1 files changed, 76 insertions, 0 deletions
diff --git a/modules/git/sha1.go b/modules/git/sha1.go
new file mode 100644
index 0000000000..6c9d53949d
--- /dev/null
+++ b/modules/git/sha1.go
@@ -0,0 +1,76 @@
+// Copyright 2015 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// EmptySHA defines empty git SHA
+const EmptySHA = "0000000000000000000000000000000000000000"
+
+// SHA1 a git commit name
+type SHA1 [20]byte
+
+// Equal returns true if s has the same SHA1 as caller.
+// Support 40-length-string, []byte, SHA1.
+func (id SHA1) Equal(s2 interface{}) bool {
+	switch v := s2.(type) {
+	case string:
+		if len(v) != 40 {
+			return false
+		}
+		return v == id.String()
+	case []byte:
+		return bytes.Equal(v, id[:])
+	case SHA1:
+		return v == id
+	default:
+		return false
+	}
+}
+
+// String returns string (hex) representation of the Oid.
+func (id SHA1) String() string {
+	return hex.EncodeToString(id[:])
+}
+
+// MustID always creates a new SHA1 from a [20]byte array with no validation of input.
+func MustID(b []byte) SHA1 {
+	var id SHA1
+	copy(id[:], b)
+	return id
+}
+
+// NewID creates a new SHA1 from a [20]byte array.
+func NewID(b []byte) (SHA1, error) {
+	if len(b) != 20 {
+		return SHA1{}, fmt.Errorf("Length must be 20: %v", b)
+	}
+	return MustID(b), nil
+}
+
+// MustIDFromString always creates a new sha from a ID with no validation of input.
+func MustIDFromString(s string) SHA1 {
+	b, _ := hex.DecodeString(s)
+	return MustID(b)
+}
+
+// NewIDFromString creates a new SHA1 from a ID string of length 40.
+func NewIDFromString(s string) (SHA1, error) {
+	var id SHA1
+	s = strings.TrimSpace(s)
+	if len(s) != 40 {
+		return id, fmt.Errorf("Length must be 40: %s", s)
+	}
+	b, err := hex.DecodeString(s)
+	if err != nil {
+		return id, err
+	}
+	return NewID(b)
+}