writer.go

Documentation: cuelabs.dev/go/oci/ociregistry/ocimem

     1  // Copyright 2023 CUE Labs AG
     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 ocimem
    16  
    17  import (
    18  	"context"
    19  	"fmt"
    20  	"io"
    21  
    22  	"cuelabs.dev/go/oci/ociregistry"
    23  	"github.com/opencontainers/go-digest"
    24  )
    25  
    26  // This file implements the ociregistry.Writer methods.
    27  
    28  func (r *Registry) PushBlob(ctx context.Context, repoName string, desc ociregistry.Descriptor, content io.Reader) (ociregistry.Descriptor, error) {
    29  	data, err := io.ReadAll(content)
    30  	if err != nil {
    31  		return ociregistry.Descriptor{}, fmt.Errorf("cannot read content: %v", err)
    32  	}
    33  	if err := CheckDescriptor(desc, data); err != nil {
    34  		return ociregistry.Descriptor{}, fmt.Errorf("invalid descriptor: %v", err)
    35  	}
    36  
    37  	r.mu.Lock()
    38  	defer r.mu.Unlock()
    39  	repo, err := r.makeRepo(repoName)
    40  	if err != nil {
    41  		return ociregistry.Descriptor{}, err
    42  	}
    43  	repo.blobs[desc.Digest] = &blob{mediaType: desc.MediaType, data: data}
    44  	return desc, nil
    45  }
    46  
    47  func (r *Registry) PushBlobChunked(ctx context.Context, repoName string, chunkSize int) (ociregistry.BlobWriter, error) {
    48  	// TODO(mvdan): Why does the ocimem implementation allow a PATCH on an upload ID which doesn't exist?
    49  	// The tests in ociserver make this assumption, so they break without this bit of code.
    50  	//
    51  	// Ideally they should start a new chunked upload to get a new ID, then use that for PATCH/PUT.
    52  	// Alternatively, add a new method to ocimem outside of the interface to start a chunked upload with a predefined ID.
    53  	// Either way, this case should be an error, per the spec.
    54  	return r.PushBlobChunkedResume(ctx, repoName, "", 0, chunkSize)
    55  }
    56  
    57  func (r *Registry) PushBlobChunkedResume(ctx context.Context, repoName, id string, offset int64, chunkSize int) (ociregistry.BlobWriter, error) {
    58  	r.mu.Lock()
    59  	defer r.mu.Unlock()
    60  	repo, err := r.makeRepo(repoName)
    61  	if err != nil {
    62  		return nil, err
    63  	}
    64  	b := repo.uploads[id]
    65  	if b == nil {
    66  		b = NewBuffer(func(b *Buffer) error {
    67  			r.mu.Lock()
    68  			defer r.mu.Unlock()
    69  			desc, data, _ := b.GetBlob()
    70  			repo.blobs[desc.Digest] = &blob{mediaType: desc.MediaType, data: data}
    71  			return nil
    72  		}, id)
    73  		repo.uploads[b.ID()] = b
    74  	}
    75  	b.checkStartOffset = offset
    76  	return b, nil
    77  }
    78  
    79  func (r *Registry) MountBlob(ctx context.Context, fromRepo, toRepo string, dig ociregistry.Digest) (ociregistry.Descriptor, error) {
    80  	r.mu.Lock()
    81  	defer r.mu.Unlock()
    82  	rto, err := r.makeRepo(toRepo)
    83  	if err != nil {
    84  		return ociregistry.Descriptor{}, err
    85  	}
    86  	b, err := r.blobForDigest(fromRepo, dig)
    87  	if err != nil {
    88  		return ociregistry.Descriptor{}, err
    89  	}
    90  	rto.blobs[dig] = b
    91  	return b.descriptor(), nil
    92  }
    93  
    94  var errCannotOverwriteTag = fmt.Errorf("%w: cannot overwrite tag", ociregistry.ErrDenied)
    95  
    96  func (r *Registry) PushManifest(ctx context.Context, repoName string, tag string, data []byte, mediaType string) (ociregistry.Descriptor, error) {
    97  	r.mu.Lock()
    98  	defer r.mu.Unlock()
    99  	repo, err := r.makeRepo(repoName)
   100  	if err != nil {
   101  		return ociregistry.Descriptor{}, err
   102  	}
   103  	dig := digest.FromBytes(data)
   104  	desc := ociregistry.Descriptor{
   105  		Digest:    dig,
   106  		MediaType: mediaType,
   107  		Size:      int64(len(data)),
   108  	}
   109  	if tag != "" {
   110  		if !ociregistry.IsValidTag(tag) {
   111  			return ociregistry.Descriptor{}, fmt.Errorf("invalid tag")
   112  		}
   113  		if r.cfg.ImmutableTags {
   114  			if currDesc, ok := repo.tags[tag]; ok {
   115  				if dig == currDesc.Digest {
   116  					if currDesc.MediaType != mediaType {
   117  						// Same digest but mismatched media type.
   118  						return ociregistry.Descriptor{}, fmt.Errorf("%w: mismatched media type", ociregistry.ErrDenied)
   119  					}
   120  					// It's got the same content already. Allow it.
   121  					return currDesc, nil
   122  				}
   123  				return ociregistry.Descriptor{}, errCannotOverwriteTag
   124  			}
   125  		}
   126  	}
   127  	// make a copy of the data to avoid potential corruption.
   128  	data = append([]byte(nil), data...)
   129  	if err := CheckDescriptor(desc, data); err != nil {
   130  		return ociregistry.Descriptor{}, fmt.Errorf("invalid descriptor: %v", err)
   131  	}
   132  	subject, err := r.checkManifest(repoName, desc.MediaType, data)
   133  	if err != nil {
   134  		return ociregistry.Descriptor{}, fmt.Errorf("invalid manifest: %v", err)
   135  	}
   136  
   137  	repo.manifests[dig] = &blob{
   138  		mediaType: mediaType,
   139  		data:      data,
   140  		subject:   subject,
   141  	}
   142  	if tag != "" {
   143  		repo.tags[tag] = desc
   144  	}
   145  	return desc, nil
   146  }
   147  
   148  func (r *Registry) checkManifest(repoName string, mediaType string, data []byte) (subject ociregistry.Digest, retErr error) {
   149  	repo, err := r.repo(repoName)
   150  	if err != nil {
   151  		return "", err
   152  	}
   153  	iter, err := manifestReferences(mediaType, data)
   154  	if err != nil {
   155  		// TODO decide what to do about errUnknownManifestMediaTypeForIteration
   156  		return "", err
   157  	}
   158  	iter(func(info descInfo) bool {
   159  		if err := CheckDescriptor(info.desc, nil); err != nil {
   160  			retErr = fmt.Errorf("bad descriptor in %s: %v", info.name, err)
   161  			return false
   162  		}
   163  		switch info.kind {
   164  		case kindBlob:
   165  			if repo.blobs[info.desc.Digest] == nil {
   166  				retErr = fmt.Errorf("blob for %s not found", info.name)
   167  				return false
   168  			}
   169  		case kindManifest:
   170  			if repo.manifests[info.desc.Digest] == nil {
   171  				retErr = fmt.Errorf("manifest for %s not found", info.name)
   172  				return false
   173  			}
   174  		case kindSubjectManifest:
   175  			subject = info.desc.Digest
   176  			// The standard explicitly specifies that we can have
   177  			// a dangling subject so don't check that it exists.
   178  		}
   179  		return true
   180  	})
   181  	return subject, retErr
   182  }
   183  
   184  // refersTo reports whether the given digest is referred to, directly or indirectly, by any item
   185  // returned by the given iterator, within the given repository.
   186  // TODO currently this iterates through all tagged manifests. A better
   187  // algorithm could amortise that work and be considerably more efficient.
   188  func refersTo(repo *repository, iter descIter, digest ociregistry.Digest) (found bool, retErr error) {
   189  	iter(func(info descInfo) bool {
   190  		if info.desc.Digest == digest {
   191  			found = true
   192  			return false
   193  		}
   194  		switch info.kind {
   195  		case kindManifest, kindSubjectManifest:
   196  			b := repo.manifests[info.desc.Digest]
   197  			if b == nil {
   198  				break
   199  			}
   200  			miter, err := manifestReferences(info.desc.MediaType, b.data)
   201  			if err != nil {
   202  				retErr = err
   203  				return false
   204  			}
   205  			found, retErr = refersTo(repo, miter, digest)
   206  			if found || retErr != nil {
   207  				return false
   208  			}
   209  		}
   210  		return true
   211  	})
   212  	return found, retErr
   213  }
   214
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