[v11.0/forgejo] fix: handle viewing a submodule entry (#7450)

**Backport:** https://codeberg.org/forgejo/forgejo/pulls/7261

- When trying to view a submodule directory via the normal `/src/branch/` path, generate a redirect link to the submodule location.
- Resolves forgejo/forgejo#5267

Co-authored-by: Gnarwhal <git.aspect893@passmail.net>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7450
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>
Co-committed-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>

routers/web/repo/view.go

@@ -1044,7 +1044,15 @@ func renderHomeCode(ctx *context.Context) {
 		return
 	}
 
-	if entry.IsDir() {
+	if entry.IsSubModule() {
+		subModuleURL, err := ctx.Repo.Commit.GetSubModule(entry.Name())
+		if err != nil {
+			HandleGitError(ctx, "Repo.Commit.GetSubModule", err)
+			return
+		}
+		subModuleFile := git.NewSubModuleFile(ctx.Repo.Commit, subModuleURL, entry.ID.String())
+		ctx.Redirect(subModuleFile.RefURL(setting.AppURL, ctx.Repo.Repository.FullName(), setting.SSH.Domain))
+	} else if entry.IsDir() {
 		renderDirectory(ctx)
 	} else {
 		renderFile(ctx, entry)

tests/integration/repo_test.go

@@ -1423,6 +1423,12 @@ func TestRepoSubmoduleView(t *testing.T) {
 
 		htmlDoc := NewHTMLParser(t, resp.Body)
 		htmlDoc.AssertElement(t, fmt.Sprintf(`tr[data-entryname="repo1"] a[href="%s"]`, u.JoinPath("/user2/repo1").String()), true)
+
+		// Check that a link to the submodule returns a redirect and that the redirect link is correct.
+		req = NewRequest(t, "GET", "/"+repo.FullName()+"/src/branch/"+repo.DefaultBranch+"/repo1")
+		resp = MakeRequest(t, req, http.StatusSeeOther)
+
+		assert.Equal(t, u.JoinPath("/user2/repo1").String(), resp.Header().Get("Location"))
 	})
 }