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 <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/[email protected]

1 files changed, 4 insertions, 0 deletions

diff --git a/src/include/c.h b/src/include/c.h
index 831c89f473d..d72b23afe4c 100644
--- a/src/include/c.h
+++ b/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