fix(sysfs): trim newline while parsing sysfs files (#666)

sysfs files like dm/uuid etc are sometimes suffixed by a newline
character which need to be trimmed off for correct parsing, else
it will result in incorrect device type being detected

Signed-off-by: Akhil Mohan <akhil.mohan@datacore.com>

Author: akhilerm

changelogs/unreleased/666-akhilerm

@@ -0,0 +1 @@
+fix sysfs parsing by trimming newline suffix when reading from sysfs files

pkg/sysfs/syspath.go

@@ -18,11 +18,12 @@ package sysfs
 
 import (
 	"fmt"
-	"github.com/openebs/node-disk-manager/blockdevice"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/openebs/node-disk-manager/blockdevice"
 )
 
 const (

pkg/sysfs/syspath_test.go

@@ -742,6 +742,20 @@ func TestSysFsDeviceGetDeviceType(t *testing.T) {
 			want:             "raid0",
 			wantErr:          false,
 		},
+		"device is a dm device with empty uuid": {
+			sysfsDevice: &Device{
+				deviceName: "dm-16",
+				path:       "/dev/dm-16",
+				sysPath: filepath.Join(tmpDir,
+					"sys/devices/virtual/block/dm-16") + "/",
+			},
+			devType:          blockdevice.BlockDeviceTypeDisk,
+			subDirectoryName: "dm",
+			subFileName:      "uuid",
+			subFileContent:   "\n",
+			want:             blockdevice.BlockDeviceTypeDMDevice,
+			wantErr:          false,
+		},
 	}
 	for name, tt := range tests {
 		t.Run(name, func(t *testing.T) {

pkg/sysfs/util.go

@@ -30,6 +30,7 @@ func readSysFSFileAsInt64(sysFilePath string) (int64, error) {
 	if err != nil {
 		return 0, err
 	}
+	// Remove tailing newline (usual in sysfs) before parsing
 	return strconv.ParseInt(strings.TrimSuffix(string(b), "\n"), 10, 64)
 }
 
@@ -38,7 +39,8 @@ func readSysFSFileAsString(sysFilePath string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return string(b), nil
+	// Remove tailing newline (usual in sysfs)
+	return strings.TrimSuffix(string(b), "\n"), nil
 }
 
 // addDevPrefix adds the /dev prefix to all the device names

pkg/sysfs/util_test.go

@@ -17,9 +17,10 @@ limitations under the License.
 package sysfs
 
 import (
-	"github.com/stretchr/testify/assert"
 	"os"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestAddDevPrefix(t *testing.T) {
@@ -55,6 +56,13 @@ func TestReadSysFSFileAsString(t *testing.T) {
 			want:        "LVM-OSlVs5gIXuqSKVPukc2aGPh0AeJw31TJqYIRuRHoodYg9Jwkmyvvk0QNYK4YulHt",
 			wantErr:     false,
 		},
+		"valid sysfs path with tailing new line": {
+			path:        "/tmp/dm-0/dm/",
+			fileName:    "uuid",
+			fileContent: "LVM-OSlVs5gIXuqSKVPukc2aGPh0AeJw31TJqYIRuRHoodYg9Jwkmyvvk0QNYK4YulHt\n",
+			want:        "LVM-OSlVs5gIXuqSKVPukc2aGPh0AeJw31TJqYIRuRHoodYg9Jwkmyvvk0QNYK4YulHt",
+			wantErr:     false,
+		},
 	}
 	for name, tt := range tests {
 		t.Run(name, func(t *testing.T) {