Add parsing support for tag GPG signatures (#124)

* Add parsing support for tag GPG signatures

* Test that signature is not left in commit message

* Fix object not found error in test

Author: christopherjmedlin

commit.go

@@ -34,14 +34,18 @@ type CommitGPGSignature struct {
 }
 
 // similar to https://github.com/git/git/blob/3bc53220cb2dcf709f7a027a3f526befd021d858/commit.c#L1128
-func newGPGSignatureFromCommitline(data []byte, signatureStart int) (*CommitGPGSignature, error) {
+func newGPGSignatureFromCommitline(data []byte, signatureStart int, tag bool) (*CommitGPGSignature, error) {
 	sig := new(CommitGPGSignature)
 	signatureEnd := bytes.LastIndex(data, []byte("-----END PGP SIGNATURE-----"))
 	if signatureEnd == -1 {
 		return nil, fmt.Errorf("end of commit signature not found")
 	}
 	sig.Signature = strings.Replace(string(data[signatureStart:signatureEnd+27]), "\n ", "\n", -1)
-	sig.Payload = string(data[:signatureStart-8]) + string(data[signatureEnd+27:])
+	if tag {
+		sig.Payload = string(data[:signatureStart-1])
+	} else {
+		sig.Payload = string(data[:signatureStart-8]) + string(data[signatureEnd+27:])
+	}
 	return sig, nil
 }
 

repo_commit.go

@@ -78,15 +78,28 @@ l:
 				}
 				commit.Committer = sig
 			case "gpgsig":
-				sig, err := newGPGSignatureFromCommitline(data, nextline+spacepos+1)
+				sig, err := newGPGSignatureFromCommitline(data, nextline+spacepos+1, false)
 				if err != nil {
 					return nil, err
 				}
 				commit.Signature = sig
 			}
 			nextline += eol + 1
 		case eol == 0:
-			commit.CommitMessage = string(data[nextline+1:])
+			cm := string(data[nextline+1:])
+
+			// Tag GPG signatures are stored below the commit message
+			sigindex := strings.Index(cm, "-----BEGIN PGP SIGNATURE-----")
+			if sigindex != -1 {
+				sig, err := newGPGSignatureFromCommitline(data, (nextline+1)+sigindex, true)
+				if err == nil && sig != nil {
+					// remove signature from commit message
+					cm = cm[:sigindex-1]
+					commit.Signature = sig
+				}
+			}
+
+			commit.CommitMessage = cm
 			break l
 		default:
 			break l

repo_commit_test.go

@@ -35,3 +35,15 @@ func TestRepository_GetBranches(t *testing.T) {
 		assert.Equal(t, testCase.ExpectedBranches, branches)
 	}
 }
+
+func TestGetTagCommitWithSignature(t *testing.T) {
+	bareRepo1Path := filepath.Join(testReposDir, "repo1_bare")
+	bareRepo1, err := OpenRepository(bareRepo1Path)
+	commit, err := bareRepo1.GetCommit("3ad28a9149a2864384548f3d17ed7f38014c9e8a")
+
+	assert.NoError(t, err)
+	assert.NotNil(t, commit)
+	assert.NotNil(t, commit.Signature)
+	// test that signature is not in message
+	assert.Equal(t, "tag", commit.CommitMessage)
+}

tests/repos/repo1_bare/objects/3a/d28a9149a2864384548f3d17ed7f38014c9e8a

@@ -0,0 +1 @@
+3ad28a9149a2864384548f3d17ed7f38014c9e8a