From: Michael Tremer <michael.tremer@ipfire.org>
Date: Sat, 27 Mar 2021 16:38:23 +0000 (+0000)
Subject: cgroups: Catch errors when writes fail
X-Git-Tag: 0.9.28~1285^2~457
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ac149196fd73fc1f763cd27c82a279ed73c36cf2;p=pakfire.git

cgroups: Catch errors when writes fail

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/libpakfire/cgroup.c b/src/libpakfire/cgroup.c
index db1c9e423..84ab8eba1 100644
--- a/src/libpakfire/cgroup.c
+++ b/src/libpakfire/cgroup.c
@@ -151,6 +151,8 @@ static FILE* pakfire_cgroup_fopen(Pakfire pakfire,
 
 static int pakfire_cgroup_fprintf(Pakfire pakfire,
 		const char* group, const char* file, const char* format, ...) {
+	char buffer[64];
+	size_t length;
 	int r;
 	va_list args;
 
@@ -158,11 +160,15 @@ static int pakfire_cgroup_fprintf(Pakfire pakfire,
 	if (!f)
 		return 1;
 
-	// Write to file
+	// Format what we have to write
 	va_start(args, format);
-	r = vfprintf(f, format, args);
+	length = vsnprintf(buffer, sizeof(buffer) - 1, format, args);
 	va_end(args);
 
+	// Use write(2) instead of fprintf/fwrite because we want to know
+	// if the operation was successful.
+	r = write(fileno(f), buffer, length);
+
 	fclose(f);
 
 	return r;
@@ -175,7 +181,7 @@ static int pakfire_cgroup_enable_controller(Pakfire pakfire,
 		"+%s", controller);
 
 	// fprintf might set errno when there was a problem, although the write itself was ok
-	if (errno) {
+	if (r < 0) {
 		// The parent group does not seem to have this controller enabled
 		if (errno == ENOENT) {
 			char* parent = pakfire_cgroup_parent_name(group);