mirror of
https://github.com/vee1e/gittuf.git
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67 lines
1.6 KiB
Go
67 lines
1.6 KiB
Go
// Copyright The gittuf Authors
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// SPDX-License-Identifier: Apache-2.0
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package gitinterface
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import (
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"bytes"
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"crypto/sha1" //nolint:gosec
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"crypto/sha256"
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"encoding/hex"
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"errors"
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)
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const (
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GitBlobHashName = "gitBlob"
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SHA256HashName = "sha256"
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)
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var (
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zeroSHA1HashBytes = [sha1.Size]byte{}
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zeroSHA256HashBytes = [sha256.Size]byte{}
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)
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var (
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ErrInvalidHashEncoding = errors.New("hash string is not hex encoded")
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ErrInvalidHashLength = errors.New("hash string is wrong length")
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)
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// Hash represents a Git object hash. It is a lightweight wrapper around the
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// standard hex encoded representation of a SHA-1 or SHA-256 hash used by Git.
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type Hash []byte
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// String returns the hex encoded hash.
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func (h Hash) String() string {
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return hex.EncodeToString(h[:])
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}
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// IsZero compares the hash to see if it's the zero hash for either SHA-1 or
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// SHA-256.
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func (h Hash) IsZero() bool {
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return bytes.Equal(h[:], zeroSHA1HashBytes[:]) || bytes.Equal(h[:], zeroSHA256HashBytes[:])
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}
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// Equal compares the hash to another provided Hash to see if they're equal.
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func (h Hash) Equal(other Hash) bool {
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return bytes.Equal(h[:], other[:])
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}
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// ZeroHash represents an empty Hash.
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// TODO: use SHA-256 zero hash for repositories that have that as the default.
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var ZeroHash = Hash(zeroSHA1HashBytes[:])
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// NewHash returns a Hash object after ensuring the input string is correctly
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// encoded.
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func NewHash(h string) (Hash, error) {
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if len(h) != (sha1.Size*2) && len(h) != (sha256.Size*2) {
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return ZeroHash, ErrInvalidHashLength
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}
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hash, err := hex.DecodeString(h)
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if err != nil {
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return ZeroHash, ErrInvalidHashEncoding
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}
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return Hash(hash), nil
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}
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