update README and misc files

README.md

@@ -17,7 +17,7 @@ tools: lxc, systemd-nspawn or systemd itself.
 Usage -- extract docker image
 -----------------------------
 
-Download `nginx` docker image from docker hub and convert it to a rootfs:
+Download `busybox` docker image from docker hub and convert it to a rootfs:
 
 ```
 skopeo copy docker://docker.io/busybox:latest docker-archive:busybox.tar

main.go

@@ -11,7 +11,7 @@ import (
 )
 
 const _usage = `Usage:
-  %s <INFILE> <OUTFILE>
+  %s <infile> <outfile>
 
 Flatten a Docker container image to a root file system.
 

main_test.go

@@ -44,12 +44,12 @@ func TestExecute(t *testing.T) {
 		{
 			name:    "infile does not exist",
 			infile:  "t3-does-not-exist.txt",
-			wantErr: "^open .*t3-does-not-exist.txt: no such file or directory$",
+			wantErr: "^open .*not-exist.txt: no such file or directory$",
 		},
 		{
 			name:    "outpath dir not writable",
 			outfile: filepath.Join("t4", "does", "not", "exist"),
-			wantErr: "^create: open .*/t4/does/not/exist: no such file or directory",
+			wantErr: "^create: open .*not/exist: no such file or directory",
 		},
 	}
 

rootfs/rootfs.go

@@ -229,7 +229,10 @@ func whiteoutDirs(whreaddir map[string]int, nlayers int) []*tree {
 }
 
 // validateManifest
-func validateManifest(layerOffsets map[string]int64, manifest dockerManifestJSON) error {
+func validateManifest(
+	layerOffsets map[string]int64,
+	manifest dockerManifestJSON,
+) error {
 	if len(manifest) == 0 {
 		return fmt.Errorf("empty or missing manifest")
 	}