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// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package git
import (
"bytes"
"encoding/hex"
"fmt"
)
type ObjectID interface {
String() string
IsZero() bool
RawValue() []byte
Type() ObjectFormat
}
/* SHA1 */
type Sha1Hash [20]byte
func (h *Sha1Hash) String() string {
return hex.EncodeToString(h[:])
}
func (h *Sha1Hash) IsZero() bool {
empty := Sha1Hash{}
return bytes.Equal(empty[:], h[:])
}
func (h *Sha1Hash) RawValue() []byte { return h[:] }
func (*Sha1Hash) Type() ObjectFormat { return Sha1ObjectFormat }
var _ ObjectID = &Sha1Hash{}
func MustIDFromString(hexHash string) ObjectID {
id, err := NewIDFromString(hexHash)
if err != nil {
panic(err)
}
return id
}
/* SHA256 */
type Sha256Hash [32]byte
func (h *Sha256Hash) String() string {
return hex.EncodeToString(h[:])
}
func (h *Sha256Hash) IsZero() bool {
empty := Sha256Hash{}
return bytes.Equal(empty[:], h[:])
}
func (h *Sha256Hash) RawValue() []byte { return h[:] }
func (*Sha256Hash) Type() ObjectFormat { return Sha256ObjectFormat }
/* utility */
func NewIDFromString(hexHash string) (ObjectID, error) {
var theObjectFormat ObjectFormat
for _, objectFormat := range SupportedObjectFormats {
if len(hexHash) == objectFormat.FullLength() {
theObjectFormat = objectFormat
break
}
}
if theObjectFormat == nil {
return nil, fmt.Errorf("length %d has no matched object format: %s", len(hexHash), hexHash)
}
b, err := hex.DecodeString(hexHash)
if err != nil {
return nil, err
}
if len(b) != theObjectFormat.FullLength()/2 {
return theObjectFormat.EmptyObjectID(), fmt.Errorf("length must be %d: %v", theObjectFormat.FullLength(), b)
}
return theObjectFormat.MustID(b), nil
}
// IsEmptyCommitID checks if an hexadecimal string represents an empty commit according to git (only '0').
// If objectFormat is not nil, the length will be checked as well (otherwise the length must match the sha1 or sha256 length).
func IsEmptyCommitID(commitID string, objectFormat ObjectFormat) bool {
if commitID == "" {
return true
}
if objectFormat == nil {
if Sha1ObjectFormat.FullLength() != len(commitID) && Sha256ObjectFormat.FullLength() != len(commitID) {
return false
}
} else if objectFormat.FullLength() != len(commitID) {
return false
}
for _, c := range commitID {
if c != '0' {
return false
}
}
return true
}
// ComputeBlobHash compute the hash for a given blob content
func ComputeBlobHash(hashType ObjectFormat, content []byte) ObjectID {
return hashType.ComputeHash(ObjectBlob, content)
}
type ErrInvalidSHA struct {
SHA string
}
func (err ErrInvalidSHA) Error() string {
return fmt.Sprintf("invalid sha: %s", err.SHA)
}
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