Rework create/fork/adopt/generate repository to make sure resources will be cleanup once failed (#31035)

Fix #28144 

To make the resources will be cleanup once failed. All repository
operations now follow a consistent pattern:

- 1. Create a database record for the repository with the status
being_migrated.
- 2. Register a deferred cleanup function to delete the repository and
its related data if the operation fails.
- 3.	Perform the actual Git and database operations step by step.
- 4. Upon successful completion, update the repository’s status to
ready.

The adopt operation is a special case — if it fails, the repository on
disk should not be deleted.

services/repository/fork_test.go

@@ -4,13 +4,16 @@
 package repository
 
 import (
+	"os"
 	"testing"
 
+	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -46,3 +49,43 @@ func TestForkRepository(t *testing.T) {
 	assert.Nil(t, fork2)
 	assert.True(t, repo_model.IsErrReachLimitOfRepo(err))
 }
+
+func TestForkRepositoryCleanup(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	// a successful fork
+	user2 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	repo10 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 10})
+
+	fork, err := ForkRepository(git.DefaultContext, user2, user2, ForkRepoOptions{
+		BaseRepo: repo10,
+		Name:     "test",
+	})
+	assert.NoError(t, err)
+	assert.NotNil(t, fork)
+
+	exist, err := util.IsExist(repo_model.RepoPath(user2.Name, "test"))
+	assert.NoError(t, err)
+	assert.True(t, exist)
+
+	err = DeleteRepositoryDirectly(db.DefaultContext, user2, fork.ID)
+	assert.NoError(t, err)
+
+	// a failed creating because some mock data
+	// create the repository directory so that the creation will fail after database record created.
+	assert.NoError(t, os.MkdirAll(repo_model.RepoPath(user2.Name, "test"), os.ModePerm))
+
+	fork2, err := ForkRepository(db.DefaultContext, user2, user2, ForkRepoOptions{
+		BaseRepo: repo10,
+		Name:     "test",
+	})
+	assert.Nil(t, fork2)
+	assert.Error(t, err)
+
+	// assert the cleanup is successful
+	unittest.AssertNotExistsBean(t, &repo_model.Repository{OwnerName: user2.Name, Name: "test"})
+
+	exist, err = util.IsExist(repo_model.RepoPath(user2.Name, "test"))
+	assert.NoError(t, err)
+	assert.False(t, exist)
+}