enable gocritic linter

The linter ensures a common code style.
- use switch/case instead of else if
- use if instead of switch/case for single case statement
- add space between comment and text
- detect the use of defer with os.Exit()
- use short form var += "..." instead of var = var + "..."
- detect problems with append()
```
newSlice := append(orgSlice, val)
```
  This could lead to nasty bugs because the orgSlice will be changed in
  place if it has enough capacity too hold the new elements. Thus we
  newSlice might not be a copy.

Of course most of the changes are just cosmetic and do not cause any
logic errors but I think it is a good idea to enforce a common style.
This should help maintainability.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

4 files changed, 10 insertions, 9 deletions

diff --git a/pkg/api/handlers/compat/containers.go b/pkg/api/handlers/compat/containers.go
index 4830ef4b7..1c339730e 100644
--- a/pkg/api/handlers/compat/containers.go
+++ b/pkg/api/handlers/compat/containers.go
@@ -293,9 +293,10 @@ func LibpodToContainer(l *libpod.Container, sz bool) (*handlers.Container, error
 		stateStr = "created"
 	}
 
-	if state == define.ContainerStateConfigured || state == define.ContainerStateCreated {
+	switch state {
+	case define.ContainerStateConfigured, define.ContainerStateCreated:
 		status = "Created"
-	} else if state == define.ContainerStateStopped || state == define.ContainerStateExited {
+	case define.ContainerStateStopped, define.ContainerStateExited:
 		exitCode, _, err := l.ExitCode()
 		if err != nil {
 			return nil, err
@@ -305,7 +306,7 @@ func LibpodToContainer(l *libpod.Container, sz bool) (*handlers.Container, error
 			return nil, err
 		}
 		status = fmt.Sprintf("Exited (%d) %s ago", exitCode, units.HumanDuration(time.Since(finishedTime)))
-	} else if state == define.ContainerStateRunning || state == define.ContainerStatePaused {
+	case define.ContainerStateRunning, define.ContainerStatePaused:
 		startedTime, err := l.StartedTime()
 		if err != nil {
 			return nil, err
@@ -314,11 +315,11 @@ func LibpodToContainer(l *libpod.Container, sz bool) (*handlers.Container, error
 		if state == define.ContainerStatePaused {
 			status += " (Paused)"
 		}
-	} else if state == define.ContainerStateRemoving {
+	case define.ContainerStateRemoving:
 		status = "Removal In Progress"
-	} else if state == define.ContainerStateStopping {
+	case define.ContainerStateStopping:
 		status = "Stopping"
-	} else {
+	default:
 		status = "Unknown"
 	}
 
diff --git a/pkg/api/handlers/compat/images.go b/pkg/api/handlers/compat/images.go
index edefce010..a690cdd40 100644
--- a/pkg/api/handlers/compat/images.go
+++ b/pkg/api/handlers/compat/images.go
@@ -532,7 +532,7 @@ func ExportImages(w http.ResponseWriter, r *http.Request) {
 		utils.Error(w, http.StatusBadRequest, errors.Wrapf(err, "failed to parse parameters for %s", r.URL.String()))
 		return
 	}
-	if len(query.Names) <= 0 {
+	if len(query.Names) == 0 {
 		utils.Error(w, http.StatusBadRequest, fmt.Errorf("no images to download"))
 		return
 	}
diff --git a/pkg/api/handlers/compat/images_build.go b/pkg/api/handlers/compat/images_build.go
index 1a24f1ae3..0f85aa717 100644
--- a/pkg/api/handlers/compat/images_build.go
+++ b/pkg/api/handlers/compat/images_build.go
@@ -286,7 +286,7 @@ func BuildImage(w http.ResponseWriter, r *http.Request) {
 						}
 					}
 				}
-				secrets = append(secrets, strings.Join(modifiedOpt[:], ","))
+				secrets = append(secrets, strings.Join(modifiedOpt, ","))
 			}
 		}
 	}
diff --git a/pkg/api/handlers/compat/images_prune.go b/pkg/api/handlers/compat/images_prune.go
index c0be9da7d..46524fcff 100644
--- a/pkg/api/handlers/compat/images_prune.go
+++ b/pkg/api/handlers/compat/images_prune.go
@@ -58,7 +58,7 @@ func PruneImages(w http.ResponseWriter, r *http.Request) {
 		idr = append(idr, types.ImageDeleteResponseItem{
 			Deleted: p.Id,
 		})
-		reclaimedSpace = reclaimedSpace + p.Size
+		reclaimedSpace += p.Size
 	}
 	if errorMsg.Len() > 0 {
 		utils.InternalServerError(w, errors.New(errorMsg.String()))