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// Copyright 2015 The appc Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package types
import (
"crypto/sha512"
"encoding/json"
"errors"
"fmt"
"reflect"
"strings"
)
const (
maxHashSize = (sha512.Size / 2) + len("sha512-")
)
// Hash encodes a hash specified in a string of the form:
// "<type>-<value>"
// for example
// "sha512-06c733b1838136838e6d2d3e8fa5aea4c7905e92[...]"
// Valid types are currently:
// * sha512
type Hash struct {
typ string
Val string
}
func NewHash(s string) (*Hash, error) {
elems := strings.Split(s, "-")
if len(elems) != 2 {
return nil, errors.New("badly formatted hash string")
}
nh := Hash{
typ: elems[0],
Val: elems[1],
}
if err := nh.assertValid(); err != nil {
return nil, err
}
return &nh, nil
}
func (h Hash) String() string {
return fmt.Sprintf("%s-%s", h.typ, h.Val)
}
func (h *Hash) Set(s string) error {
nh, err := NewHash(s)
if err == nil {
*h = *nh
}
return err
}
func (h Hash) Empty() bool {
return reflect.DeepEqual(h, Hash{})
}
func (h Hash) assertValid() error {
switch h.typ {
case "sha512":
case "":
return fmt.Errorf("unexpected empty hash type")
default:
return fmt.Errorf("unrecognized hash type: %v", h.typ)
}
if h.Val == "" {
return fmt.Errorf("unexpected empty hash value")
}
return nil
}
func (h *Hash) UnmarshalJSON(data []byte) error {
var s string
if err := json.Unmarshal(data, &s); err != nil {
return err
}
nh, err := NewHash(s)
if err != nil {
return err
}
*h = *nh
return nil
}
func (h Hash) MarshalJSON() ([]byte, error) {
if err := h.assertValid(); err != nil {
return nil, err
}
return json.Marshal(h.String())
}
func NewHashSHA512(b []byte) *Hash {
h := sha512.New()
h.Write(b)
nh, _ := NewHash(fmt.Sprintf("sha512-%x", h.Sum(nil)))
return nh
}
func ShortHash(hash string) string {
if len(hash) > maxHashSize {
return hash[:maxHashSize]
}
return hash
}
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