From c180fd5c85f7f902adfec45b9eadb36ed88a09e2 Mon Sep 17 00:00:00 2001
From: Achilleas Tzenetopoulos <atzenetopoulos@gmail.com>
Date: Sun, 17 Jan 2021 21:47:50 +0200
Subject: [PATCH] lists filtered unused volumes in non-force mode

Signed-off-by: Achilleas Tzenetopoulos <atzenetopoulos@gmail.com>
---
 cmd/podman/volumes/prune.go   | 42 +++++++++++++++++++++++++++++------
 pkg/domain/filters/volumes.go | 25 +++++++++++++++++++++
 2 files changed, 60 insertions(+), 7 deletions(-)

diff --git a/cmd/podman/volumes/prune.go b/cmd/podman/volumes/prune.go
index ca8f71a732..78f70365ed 100644
--- a/cmd/podman/volumes/prune.go
+++ b/cmd/podman/volumes/prune.go
@@ -49,8 +49,9 @@ func init() {
 
 func prune(cmd *cobra.Command, args []string) error {
 	var (
-		pruneOptions = entities.VolumePruneOptions{}
-		listOptions  = entities.VolumeListOptions{}
+		pruneOptions  = entities.VolumePruneOptions{}
+		listOptions   = entities.VolumeListOptions{}
+		unusedOptions = entities.VolumeListOptions{}
 	)
 	// Prompt for confirmation if --force is not set
 	force, err := cmd.Flags().GetBool("force")
@@ -60,15 +61,32 @@ func prune(cmd *cobra.Command, args []string) error {
 	if !force {
 		reader := bufio.NewReader(os.Stdin)
 		fmt.Println("WARNING! This will remove all volumes not used by at least one container. The following volumes will be removed:")
+		pruneOptions.Filters, err = filters.ParseFilterArgumentsIntoFilters(filter)
 		listOptions.Filter, err = filters.ParseFilterArgumentsIntoFilters(filter)
 		if err != nil {
 			return err
 		}
+		// filter all the unused (unbound) volumes
+		unusedOptions.Filter = make(map[string][]string, 1)
+		unusedOptions.Filter["unused"] = []string{"true"}
+		if err != nil {
+			return err
+		}
+		unusedVolumes, err := registry.ContainerEngine().VolumeList(context.Background(), unusedOptions)
+		if err != nil {
+			return err
+		}
+		// filter volumes based on user input
 		filteredVolumes, err := registry.ContainerEngine().VolumeList(context.Background(), listOptions)
 		if err != nil {
 			return err
 		}
-		for _, fv := range filteredVolumes {
+		finalVolumes := getUnion(unusedVolumes, filteredVolumes)
+		if len(finalVolumes) < 1 {
+			fmt.Println("No unused volumes found")
+			return nil
+		}
+		for _, fv := range finalVolumes {
 			fmt.Println(fv.Name)
 		}
 		fmt.Print("Are you sure you want to continue? [y/N] ")
@@ -80,13 +98,23 @@ func prune(cmd *cobra.Command, args []string) error {
 			return nil
 		}
 	}
-	pruneOptions.Filters, err = filters.ParseFilterArgumentsIntoFilters(filter)
-	if err != nil {
-		return err
-	}
 	responses, err := registry.ContainerEngine().VolumePrune(context.Background(), pruneOptions)
 	if err != nil {
 		return err
 	}
 	return utils.PrintVolumePruneResults(responses, false)
 }
+
+func getUnion(a, b []*entities.VolumeListReport) []*entities.VolumeListReport {
+	var intersection []*entities.VolumeListReport
+	hash := make(map[string]bool, len(a))
+	for _, aa := range a {
+		hash[aa.Name] = true
+	}
+	for _, bb := range b {
+		if hash[bb.Name] {
+			intersection = append(intersection, bb)
+		}
+	}
+	return intersection
+}
diff --git a/pkg/domain/filters/volumes.go b/pkg/domain/filters/volumes.go
index 7890459f5d..87aa0f4c7d 100644
--- a/pkg/domain/filters/volumes.go
+++ b/pkg/domain/filters/volumes.go
@@ -85,6 +85,31 @@ func GenerateVolumeFilters(filters url.Values) ([]libpod.VolumeFilter, error) {
 					}
 					return dangling
 				})
+			case "unused":
+				invert := false
+				unusedVal := val
+				switch strings.ToLower(unusedVal) {
+				case "true", "1":
+					// do nth
+				case "false", "0":
+					invert = true
+
+				default:
+					return nil, errors.Errorf("%q is not a valid value for the \"unused\" filter - must be true or false", unusedVal)
+				}
+				vf = append(vf, func(v *libpod.Volume) bool {
+					resp, err := v.VolumeInUse()
+					if err != nil || len(resp) > 0 {
+						if !invert {
+							return false
+						}
+						return true
+					}
+					if !invert {
+						return true
+					}
+					return false
+				})
 			default:
 				return nil, errors.Errorf("%q is in an invalid volume filter", filter)
 			}