first-commit

modules/git/object_id.go

@@ -0,0 +1,103 @@
+// 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
+}
+
+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
+}
+
+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 }
+
+func NewIDFromString(hexHash string) (ObjectID, error) {
+	var theObjectFormat ObjectFormat
+	for _, objectFormat := range DefaultFeatures().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
+}
+
+func IsEmptyCommitID(commitID string) bool {
+	if commitID == "" {
+		return true
+	}
+
+	id, err := NewIDFromString(commitID)
+	if err != nil {
+		return false
+	}
+
+	return id.IsZero()
+}
+
+// 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 "invalid sha: " + err.SHA
+}