package layer // import "github.com/docker/docker/layer" import ( "fmt" "io" "github.com/docker/distribution" "github.com/opencontainers/go-digest" ) type roLayer struct { chainID ChainID diffID DiffID parent *roLayer cacheID string size int64 layerStore *layerStore descriptor distribution.Descriptor referenceCount int references map[Layer]struct{} } // TarStream for roLayer guarantees that the data that is produced is the exact // data that the layer was registered with. func (rl *roLayer) TarStream() (io.ReadCloser, error) { rc, err := rl.layerStore.getTarStream(rl) if err != nil { return nil, err } vrc, err := newVerifiedReadCloser(rc, digest.Digest(rl.diffID)) if err != nil { return nil, err } return vrc, nil } // TarStreamFrom does not make any guarantees to the correctness of the produced // data. As such it should not be used when the layer content must be verified // to be an exact match to the registered layer. func (rl *roLayer) TarStreamFrom(parent ChainID) (io.ReadCloser, error) { var parentCacheID string for pl := rl.parent; pl != nil; pl = pl.parent { if pl.chainID == parent { parentCacheID = pl.cacheID break } } if parent != ChainID("") && parentCacheID == "" { return nil, fmt.Errorf("layer ID '%s' is not a parent of the specified layer: cannot provide diff to non-parent", parent) } return rl.layerStore.driver.Diff(rl.cacheID, parentCacheID) } func (rl *roLayer) ChainID() ChainID { return rl.chainID } func (rl *roLayer) DiffID() DiffID { return rl.diffID } func (rl *roLayer) Parent() Layer { if rl.parent == nil { return nil } return rl.parent } func (rl *roLayer) Size() (size int64, err error) { if rl.parent != nil { size, err = rl.parent.Size() if err != nil { return } } return size + rl.size, nil } func (rl *roLayer) DiffSize() (size int64, err error) { return rl.size, nil } func (rl *roLayer) Metadata() (map[string]string, error) { return rl.layerStore.driver.GetMetadata(rl.cacheID) } type referencedCacheLayer struct { *roLayer } func (rl *roLayer) getReference() Layer { ref := &referencedCacheLayer{ roLayer: rl, } rl.references[ref] = struct{}{} return ref } func (rl *roLayer) hasReference(ref Layer) bool { _, ok := rl.references[ref] return ok } func (rl *roLayer) hasReferences() bool { return len(rl.references) > 0 } func (rl *roLayer) deleteReference(ref Layer) { delete(rl.references, ref) } func (rl *roLayer) depth() int { if rl.parent == nil { return 1 } return rl.parent.depth() + 1 } func storeLayer(tx *fileMetadataTransaction, layer *roLayer) error { if err := tx.SetDiffID(layer.diffID); err != nil { return err } if err := tx.SetSize(layer.size); err != nil { return err } if err := tx.SetCacheID(layer.cacheID); err != nil { return err } // Do not store empty descriptors if layer.descriptor.Digest != "" { if err := tx.SetDescriptor(layer.descriptor); err != nil { return err } } if layer.parent != nil { if err := tx.SetParent(layer.parent.chainID); err != nil { return err } } return tx.setOS(layer.layerStore.os) } func newVerifiedReadCloser(rc io.ReadCloser, dgst digest.Digest) (io.ReadCloser, error) { return &verifiedReadCloser{ rc: rc, dgst: dgst, verifier: dgst.Verifier(), }, nil } type verifiedReadCloser struct { rc io.ReadCloser dgst digest.Digest verifier digest.Verifier } func (vrc *verifiedReadCloser) Read(p []byte) (n int, err error) { n, err = vrc.rc.Read(p) if n > 0 { if n, err := vrc.verifier.Write(p[:n]); err != nil { return n, err } } if err == io.EOF { if !vrc.verifier.Verified() { err = fmt.Errorf("could not verify layer data for: %s. This may be because internal files in the layer store were modified. Re-pulling or rebuilding this image may resolve the issue", vrc.dgst) } } return } func (vrc *verifiedReadCloser) Close() error { return vrc.rc.Close() }