Allow admins to fork repos even when creation limits are exhausted (#3277)

This is a continuation of #2728, with a test case added.

Fixes #2633.

I kept @zareck 's commit as is, because I believe it is correct. We can't move the check to `owner.CanForkRepo()`, because `owner` is the future owner of the forked repo, and may be an organization. We need to check the admin permission of the `doer`, like in the case of repository creation.

I verified that the test fails without the `ForkRepository` change, and passes with it.

Co-authored-by: Cassio Zareck <cassiomilczareck@gmail.com>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3277
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Gergely Nagy <forgejo@gergo.csillger.hu>
Co-committed-by: Gergely Nagy <forgejo@gergo.csillger.hu>

services/repository/fork.go

@@ -54,7 +54,7 @@ type ForkRepoOptions struct {
 // ForkRepository forks a repository
 func ForkRepository(ctx context.Context, doer, owner *user_model.User, opts ForkRepoOptions) (*repo_model.Repository, error) {
 	// Fork is prohibited, if user has reached maximum limit of repositories
-	if !owner.CanForkRepo() {
+	if !doer.IsAdmin && !owner.CanForkRepo() {
 		return nil, repo_model.ErrReachLimitOfRepo{
 			Limit: owner.MaxRepoCreation,
 		}

tests/integration/api_fork_test.go

@@ -5,10 +5,14 @@
 package integration
 
 import (
+	"fmt"
 	"net/http"
 	"net/url"
 	"testing"
 
+	auth_model "code.gitea.io/gitea/models/auth"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/test"
@@ -16,6 +20,65 @@ import (
 	"code.gitea.io/gitea/tests"
 )
 
+func TestAPIForkAsAdminIgnoringLimits(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+	defer test.MockVariableValue(&setting.Repository.AllowForkWithoutMaximumLimit, false)()
+	defer test.MockVariableValue(&setting.Repository.MaxCreationLimit, 0)()
+
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{Name: "user2"})
+	userSession := loginUser(t, user.Name)
+	userToken := getTokenForLoggedInUser(t, userSession, auth_model.AccessTokenScopeWriteRepository)
+	adminUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{IsAdmin: true})
+	adminSession := loginUser(t, adminUser.Name)
+	adminToken := getTokenForLoggedInUser(t, adminSession,
+		auth_model.AccessTokenScopeWriteRepository,
+		auth_model.AccessTokenScopeWriteOrganization)
+
+	originForkURL := "/api/v1/repos/user12/repo10/forks"
+	orgName := "fork-org"
+
+	// Create an organization
+	req := NewRequestWithJSON(t, "POST", "/api/v1/orgs", &api.CreateOrgOption{
+		UserName: orgName,
+	}).AddTokenAuth(adminToken)
+	MakeRequest(t, req, http.StatusCreated)
+
+	// Create a team
+	teamToCreate := &api.CreateTeamOption{
+		Name:                    "testers",
+		IncludesAllRepositories: true,
+		Permission:              "write",
+		Units:                   []string{"repo.code", "repo.issues"},
+	}
+
+	req = NewRequestWithJSON(t, "POST", fmt.Sprintf("/api/v1/orgs/%s/teams", orgName), &teamToCreate).AddTokenAuth(adminToken)
+	resp := MakeRequest(t, req, http.StatusCreated)
+	var team api.Team
+	DecodeJSON(t, resp, &team)
+
+	// Add user2 to the team
+	req = NewRequestf(t, "PUT", "/api/v1/teams/%d/members/user2", team.ID).AddTokenAuth(adminToken)
+	MakeRequest(t, req, http.StatusNoContent)
+
+	t.Run("forking as regular user", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequestWithJSON(t, "POST", originForkURL, &api.CreateForkOption{
+			Organization: &orgName,
+		}).AddTokenAuth(userToken)
+		MakeRequest(t, req, http.StatusConflict)
+	})
+
+	t.Run("forking as an instance admin", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequestWithJSON(t, "POST", originForkURL, &api.CreateForkOption{
+			Organization: &orgName,
+		}).AddTokenAuth(adminToken)
+		MakeRequest(t, req, http.StatusAccepted)
+	})
+}
+
 func TestCreateForkNoLogin(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
 	req := NewRequestWithJSON(t, "POST", "/api/v1/repos/user2/repo1/forks", &api.CreateForkOption{})