Add dry run flag

drive-demuxer.go

@@ -17,6 +17,7 @@ type TopLevel struct {
 	CombinedOutput string
 	RightOutput    string
 	OpenHandles    chan int
+	DryRun         bool
 }
 
 type Step struct {
@@ -96,6 +97,10 @@ func (s *Step) SeparateLeft(child string) {
 	leftInPath := s.InputPath(child, LEFT)
 	leftOutPath := s.OutputPath(child, LEFT)
 
+	if s.DryRun {
+		return
+	}
+
 	leftBase := path.Dir(leftOutPath)
 	err := os.MkdirAll(leftBase, 0755)
 	if err != nil {
@@ -111,6 +116,10 @@ func (s *Step) SeparateRight(child string) {
 	rightInPath := s.InputPath(child, RIGHT)
 	rightOutPath := s.OutputPath(child, RIGHT)
 
+	if s.DryRun {
+		return
+	}
+
 	rightBase := path.Dir(rightOutPath)
 	err := os.MkdirAll(rightBase, 0755)
 	if err != nil {
@@ -127,6 +136,10 @@ func (s *Step) Combine(child string) {
 	rightInPath := s.InputPath(child, RIGHT)
 	combinedOutPath := s.OutputPath(child, COMBINED)
 
+	if s.DryRun {
+		return
+	}
+
 	combinedBase := path.Dir(combinedOutPath)
 	err := os.MkdirAll(combinedBase, 0755)
 	if err != nil {
@@ -144,6 +157,11 @@ func (s *Step) Combine(child string) {
 
 func (s *Step) MakeCombinedDir(child string) {
 	combinedOutPath := s.OutputPath(child, COMBINED)
+
+	if s.DryRun {
+		return
+	}
+
 	err := os.MkdirAll(combinedOutPath, 0755)
 	if err != nil {
 		log.Printf("Failed creating %s: %s\n", combinedOutPath, err)
@@ -153,6 +171,11 @@ func (s *Step) MakeCombinedDir(child string) {
 func (s *Step) RemoveInputDirs(child string) {
 	leftInPath := s.InputPath(child, LEFT)
 	rightInPath := s.InputPath(child, RIGHT)
+
+	if s.DryRun {
+		return
+	}
+
 	err := os.Remove(leftInPath)
 	if err != nil && !os.IsNotExist(err) {
 		log.Printf("Failed removing %s: %s\n", leftInPath, err)
@@ -332,6 +355,8 @@ func main() {
 		"combined-output", "./output/combined", "The name of the combined side of the output.")
 	flag.StringVar(&settings.RightOutput,
 		"right-output", "./output/right", "The name of the right side of the output.")
+	flag.BoolVar(&settings.DryRun,
+		"dry-run", true, "True if no actual operation should be performed.")
 	flag.Parse()
 	(&Step{
 		TopLevel: &settings,