60 lines
1.6 KiB
Go
60 lines
1.6 KiB
Go
package storage
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import (
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"fmt"
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"hash"
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"strings"
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)
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// Digest allows simple protection of hex formatted digest strings, prefixed
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// by their algorithm. Strings of type Digest have some guarantee of being in
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// the correct format and it provides quick access to the components of a
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// digest string.
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//
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// The following is an example of the contents of Digest types:
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//
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// sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
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//
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type Digest string
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// NewDigest returns a Digest from alg and a hash.Hash object.
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func NewDigest(alg string, h hash.Hash) Digest {
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return Digest(fmt.Sprintf("%s:%x", alg, h.Sum(nil)))
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}
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var (
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// ErrDigestInvalidFormat returned when digest format invalid.
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ErrDigestInvalidFormat = fmt.Errorf("invalid checksum digest format")
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// ErrDigestUnsupported returned when the digest algorithm is unsupported by registry.
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ErrDigestUnsupported = fmt.Errorf("unsupported digest algorithm")
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)
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// ParseDigest parses s and returns the validated digest object. An error will
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// be returned if the format is invalid.
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func ParseDigest(s string) (Digest, error) {
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parts := strings.SplitN(s, ":", 2)
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if len(parts) != 2 {
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return "", ErrDigestInvalidFormat
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}
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switch parts[0] {
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case "sha256":
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break
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default:
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return "", ErrDigestUnsupported
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}
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return Digest(s), nil
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}
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// Algorithm returns the algorithm portion of the digest.
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func (d Digest) Algorithm() string {
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return strings.SplitN(string(d), ":", 2)[0]
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}
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// Hex returns the hex digest portion of the digest.
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func (d Digest) Hex() string {
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return strings.SplitN(string(d), ":", 2)[1]
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}
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