0270bec916
Several API tests were added to ensure correct acceptance of zero-size and empty tar files. This led to several changes in the storage backend around the guarantees of remote file reading, which backs the layer and layer upload type. In support of these changes, zero-length and empty checks have been added to the digest package. These provide a sanity check against upstream tarsum changes. The fileReader has been modified to be more robust when reading and seeking on zero-length or non-existent files. The file no longer needs to exist for the reader to be created. Seeks can now move beyond the end of the file, causing reads to issue an io.EOF. This eliminates errors during certain race conditions for reading files which should be detected by stat calls. As a part of this, a few error types were factored out and the read buffer size was increased to something more reasonable. Signed-off-by: Stephen J Day <stephen.day@docker.com>
89 lines
2.4 KiB
Go
89 lines
2.4 KiB
Go
package storage
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import (
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"fmt"
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"io"
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"time"
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"github.com/docker/distribution/digest"
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"github.com/docker/distribution/manifest"
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)
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// Layer provides a readable and seekable layer object. Typically,
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// implementations are *not* goroutine safe.
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type Layer interface {
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// http.ServeContent requires an efficient implementation of
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// ReadSeeker.Seek(0, os.SEEK_END).
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io.ReadSeeker
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io.Closer
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// Name returns the repository under which this layer is linked.
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Name() string // TODO(stevvooe): struggling with nomenclature: should this be "repo" or "name"?
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// Digest returns the unique digest of the blob, which is the tarsum for
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// layers.
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Digest() digest.Digest
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// CreatedAt returns the time this layer was created.
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CreatedAt() time.Time
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}
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// LayerUpload provides a handle for working with in-progress uploads.
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// Instances can be obtained from the LayerService.Upload and
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// LayerService.Resume.
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type LayerUpload interface {
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io.WriteSeeker
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io.Closer
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// Name of the repository under which the layer will be linked.
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Name() string
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// UUID returns the identifier for this upload.
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UUID() string
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// StartedAt returns the time this layer upload was started.
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StartedAt() time.Time
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// Finish marks the upload as completed, returning a valid handle to the
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// uploaded layer. The digest is validated against the contents of the
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// uploaded layer.
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Finish(digest digest.Digest) (Layer, error)
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// Cancel the layer upload process.
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Cancel() error
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}
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var (
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// ErrLayerExists returned when layer already exists
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ErrLayerExists = fmt.Errorf("layer exists")
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// ErrLayerTarSumVersionUnsupported when tarsum is unsupported version.
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ErrLayerTarSumVersionUnsupported = fmt.Errorf("unsupported tarsum version")
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// ErrLayerUploadUnknown returned when upload is not found.
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ErrLayerUploadUnknown = fmt.Errorf("layer upload unknown")
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// ErrLayerClosed returned when an operation is attempted on a closed
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// Layer or LayerUpload.
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ErrLayerClosed = fmt.Errorf("layer closed")
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)
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// ErrUnknownLayer returned when layer cannot be found.
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type ErrUnknownLayer struct {
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FSLayer manifest.FSLayer
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}
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func (err ErrUnknownLayer) Error() string {
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return fmt.Sprintf("unknown layer %v", err.FSLayer.BlobSum)
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}
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// ErrLayerInvalidDigest returned when tarsum check fails.
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type ErrLayerInvalidDigest struct {
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Digest digest.Digest
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Reason error
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}
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func (err ErrLayerInvalidDigest) Error() string {
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return fmt.Sprintf("invalid digest for referenced layer: %v, %v",
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err.Digest, err.Reason)
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}
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