libcontainer/cgroups/fs: replace strings.Fields with strings.SplitN

Signed-off-by: Stavros Panakakis <[email protected]>

libcontainer/cgroups/fs/cpuacct.go

@@ -91,15 +91,31 @@ func getCpuUsageBreakdown(path string) (uint64, uint64, error) {
 	if err != nil {
 		return 0, 0, err
 	}
-	// TODO: use strings.SplitN instead.
-	fields := strings.Fields(data)
-	if len(fields) < 4 || fields[0] != userField || fields[2] != systemField {
+
+	lines := strings.SplitN(data, "\n", 2)
+	if len(lines) < 2 {
+		return 0, 0, malformedLine(path, file, data)
+	}
+
+	userLine := lines[0]
+	userLineFields := strings.SplitN(userLine, " ", 2)
+	if len(userLineFields) != 2 || userLineFields[0] != userField {
 		return 0, 0, malformedLine(path, file, data)
 	}
-	if userModeUsage, err = strconv.ParseUint(fields[1], 10, 64); err != nil {
+
+	userUsageInTicks := strings.TrimSpace(userLineFields[1])
+	if userModeUsage, err = strconv.ParseUint(userUsageInTicks, 10, 64); err != nil {
 		return 0, 0, &parseError{Path: path, File: file, Err: err}
 	}
-	if kernelModeUsage, err = strconv.ParseUint(fields[3], 10, 64); err != nil {
+
+	systemLine := lines[1]
+	systemLineFields := strings.SplitN(systemLine, " ", 2)
+	if len(systemLineFields) != 2 || systemLineFields[0] != systemField {
+		return 0, 0, malformedLine(path, file, data)
+	}
+
+	systemUsageInTicks := strings.TrimSpace(systemLineFields[1])
+	if kernelModeUsage, err = strconv.ParseUint(systemUsageInTicks, 10, 64); err != nil {
 		return 0, 0, &parseError{Path: path, File: file, Err: err}
 	}