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oci.go
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oci.go
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package manifest
import (
"encoding/json"
"fmt"
"strings"
compressiontypes "github.com/containers/image/v5/pkg/compression/types"
"github.com/containers/image/v5/types"
ociencspec "github.com/containers/ocicrypt/spec"
"github.com/opencontainers/go-digest"
"github.com/opencontainers/image-spec/specs-go"
imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
)
// BlobInfoFromOCI1Descriptor returns a types.BlobInfo based on the input OCI1 descriptor.
func BlobInfoFromOCI1Descriptor(desc imgspecv1.Descriptor) types.BlobInfo {
return types.BlobInfo{
Digest: desc.Digest,
Size: desc.Size,
URLs: desc.URLs,
Annotations: desc.Annotations,
MediaType: desc.MediaType,
}
}
// OCI1 is a manifest.Manifest implementation for OCI images.
// The underlying data from imgspecv1.Manifest is also available.
type OCI1 struct {
imgspecv1.Manifest
}
// SupportedOCI1MediaType checks if the specified string is a supported OCI1
// media type.
//
// Deprecated: blindly rejecting unknown MIME types when the consumer does not
// need to process the input just reduces interoperability (and violates the
// standard) with no benefit, and that this function does not check that the
// media type is appropriate for any specific purpose, so it’s not all that
// useful for validation anyway.
func SupportedOCI1MediaType(m string) error {
switch m {
case imgspecv1.MediaTypeDescriptor, imgspecv1.MediaTypeImageConfig, imgspecv1.MediaTypeImageLayer, imgspecv1.MediaTypeImageLayerGzip, imgspecv1.MediaTypeImageLayerNonDistributable, imgspecv1.MediaTypeImageLayerNonDistributableGzip, imgspecv1.MediaTypeImageLayerNonDistributableZstd, imgspecv1.MediaTypeImageLayerZstd, imgspecv1.MediaTypeImageManifest, imgspecv1.MediaTypeLayoutHeader, ociencspec.MediaTypeLayerEnc, ociencspec.MediaTypeLayerGzipEnc:
return nil
default:
return fmt.Errorf("unsupported OCIv1 media type: %q", m)
}
}
// OCI1FromManifest creates an OCI1 manifest instance from a manifest blob.
func OCI1FromManifest(manifest []byte) (*OCI1, error) {
oci1 := OCI1{}
if err := json.Unmarshal(manifest, &oci1); err != nil {
return nil, err
}
if err := validateUnambiguousManifestFormat(manifest, imgspecv1.MediaTypeImageIndex,
allowedFieldConfig|allowedFieldLayers); err != nil {
return nil, err
}
return &oci1, nil
}
// OCI1FromComponents creates an OCI1 manifest instance from the supplied data.
func OCI1FromComponents(config imgspecv1.Descriptor, layers []imgspecv1.Descriptor) *OCI1 {
return &OCI1{
imgspecv1.Manifest{
Versioned: specs.Versioned{SchemaVersion: 2},
MediaType: imgspecv1.MediaTypeImageManifest,
Config: config,
Layers: layers,
},
}
}
// OCI1Clone creates a copy of the supplied OCI1 manifest.
func OCI1Clone(src *OCI1) *OCI1 {
return &OCI1{
Manifest: src.Manifest,
}
}
// ConfigInfo returns a complete BlobInfo for the separate config object, or a BlobInfo{Digest:""} if there isn't a separate object.
func (m *OCI1) ConfigInfo() types.BlobInfo {
return BlobInfoFromOCI1Descriptor(m.Config)
}
// LayerInfos returns a list of LayerInfos of layers referenced by this image, in order (the root layer first, and then successive layered layers).
// The Digest field is guaranteed to be provided; Size may be -1.
// WARNING: The list may contain duplicates, and they are semantically relevant.
func (m *OCI1) LayerInfos() []LayerInfo {
blobs := []LayerInfo{}
for _, layer := range m.Layers {
blobs = append(blobs, LayerInfo{
BlobInfo: BlobInfoFromOCI1Descriptor(layer),
EmptyLayer: false,
})
}
return blobs
}
var oci1CompressionMIMETypeSets = []compressionMIMETypeSet{
{
mtsUncompressed: imgspecv1.MediaTypeImageLayerNonDistributable,
compressiontypes.GzipAlgorithmName: imgspecv1.MediaTypeImageLayerNonDistributableGzip,
compressiontypes.ZstdAlgorithmName: imgspecv1.MediaTypeImageLayerNonDistributableZstd,
},
{
mtsUncompressed: imgspecv1.MediaTypeImageLayer,
compressiontypes.GzipAlgorithmName: imgspecv1.MediaTypeImageLayerGzip,
compressiontypes.ZstdAlgorithmName: imgspecv1.MediaTypeImageLayerZstd,
},
}
// UpdateLayerInfos replaces the original layers with the specified BlobInfos (size+digest+urls+mediatype), in order (the root layer first, and then successive layered layers)
// The returned error will be a manifest.ManifestLayerCompressionIncompatibilityError if any of the layerInfos includes a combination of CompressionOperation and
// CompressionAlgorithm that isn't supported by OCI.
func (m *OCI1) UpdateLayerInfos(layerInfos []types.BlobInfo) error {
if len(m.Layers) != len(layerInfos) {
return errors.Errorf("Error preparing updated manifest: layer count changed from %d to %d", len(m.Layers), len(layerInfos))
}
original := m.Layers
m.Layers = make([]imgspecv1.Descriptor, len(layerInfos))
for i, info := range layerInfos {
mimeType := original[i].MediaType
if info.CryptoOperation == types.Decrypt {
decMimeType, err := getDecryptedMediaType(mimeType)
if err != nil {
return fmt.Errorf("error preparing updated manifest: decryption specified but original mediatype is not encrypted: %q", mimeType)
}
mimeType = decMimeType
}
mimeType, err := updatedMIMEType(oci1CompressionMIMETypeSets, mimeType, info)
if err != nil {
return errors.Wrapf(err, "preparing updated manifest, layer %q", info.Digest)
}
if info.CryptoOperation == types.Encrypt {
encMediaType, err := getEncryptedMediaType(mimeType)
if err != nil {
return fmt.Errorf("error preparing updated manifest: encryption specified but no counterpart for mediatype: %q", mimeType)
}
mimeType = encMediaType
}
m.Layers[i].MediaType = mimeType
m.Layers[i].Digest = info.Digest
m.Layers[i].Size = info.Size
m.Layers[i].Annotations = info.Annotations
m.Layers[i].URLs = info.URLs
}
return nil
}
// Serialize returns the manifest in a blob format.
// NOTE: Serialize() does not in general reproduce the original blob if this object was loaded from one, even if no modifications were made!
func (m *OCI1) Serialize() ([]byte, error) {
return json.Marshal(*m)
}
// Inspect returns various information for (skopeo inspect) parsed from the manifest and configuration.
func (m *OCI1) Inspect(configGetter func(types.BlobInfo) ([]byte, error)) (*types.ImageInspectInfo, error) {
config, err := configGetter(m.ConfigInfo())
if err != nil {
return nil, err
}
v1 := &imgspecv1.Image{}
if err := json.Unmarshal(config, v1); err != nil {
return nil, err
}
d1 := &Schema2V1Image{}
if err := json.Unmarshal(config, d1); err != nil {
return nil, err
}
i := &types.ImageInspectInfo{
Tag: "",
Created: v1.Created,
DockerVersion: d1.DockerVersion,
Labels: v1.Config.Labels,
Architecture: v1.Architecture,
Os: v1.OS,
Layers: layerInfosToStrings(m.LayerInfos()),
Env: v1.Config.Env,
}
return i, nil
}
// ImageID computes an ID which can uniquely identify this image by its contents.
func (m *OCI1) ImageID([]digest.Digest) (string, error) {
if err := m.Config.Digest.Validate(); err != nil {
return "", err
}
return m.Config.Digest.Hex(), nil
}
// getEncryptedMediaType will return the mediatype to its encrypted counterpart and return
// an error if the mediatype does not support encryption
func getEncryptedMediaType(mediatype string) (string, error) {
for _, s := range strings.Split(mediatype, "+")[1:] {
if s == "encrypted" {
return "", errors.Errorf("unsupportedmediatype: %v already encrypted", mediatype)
}
}
unsuffixedMediatype := strings.Split(mediatype, "+")[0]
switch unsuffixedMediatype {
case DockerV2Schema2LayerMediaType, imgspecv1.MediaTypeImageLayer, imgspecv1.MediaTypeImageLayerNonDistributable:
return mediatype + "+encrypted", nil
}
return "", errors.Errorf("unsupported mediatype to encrypt: %v", mediatype)
}
// getEncryptedMediaType will return the mediatype to its encrypted counterpart and return
// an error if the mediatype does not support decryption
func getDecryptedMediaType(mediatype string) (string, error) {
if !strings.HasSuffix(mediatype, "+encrypted") {
return "", errors.Errorf("unsupported mediatype to decrypt %v:", mediatype)
}
return strings.TrimSuffix(mediatype, "+encrypted"), nil
}