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|
package layer // import "github.com/docker/docker/layer"
import (
"fmt"
"io"
"github.com/docker/distribution"
digest "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) CacheID() string {
return rl.cacheID
}
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()
}
|
