image.go

Documentation: github.com/google/go-containerregistry/pkg/v1/layout

     1  // Copyright 2018 Google LLC All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //    http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package layout
    16  
    17  import (
    18  	"fmt"
    19  	"io"
    20  	"os"
    21  	"sync"
    22  
    23  	v1 "github.com/google/go-containerregistry/pkg/v1"
    24  	"github.com/google/go-containerregistry/pkg/v1/partial"
    25  	"github.com/google/go-containerregistry/pkg/v1/types"
    26  )
    27  
    28  type layoutImage struct {
    29  	path         Path
    30  	desc         v1.Descriptor
    31  	manifestLock sync.Mutex // Protects rawManifest
    32  	rawManifest  []byte
    33  }
    34  
    35  var _ partial.CompressedImageCore = (*layoutImage)(nil)
    36  
    37  // Image reads a v1.Image with digest h from the Path.
    38  func (l Path) Image(h v1.Hash) (v1.Image, error) {
    39  	ii, err := l.ImageIndex()
    40  	if err != nil {
    41  		return nil, err
    42  	}
    43  
    44  	return ii.Image(h)
    45  }
    46  
    47  func (li *layoutImage) MediaType() (types.MediaType, error) {
    48  	return li.desc.MediaType, nil
    49  }
    50  
    51  // Implements WithManifest for partial.Blobset.
    52  func (li *layoutImage) Manifest() (*v1.Manifest, error) {
    53  	return partial.Manifest(li)
    54  }
    55  
    56  func (li *layoutImage) RawManifest() ([]byte, error) {
    57  	li.manifestLock.Lock()
    58  	defer li.manifestLock.Unlock()
    59  	if li.rawManifest != nil {
    60  		return li.rawManifest, nil
    61  	}
    62  
    63  	b, err := li.path.Bytes(li.desc.Digest)
    64  	if err != nil {
    65  		return nil, err
    66  	}
    67  
    68  	li.rawManifest = b
    69  	return li.rawManifest, nil
    70  }
    71  
    72  func (li *layoutImage) RawConfigFile() ([]byte, error) {
    73  	manifest, err := li.Manifest()
    74  	if err != nil {
    75  		return nil, err
    76  	}
    77  
    78  	return li.path.Bytes(manifest.Config.Digest)
    79  }
    80  
    81  func (li *layoutImage) LayerByDigest(h v1.Hash) (partial.CompressedLayer, error) {
    82  	manifest, err := li.Manifest()
    83  	if err != nil {
    84  		return nil, err
    85  	}
    86  
    87  	if h == manifest.Config.Digest {
    88  		return &compressedBlob{
    89  			path: li.path,
    90  			desc: manifest.Config,
    91  		}, nil
    92  	}
    93  
    94  	for _, desc := range manifest.Layers {
    95  		if h == desc.Digest {
    96  			return &compressedBlob{
    97  				path: li.path,
    98  				desc: desc,
    99  			}, nil
   100  		}
   101  	}
   102  
   103  	return nil, fmt.Errorf("could not find layer in image: %s", h)
   104  }
   105  
   106  type compressedBlob struct {
   107  	path Path
   108  	desc v1.Descriptor
   109  }
   110  
   111  func (b *compressedBlob) Digest() (v1.Hash, error) {
   112  	return b.desc.Digest, nil
   113  }
   114  
   115  func (b *compressedBlob) Compressed() (io.ReadCloser, error) {
   116  	return b.path.Blob(b.desc.Digest)
   117  }
   118  
   119  func (b *compressedBlob) Size() (int64, error) {
   120  	return b.desc.Size, nil
   121  }
   122  
   123  func (b *compressedBlob) MediaType() (types.MediaType, error) {
   124  	return b.desc.MediaType, nil
   125  }
   126  
   127  // Descriptor implements partial.withDescriptor.
   128  func (b *compressedBlob) Descriptor() (*v1.Descriptor, error) {
   129  	return &b.desc, nil
   130  }
   131  
   132  // See partial.Exists.
   133  func (b *compressedBlob) Exists() (bool, error) {
   134  	_, err := os.Stat(b.path.blobPath(b.desc.Digest))
   135  	if os.IsNotExist(err) {
   136  		return false, nil
   137  	}
   138  	return err == nil, err
   139  }
   140
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