ifdef ENABLE_SSPI
+		if (!use_unix_sockets)
 			config_sspi_auth(config_auth_datadir, user);
 #endif
 		exit(0);
@@ -2364,13 +2374,15 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 		fclose(pg_conf);
 
 #ifdef ENABLE_SSPI
-
+		if (!use_unix_sockets)
+		{
 			/*
 			 * Since we successfully used the same buffer for the much-longer
 			 * "initdb" command, this can't truncate.
 			 */
 			snprintf(buf, sizeof(buf), "%s/data", temp_instance);
 			config_sspi_auth(buf, NULL);
+		}
 #elif !defined(HAVE_UNIX_SOCKETS)
 #error Platform has no means to secure the test installation.
 #endif