image prune: remove unused images only with `--all`

Fix a regression in `podman image prune` where unused images were
accidentally removed even when `--all=false`.  Extend and partially
rewrite the e2e tests to make sure we're not regressing again in the
future.

Fixing the aforementioned issue revealed another issue in the default
prune filter.  While prune should remove all "dangling" images (i.e.,
those without tag), it removed only "intermediate" ones; dangling images
without children.  Remove the mistaken comment from the libimage
migration.

Also clarify the help message and man page.

Fixes: #10350
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

1 files changed, 7 insertions, 23 deletions

diff --git a/pkg/domain/infra/abi/images.go b/pkg/domain/infra/abi/images.go
index 0364b00a3..79e815490 100644
--- a/pkg/domain/infra/abi/images.go
+++ b/pkg/domain/infra/abi/images.go
@@ -40,25 +40,13 @@ func (ir *ImageEngine) Exists(_ context.Context, nameOrID string) (*entities.Boo
 }
 
 func (ir *ImageEngine) Prune(ctx context.Context, opts entities.ImagePruneOptions) ([]*reports.PruneReport, error) {
-	// NOTE: the terms "dangling" and "intermediate" are not used
-	// consistently across our code base.  In libimage, "dangling" means
-	// that an image has no tags.  "intermediate" means that an image is
-	// dangling and that no other image depends on it (i.e., has no
-	// children).
-	//
-	// While pruning usually refers to "dangling" images, it has always
-	// removed "intermediate" ones.
-	defaultOptions := &libimage.RemoveImagesOptions{
-		Filters:  append(opts.Filter, "intermediate=true", "containers=false", "readonly=false"),
+	pruneOptions := &libimage.RemoveImagesOptions{
+		Filters:  append(opts.Filter, "containers=false", "readonly=false"),
 		WithSize: true,
 	}
 
-	// `image prune --all` means to *also* remove images which are not in
-	// use by any container.  Since image filters are chained, we need to
-	// do two look ups since the default ones are a subset of all.
-	unusedOptions := &libimage.RemoveImagesOptions{
-		Filters:  append(opts.Filter, "containers=false", "readonly=false"),
-		WithSize: true,
+	if !opts.All {
+		pruneOptions.Filters = append(pruneOptions.Filters, "dangling=true")
 	}
 
 	var pruneReports []*reports.PruneReport
@@ -66,16 +54,12 @@ func (ir *ImageEngine) Prune(ctx context.Context, opts entities.ImagePruneOption
 	// Now prune all images until we converge.
 	numPreviouslyRemovedImages := 1
 	for {
-		removedDefault, rmErrors := ir.Libpod.LibimageRuntime().RemoveImages(ctx, nil, defaultOptions)
-		if rmErrors != nil {
-			return nil, errorhandling.JoinErrors(rmErrors)
-		}
-		removedUnused, rmErrors := ir.Libpod.LibimageRuntime().RemoveImages(ctx, nil, unusedOptions)
+		removedImages, rmErrors := ir.Libpod.LibimageRuntime().RemoveImages(ctx, nil, pruneOptions)
 		if rmErrors != nil {
 			return nil, errorhandling.JoinErrors(rmErrors)
 		}
 
-		for _, rmReport := range append(removedDefault, removedUnused...) {
+		for _, rmReport := range removedImages {
 			r := *rmReport
 			pruneReports = append(pruneReports, &reports.PruneReport{
 				Id:   r.ID,
@@ -83,7 +67,7 @@ func (ir *ImageEngine) Prune(ctx context.Context, opts entities.ImagePruneOption
 			})
 		}
 
-		numRemovedImages := len(removedDefault) + len(removedUnused)
+		numRemovedImages := len(removedImages)
 		if numRemovedImages+numPreviouslyRemovedImages == 0 {
 			break
 		}