defaultBranch: Implement proper error handling

The branchName is passed via an input parameter, instead of relying on
the return value.

Author: vHanda

lib/go_git_dart.dart

@@ -150,23 +150,30 @@ class GitBindings {
 
     var remoteUrlN = remoteUrl.toNativeUtf8();
     var pemPassphrase = password.toNativeUtf8();
+    var outputBranch = malloc.allocate<Pointer<Char>>(0);
 
     var retValue = lib.GitDefaultBranch(
       remoteUrlN.cast<Char>(),
       cPemBytes.cast<Char>(),
       pemBytes.length,
       pemPassphrase.cast<Char>(),
+      outputBranch,
     );
-    // if (retValue != 0) {
-    // throw Exception("GitDefaultBranch failed with error code: $retValue");
-    // }
+    if (retValue != nullptr) {
+      var err = retValue.cast<Utf8>().toDartString();
+      lib.free(retValue.cast());
+
+      throw Exception("GitPush failed with error code: $err");
+    }
 
     malloc.free(cPemBytes);
     malloc.free(remoteUrlN);
     malloc.free(pemPassphrase);
 
-    var branch = retValue.cast<Utf8>().toDartString();
-    lib.free(retValue.cast());
+    var branch = outputBranch.value.cast<Utf8>().toDartString();
+    lib.free(outputBranch.value.cast());
+    malloc.free(outputBranch);
+
     return branch;
   }
 }

lib/go_git_dart_bindings_generated.dart

@@ -2164,12 +2164,14 @@ class GoGitDartBindings {
     ffi.Pointer<ffi.Char> privateKey,
     int privateKeyLen,
     ffi.Pointer<ffi.Char> password,
+    ffi.Pointer<ffi.Pointer<ffi.Char>> outputBranchName,
   ) {
     return _GitDefaultBranch(
       remoteUrl,
       privateKey,
       privateKeyLen,
       password,
+      outputBranchName,
     );
   }
 
@@ -2179,10 +2181,15 @@ class GoGitDartBindings {
               ffi.Pointer<ffi.Char>,
               ffi.Pointer<ffi.Char>,
               ffi.Int,
-              ffi.Pointer<ffi.Char>)>>('GitDefaultBranch');
+              ffi.Pointer<ffi.Char>,
+              ffi.Pointer<ffi.Pointer<ffi.Char>>)>>('GitDefaultBranch');
   late final _GitDefaultBranch = _GitDefaultBranchPtr.asFunction<
-      ffi.Pointer<ffi.Char> Function(ffi.Pointer<ffi.Char>,
-          ffi.Pointer<ffi.Char>, int, ffi.Pointer<ffi.Char>)>();
+      ffi.Pointer<ffi.Char> Function(
+          ffi.Pointer<ffi.Char>,
+          ffi.Pointer<ffi.Char>,
+          int,
+          ffi.Pointer<ffi.Char>,
+          ffi.Pointer<ffi.Pointer<ffi.Char>>)>();
 }
 
 final class __mbstate_t extends ffi.Union {

src/git.go

@@ -113,10 +113,10 @@ func gitPush(remote string, directory string, privateKey []byte, password string
 	return nil
 }
 
-func gitDefaultBranch(remoteUrl string, privateKey []byte, password string) (int, string) {
+func gitDefaultBranch(remoteUrl string, privateKey []byte, password string) (string, error) {
 	auth, err := buildAuth(remoteUrl, privateKey, password)
 	if err != nil {
-		return 1, ""
+		return "", err
 	}
 
 	remote := git.NewRemote(memory.NewStorage(), &config.RemoteConfig{
@@ -126,8 +126,7 @@ func gitDefaultBranch(remoteUrl string, privateKey []byte, password string) (int
 
 	refs, err := remote.List(&git.ListOptions{Auth: auth})
 	if err != nil {
-		fmt.Println("git remote list failed:", err.Error())
-		return 1, ""
+		return "", err
 	}
 
 	defaultBranch := ""
@@ -138,5 +137,5 @@ func gitDefaultBranch(remoteUrl string, privateKey []byte, password string) (int
 		}
 	}
 
-	return 0, defaultBranch
+	return defaultBranch, nil
 }

src/gitjournal.go

@@ -40,12 +40,14 @@ func GitPush(remote *C.char, directory *C.char, privateKey *C.char, privateKeyLe
 }
 
 //export GitDefaultBranch
-func GitDefaultBranch(remoteUrl *C.char, privateKey *C.char, privateKeyLen C.int, password *C.char) *C.char {
-	err, val := gitDefaultBranch(C.GoString(remoteUrl), C.GoBytes(unsafe.Pointer(privateKey), privateKeyLen), C.GoString(password))
-	if err != 0 {
-		return nil
+func GitDefaultBranch(remoteUrl *C.char, privateKey *C.char, privateKeyLen C.int, password *C.char, outputBranchName **C.char) *C.char {
+	val, err := gitDefaultBranch(C.GoString(remoteUrl), C.GoBytes(unsafe.Pointer(privateKey), privateKeyLen), C.GoString(password))
+	if err != nil {
+		return C.CString(err.Error())
 	}
-	return C.CString(val)
+
+	*outputBranchName = C.CString(val)
+	return nil
 }
 
 func main() {}