Create doctor command to fix repo_units broken by dumps from 1.14.3-1.14.6 (#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>

models/helper.go

@@ -51,7 +51,7 @@ 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)

models/repo_unit.go

@@ -220,3 +220,9 @@ func getUnitsByRepoID(e db.Engine, repoID int64) (units []*RepoUnit, err error)
 
 	return units, nil
 }
+
+// UpdateRepoUnit updates the provided repo unit
+func UpdateRepoUnit(unit *RepoUnit) error {
+	_, err := db.GetEngine(db.DefaultContext).ID(unit.ID).Update(unit)
+	return err
+}

modules/doctor/fix16961_test.go

@@ -0,0 +1,271 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package doctor
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_fixUnitConfig_16961(t *testing.T) {
+	tests := []struct {
+		name      string
+		bs        string
+		wantFixed bool
+		wantErr   bool
+	}{
+		{
+			name:      "empty",
+			bs:        "",
+			wantFixed: true,
+			wantErr:   false,
+		},
+		{
+			name:      "normal: {}",
+			bs:        "{}",
+			wantFixed: false,
+			wantErr:   false,
+		},
+		{
+			name:      "broken but fixable: &{}",
+			bs:        "&{}",
+			wantFixed: true,
+			wantErr:   false,
+		},
+		{
+			name:      "broken but unfixable: &{asdasd}",
+			bs:        "&{asdasd}",
+			wantFixed: false,
+			wantErr:   true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotFixed, err := fixUnitConfig16961([]byte(tt.bs), &models.UnitConfig{})
+			if (err != nil) != tt.wantErr {
+				t.Errorf("fixUnitConfig_16961() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if gotFixed != tt.wantFixed {
+				t.Errorf("fixUnitConfig_16961() = %v, want %v", gotFixed, tt.wantFixed)
+			}
+		})
+	}
+}
+
+func Test_fixExternalWikiConfig_16961(t *testing.T) {
+	tests := []struct {
+		name      string
+		bs        string
+		expected  string
+		wantFixed bool
+		wantErr   bool
+	}{
+		{
+			name:      "normal: {\"ExternalWikiURL\":\"http://someurl\"}",
+			bs:        "{\"ExternalWikiURL\":\"http://someurl\"}",
+			expected:  "http://someurl",
+			wantFixed: false,
+			wantErr:   false,
+		},
+		{
+			name:      "broken: &{http://someurl}",
+			bs:        "&{http://someurl}",
+			expected:  "http://someurl",
+			wantFixed: true,
+			wantErr:   false,
+		},
+		{
+			name:      "broken but unfixable: http://someurl",
+			bs:        "http://someurl",
+			wantFixed: false,
+			wantErr:   true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := &models.ExternalWikiConfig{}
+			gotFixed, err := fixExternalWikiConfig16961([]byte(tt.bs), cfg)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("fixExternalWikiConfig_16961() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if gotFixed != tt.wantFixed {
+				t.Errorf("fixExternalWikiConfig_16961() = %v, want %v", gotFixed, tt.wantFixed)
+			}
+			if cfg.ExternalWikiURL != tt.expected {
+				t.Errorf("fixExternalWikiConfig_16961().ExternalWikiURL = %v, want %v", cfg.ExternalWikiURL, tt.expected)
+			}
+		})
+	}
+}
+
+func Test_fixExternalTrackerConfig_16961(t *testing.T) {
+	tests := []struct {
+		name      string
+		bs        string
+		expected  models.ExternalTrackerConfig
+		wantFixed bool
+		wantErr   bool
+	}{
+		{
+			name: "normal",
+			bs:   `{"ExternalTrackerURL":"a","ExternalTrackerFormat":"b","ExternalTrackerStyle":"c"}`,
+			expected: models.ExternalTrackerConfig{
+				ExternalTrackerURL:    "a",
+				ExternalTrackerFormat: "b",
+				ExternalTrackerStyle:  "c",
+			},
+			wantFixed: false,
+			wantErr:   false,
+		},
+		{
+			name: "broken",
+			bs:   "&{a b c}",
+			expected: models.ExternalTrackerConfig{
+				ExternalTrackerURL:    "a",
+				ExternalTrackerFormat: "b",
+				ExternalTrackerStyle:  "c",
+			},
+			wantFixed: true,
+			wantErr:   false,
+		},
+		{
+			name:      "broken - too many fields",
+			bs:        "&{a b c d}",
+			wantFixed: false,
+			wantErr:   true,
+		},
+		{
+			name:      "broken - wrong format",
+			bs:        "a b c d}",
+			wantFixed: false,
+			wantErr:   true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := &models.ExternalTrackerConfig{}
+			gotFixed, err := fixExternalTrackerConfig16961([]byte(tt.bs), cfg)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("fixExternalTrackerConfig_16961() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if gotFixed != tt.wantFixed {
+				t.Errorf("fixExternalTrackerConfig_16961() = %v, want %v", gotFixed, tt.wantFixed)
+			}
+			if cfg.ExternalTrackerFormat != tt.expected.ExternalTrackerFormat {
+				t.Errorf("fixExternalTrackerConfig_16961().ExternalTrackerFormat = %v, want %v", tt.expected.ExternalTrackerFormat, cfg.ExternalTrackerFormat)
+			}
+			if cfg.ExternalTrackerStyle != tt.expected.ExternalTrackerStyle {
+				t.Errorf("fixExternalTrackerConfig_16961().ExternalTrackerStyle = %v, want %v", tt.expected.ExternalTrackerStyle, cfg.ExternalTrackerStyle)
+			}
+			if cfg.ExternalTrackerURL != tt.expected.ExternalTrackerURL {
+				t.Errorf("fixExternalTrackerConfig_16961().ExternalTrackerURL = %v, want %v", tt.expected.ExternalTrackerURL, cfg.ExternalTrackerURL)
+			}
+		})
+	}
+}
+
+func Test_fixPullRequestsConfig_16961(t *testing.T) {
+	tests := []struct {
+		name      string
+		bs        string
+		expected  models.PullRequestsConfig
+		wantFixed bool
+		wantErr   bool
+	}{
+		{
+			name: "normal",
+			bs:   `{"IgnoreWhitespaceConflicts":false,"AllowMerge":false,"AllowRebase":false,"AllowRebaseMerge":false,"AllowSquash":false,"AllowManualMerge":false,"AutodetectManualMerge":false,"DefaultDeleteBranchAfterMerge":false,"DefaultMergeStyle":""}`,
+		},
+		{
+			name: "broken - 1.14",
+			bs:   `&{%!s(bool=false) %!s(bool=true) %!s(bool=true) %!s(bool=true) %!s(bool=true) %!s(bool=false) %!s(bool=false)}`,
+			expected: models.PullRequestsConfig{
+				IgnoreWhitespaceConflicts: false,
+				AllowMerge:                true,
+				AllowRebase:               true,
+				AllowRebaseMerge:          true,
+				AllowSquash:               true,
+				AllowManualMerge:          false,
+				AutodetectManualMerge:     false,
+			},
+			wantFixed: true,
+		},
+		{
+			name: "broken - 1.15",
+			bs:   `&{%!s(bool=false) %!s(bool=true) %!s(bool=true) %!s(bool=true) %!s(bool=true) %!s(bool=false) %!s(bool=false) %!s(bool=false) merge}`,
+			expected: models.PullRequestsConfig{
+				AllowMerge:        true,
+				AllowRebase:       true,
+				AllowRebaseMerge:  true,
+				AllowSquash:       true,
+				DefaultMergeStyle: models.MergeStyleMerge,
+			},
+			wantFixed: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := &models.PullRequestsConfig{}
+			gotFixed, err := fixPullRequestsConfig16961([]byte(tt.bs), cfg)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("fixPullRequestsConfig_16961() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if gotFixed != tt.wantFixed {
+				t.Errorf("fixPullRequestsConfig_16961() = %v, want %v", gotFixed, tt.wantFixed)
+			}
+			assert.EqualValues(t, &tt.expected, cfg)
+		})
+	}
+}
+
+func Test_fixIssuesConfig_16961(t *testing.T) {
+	tests := []struct {
+		name      string
+		bs        string
+		expected  models.IssuesConfig
+		wantFixed bool
+		wantErr   bool
+	}{
+		{
+			name: "normal",
+			bs:   `{"EnableTimetracker":true,"AllowOnlyContributorsToTrackTime":true,"EnableDependencies":true}`,
+			expected: models.IssuesConfig{
+				EnableTimetracker:                true,
+				AllowOnlyContributorsToTrackTime: true,
+				EnableDependencies:               true,
+			},
+		},
+		{
+			name: "broken",
+			bs:   `&{%!s(bool=true) %!s(bool=true) %!s(bool=true)}`,
+			expected: models.IssuesConfig{
+				EnableTimetracker:                true,
+				AllowOnlyContributorsToTrackTime: true,
+				EnableDependencies:               true,
+			},
+			wantFixed: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := &models.IssuesConfig{}
+			gotFixed, err := fixIssuesConfig16961([]byte(tt.bs), cfg)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("fixIssuesConfig_16961() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if gotFixed != tt.wantFixed {
+				t.Errorf("fixIssuesConfig_16961() = %v, want %v", gotFixed, tt.wantFixed)
+			}
+			assert.EqualValues(t, &tt.expected, cfg)
+		})
+	}
+}