Create doctor command to fix repo_units broken by dumps from 1.14.3-1.14.6 (#17136) (#17137)

Backport #17136

There was a serious issue with the `gitea dump` command in 1.14.3-1.14.6 which led to corruption of the `config` field of the `repo_unit` table. 

This PR adds a doctor command to attempt to fix the broken repo_units. Users affected by #16961 should run:

```
gitea doctor --fix --run fix-broken-repo-units
```

Fix #16961

Signed-off-by: Andrew Thornton <art27@cantab.net>

2 files changed, 19 insertions, 13 deletions

diff --git a/models/login_source.go b/models/login_source.go
index 5674196e0c..5897743269 100644
--- a/models/login_source.go
+++ b/models/login_source.go
@@ -71,9 +71,9 @@ var (
 	_ convert.Conversion = &SSPIConfig{}
 )
 
-// jsonUnmarshalHandleDoubleEncode - due to a bug in xorm (see https://gitea.com/xorm/xorm/pulls/1957) - it's
+// JSONUnmarshalHandleDoubleEncode - due to a bug in xorm (see https://gitea.com/xorm/xorm/pulls/1957) - it's
 // possible that a Blob may be double encoded or gain an unwanted prefix of 0xff 0xfe.
-func jsonUnmarshalHandleDoubleEncode(bs []byte, v interface{}) error {
+func JSONUnmarshalHandleDoubleEncode(bs []byte, v interface{}) error {
 	json := jsoniter.ConfigCompatibleWithStandardLibrary
 	err := json.Unmarshal(bs, v)
 	if err != nil {
@@ -89,7 +89,7 @@ func jsonUnmarshalHandleDoubleEncode(bs []byte, v interface{}) error {
 			rs = append(rs, temp...)
 		}
 		if ok {
-			if rs[0] == 0xff && rs[1] == 0xfe {
+			if len(rs) > 1 && rs[0] == 0xff && rs[1] == 0xfe {
 				rs = rs[2:]
 			}
 			err = json.Unmarshal(rs, v)
@@ -108,7 +108,7 @@ type LDAPConfig struct {
 
 // FromDB fills up a LDAPConfig from serialized format.
 func (cfg *LDAPConfig) FromDB(bs []byte) error {
-	err := jsonUnmarshalHandleDoubleEncode(bs, &cfg)
+	err := JSONUnmarshalHandleDoubleEncode(bs, &cfg)
 	if err != nil {
 		return err
 	}
@@ -149,7 +149,7 @@ type SMTPConfig struct {
 
 // FromDB fills up an SMTPConfig from serialized format.
 func (cfg *SMTPConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, cfg)
 }
 
 // ToDB exports an SMTPConfig to a serialized format.
@@ -166,7 +166,7 @@ type PAMConfig struct {
 
 // FromDB fills up a PAMConfig from serialized format.
 func (cfg *PAMConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, cfg)
 }
 
 // ToDB exports a PAMConfig to a serialized format.
@@ -187,7 +187,7 @@ type OAuth2Config struct {
 
 // FromDB fills up an OAuth2Config from serialized format.
 func (cfg *OAuth2Config) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, cfg)
 }
 
 // ToDB exports an SMTPConfig to a serialized format.
@@ -207,7 +207,7 @@ type SSPIConfig struct {
 
 // FromDB fills up an SSPIConfig from serialized format.
 func (cfg *SSPIConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, cfg)
 }
 
 // ToDB exports an SSPIConfig to a serialized format.
diff --git a/models/repo_unit.go b/models/repo_unit.go
index f430e4f7f3..143ba1a42d 100644
--- a/models/repo_unit.go
+++ b/models/repo_unit.go
@@ -28,7 +28,7 @@ type UnitConfig struct{}
 
 // FromDB fills up a UnitConfig from serialized format.
 func (cfg *UnitConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, &cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, &cfg)
 }
 
 // ToDB exports a UnitConfig to a serialized format.
@@ -44,7 +44,7 @@ type ExternalWikiConfig struct {
 
 // FromDB fills up a ExternalWikiConfig from serialized format.
 func (cfg *ExternalWikiConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, &cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, &cfg)
 }
 
 // ToDB exports a ExternalWikiConfig to a serialized format.
@@ -62,7 +62,7 @@ type ExternalTrackerConfig struct {
 
 // FromDB fills up a ExternalTrackerConfig from serialized format.
 func (cfg *ExternalTrackerConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, &cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, &cfg)
 }
 
 // ToDB exports a ExternalTrackerConfig to a serialized format.
@@ -80,7 +80,7 @@ type IssuesConfig struct {
 
 // FromDB fills up a IssuesConfig from serialized format.
 func (cfg *IssuesConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, &cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, &cfg)
 }
 
 // ToDB exports a IssuesConfig to a serialized format.
@@ -104,7 +104,7 @@ type PullRequestsConfig struct {
 
 // FromDB fills up a PullRequestsConfig from serialized format.
 func (cfg *PullRequestsConfig) FromDB(bs []byte) error {
-	return jsonUnmarshalHandleDoubleEncode(bs, &cfg)
+	return JSONUnmarshalHandleDoubleEncode(bs, &cfg)
 }
 
 // ToDB exports a PullRequestsConfig to a serialized format.
@@ -219,3 +219,9 @@ func getUnitsByRepoID(e Engine, repoID int64) (units []*RepoUnit, err error) {
 
 	return units, nil
 }
+
+// UpdateRepoUnit updates the provided repo unit
+func UpdateRepoUnit(unit *RepoUnit) error {
+	_, err := x.ID(unit.ID).Update(unit)
+	return err
+}