From d9406b061cef40bd42ed813e13bd02b3a285adae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Cami?= <fcami@fedoraproject.org>
Date: Fri, 23 Jun 2017 23:56:50 +0200
Subject: [PATCH 44/60] Be more thorough about flushing our config file
when
 writing.

Add missing fclose() at the end of writeConfig
Use fflush(out) + fsync(fileno(out) on temporary file
fsync() the destination directory after rename
---
 grubby.c | 40 ++++++++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/grubby.c b/grubby.c
index 345195c..951abb7 100644
--- a/grubby.c
+++ b/grubby.c
@@ -1591,6 +1591,7 @@ static int writeConfig(struct grubConfig * cfg, char * outName,
     int needs = MAIN_DEFAULT;
     struct stat sb;
     int i;
+    int rc = 0;
 
     if (!strcmp(outName, "-")) {
 	out = stdout;
@@ -1694,15 +1695,42 @@ static int writeConfig(struct grubConfig * cfg, char * outName,
     }
 
     if (tmpOutName) {
-	if (rename(tmpOutName, outName)) {
-	    fprintf(stderr, _("grubby: error moving %s to %s: %s\n"),
-		    tmpOutName, outName, strerror(errno));
-	    unlink(outName);
-            return 1;
+        /* write userspace buffers */
+        if (fflush(out))
+            rc = 1;
+
+        /* purge the write-back cache with fsync() */
+        if (fsync(fileno(out)))
+            rc = 1;
+
+        if (fclose(out))
+            rc = 1;
+
+        if (rc == 0 && rename(tmpOutName, outName)) {
+            unlink(tmpOutName);
+            rc = 1;
+        }
+
+        /* fsync() the destination directory after rename */
+        if (rc == 0) {
+            int dirfd;
+
+            dirfd = open(dirname(strdupa(outName)), O_RDONLY);
+            if (dirfd < 0)
+                rc = 1;
+            else if (fsync(dirfd))
+                rc = 1;
+
+            if (dirfd >= 0)
+                close(dirfd);
 	}
+
+        if (rc == 1)
+            fprintf(stderr,
+                   _("grubby: error flushing data: %m\n"));
     }
 
-    return 0;
+    return rc;
 }
 
 static int numEntries(struct grubConfig *cfg) {
-- 
2.19.1