Fix unportable setvbuf() usage in initdb.

In yesterday's commit 2dc4f011, I tried
to force buffering of stdout/stderr in initdb to be what it is by
default when the program is run interactively on Unix (since that's how
most manual testing is done).  This tripped over the fact that Windows
doesn't support _IOLBF mode.  We dealt with that a long time ago in
syslogger.c by falling back to unbuffered mode on Windows.  Export that
solution in port.h and use it in initdb.

Back-patch to 8.4, like the previous commit.

src/backend/postmaster/syslogger.c

@@ -47,17 +47,6 @@
 #include "utils/ps_status.h"
 #include "utils/timestamp.h"
 
-/*
- * We really want line-buffered mode for logfile output, but Windows does
- * not have it, and interprets _IOLBF as _IOFBF (bozos).  So use _IONBF
- * instead on Windows.
- */
-#ifdef WIN32
-#define LBF_MODE	_IONBF
-#else
-#define LBF_MODE	_IOLBF
-#endif
-
 /*
  * We read() into a temp buffer twice as big as a chunk, so that any fragment
  * left after processing can be moved down to the front and we'll still have
@@ -765,7 +754,7 @@ syslogger_parseArgs(int argc, char *argv[])
 	if (fd != -1)
 	{
 		syslogFile = fdopen(fd, "a");
-		setvbuf(syslogFile, NULL, LBF_MODE, 0);
+		setvbuf(syslogFile, NULL, PG_IOLBF, 0);
 	}
 #else							/* WIN32 */
 	fd = atoi(*argv++);
@@ -775,7 +764,7 @@ syslogger_parseArgs(int argc, char *argv[])
 		if (fd > 0)
 		{
 			syslogFile = fdopen(fd, "a");
-			setvbuf(syslogFile, NULL, LBF_MODE, 0);
+			setvbuf(syslogFile, NULL, PG_IOLBF, 0);
 		}
 	}
 #endif   /* WIN32 */
@@ -1154,7 +1143,7 @@ logfile_open(const char *filename, const char *mode, bool allow_errors)
 
 	if (fh)
 	{
-		setvbuf(fh, NULL, LBF_MODE, 0);
+		setvbuf(fh, NULL, PG_IOLBF, 0);
 
 #ifdef WIN32
 		/* use CRLF line endings on Windows */

src/bin/initdb/initdb.c

@@ -3529,7 +3529,7 @@ main(int argc, char *argv[])
 	 * unexpected output ordering when, eg, output is redirected to a file.
 	 * POSIX says we must do this before any other usage of these files.
 	 */
-	setvbuf(stdout, NULL, _IOLBF, 0);
+	setvbuf(stdout, NULL, PG_IOLBF, 0);
 	setvbuf(stderr, NULL, _IONBF, 0);
 
 	progname = get_progname(argv[0]);

src/include/port.h

@@ -338,6 +338,20 @@ extern int	gettimeofday(struct timeval * tp, struct timezone * tzp);
 #define closesocket close
 #endif   /* WIN32 */
 
+/*
+ * On Windows, setvbuf() does not support _IOLBF mode, and interprets that
+ * as _IOFBF.  To add insult to injury, setvbuf(file, NULL, _IOFBF, 0)
+ * crashes outright if "parameter validation" is enabled.  Therefore, in
+ * places where we'd like to select line-buffered mode, we fall back to
+ * unbuffered mode instead on Windows.  Always use PG_IOLBF not _IOLBF
+ * directly in order to implement this behavior.
+ */
+#ifndef WIN32
+#define PG_IOLBF	_IOLBF
+#else
+#define PG_IOLBF	_IONBF
+#endif
+
 /*
  * Default "extern" declarations or macro substitutes for library routines.
  * When necessary, these routines are provided by files in src/port/.