From fe4d0fbc7c88acf4f2d1a4f6d612f123b56fbd98 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Wed, 5 Oct 2016 12:20:02 +1100
Subject: [PATCH] 4473.   [bug]           Only call fsync / _commit on regular
 files. [RT #43196]

---
 CHANGES               |  2 ++
 lib/isc/unix/stdio.c  | 14 ++++++++++----
 lib/isc/win32/stdio.c | 13 +++++++++++++
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/CHANGES b/CHANGES
index 0f085a5570..8a7bf7eb59 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+4473.	[bug]		Only call fsync / _commit on regular files. [RT #43196]
+
 4472.	[bug]		Named could fail to find the correct NSEC3 records when
 			a zone was updated between looking for the answer and
 			looking for the NSEC3 records proving non-existance
diff --git a/lib/isc/unix/stdio.c b/lib/isc/unix/stdio.c
index 03d0e7c316..d10d1121ca 100644
--- a/lib/isc/unix/stdio.c
+++ b/lib/isc/unix/stdio.c
@@ -128,14 +128,20 @@ isc_stdio_flush(FILE *f) {
 
 isc_result_t
 isc_stdio_sync(FILE *f) {
+	struct stat buf;
 	int r;
 
-	r = fsync(fileno(f));
+	if (fstat(fileno(f), &buf) != 0)
+		return (isc__errno2result(errno));
+ 
 	/*
-	 * fsync is not supported on sockets and pipes which
-	 * result in EINVAL / ENOTSUP.
+	 * Only call fsync() on regular files.
 	 */
-	if (r == 0 || errno == EINVAL || errno == ENOTSUP)
+	if ((buf.st_mode & S_IFMT) != S_IFREG)
+		return (ISC_R_SUCCESS);
+
+	r = fsync(fileno(f));
+	if (r == 0)
 		return (ISC_R_SUCCESS);
 	else
 		return (isc__errno2result(errno));
diff --git a/lib/isc/win32/stdio.c b/lib/isc/win32/stdio.c
index 6735d2ba6f..a03a37ae48 100644
--- a/lib/isc/win32/stdio.c
+++ b/lib/isc/win32/stdio.c
@@ -16,6 +16,9 @@
 #include <isc/stdio.h>
 #include <isc/util.h>
 
+#include <sys/stat.h>
+#include <sys/types.h>
+
 #include "errno2result.h"
 
 isc_result_t
@@ -124,8 +127,18 @@ isc_stdio_flush(FILE *f) {
 
 isc_result_t
 isc_stdio_sync(FILE *f) {
+	struct _stat buf;
 	int r;
 
+	if (_fstat(_fileno(f), &buf) != 0)
+		return (isc__errno2result(errno));
+
+	/*
+	 * Only call _commit() on regular files.
+	 */
+	if ((buf.st_mode & S_IFMT) != S_IFREG)
+		return (ISC_R_SUCCESS);
+
 	r = _commit(_fileno(f));
 	if (r == 0)
 		return (ISC_R_SUCCESS);