72 lines
1.9 KiB
Go
72 lines
1.9 KiB
Go
/*
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Copyright 2022 The Flux 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 digest
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import (
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"fmt"
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"io"
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"github.com/opencontainers/go-digest"
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)
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// MultiDigester is a digester that writes to multiple digesters to calculate
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// the checksum of different algorithms.
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type MultiDigester struct {
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d map[digest.Algorithm]digest.Digester
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}
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// NewMultiDigester returns a new MultiDigester that writes to newly
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// initialized digesters for the given algorithms. If a provided algorithm is
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// not available, it returns a digest.ErrDigestUnsupported error.
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func NewMultiDigester(algos ...digest.Algorithm) (*MultiDigester, error) {
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d := make(map[digest.Algorithm]digest.Digester, len(algos))
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for _, a := range algos {
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if _, ok := d[a]; ok {
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continue
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}
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if !a.Available() {
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return nil, fmt.Errorf("%w: %s", digest.ErrDigestUnsupported, a)
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}
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d[a] = a.Digester()
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}
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return &MultiDigester{d: d}, nil
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}
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// Write writes p to all underlying digesters.
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func (w *MultiDigester) Write(p []byte) (n int, err error) {
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for _, d := range w.d {
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n, err = d.Hash().Write(p)
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if err != nil {
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return
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}
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if n != len(p) {
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err = io.ErrShortWrite
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return
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}
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}
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return len(p), nil
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}
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// Digest returns the digest of the data written to the digester of the given
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// algorithm, or an empty digest if the algorithm is not available.
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func (w *MultiDigester) Digest(algo digest.Algorithm) digest.Digest {
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if d, ok := w.d[algo]; ok {
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return d.Digest()
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}
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return ""
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}
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