From 4ba60a2f5c3f5405c599caddc5a124c5781c9beb Mon Sep 17 00:00:00 2001
Message-Id: <4ba60a2f5c3f5405c599caddc5a124c5781c9beb.1566225007.git.aquini@redhat.com>
In-Reply-To: <d42f467a923dfc09309acb7a83b42e3285fbd8f4.1566225007.git.aquini@redhat.com>
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From: Sandipan Das <sandipan@linux.ibm.com>
Date: Thu, 15 Aug 2019 13:08:35 +0530
Subject: [RHEL7 PATCH 08/31] hugeutils: Make writing a ulong to a file more
 reliable

This makes file_write_ulong() more reliable in terms of error
detection for certain cases like writing an invalid value to
a file under procfs or sysfs. Also, using fprintf() does not
guarantee that errno would be set under such circumstances.

Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Rafael Aquini <aquini@redhat.com>
---
 hugeutils.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/hugeutils.c b/hugeutils.c
index 60488e8..fc64946 100644
--- a/hugeutils.c
+++ b/hugeutils.c
@@ -219,17 +219,18 @@ long file_read_ulong(char *file, const char *tag)
 
 int file_write_ulong(char *file, unsigned long val)
 {
-	FILE *f;
-	int ret;
+	int fd, ret, buflen;
+	char buf[20];
 
-	f = fopen(file, "w");
-	if (!f) {
+	fd = open(file, O_WRONLY);
+	if (fd < 0) {
 		ERROR("Couldn't open %s: %s\n", file, strerror(errno));
 		return -1;
 	}
 
-	ret = fprintf(f, "%lu", val);
-	fclose(f);
+	buflen = sprintf(buf, "%lu", val);
+	ret = write(fd, buf, buflen);
+	close(fd);
 	return ret > 0 ? 0 : -1;
 }
 
-- 
1.8.3.1