Remove all instances of named return "err" from Libpod

This was inspired by https://github.com/cri-o/cri-o/pull/3934 and
much of the logic for it is contained there. However, in brief,
a named return called "err" can cause lots of code confusion and
encourages using the wrong err variable in defer statements,
which can make them work incorrectly. Using a separate name which
is not used elsewhere makes it very clear what the defer should
be doing.

As part of this, remove a large number of named returns that were
not used anywhere. Most of them were once needed, but are no
longer necessary after previous refactors (but were accidentally
retained).

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 10 insertions, 11 deletions

diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
index a3a57ae0f..b2711745e 100644
--- a/libpod/container_internal_linux.go
+++ b/libpod/container_internal_linux.go
@@ -612,7 +612,7 @@ func (c *Container) addNamespaceContainer(g *generate.Generator, ns LinuxNS, ctr
 	return nil
 }
 
-func (c *Container) exportCheckpoint(dest string, ignoreRootfs bool) (err error) {
+func (c *Container) exportCheckpoint(dest string, ignoreRootfs bool) error {
 	if (len(c.config.NamedVolumes) > 0) || (len(c.Dependencies()) > 0) {
 		return errors.Errorf("Cannot export checkpoints of containers with named volumes or dependencies")
 	}
@@ -723,7 +723,7 @@ func (c *Container) exportCheckpoint(dest string, ignoreRootfs bool) (err error)
 	return nil
 }
 
-func (c *Container) checkpointRestoreSupported() (err error) {
+func (c *Container) checkpointRestoreSupported() error {
 	if !criu.CheckForCriu() {
 		return errors.Errorf("Checkpoint/Restore requires at least CRIU %d", criu.MinCriuVersion)
 	}
@@ -733,7 +733,7 @@ func (c *Container) checkpointRestoreSupported() (err error) {
 	return nil
 }
 
-func (c *Container) checkpointRestoreLabelLog(fileName string) (err error) {
+func (c *Container) checkpointRestoreLabelLog(fileName string) error {
 	// Create the CRIU log file and label it
 	dumpLog := filepath.Join(c.bundlePath(), fileName)
 
@@ -750,7 +750,7 @@ func (c *Container) checkpointRestoreLabelLog(fileName string) (err error) {
 	return nil
 }
 
-func (c *Container) checkpoint(ctx context.Context, options ContainerCheckpointOptions) (err error) {
+func (c *Container) checkpoint(ctx context.Context, options ContainerCheckpointOptions) error {
 	if err := c.checkpointRestoreSupported(); err != nil {
 		return err
 	}
@@ -820,7 +820,7 @@ func (c *Container) checkpoint(ctx context.Context, options ContainerCheckpointO
 	return c.save()
 }
 
-func (c *Container) importCheckpoint(input string) (err error) {
+func (c *Container) importCheckpoint(input string) error {
 	archiveFile, err := os.Open(input)
 	if err != nil {
 		return errors.Wrapf(err, "Failed to open checkpoint archive %s for import", input)
@@ -849,8 +849,7 @@ func (c *Container) importCheckpoint(input string) (err error) {
 	return nil
 }
 
-func (c *Container) restore(ctx context.Context, options ContainerCheckpointOptions) (err error) {
-
+func (c *Container) restore(ctx context.Context, options ContainerCheckpointOptions) (retErr error) {
 	if err := c.checkpointRestoreSupported(); err != nil {
 		return err
 	}
@@ -860,7 +859,7 @@ func (c *Container) restore(ctx context.Context, options ContainerCheckpointOpti
 	}
 
 	if options.TargetFile != "" {
-		if err = c.importCheckpoint(options.TargetFile); err != nil {
+		if err := c.importCheckpoint(options.TargetFile); err != nil {
 			return err
 		}
 	}
@@ -946,9 +945,9 @@ func (c *Container) restore(ctx context.Context, options ContainerCheckpointOpti
 	}
 
 	defer func() {
-		if err != nil {
-			if err2 := c.cleanup(ctx); err2 != nil {
-				logrus.Errorf("error cleaning up container %s: %v", c.ID(), err2)
+		if retErr != nil {
+			if err := c.cleanup(ctx); err != nil {
+				logrus.Errorf("error cleaning up container %s: %v", c.ID(), err)
 			}
 		}
 	}()