restic/backend/id.go

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package backend
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import (
"bytes"
"crypto/sha256"
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"encoding/hex"
"encoding/json"
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"errors"
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"sync"
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)
// IDSize contains the size of an ID, in bytes.
const IDSize = sha256.Size
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// References content within a repository.
type ID []byte
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var idPool = sync.Pool{New: func() interface{} { return ID(make([]byte, IDSize)) }}
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// ParseID converts the given string to an ID.
func ParseID(s string) (ID, error) {
b, err := hex.DecodeString(s)
if err != nil {
return nil, err
}
if len(b) != IDSize {
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return nil, errors.New("invalid length for sha256 hash")
}
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return ID(b), nil
}
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func (id ID) String() string {
return hex.EncodeToString(id)
}
const shortStr = 4
func (id ID) Str() string {
return hex.EncodeToString(id[:shortStr])
}
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// Equal compares an ID to another other.
func (id ID) Equal(other ID) bool {
return bytes.Equal(id, other)
}
// EqualString compares this ID to another one, given as a string.
func (id ID) EqualString(other string) (bool, error) {
s, err := hex.DecodeString(other)
if err != nil {
return false, err
}
return id.Equal(ID(s)), nil
}
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// Compare compares this ID to another one, returning -1, 0, or 1.
func (id ID) Compare(other ID) int {
return bytes.Compare(other, id)
}
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func (id ID) MarshalJSON() ([]byte, error) {
return json.Marshal(id.String())
}
func (id *ID) UnmarshalJSON(b []byte) error {
var s string
err := json.Unmarshal(b, &s)
if err != nil {
return err
}
*id = idPool.Get().(ID)
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_, err = hex.Decode(*id, []byte(s))
if err != nil {
return err
}
return nil
}
func IDFromData(d []byte) ID {
hash := sha256.Sum256(d)
id := idPool.Get().(ID)
copy(id, hash[:])
return id
}
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// Free returns the ID byte slice back to the allocation pool.
func (id ID) Free() {
idPool.Put(id)
}
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type IDs []ID
func (ids IDs) Len() int {
return len(ids)
}
func (ids IDs) Less(i, j int) bool {
if len(ids[i]) < len(ids[j]) {
return true
}
for k, b := range ids[i] {
if b == ids[j][k] {
continue
}
if b < ids[j][k] {
return true
} else {
return false
}
}
return false
}
func (ids IDs) Swap(i, j int) {
ids[i], ids[j] = ids[j], ids[i]
}