Add anonymous access support for private repositories (backend) (#33257)

Follow #33127

This PR add backend logic and test for "anonymous access", it shares the
same logic as "everyone access", so not too much change.

By the way, split `SettingsPost` into small functions to make it easier
to make frontend-related changes in the future.

Next PR will add frontend support for "anonymous access"

Author: wxiaoguang

models/migrations/migrations.go

@@ -378,6 +378,7 @@ func prepareMigrationTasks() []*migration {
 		newMigration(315, "Add Ephemeral to ActionRunner", v1_24.AddEphemeralToActionRunner),
 		newMigration(316, "Add description for secrets and variables", v1_24.AddDescriptionForSecretsAndVariables),
 		newMigration(317, "Add new index for action for heatmap", v1_24.AddNewIndexForUserDashboard),
+		newMigration(318, "Add anonymous_access_mode for repo_unit", v1_24.AddRepoUnitAnonymousAccessMode),
 	}
 	return preparedMigrations
 }

models/migrations/v1_24/v318.go

@@ -0,0 +1,17 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_24 //nolint
+
+import (
+	"code.gitea.io/gitea/models/perm"
+
+	"xorm.io/xorm"
+)
+
+func AddRepoUnitAnonymousAccessMode(x *xorm.Engine) error {
+	type RepoUnit struct { //revive:disable-line:exported
+		AnonymousAccessMode perm.AccessMode `xorm:"NOT NULL DEFAULT 0"`
+	}
+	return x.Sync(&RepoUnit{})
+}

models/perm/access/repo_permission.go

@@ -25,7 +25,8 @@ type Permission struct {
 	units     []*repo_model.RepoUnit
 	unitsMode map[unit.Type]perm_model.AccessMode
 
-	everyoneAccessMode map[unit.Type]perm_model.AccessMode
+	everyoneAccessMode  map[unit.Type]perm_model.AccessMode // the unit's minimal access mode for every signed-in user
+	anonymousAccessMode map[unit.Type]perm_model.AccessMode // the unit's minimal access mode for anonymous (non-signed-in) user
 }
 
 // IsOwner returns true if current user is the owner of repository.
@@ -39,7 +40,7 @@ func (p *Permission) IsAdmin() bool {
 }
 
 // HasAnyUnitAccess returns true if the user might have at least one access mode to any unit of this repository.
-// It doesn't count the "everyone access mode".
+// It doesn't count the "public(anonymous/everyone) access mode".
 func (p *Permission) HasAnyUnitAccess() bool {
 	for _, v := range p.unitsMode {
 		if v >= perm_model.AccessModeRead {
@@ -49,7 +50,12 @@ func (p *Permission) HasAnyUnitAccess() bool {
 	return p.AccessMode >= perm_model.AccessModeRead
 }
 
-func (p *Permission) HasAnyUnitAccessOrEveryoneAccess() bool {
+func (p *Permission) HasAnyUnitAccessOrPublicAccess() bool {
+	for _, v := range p.anonymousAccessMode {
+		if v >= perm_model.AccessModeRead {
+			return true
+		}
+	}
 	for _, v := range p.everyoneAccessMode {
 		if v >= perm_model.AccessModeRead {
 			return true
@@ -73,14 +79,16 @@ func (p *Permission) GetFirstUnitRepoID() int64 {
 }
 
 // UnitAccessMode returns current user access mode to the specify unit of the repository
-// It also considers "everyone access mode"
+// It also considers "public (anonymous/everyone) access mode"
 func (p *Permission) UnitAccessMode(unitType unit.Type) perm_model.AccessMode {
 	// if the units map contains the access mode, use it, but admin/owner mode could override it
 	if m, ok := p.unitsMode[unitType]; ok {
 		return util.Iif(p.AccessMode >= perm_model.AccessModeAdmin, p.AccessMode, m)
 	}
 	// if the units map does not contain the access mode, return the default access mode if the unit exists
-	unitDefaultAccessMode := max(p.AccessMode, p.everyoneAccessMode[unitType])
+	unitDefaultAccessMode := p.AccessMode
+	unitDefaultAccessMode = max(unitDefaultAccessMode, p.anonymousAccessMode[unitType])
+	unitDefaultAccessMode = max(unitDefaultAccessMode, p.everyoneAccessMode[unitType])
 	hasUnit := slices.ContainsFunc(p.units, func(u *repo_model.RepoUnit) bool { return u.Type == unitType })
 	return util.Iif(hasUnit, unitDefaultAccessMode, perm_model.AccessModeNone)
 }
@@ -171,27 +179,38 @@ func (p *Permission) LogString() string {
 		format += "\n\tunitsMode[%-v]: %-v"
 		args = append(args, key.LogString(), value.LogString())
 	}
+	format += "\n\tanonymousAccessMode: %-v"
+	args = append(args, p.anonymousAccessMode)
 	format += "\n\teveryoneAccessMode: %-v"
 	args = append(args, p.everyoneAccessMode)
 	format += "\n\t]>"
 	return fmt.Sprintf(format, args...)
 }
 
+func applyPublicAccessPermission(unitType unit.Type, accessMode perm_model.AccessMode, modeMap *map[unit.Type]perm_model.AccessMode) {
+	if accessMode >= perm_model.AccessModeRead && accessMode > (*modeMap)[unitType] {
+		if *modeMap == nil {
+			*modeMap = make(map[unit.Type]perm_model.AccessMode)
+		}
+		(*modeMap)[unitType] = accessMode
+	}
+}
+
 func finalProcessRepoUnitPermission(user *user_model.User, perm *Permission) {
+	// apply public (anonymous) access permissions
+	for _, u := range perm.units {
+		applyPublicAccessPermission(u.Type, u.AnonymousAccessMode, &perm.anonymousAccessMode)
+	}
+
 	if user == nil || user.ID <= 0 {
 		// for anonymous access, it could be:
 		// AccessMode is None or Read, units has repo units, unitModes is nil
 		return
 	}
 
-	// apply everyone access permissions
+	// apply public (everyone) access permissions
 	for _, u := range perm.units {
-		if u.EveryoneAccessMode >= perm_model.AccessModeRead && u.EveryoneAccessMode > perm.everyoneAccessMode[u.Type] {
-			if perm.everyoneAccessMode == nil {
-				perm.everyoneAccessMode = make(map[unit.Type]perm_model.AccessMode)
-			}
-			perm.everyoneAccessMode[u.Type] = u.EveryoneAccessMode
-		}
+		applyPublicAccessPermission(u.Type, u.EveryoneAccessMode, &perm.everyoneAccessMode)
 	}
 
 	if perm.unitsMode == nil {
@@ -209,6 +228,11 @@ func finalProcessRepoUnitPermission(user *user_model.User, perm *Permission) {
 				break
 			}
 		}
+		for t := range perm.anonymousAccessMode {
+			if shouldKeep = shouldKeep || u.Type == t; shouldKeep {
+				break
+			}
+		}
 		for t := range perm.everyoneAccessMode {
 			if shouldKeep = shouldKeep || u.Type == t; shouldKeep {
 				break

models/perm/access/repo_permission_test.go

@@ -22,14 +22,21 @@ func TestHasAnyUnitAccess(t *testing.T) {
 		units: []*repo_model.RepoUnit{{Type: unit.TypeWiki}},
 	}
 	assert.False(t, perm.HasAnyUnitAccess())
-	assert.False(t, perm.HasAnyUnitAccessOrEveryoneAccess())
+	assert.False(t, perm.HasAnyUnitAccessOrPublicAccess())
 
 	perm = Permission{
 		units:              []*repo_model.RepoUnit{{Type: unit.TypeWiki}},
 		everyoneAccessMode: map[unit.Type]perm_model.AccessMode{unit.TypeIssues: perm_model.AccessModeRead},
 	}
 	assert.False(t, perm.HasAnyUnitAccess())
-	assert.True(t, perm.HasAnyUnitAccessOrEveryoneAccess())
+	assert.True(t, perm.HasAnyUnitAccessOrPublicAccess())
+
+	perm = Permission{
+		units:               []*repo_model.RepoUnit{{Type: unit.TypeWiki}},
+		anonymousAccessMode: map[unit.Type]perm_model.AccessMode{unit.TypeIssues: perm_model.AccessModeRead},
+	}
+	assert.False(t, perm.HasAnyUnitAccess())
+	assert.True(t, perm.HasAnyUnitAccessOrPublicAccess())
 
 	perm = Permission{
 		AccessMode: perm_model.AccessModeRead,
@@ -43,7 +50,7 @@ func TestHasAnyUnitAccess(t *testing.T) {
 	assert.True(t, perm.HasAnyUnitAccess())
 }
 
-func TestApplyEveryoneRepoPermission(t *testing.T) {
+func TestApplyPublicAccessRepoPermission(t *testing.T) {
 	perm := Permission{
 		AccessMode: perm_model.AccessModeNone,
 		units: []*repo_model.RepoUnit{
@@ -53,6 +60,15 @@ func TestApplyEveryoneRepoPermission(t *testing.T) {
 	finalProcessRepoUnitPermission(nil, &perm)
 	assert.False(t, perm.CanRead(unit.TypeWiki))
 
+	perm = Permission{
+		AccessMode: perm_model.AccessModeNone,
+		units: []*repo_model.RepoUnit{
+			{Type: unit.TypeWiki, AnonymousAccessMode: perm_model.AccessModeRead},
+		},
+	}
+	finalProcessRepoUnitPermission(nil, &perm)
+	assert.True(t, perm.CanRead(unit.TypeWiki))
+
 	perm = Permission{
 		AccessMode: perm_model.AccessModeNone,
 		units: []*repo_model.RepoUnit{

models/repo/repo_unit.go

@@ -42,12 +42,13 @@ func (err ErrUnitTypeNotExist) Unwrap() error {
 
 // RepoUnit describes all units of a repository
 type RepoUnit struct { //revive:disable-line:exported
-	ID                 int64
-	RepoID             int64              `xorm:"INDEX(s)"`
-	Type               unit.Type          `xorm:"INDEX(s)"`
-	Config             convert.Conversion `xorm:"TEXT"`
-	CreatedUnix        timeutil.TimeStamp `xorm:"INDEX CREATED"`
-	EveryoneAccessMode perm.AccessMode    `xorm:"NOT NULL DEFAULT 0"`
+	ID                  int64
+	RepoID              int64              `xorm:"INDEX(s)"`
+	Type                unit.Type          `xorm:"INDEX(s)"`
+	Config              convert.Conversion `xorm:"TEXT"`
+	CreatedUnix         timeutil.TimeStamp `xorm:"INDEX CREATED"`
+	AnonymousAccessMode perm.AccessMode    `xorm:"NOT NULL DEFAULT 0"`
+	EveryoneAccessMode  perm.AccessMode    `xorm:"NOT NULL DEFAULT 0"`
 }
 
 func init() {