digest.go

Documentation: github.com/google/go-containerregistry/pkg/name

     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 name
    16  
    17  import (
    18  	// nolint: depguard
    19  	_ "crypto/sha256" // Recommended by go-digest.
    20  	"strings"
    21  
    22  	"github.com/opencontainers/go-digest"
    23  )
    24  
    25  const digestDelim = "@"
    26  
    27  // Digest stores a digest name in a structured form.
    28  type Digest struct {
    29  	Repository
    30  	digest   string
    31  	original string
    32  }
    33  
    34  // Ensure Digest implements Reference
    35  var _ Reference = (*Digest)(nil)
    36  
    37  // Context implements Reference.
    38  func (d Digest) Context() Repository {
    39  	return d.Repository
    40  }
    41  
    42  // Identifier implements Reference.
    43  func (d Digest) Identifier() string {
    44  	return d.DigestStr()
    45  }
    46  
    47  // DigestStr returns the digest component of the Digest.
    48  func (d Digest) DigestStr() string {
    49  	return d.digest
    50  }
    51  
    52  // Name returns the name from which the Digest was derived.
    53  func (d Digest) Name() string {
    54  	return d.Repository.Name() + digestDelim + d.DigestStr()
    55  }
    56  
    57  // String returns the original input string.
    58  func (d Digest) String() string {
    59  	return d.original
    60  }
    61  
    62  // NewDigest returns a new Digest representing the given name.
    63  func NewDigest(name string, opts ...Option) (Digest, error) {
    64  	// Split on "@"
    65  	parts := strings.Split(name, digestDelim)
    66  	if len(parts) != 2 {
    67  		return Digest{}, newErrBadName("a digest must contain exactly one '@' separator (e.g. registry/repository@digest) saw: %s", name)
    68  	}
    69  	base := parts[0]
    70  	dig := parts[1]
    71  	prefix := digest.Canonical.String() + ":"
    72  	if !strings.HasPrefix(dig, prefix) {
    73  		return Digest{}, newErrBadName("unsupported digest algorithm: %s", dig)
    74  	}
    75  	hex := strings.TrimPrefix(dig, prefix)
    76  	if err := digest.Canonical.Validate(hex); err != nil {
    77  		return Digest{}, err
    78  	}
    79  
    80  	tag, err := NewTag(base, opts...)
    81  	if err == nil {
    82  		base = tag.Repository.Name()
    83  	}
    84  
    85  	repo, err := NewRepository(base, opts...)
    86  	if err != nil {
    87  		return Digest{}, err
    88  	}
    89  	return Digest{
    90  		Repository: repo,
    91  		digest:     dig,
    92  		original:   name,
    93  	}, nil
    94  }
    95
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