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81 lines
2.3 KiB
Go
81 lines
2.3 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package images
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import (
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"compress/gzip"
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"context"
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"io"
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"github.com/containerd/containerd/content"
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"github.com/containerd/containerd/labels"
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"github.com/opencontainers/go-digest"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/sirupsen/logrus"
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)
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// GetDiffID gets the diff ID of the layer blob descriptor.
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func GetDiffID(ctx context.Context, cs content.Store, desc ocispec.Descriptor) (digest.Digest, error) {
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switch desc.MediaType {
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case
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// If the layer is already uncompressed, we can just return its digest
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MediaTypeDockerSchema2Layer,
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ocispec.MediaTypeImageLayer,
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MediaTypeDockerSchema2LayerForeign,
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ocispec.MediaTypeImageLayerNonDistributable:
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return desc.Digest, nil
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}
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info, err := cs.Info(ctx, desc.Digest)
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if err != nil {
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return "", err
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}
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v, ok := info.Labels[labels.LabelUncompressed]
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if ok {
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// Fast path: if the image is already unpacked, we can use the label value
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return digest.Parse(v)
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}
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// if the image is not unpacked, we may not have the label
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ra, err := cs.ReaderAt(ctx, desc)
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if err != nil {
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return "", err
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}
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defer ra.Close()
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r := content.NewReader(ra)
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gzR, err := gzip.NewReader(r)
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if err != nil {
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return "", err
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}
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digester := digest.Canonical.Digester()
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hashW := digester.Hash()
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if _, err := io.Copy(hashW, gzR); err != nil {
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return "", err
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}
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if err := ra.Close(); err != nil {
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return "", err
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}
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digest := digester.Digest()
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// memorize the computed value
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if info.Labels == nil {
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info.Labels = make(map[string]string)
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}
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info.Labels[labels.LabelUncompressed] = digest.String()
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if _, err := cs.Update(ctx, info, "labels"); err != nil {
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logrus.WithError(err).Warnf("failed to set %s label for %s", labels.LabelUncompressed, desc.Digest)
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}
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return digest, nil
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}
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