Make repo migration cancelable and fix various bugs (#24605)

Replace #12917

Close #24601
Close #12845


![image](39378118-064d-40fb-8396-4579ebf33917)


![image](faf37418-191c-46a6-90a8-353141e00e2d)


![image](fdc8ee4d-125f-4737-9990-89bcdf9eb388)


![image](9a3bd2c2-fe20-4011-81f0-990ed869d139)

---------

Co-authored-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>

routers/web/repo/migrate.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/models"
+	admin_model "code.gitea.io/gitea/models/admin"
 	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
@@ -257,3 +258,20 @@ func setMigrationContextData(ctx *context.Context, serviceType structs.GitServic
 	ctx.Data["Services"] = append([]structs.GitServiceType{structs.PlainGitService}, structs.SupportedFullGitService...)
 	ctx.Data["service"] = serviceType
 }
+
+func MigrateCancelPost(ctx *context.Context) {
+	migratingTask, err := admin_model.GetMigratingTask(ctx.Repo.Repository.ID)
+	if err != nil {
+		log.Error("GetMigratingTask: %v", err)
+		ctx.Redirect(ctx.Repo.Repository.Link())
+		return
+	}
+	if migratingTask.Status == structs.TaskStatusRunning {
+		taskUpdate := &admin_model.Task{ID: migratingTask.ID, Status: structs.TaskStatusFailed, Message: "canceled"}
+		if err = taskUpdate.UpdateCols("status", "message"); err != nil {
+			ctx.ServerError("task.UpdateCols", err)
+			return
+		}
+	}
+	ctx.Redirect(ctx.Repo.Repository.Link())
+}

routers/web/web.go

@@ -939,6 +939,7 @@ func registerRoutes(m *web.Route) {
 				addSettingsRunnersRoutes()
 				addSettingsSecretsRoutes()
 			}, actions.MustEnableActions)
+			m.Post("/migrate/cancel", repo.MigrateCancelPost) // this handler must be under "settings", otherwise this incomplete repo can't be accessed
 		}, ctxDataSet("PageIsRepoSettings", true, "LFSStartServer", setting.LFS.StartServer))
 	}, reqSignIn, context.RepoAssignment, context.UnitTypes(), reqRepoAdmin, context.RepoRef())