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73 lines
1.4 KiB
73 lines
1.4 KiB
package plumbing
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import (
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"bytes"
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"crypto/sha1"
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"encoding/hex"
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"hash"
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"sort"
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"strconv"
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)
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// Hash SHA1 hased content
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type Hash [20]byte
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// ZeroHash is Hash with value zero
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var ZeroHash Hash
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// ComputeHash compute the hash for a given ObjectType and content
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func ComputeHash(t ObjectType, content []byte) Hash {
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h := NewHasher(t, int64(len(content)))
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h.Write(content)
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return h.Sum()
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}
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// NewHash return a new Hash from a hexadecimal hash representation
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func NewHash(s string) Hash {
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b, _ := hex.DecodeString(s)
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var h Hash
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copy(h[:], b)
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return h
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}
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func (h Hash) IsZero() bool {
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var empty Hash
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return h == empty
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}
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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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type Hasher struct {
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hash.Hash
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}
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func NewHasher(t ObjectType, size int64) Hasher {
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h := Hasher{sha1.New()}
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h.Write(t.Bytes())
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h.Write([]byte(" "))
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h.Write([]byte(strconv.FormatInt(size, 10)))
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h.Write([]byte{0})
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return h
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}
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func (h Hasher) Sum() (hash Hash) {
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copy(hash[:], h.Hash.Sum(nil))
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return
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}
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// HashesSort sorts a slice of Hashes in increasing order.
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func HashesSort(a []Hash) {
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sort.Sort(HashSlice(a))
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}
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// HashSlice attaches the methods of sort.Interface to []Hash, sorting in
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// increasing order.
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type HashSlice []Hash
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func (p HashSlice) Len() int { return len(p) }
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func (p HashSlice) Less(i, j int) bool { return bytes.Compare(p[i][:], p[j][:]) < 0 }
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func (p HashSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
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