2 files changed, 21 insertions, 2 deletions
diff --git a/internal/gitutil/submodule.go b/internal/gitutil/submodule.go
index e46f48a1..73e08040 100644
--- a/internal/gitutil/submodule.go
+++ b/internal/gitutil/submodule.go
@@ -17,10 +17,21 @@ import (
 var scpSyntax = lazyregexp.New(`^([a-zA-Z0-9_]+@)?([a-zA-Z0-9._-]+):(.*)$`)
 
 // InferSubmoduleURL returns the inferred external URL of the submodule at best effort.
-func InferSubmoduleURL(mod *git.Submodule) string {
+// The `baseURL` should be the URL of the current repository. If the submodule URL looks
+// like a relative path, it assumes that the submodule is another repository on the same
+// Gogs instance by appending it to the `baseURL` with the commit.
+func InferSubmoduleURL(baseURL string, mod *git.Submodule) string {
+	if !strings.HasSuffix(baseURL, "/") {
+		baseURL += "/"
+	}
+
 	raw := strings.TrimSuffix(mod.URL, "/")
 	raw = strings.TrimSuffix(raw, ".git")
 
+	if strings.HasPrefix(raw, "../") {
+		return fmt.Sprintf("%s%s/commit/%s", baseURL, raw, mod.Commit)
+	}
+
 	parsed, err := url.Parse(raw)
 	if err != nil {
 		// Try parse as SCP syntax again
diff --git a/internal/gitutil/submodule_test.go b/internal/gitutil/submodule_test.go
index 2bfe5706..53f48766 100644
--- a/internal/gitutil/submodule_test.go
+++ b/internal/gitutil/submodule_test.go
@@ -42,6 +42,14 @@ func TestInferSubmoduleURL(t *testing.T) {
 			expURL: "http://github.com/gogs/docs-api/commit/6b08f76a5313fa3d26859515b30aa17a5faa2807",
 		},
 		{
+			name: "relative path",
+			submodule: &git.Submodule{
+				URL:    "../repo2.git",
+				Commit: "6b08f76a5313fa3d26859515b30aa17a5faa2807",
+			},
+			expURL: "https://gogs.example.com/user/repo/../repo2/commit/6b08f76a5313fa3d26859515b30aa17a5faa2807",
+		},
+		{
 			name: "bad URL",
 			submodule: &git.Submodule{
 				URL:    "ftp://example.com",
@@ -52,7 +60,7 @@ func TestInferSubmoduleURL(t *testing.T) {
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			assert.Equal(t, test.expURL, InferSubmoduleURL(test.submodule))
+			assert.Equal(t, test.expURL, InferSubmoduleURL("https://gogs.example.com/user/repo", test.submodule))
 		})
 	}
 }