Fix simplification linter errors

Signed-off-by: Amir Mohamad Ehsandar <[email protected]>

libcontainer/cgroups/ebpf/ebpf.go

@@ -32,10 +32,12 @@ func LoadAttachCgroupDeviceFilter(insts asm.Instructions, license string, dirFD
 	if err != nil {
 		return nilCloser, err
 	}
+	//nolint:staticcheck
 	if err := prog.Attach(dirFD, ebpf.AttachCGroupDevice, unix.BPF_F_ALLOW_MULTI); err != nil {
 		return nilCloser, errors.Wrap(err, "failed to call BPF_PROG_ATTACH (BPF_CGROUP_DEVICE, BPF_F_ALLOW_MULTI)")
 	}
 	closer := func() error {
+		//nolint:staticcheck
 		if err := prog.Detach(dirFD, ebpf.AttachCGroupDevice, unix.BPF_F_ALLOW_MULTI); err != nil {
 			return errors.Wrap(err, "failed to call BPF_PROG_DETACH (BPF_CGROUP_DEVICE, BPF_F_ALLOW_MULTI)")
 		}

libcontainer/cgroups/fs/name.go

@@ -16,12 +16,12 @@ func (s *NameGroup) Name() string {
 	return s.GroupName
 }
 
-func (s *NameGroup) Apply(path string, d *cgroupData) error {
+func (s *NameGroup) Apply(path string, d *cgroupData) (err error) {
 	if s.Join {
 		// ignore errors if the named cgroup does not exist
-		join(path, d.pid)
+		err = join(path, d.pid)
 	}
-	return nil
+	return
 }
 
 func (s *NameGroup) Set(path string, cgroup *configs.Cgroup) error {

libcontainer/cgroups/systemd/common.go

@@ -333,11 +333,11 @@ func startUnit(dbusConnection *systemdDbus.Conn, unitName string, properties []s
 			close(statusChan)
 			// Please refer to https://godoc.org/github.com/coreos/go-systemd/dbus#Conn.StartUnit
 			if s != "done" {
-				dbusConnection.ResetFailedUnit(unitName)
+				_ = dbusConnection.ResetFailedUnit(unitName)
 				return errors.Errorf("error creating systemd unit `%s`: got `%s`", unitName, s)
 			}
 		case <-timeout.C:
-			dbusConnection.ResetFailedUnit(unitName)
+			_ = dbusConnection.ResetFailedUnit(unitName)
 			return errors.New("Timeout waiting for systemd to create " + unitName)
 		}
 	} else if !isUnitExists(err) {

libcontainer/cgroups/utils.go

@@ -270,7 +270,7 @@ func RemovePaths(paths map[string]string) (err error) {
 			}
 		}
 		if len(paths) == 0 {
-			//nolint:ineffassign // done to help garbage collecting: opencontainers/runc#2506
+			//nolint:staticcheck,ineffassign  // done to help garbage collecting: opencontainers/runc#2506
 			paths = make(map[string]string)
 			return nil
 		}

libcontainer/container_linux.go

@@ -680,8 +680,7 @@ var criuFeatures *criurpc.CriuFeatures
 
 func (c *linuxContainer) checkCriuFeatures(criuOpts *CriuOpts, rpcOpts *criurpc.CriuOpts, criuFeat *criurpc.CriuFeatures) error {
 
-	var t criurpc.CriuReqType
-	t = criurpc.CriuReqType_FEATURE_CHECK
+	var t criurpc.CriuReqType = criurpc.CriuReqType_FEATURE_CHECK
 
 	// make sure the features we are looking for are really not from
 	// some previous check
@@ -764,10 +763,7 @@ func (c *linuxContainer) checkCriuVersion(minVersion int) error {
 const descriptorsFilename = "descriptors.json"
 
 func (c *linuxContainer) addCriuDumpMount(req *criurpc.CriuReq, m *configs.Mount) {
-	mountDest := m.Destination
-	if strings.HasPrefix(mountDest, c.config.Rootfs) {
-		mountDest = mountDest[len(c.config.Rootfs):]
-	}
+	mountDest := strings.TrimPrefix(m.Destination, c.config.Rootfs)
 
 	extMnt := &criurpc.ExtMountMap{
 		Key: proto.String(mountDest),
@@ -1108,10 +1104,7 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 }
 
 func (c *linuxContainer) addCriuRestoreMount(req *criurpc.CriuReq, m *configs.Mount) {
-	mountDest := m.Destination
-	if strings.HasPrefix(mountDest, c.config.Rootfs) {
-		mountDest = mountDest[len(c.config.Rootfs):]
-	}
+	mountDest := strings.TrimPrefix(m.Destination, c.config.Rootfs)
 
 	extMnt := &criurpc.ExtMountMap{
 		Key: proto.String(mountDest),
@@ -1216,7 +1209,7 @@ func (c *linuxContainer) prepareCriuRestoreMounts(mounts []*configs.Mount) error
 	return nil
 }
 
-func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
+func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) (err error) {
 	c.m.Lock()
 	defer c.m.Unlock()
 
@@ -1243,15 +1236,20 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 	if err != nil {
 		return err
 	}
-	defer workDir.Close()
+	defer func() {
+		err = workDir.Close()
+	}()
+
 	if criuOpts.ImagesDirectory == "" {
 		return errors.New("invalid directory to restore checkpoint")
 	}
 	imageDir, err := os.Open(criuOpts.ImagesDirectory)
 	if err != nil {
 		return err
 	}
-	defer imageDir.Close()
+	defer func() {
+		err = imageDir.Close()
+	}()
 	// CRIU has a few requirements for a root directory:
 	// * it must be a mount point
 	// * its parent must not be overmounted
@@ -1261,7 +1259,9 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 	if err := os.Mkdir(root, 0755); err != nil {
 		return err
 	}
-	defer os.Remove(root)
+	defer func() {
+		err = os.Remove(root)
+	}()
 	root, err = filepath.EvalSymlinks(root)
 	if err != nil {
 		return err
@@ -1270,7 +1270,9 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 	if err != nil {
 		return err
 	}
-	defer unix.Unmount(root, unix.MNT_DETACH)
+	defer func() {
+		err = unix.Unmount(root, unix.MNT_DETACH)
+	}()
 	t := criurpc.CriuReqType_RESTORE
 	req := &criurpc.CriuReq{
 		Type: &t,
@@ -1378,7 +1380,7 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 
 	// Now that CRIU is done let's close all opened FDs CRIU needed.
 	for _, fd := range extraFiles {
-		fd.Close()
+		_ = fd.Close()
 	}
 
 	return err
@@ -1592,7 +1594,7 @@ func (c *linuxContainer) criuSwrk(process *Process, req *criurpc.CriuReq, opts *
 		break
 	}
 
-	criuClientCon.CloseWrite()
+	_ = criuClientCon.CloseWrite()
 	// cmd.Wait() waits cmd.goroutines which are used for proxying file descriptors.
 	// Here we want to wait only the CRIU process.
 	criuProcessState, err = criuProcess.Wait()
@@ -1780,6 +1782,7 @@ func (c *linuxContainer) saveState(s *State) (retErr error) {
 	return os.Rename(tmpFile.Name(), stateFilePath)
 }
 
+//nolint:unused
 func (c *linuxContainer) deleteState() error {
 	return os.Remove(filepath.Join(c.root, stateFilename))
 }

libcontainer/integration/exec_test.go

@@ -370,7 +370,7 @@ func TestProcessEmptyCaps(t *testing.T) {
 	// Wait for process
 	waitProcess(&pconfig, t)
 
-	outputStatus := string(stdout.Bytes())
+	outputStatus := stdout.String()
 
 	lines := strings.Split(outputStatus, "\n")
 
@@ -423,7 +423,7 @@ func TestProcessCaps(t *testing.T) {
 	// Wait for process
 	waitProcess(&pconfig, t)
 
-	outputStatus := string(stdout.Bytes())
+	outputStatus := stdout.String()
 
 	lines := strings.Split(outputStatus, "\n")
 
@@ -449,8 +449,7 @@ func TestProcessCaps(t *testing.T) {
 	}
 
 	var netAdminMask uint64
-	var netAdminBit uint
-	netAdminBit = 12 // from capability.h
+	var netAdminBit = uint(12) // from capability.h
 	netAdminMask = 1 << netAdminBit
 	if effectiveCaps&netAdminMask != netAdminMask {
 		t.Fatal("CAP_NET_ADMIN is not set as expected")
@@ -487,7 +486,7 @@ func TestAdditionalGroups(t *testing.T) {
 	// Wait for process
 	waitProcess(&pconfig, t)
 
-	outputGroups := string(stdout.Bytes())
+	outputGroups := stdout.String()
 
 	// Check that the groups output has the groups that we specified
 	if !strings.Contains(outputGroups, "audio") {

libcontainer/intelrdt/monitoring.go

@@ -21,7 +21,9 @@ type monFeatures struct {
 
 func getMonFeatures(intelRdtRoot string) (monFeatures, error) {
 	file, err := os.Open(filepath.Join(intelRdtRoot, "info", "L3_MON", "mon_features"))
-	defer file.Close()
+	defer func() {
+		_ = file.Close()
+	}()
 	if err != nil {
 		return monFeatures{}, err
 	}

libcontainer/system/proc.go

@@ -96,8 +96,14 @@ func parseStat(data string) (stat Stat_t, err error) {
 	// one (PID) and two (Name) in the paren-split.
 	parts = strings.Split(data[i+2:], " ")
 	var state int
-	fmt.Sscanf(parts[3-3], "%c", &state)
+
+	if _, err = fmt.Sscanf(parts[3-3], "%c", &state); err != nil {
+		return Stat_t{}, err
+	}
 	stat.State = State(state)
-	fmt.Sscanf(parts[22-3], "%d", &stat.StartTime)
+
+	if _, err = fmt.Sscanf(parts[22-3], "%d", &stat.StartTime); err != nil {
+		return Stat_t{}, err
+	}
 	return stat, nil
 }