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-rw-r--r--modules/git/object_id.go114
1 files changed, 114 insertions, 0 deletions
diff --git a/modules/git/object_id.go b/modules/git/object_id.go
new file mode 100644
index 0000000..ecbc158
--- /dev/null
+++ b/modules/git/object_id.go
@@ -0,0 +1,114 @@
+// 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)
+}