mirror of https://github.com/perkeep/perkeep.git
105 lines
2.2 KiB
Go
105 lines
2.2 KiB
Go
/*
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Copyright 2011 Google Inc.
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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 blobref
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import (
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"crypto/sha1"
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"fmt"
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"hash"
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"io"
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"regexp"
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)
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var kBlobRefPattern *regexp.Regexp = regexp.MustCompile(`^([a-z0-9]+)-([a-f0-9]+)$`)
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var supportedDigests = map[string]func()hash.Hash{
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"sha1": func() hash.Hash {
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return sha1.New()
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},
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}
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type BlobRef struct {
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hashName string
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digest string
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}
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type ReadSeekCloser interface {
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io.Reader
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io.Seeker
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io.Closer
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}
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func (b *BlobRef) HashName() string {
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return b.hashName
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}
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func (b *BlobRef) Digest() string {
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return b.digest
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}
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func (o *BlobRef) String() string {
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return fmt.Sprintf("%s-%s", o.hashName, o.digest)
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}
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func (o *BlobRef) Hash() hash.Hash {
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fn, ok := supportedDigests[o.hashName]
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if !ok {
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return nil
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}
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return fn()
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}
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func (o *BlobRef) HashMatches(h hash.Hash) bool {
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return fmt.Sprintf("%x", h.Sum()) == o.digest
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}
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func (o *BlobRef) IsSupported() bool {
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_, ok := supportedDigests[o.hashName]
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return ok
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}
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var kExpectedDigestSize = map[string]int{
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"md5": 32,
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"sha1": 40,
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}
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func blobIfValid(hashname, digest string) *BlobRef {
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expectedSize := kExpectedDigestSize[hashname]
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if expectedSize != 0 && len(digest) != expectedSize {
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return nil
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}
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return &BlobRef{hashname, digest}
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}
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func FromHash(name string, h hash.Hash) *BlobRef {
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return &BlobRef{name, fmt.Sprintf("%x", h.Sum())}
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}
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// FromPattern takes a pattern and if it matches 's' with two exactly two valid
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// submatches, returns a BlobRef, else returns nil.
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func FromPattern(r *regexp.Regexp, s string) *BlobRef {
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matches := r.FindStringSubmatch(s)
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if len(matches) != 3 {
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return nil
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}
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return blobIfValid(matches[1], matches[2])
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}
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func Parse(ref string) *BlobRef {
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return FromPattern(kBlobRefPattern, ref)
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}
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