layer tree: handle more errors

Commit 97961a6 took a first stab at making operating on the layer
tree more resilient by detecting unknown-image errors.  Testing in
containers/podman/pull/18980 revealed that we also need to detect
unknown-layer and -size errors as well.

Move the errors checks into a convenience function and update the
relevant call sites to facilitate future changes.

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

libimage/layer_tree.go

@@ -5,6 +5,7 @@ import (
  "errors"
 
  "github.com/containers/storage"
+ storageTypes "github.com/containers/storage/types"
  ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
  "github.com/sirupsen/logrus"
 )
@@ -31,10 +32,19 @@ func (t *layerTree) node(layerID string) *layerNode {
  return node
 }
 
+// errorImageIsRemoved returns true if the specified error indicates that an
+// image is unknown or has been partially removed (e.g., a missing layer).
+func errorImageIsRemoved(err error) bool {
+ return errors.Is(err, storage.ErrImageUnknown) ||
+ errors.Is(err, storageTypes.ErrLayerUnknown) ||
+ errors.Is(err, storageTypes.ErrSizeUnknown)
+}
+
 // toOCI returns an OCI image for the specified image.
 //
 // WARNING: callers are responsible for handling cases where the target image
-// has been removed and need to check for `storage.ErrImageUnknown`.
+// has been (partially) removed and can use `errorImageIsRemoved()` to detect
+// it.
 func (t *layerTree) toOCI(ctx context.Context, i *Image) (*ociv1.Image, error) {
  var err error
  oci, exists := t.ociCache[i.ID()]
@@ -159,7 +169,7 @@ func (t *layerTree) children(ctx context.Context, parent *Image, all bool) ([]*I
  parentID := parent.ID()
  parentOCI, err := t.toOCI(ctx, parent)
  if err != nil {
- if errors.Is(err, storage.ErrImageUnknown) {
+ if errorImageIsRemoved(err) {
  return nil, nil
  }
  return nil, err
@@ -172,7 +182,7 @@ func (t *layerTree) children(ctx context.Context, parent *Image, all bool) ([]*I
  }
  childOCI, err := t.toOCI(ctx, child)
  if err != nil {
- if errors.Is(err, storage.ErrImageUnknown) {
+ if errorImageIsRemoved(err) {
  return false, nil
  }
  return false, err
@@ -265,7 +275,7 @@ func (t *layerTree) parent(ctx context.Context, child *Image) (*Image, error) {
  childID := child.ID()
  childOCI, err := t.toOCI(ctx, child)
  if err != nil {
- if errors.Is(err, storage.ErrImageUnknown) {
+ if errorImageIsRemoved(err) {
  return nil, nil
  }
  return nil, err
@@ -281,7 +291,7 @@ func (t *layerTree) parent(ctx context.Context, child *Image) (*Image, error) {
  }
  emptyOCI, err := t.toOCI(ctx, empty)
  if err != nil {
- if errors.Is(err, storage.ErrImageUnknown) {
+ if errorImageIsRemoved(err) {
  return nil, nil
  }
  return nil, err
@@ -316,7 +326,7 @@ func (t *layerTree) parent(ctx context.Context, child *Image) (*Image, error) {
  }
  parentOCI, err := t.toOCI(ctx, parent)
  if err != nil {
- if errors.Is(err, storage.ErrImageUnknown) {
+ if errorImageIsRemoved(err) {
  return nil, nil
  }
  return nil, err

libimage/runtime.go

@@ -584,8 +584,10 @@ func (r *Runtime) ListImages(ctx context.Context, names []string, options *ListI
 
  tree, err := r.layerTree(images)
  if err != nil {
+ logrus.Errorf("Layer tree!")
  return nil, err
  }
+ logrus.Errorf("Not Layer tree!")
 
  for i := range filtered {
  isDangling, err := filtered[i].isDangling(ctx, tree)