Enable Unix-domain sockets support on Windows

As of Windows 10 version 1803, Unix-domain sockets are supported on
Windows.  But it's not automatically detected by configure because it
looks for struct sockaddr_un and Windows doesn't define that.  So we
just make our own definition on Windows and override the configure
result.

Set DEFAULT_PGSOCKET_DIR to empty on Windows so by default no
Unix-domain socket is used, because there is no good standard
location.

In pg_upgrade, we have to do some extra tweaking to preserve the
existing behavior of not using Unix-domain sockets on Windows.  Adding
support would be desirable, but it needs further work, in particular a
way to select whether to use Unix-domain sockets from the command-line
or with a run-time test.

The pg_upgrade test script needs a fix.  The previous code passed
"localhost" to postgres -k, which only happened to work because
Windows used to ignore the -k argument value altogether.  We instead
need to pass an empty string to get the desired effect.

The test suites will continue to not use Unix-domain sockets on
Windows.  This requires a small tweak in pg_regress.c.  The TAP tests
don't need to be changed because they decide by the operating system
rather than HAVE_UNIX_SOCKETS.

Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/54bde68c-d134-4eb8-5bd3-8af33b72a010@2ndquadrant.com

Author: petere

config/c-library.m4

@@ -102,10 +102,11 @@ AC_DEFUN([PGAC_UNION_SEMUN],
 
 # PGAC_STRUCT_SOCKADDR_UN
 # -----------------------
-# If `struct sockaddr_un' exists, define HAVE_UNIX_SOCKETS.
+# If `struct sockaddr_un' exists, define HAVE_STRUCT_SOCKADDR_UN.
+# If it is missing then one could define it.
 # (Requires test for <sys/un.h>!)
 AC_DEFUN([PGAC_STRUCT_SOCKADDR_UN],
-[AC_CHECK_TYPE([struct sockaddr_un], [AC_DEFINE(HAVE_UNIX_SOCKETS, 1, [Define to 1 if you have unix sockets.])], [],
+[AC_CHECK_TYPES([struct sockaddr_un], [], [],
 [#include <sys/types.h>
 #ifdef HAVE_SYS_UN_H
 #include <sys/un.h>

configure

@@ -14096,7 +14096,10 @@ ac_fn_c_check_type "$LINENO" "struct sockaddr_un" "ac_cv_type_struct_sockaddr_un
 "
 if test "x$ac_cv_type_struct_sockaddr_un" = xyes; then :
 
-$as_echo "#define HAVE_UNIX_SOCKETS 1" >>confdefs.h
+cat >>confdefs.h <<_ACEOF
+#define HAVE_STRUCT_SOCKADDR_UN 1
+_ACEOF
+
 
 fi
 

src/bin/pg_upgrade/option.c

@@ -468,7 +468,7 @@ adjust_data_dir(ClusterInfo *cluster)
 void
 get_sock_dir(ClusterInfo *cluster, bool live_check)
 {
-#ifdef HAVE_UNIX_SOCKETS
+#if defined(HAVE_UNIX_SOCKETS) && !defined(WIN32)
 
 	/*
 	 * sockdir and port were added to postmaster.pid in PG 9.1. Pre-9.1 cannot
@@ -530,7 +530,7 @@ get_sock_dir(ClusterInfo *cluster, bool live_check)
 		 * default
 		 */
 		cluster->sockdir = NULL;
-#else							/* !HAVE_UNIX_SOCKETS */
+#else							/* !HAVE_UNIX_SOCKETS || WIN32 */
 	cluster->sockdir = NULL;
 #endif
 }

src/bin/pg_upgrade/server.c

@@ -210,7 +210,7 @@ start_postmaster(ClusterInfo *cluster, bool report_and_exit_on_error)
 
 	socket_string[0] = '\0';
 
-#ifdef HAVE_UNIX_SOCKETS
+#if defined(HAVE_UNIX_SOCKETS) && !defined(WIN32)
 	/* prevent TCP/IP connections, restrict socket access */
 	strcat(socket_string,
 		   " -c listen_addresses='' -c unix_socket_permissions=0700");

src/bin/pg_upgrade/test.sh

@@ -39,14 +39,14 @@ testhost=`uname -s | sed 's/^MSYS/MINGW/'`
 case $testhost in
 	MINGW*)
 		LISTEN_ADDRESSES="localhost"
+		PG_REGRESS_SOCKET_DIR=""
 		PGHOST=localhost
 		;;
 	*)
 		LISTEN_ADDRESSES=""
 		# Select a socket directory.  The algorithm is from the "configure"
 		# script; the outcome mimics pg_regress.c:make_temp_sockdir().
-		PGHOST=$PG_REGRESS_SOCK_DIR
-		if [ "x$PGHOST" = x ]; then
+		if [ x"$PG_REGRESS_SOCKET_DIR" = x ]; then
 			set +e
 			dir=`(umask 077 &&
 				  mktemp -d /tmp/pg_upgrade_check-XXXXXX) 2>/dev/null`
@@ -59,14 +59,15 @@ case $testhost in
 				fi
 			fi
 			set -e
-			PGHOST=$dir
-			trap 'rm -rf "$PGHOST"' 0
+			PG_REGRESS_SOCKET_DIR=$dir
+			trap 'rm -rf "$PG_REGRESS_SOCKET_DIR"' 0
 			trap 'exit 3' 1 2 13 15
 		fi
+		PGHOST=$PG_REGRESS_SOCKET_DIR
 		;;
 esac
 
-POSTMASTER_OPTS="-F -c listen_addresses=\"$LISTEN_ADDRESSES\" -k \"$PGHOST\""
+POSTMASTER_OPTS="-F -c listen_addresses=\"$LISTEN_ADDRESSES\" -k \"$PG_REGRESS_SOCKET_DIR\""
 export PGHOST
 
 # don't rely on $PWD here, as old shells don't set it

src/include/c.h

@@ -1076,6 +1076,10 @@ extern void ExceptionalCondition(const char *conditionName,
  * ----------------------------------------------------------------
  */
 
+#ifdef HAVE_STRUCT_SOCKADDR_UN
+#define HAVE_UNIX_SOCKETS 1
+#endif
+
 /*
  * Invert the sign of a qsort-style comparison result, ie, exchange negative
  * and positive integer values, being careful not to get the wrong answer

src/include/pg_config.h.in

@@ -566,6 +566,9 @@
 /* Define to 1 if `__ss_len' is a member of `struct sockaddr_storage'. */
 #undef HAVE_STRUCT_SOCKADDR_STORAGE___SS_LEN
 
+/* Define to 1 if the system has the type `struct sockaddr_un'. */
+#undef HAVE_STRUCT_SOCKADDR_UN
+
 /* Define to 1 if `tm_zone' is a member of `struct tm'. */
 #undef HAVE_STRUCT_TM_TM_ZONE
 
@@ -647,9 +650,6 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 
-/* Define to 1 if you have unix sockets. */
-#undef HAVE_UNIX_SOCKETS
-
 /* Define to 1 if you have the `unsetenv' function. */
 #undef HAVE_UNSETENV
 

src/include/pg_config_manual.h

@@ -135,13 +135,6 @@
 #define EXEC_BACKEND
 #endif
 
-/*
- * Disable UNIX sockets for certain operating systems.
- */
-#if defined(WIN32)
-#undef HAVE_UNIX_SOCKETS
-#endif
-
 /*
  * USE_POSIX_FADVISE controls whether Postgres will attempt to use the
  * posix_fadvise() kernel call.  Usually the automatic configure tests are
@@ -202,8 +195,16 @@
  * server will not create an AF_UNIX socket unless the run-time configuration
  * is changed, a client will connect via TCP/IP by default and will only use
  * an AF_UNIX socket if one is explicitly specified.
+ *
+ * This is done by default on Windows because there is no good standard
+ * location for AF_UNIX sockets and many installations on Windows don't
+ * support them yet.
  */
+#ifndef WIN32
 #define DEFAULT_PGSOCKET_DIR  "/tmp"
+#else
+#define DEFAULT_PGSOCKET_DIR ""
+#endif
 
 /*
  * This is the default event source for Windows event log.

src/include/port/win32.h

@@ -56,3 +56,14 @@
 #else
 #define PGDLLEXPORT
 #endif
+
+/*
+ * Windows headers don't define this structure, but you can define it yourself
+ * to use the functionality.
+ */
+struct sockaddr_un
+{
+	unsigned short sun_family;
+	char sun_path[108];
+};
+#define HAVE_STRUCT_SOCKADDR_UN 1

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
- * Windows is not a HAVE_UNIX_SOCKETS platform.
+ * on Windows, pg_regress does not use Unix sockets.
  */
 static void
 remove_temp(void)
@@ -2120,8 +2120,12 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 
 	atexit(stop_postmaster);
 
-#ifndef HAVE_UNIX_SOCKETS
-	/* no unix domain sockets available, so change default */
+#if !defined(HAVE_UNIX_SOCKETS) || 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.)
+	 */
 	hostname = "localhost";
 #endif