[UPGRADE] run sanity checks before the database is upgraded

(cherry picked from commit 69741e4e66932a9ac092089e7ba27399c55dcd1a)
(cherry picked from commit 2a3c7b09cbdfd62cca2619aaf37b6913a373d142)
(cherry picked from commit a1554c1168d897e8db4024d716a837c012bf74e9)
(cherry picked from commit edae2c6d2dda7f44e40ae88fba60a15f61b72232)
(cherry picked from commit 49737cf009a6a0fc119cf8a1a1593493c77c841a)
(cherry picked from commit ec53704c34a3e9491b4f210250d5e053f4b221e5)
(cherry picked from commit 7a1c5c0f323cb5e9235d8fa6e59a0a1b172d3abb)
(cherry picked from commit e658c20c0f21b42f741c0149e0e79ea0bb3b949c)
(cherry picked from commit baf575468f39c5dd0c2ff3498ef9f706d12d114e)
(cherry picked from commit 40cb14eff427c801243e374f7c60fef994bcb792)
(cherry picked from commit bfee7eae52ac4ea6a8cbb3d40c03960e1d331705)
(cherry picked from commit e94541cbf38c89dcf4ec174934c77c385bcf8e89)
(cherry picked from commit dfe672ef4c80f9a09532c07c5af6357b5d470280)
(cherry picked from commit 62fb4986018c773f682a4b921956636ac1f3c494)
(cherry picked from commit 24e17896435c440ba6c38cbcce4bb24104920fbe)

models/migrations/migrations.go

@@ -28,6 +28,7 @@ import (
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
+	forgejo_services "code.gitea.io/gitea/services/forgejo"
 
 	"xorm.io/xorm"
 	"xorm.io/xorm/names"
@@ -597,6 +598,7 @@ func Migrate(x *xorm.Engine) error {
 		return fmt.Errorf("sync: %w", err)
 	}
 
+	var previousVersion int64
 	currentVersion := &Version{ID: 1}
 	has, err := x.Get(currentVersion)
 	if err != nil {
@@ -610,6 +612,8 @@ func Migrate(x *xorm.Engine) error {
 		if _, err = x.InsertOne(currentVersion); err != nil {
 			return fmt.Errorf("insert: %w", err)
 		}
+	} else {
+		previousVersion = currentVersion.Version
 	}
 
 	v := currentVersion.Version
@@ -637,6 +641,10 @@ Please try upgrading to a lower version first (suggested v1.6.4), then upgrade t
 		}
 	}
 
+	if err := forgejo_services.PreMigrationSanityChecks(x, previousVersion, setting.CfgProvider); err != nil {
+		return err
+	}
+
 	// Migrate
 	for i, m := range migrations[v-minDBVersion:] {
 		log.Info("Migration[%d]: %s", v+int64(i), m.Description())

services/forgejo/main_test.go

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: MIT
+
+package forgejo
+
+import (
+	"path/filepath"
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+
+	_ "code.gitea.io/gitea/models"
+	_ "code.gitea.io/gitea/models/actions"
+	_ "code.gitea.io/gitea/models/activities"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m, &unittest.TestOptions{
+		GiteaRootPath: filepath.Join("..", ".."),
+	})
+}

services/forgejo/sanity.go

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+
+package forgejo
+
+import (
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+var (
+	ForgejoV5DatabaseVersion = int64(260)
+	ForgejoV4DatabaseVersion = int64(244)
+)
+
+var logFatal = log.Fatal
+
+func fatal(err error) error {
+	logFatal("%v", err)
+	return err
+}
+
+func PreMigrationSanityChecks(e db.Engine, dbVersion int64, cfg setting.ConfigProvider) error {
+	return nil
+}

services/forgejo/sanity_test.go

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MIT
+
+package forgejo
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestForgejo_PreMigrationSanityChecks(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	ctx := db.DefaultContext
+	e := db.GetEngine(ctx)
+
+	assert.NoError(t, PreMigrationSanityChecks(e, ForgejoV4DatabaseVersion, configFixture(t, "")))
+}
+
+func configFixture(t *testing.T, content string) setting.ConfigProvider {
+	config := filepath.Join(t.TempDir(), "app.ini")
+	assert.NoError(t, os.WriteFile(config, []byte(content), 0o777))
+	cfg, err := setting.NewConfigProviderFromFile(config)
+	assert.NoError(t, err)
+	return cfg
+}