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, 5 insertions, 4 deletions

diff --git a/libpod/oci_conmon_linux.go b/libpod/oci_conmon_linux.go
index 534622382..bd6af5281 100644
--- a/libpod/oci_conmon_linux.go
+++ b/libpod/oci_conmon_linux.go
@@ -191,7 +191,7 @@ func hasCurrentUserMapped(ctr *Container) bool {
 }
 
 // CreateContainer creates a container.
-func (r *ConmonOCIRuntime) CreateContainer(ctr *Container, restoreOptions *ContainerCheckpointOptions) (err error) {
+func (r *ConmonOCIRuntime) CreateContainer(ctr *Container, restoreOptions *ContainerCheckpointOptions) error {
 	if !hasCurrentUserMapped(ctr) {
 		for _, i := range []string{ctr.state.RunDir, ctr.runtime.config.Engine.TmpDir, ctr.config.StaticDir, ctr.state.Mountpoint, ctr.runtime.config.Engine.VolumePath} {
 			if err := makeAccessible(i, ctr.RootUID(), ctr.RootGID()); err != nil {
@@ -853,7 +853,7 @@ func (r *ConmonOCIRuntime) getLogTag(ctr *Container) (string, error) {
 }
 
 // createOCIContainer generates this container's main conmon instance and prepares it for starting
-func (r *ConmonOCIRuntime) createOCIContainer(ctr *Container, restoreOptions *ContainerCheckpointOptions) (err error) {
+func (r *ConmonOCIRuntime) createOCIContainer(ctr *Container, restoreOptions *ContainerCheckpointOptions) error {
 	var stderrBuf bytes.Buffer
 
 	runtimeDir, err := util.GetRuntimeDir()
@@ -1343,8 +1343,9 @@ func (r *ConmonOCIRuntime) moveConmonToCgroupAndSignal(ctr *Container, cmd *exec
 	return nil
 }
 
-// newPipe creates a unix socket pair for communication
-func newPipe() (parent *os.File, child *os.File, err error) {
+// newPipe creates a unix socket pair for communication.
+// Returns two files - first is parent, second is child.
+func newPipe() (*os.File, *os.File, error) {
 	fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_SEQPACKET|unix.SOCK_CLOEXEC, 0)
 	if err != nil {
 		return nil, nil, err