Support repo license (#24872)

Close #278
Close #24076

## Solutions:
- Use
[google/licenseclassifier](https://github.com/google/licenseclassifier/)
Test result between
[google/licensecheck](https://github.com/google/licensecheck) and
[go-license-detector](https://github.com/go-enry/go-license-detector):
https://github.com/go-gitea/gitea/pull/24872#issuecomment-1560361167
Test result between
[google/licensecheck](https://github.com/google/licensecheck) and
[google/licenseclassifier](https://github.com/google/licenseclassifier/):
https://github.com/go-gitea/gitea/pull/24872#issuecomment-1576092178
- Generate License Convert Name List to avoid import license templates
with same contents
Gitea automatically get latest license data from[
spdx/license-list-data](https://github.com/spdx/license-list-data).
But unfortunately, some license templates have same contents. #20915
[click here to see the
list](https://github.com/go-gitea/gitea/pull/24872#issuecomment-1584141684)
So we will generate a list of these license templates with same contents
and create a new file to save the result when using `make
generate-license`. (Need to decide the save path)
- Save License info into a new table `repo_license`
Can easily support searching repo by license in the future.

## Screen shot
Single License:

![image](https://github.com/go-gitea/gitea/assets/18380374/41260bd7-0b4c-4038-8592-508706cffa9f)

Multiple Licenses:

![image](https://github.com/go-gitea/gitea/assets/18380374/34ce2f73-7e18-446b-9b96-ecc4fb61bd70)

Triggers:
- [x] Push commit to default branch
- [x] Create repo
- [x] Mirror repo
- [x] When Default Branch is changed, licenses should be updated

Todo:
- [x] Save Licenses info in to DB when there's a change to license file
in the commit
- [x] DB Migration
- [x] A nominal test?
- [x] Select which library to
use(https://github.com/go-gitea/gitea/pull/24872#issuecomment-1560361167)
- [x] API Support
- [x] Add repo license table
- ~Select license in settings if there are several licenses(Not
recommended)~
- License board(later, not in this PR)

![image](https://github.com/go-gitea/gitea/assets/18380374/2c3c3bf8-bcc2-4c6d-8ce0-81d1a9733878)

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Denys Konovalov <kontakt@denyskon.de>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: 6543 <m.huber@kithara.com>
Co-authored-by: a1012112796 <1012112796@qq.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.com>

build/generate-licenses.go

@@ -1,3 +1,6 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
 //go:build ignore
 
 package main
@@ -5,6 +8,8 @@ package main
 import (
 	"archive/tar"
 	"compress/gzip"
+	"crypto/md5"
+	"encoding/hex"
 	"flag"
 	"fmt"
 	"io"
@@ -15,6 +20,8 @@ import (
 	"path/filepath"
 	"strings"
 
+	"code.gitea.io/gitea/build/license"
+	"code.gitea.io/gitea/modules/json"
 	"code.gitea.io/gitea/modules/util"
 )
 
@@ -77,7 +84,7 @@ func main() {
 	}
 
 	tr := tar.NewReader(gz)
-
+	aliasesFiles := make(map[string][]string)
 	for {
 		hdr, err := tr.Next()
 
@@ -97,26 +104,73 @@ func main() {
 			continue
 		}
 
-		if strings.HasPrefix(filepath.Base(hdr.Name), "README") {
+		fileBaseName := filepath.Base(hdr.Name)
+		licenseName := strings.TrimSuffix(fileBaseName, ".txt")
+
+		if strings.HasPrefix(fileBaseName, "README") {
 			continue
 		}
 
-		if strings.HasPrefix(filepath.Base(hdr.Name), "deprecated_") {
+		if strings.HasPrefix(fileBaseName, "deprecated_") {
 			continue
 		}
-		out, err := os.Create(path.Join(destination, strings.TrimSuffix(filepath.Base(hdr.Name), ".txt")))
+		out, err := os.Create(path.Join(destination, licenseName))
 		if err != nil {
 			log.Fatalf("Failed to create new file. %s", err)
 		}
 
 		defer out.Close()
 
-		if _, err := io.Copy(out, tr); err != nil {
+		// some license files have same content, so we need to detect these files and create a convert map into a json file
+		// Later we use this convert map to avoid adding same license content with different license name
+		h := md5.New()
+		// calculate md5 and write file in the same time
+		r := io.TeeReader(tr, h)
+		if _, err := io.Copy(out, r); err != nil {
 			log.Fatalf("Failed to write new file. %s", err)
 		} else {
 			fmt.Printf("Written %s\n", out.Name())
+
+			md5 := hex.EncodeToString(h.Sum(nil))
+			aliasesFiles[md5] = append(aliasesFiles[md5], licenseName)
 		}
 	}
 
+	// generate convert license name map
+	licenseAliases := make(map[string]string)
+	for _, fileNames := range aliasesFiles {
+		if len(fileNames) > 1 {
+			licenseName := license.GetLicenseNameFromAliases(fileNames)
+			if licenseName == "" {
+				// license name should not be empty as expected
+				// if it is empty, we need to rewrite the logic of GetLicenseNameFromAliases
+				log.Fatalf("GetLicenseNameFromAliases: license name is empty")
+			}
+			for _, fileName := range fileNames {
+				licenseAliases[fileName] = licenseName
+			}
+		}
+	}
+	// save convert license name map to file
+	b, err := json.Marshal(licenseAliases)
+	if err != nil {
+		log.Fatalf("Failed to create json bytes. %s", err)
+	}
+
+	licenseAliasesDestination := filepath.Join(destination, "etc", "license-aliases.json")
+	if err := os.MkdirAll(filepath.Dir(licenseAliasesDestination), 0o755); err != nil {
+		log.Fatalf("Failed to create directory for license aliases json file. %s", err)
+	}
+
+	f, err := os.Create(licenseAliasesDestination)
+	if err != nil {
+		log.Fatalf("Failed to create license aliases json file. %s", err)
+	}
+	defer f.Close()
+
+	if _, err = f.Write(b); err != nil {
+		log.Fatalf("Failed to write license aliases json file. %s", err)
+	}
+
 	fmt.Println("Done")
 }

build/license/aliasgenerator.go

@@ -0,0 +1,41 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package license
+
+import "strings"
+
+func GetLicenseNameFromAliases(fnl []string) string {
+	if len(fnl) == 0 {
+		return ""
+	}
+
+	shortestItem := func(list []string) string {
+		s := list[0]
+		for _, l := range list[1:] {
+			if len(l) < len(s) {
+				s = l
+			}
+		}
+		return s
+	}
+	allHasPrefix := func(list []string, s string) bool {
+		for _, l := range list {
+			if !strings.HasPrefix(l, s) {
+				return false
+			}
+		}
+		return true
+	}
+
+	sl := shortestItem(fnl)
+	slv := strings.Split(sl, "-")
+	var result string
+	for i := len(slv); i >= 0; i-- {
+		result = strings.Join(slv[:i], "-")
+		if allHasPrefix(fnl, result) {
+			return result
+		}
+	}
+	return ""
+}

build/license/aliasgenerator_test.go

@@ -0,0 +1,39 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package license
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetLicenseNameFromAliases(t *testing.T) {
+	tests := []struct {
+		target string
+		inputs []string
+	}{
+		{
+			// real case which you can find in license-aliases.json
+			target: "AGPL-1.0",
+			inputs: []string{
+				"AGPL-1.0-only",
+				"AGPL-1.0-or-late",
+			},
+		},
+		{
+			target: "",
+			inputs: []string{
+				"APSL-1.0",
+				"AGPL-1.0-only",
+				"AGPL-1.0-or-late",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		result := GetLicenseNameFromAliases(tt.inputs)
+		assert.Equal(t, result, tt.target)
+	}
+}

go.mod

@@ -68,6 +68,7 @@ require (
 	github.com/gogs/go-gogs-client v0.0.0-20210131175652-1d7215cd8d85
 	github.com/golang-jwt/jwt/v5 v5.2.1
 	github.com/google/go-github/v61 v61.0.0
+	github.com/google/licenseclassifier/v2 v2.0.0
 	github.com/google/pprof v0.0.0-20240618054019-d3b898a103f8
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/feeds v1.2.0

go.sum

@@ -441,6 +441,8 @@ github.com/google/go-tpm v0.9.0/go.mod h1:FkNVkc6C+IsvDI9Jw1OveJmxGZUUaKxtrpOS47
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/gofuzz v1.2.0 h1:xRy4A+RhZaiKjJ1bPfwQ8sedCA+YS2YcCHW6ec7JMi0=
 github.com/google/gofuzz v1.2.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/licenseclassifier/v2 v2.0.0 h1:1Y57HHILNf4m0ABuMVb6xk4vAJYEUO0gDxNpog0pyeA=
+github.com/google/licenseclassifier/v2 v2.0.0/go.mod h1:cOjbdH0kyC9R22sdQbYsFkto4NGCAc+ZSwbeThazEtM=
 github.com/google/pprof v0.0.0-20240227163752-401108e1b7e7/go.mod h1:czg5+yv1E0ZGTi6S6vVK1mke0fV+FaUhNGcd6VRS9Ik=
 github.com/google/pprof v0.0.0-20240618054019-d3b898a103f8 h1:ASJ/LAqdCHOyMYI+dwNxn7Rd8FscNkMyTr1KZU1JI/M=
 github.com/google/pprof v0.0.0-20240618054019-d3b898a103f8/go.mod h1:K1liHPHnj73Fdn/EKuT8nrFqBihUSKXoLYU0BuatOYo=
@@ -735,6 +737,7 @@ github.com/sassoftware/go-rpmutils v0.4.0/go.mod h1:3goNWi7PGAT3/dlql2lv3+MSN5jN
 github.com/segmentio/asm v1.2.0 h1:9BQrFxC+YOHJlTlHGkTrFWf59nbL3XnCoFLTwDCI7ys=
 github.com/segmentio/asm v1.2.0/go.mod h1:BqMnlJP91P8d+4ibuonYZw9mfnzI9HfxselHZr5aAcs=
 github.com/serenize/snaker v0.0.0-20171204205717-a683aaf2d516/go.mod h1:Yow6lPLSAXx2ifx470yD/nUe22Dv5vBvxK/UK9UUTVs=
+github.com/sergi/go-diff v1.1.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
 github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 h1:n661drycOFuPLCN3Uc8sB6B/s6Z4t2xvBgU1htSHuq8=
 github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3/go.mod h1:A0bzQcvG0E7Rwjx0REVgAGH58e96+X0MeOfepqsbeW4=
 github.com/shopspring/decimal v1.2.0/go.mod h1:DKyhrW/HYNuLGql+MJL6WCR6knT2jwCFRcu2hWCYk4o=

models/fixtures/repo_license.yml

@@ -0,0 +1 @@
+[] # empty

models/fixtures/repository.yml

@@ -26,7 +26,7 @@
   fork_id: 0
   is_template: false
   template_id: 0
-  size: 7597
+  size: 8478
   is_fsck_enabled: true
   close_issues_via_commit_in_any_branch: false
 

models/migrations/migrations.go

@@ -500,7 +500,7 @@ var migrations = []Migration{
 	// v259 -> v260
 	NewMigration("Convert scoped access tokens", v1_20.ConvertScopedAccessTokens),
 
-	// Gitea 1.20.0 ends at 260
+	// Gitea 1.20.0 ends at v260
 
 	// v260 -> v261
 	NewMigration("Drop custom_labels column of action_runner table", v1_21.DropCustomLabelsColumnOfActionRunner),
@@ -601,6 +601,8 @@ var migrations = []Migration{
 	NewMigration("Add metadata column for comment table", v1_23.AddCommentMetaDataColumn),
 	// v304 -> v305
 	NewMigration("Add index for release sha1", v1_23.AddIndexForReleaseSha1),
+	// v305 -> v306
+	NewMigration("Add Repository Licenses", v1_23.AddRepositoryLicenses),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_23/v305.go

@@ -0,0 +1,23 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_23 //nolint
+
+import (
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/xorm"
+)
+
+func AddRepositoryLicenses(x *xorm.Engine) error {
+	type RepoLicense struct {
+		ID          int64 `xorm:"pk autoincr"`
+		RepoID      int64 `xorm:"UNIQUE(s) NOT NULL"`
+		CommitID    string
+		License     string             `xorm:"VARCHAR(255) UNIQUE(s) NOT NULL"`
+		CreatedUnix timeutil.TimeStamp `xorm:"INDEX CREATED"`
+		UpdatedUnix timeutil.TimeStamp `xorm:"INDEX UPDATED"`
+	}
+
+	return x.Sync(new(RepoLicense))
+}

models/repo/license.go

@@ -0,0 +1,120 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+func init() {
+	db.RegisterModel(new(RepoLicense))
+}
+
+type RepoLicense struct { //revive:disable-line:exported
+	ID          int64 `xorm:"pk autoincr"`
+	RepoID      int64 `xorm:"UNIQUE(s) NOT NULL"`
+	CommitID    string
+	License     string             `xorm:"VARCHAR(255) UNIQUE(s) NOT NULL"`
+	CreatedUnix timeutil.TimeStamp `xorm:"INDEX CREATED"`
+	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX UPDATED"`
+}
+
+// RepoLicenseList defines a list of repo licenses
+type RepoLicenseList []*RepoLicense //revive:disable-line:exported
+
+func (rll RepoLicenseList) StringList() []string {
+	var licenses []string
+	for _, rl := range rll {
+		licenses = append(licenses, rl.License)
+	}
+	return licenses
+}
+
+// GetRepoLicenses returns the license statistics for a repository
+func GetRepoLicenses(ctx context.Context, repo *Repository) (RepoLicenseList, error) {
+	licenses := make(RepoLicenseList, 0)
+	if err := db.GetEngine(ctx).Where("`repo_id` = ?", repo.ID).Asc("`license`").Find(&licenses); err != nil {
+		return nil, err
+	}
+	return licenses, nil
+}
+
+// UpdateRepoLicenses updates the license statistics for repository
+func UpdateRepoLicenses(ctx context.Context, repo *Repository, commitID string, licenses []string) error {
+	oldLicenses, err := GetRepoLicenses(ctx, repo)
+	if err != nil {
+		return err
+	}
+	for _, license := range licenses {
+		upd := false
+		for _, o := range oldLicenses {
+			// Update already existing license
+			if o.License == license {
+				if _, err := db.GetEngine(ctx).ID(o.ID).Cols("`commit_id`").Update(o); err != nil {
+					return err
+				}
+				upd = true
+				break
+			}
+		}
+		// Insert new license
+		if !upd {
+			if err := db.Insert(ctx, &RepoLicense{
+				RepoID:   repo.ID,
+				CommitID: commitID,
+				License:  license,
+			}); err != nil {
+				return err
+			}
+		}
+	}
+	// Delete old licenses
+	licenseToDelete := make([]int64, 0, len(oldLicenses))
+	for _, o := range oldLicenses {
+		if o.CommitID != commitID {
+			licenseToDelete = append(licenseToDelete, o.ID)
+		}
+	}
+	if len(licenseToDelete) > 0 {
+		if _, err := db.GetEngine(ctx).In("`id`", licenseToDelete).Delete(&RepoLicense{}); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// CopyLicense Copy originalRepo license information to destRepo (use for forked repo)
+func CopyLicense(ctx context.Context, originalRepo, destRepo *Repository) error {
+	repoLicenses, err := GetRepoLicenses(ctx, originalRepo)
+	if err != nil {
+		return err
+	}
+	if len(repoLicenses) > 0 {
+		newRepoLicenses := make(RepoLicenseList, 0, len(repoLicenses))
+
+		for _, rl := range repoLicenses {
+			newRepoLicense := &RepoLicense{
+				RepoID:   destRepo.ID,
+				CommitID: rl.CommitID,
+				License:  rl.License,
+			}
+			newRepoLicenses = append(newRepoLicenses, newRepoLicense)
+		}
+		if err := db.Insert(ctx, &newRepoLicenses); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// CleanRepoLicenses will remove all license record of the repo
+func CleanRepoLicenses(ctx context.Context, repo *Repository) error {
+	return db.DeleteBeans(ctx, &RepoLicense{
+		RepoID: repo.ID,
+	})
+}

modules/repository/license.go

@@ -23,7 +23,7 @@ type LicenseValues struct {
 func GetLicense(name string, values *LicenseValues) ([]byte, error) {
 	data, err := options.License(name)
 	if err != nil {
-		return nil, fmt.Errorf("GetRepoInitFile[%s]: %w", name, err)
+		return nil, fmt.Errorf("GetLicense[%s]: %w", name, err)
 	}
 	return fillLicensePlaceholder(name, values, data), nil
 }

modules/structs/repo.go

@@ -114,6 +114,7 @@ type Repository struct {
 	MirrorUpdated time.Time     `json:"mirror_updated,omitempty"`
 	RepoTransfer  *RepoTransfer `json:"repo_transfer"`
 	Topics        []string      `json:"topics"`
+	Licenses      []string      `json:"licenses"`
 }
 
 // CreateRepoOption options when creating repository

options/license/etc/license-aliases.json

@@ -0,0 +1 @@
+{"AGPL-1.0-only":"AGPL-1.0","AGPL-1.0-or-later":"AGPL-1.0","AGPL-3.0-only":"AGPL-3.0","AGPL-3.0-or-later":"AGPL-3.0","CAL-1.0":"CAL-1.0","CAL-1.0-Combined-Work-Exception":"CAL-1.0","GFDL-1.1-invariants-only":"GFDL-1.1","GFDL-1.1-invariants-or-later":"GFDL-1.1","GFDL-1.1-no-invariants-only":"GFDL-1.1","GFDL-1.1-no-invariants-or-later":"GFDL-1.1","GFDL-1.1-only":"GFDL-1.1","GFDL-1.1-or-later":"GFDL-1.1","GFDL-1.2-invariants-only":"GFDL-1.2","GFDL-1.2-invariants-or-later":"GFDL-1.2","GFDL-1.2-no-invariants-only":"GFDL-1.2","GFDL-1.2-no-invariants-or-later":"GFDL-1.2","GFDL-1.2-only":"GFDL-1.2","GFDL-1.2-or-later":"GFDL-1.2","GFDL-1.3-invariants-only":"GFDL-1.3","GFDL-1.3-invariants-or-later":"GFDL-1.3","GFDL-1.3-no-invariants-only":"GFDL-1.3","GFDL-1.3-no-invariants-or-later":"GFDL-1.3","GFDL-1.3-only":"GFDL-1.3","GFDL-1.3-or-later":"GFDL-1.3","GPL-1.0-only":"GPL-1.0","GPL-1.0-or-later":"GPL-1.0","GPL-2.0-only":"GPL-2.0","GPL-2.0-or-later":"GPL-2.0","GPL-3.0-only":"GPL-3.0","GPL-3.0-or-later":"GPL-3.0","LGPL-2.0-only":"LGPL-2.0","LGPL-2.0-or-later":"LGPL-2.0","LGPL-2.1-only":"LGPL-2.1","LGPL-2.1-or-later":"LGPL-2.1","LGPL-3.0-only":"LGPL-3.0","LGPL-3.0-or-later":"LGPL-3.0","MPL-2.0":"MPL-2.0","MPL-2.0-no-copyleft-exception":"MPL-2.0","OFL-1.0":"OFL-1.0","OFL-1.0-RFN":"OFL-1.0","OFL-1.0-no-RFN":"OFL-1.0","OFL-1.1":"OFL-1.1","OFL-1.1-RFN":"OFL-1.1","OFL-1.1-no-RFN":"OFL-1.1"}

options/locale/locale_en-US.ini

@@ -1040,6 +1040,7 @@ issue_labels_helper = Select an issue label set.
 license = License
 license_helper = Select a license file.
 license_helper_desc = A license governs what others can and can't do with your code. Not sure which one is right for your project? See <a target="_blank" rel="noopener noreferrer" href="%s">Choose a license.</a>
+multiple_licenses = Multiple Licenses
 object_format = Object Format
 object_format_helper = Object format of the repository. Cannot be changed later. SHA1 is most compatible.
 readme = README
@@ -2942,6 +2943,7 @@ dashboard.start_schedule_tasks = Start actions schedule tasks
 dashboard.sync_branch.started = Branches Sync started
 dashboard.sync_tag.started = Tags Sync started
 dashboard.rebuild_issue_indexer = Rebuild issue indexer
+dashboard.sync_repo_licenses = Sync repo licenses
 
 users.user_manage_panel = User Account Management
 users.new_account = Create User Account

routers/api/v1/api.go

@@ -1327,6 +1327,7 @@ func Routes() *web.Router {
 				m.Get("/issue_config", context.ReferencesGitRepo(), repo.GetIssueConfig)
 				m.Get("/issue_config/validate", context.ReferencesGitRepo(), repo.ValidateIssueConfig)
 				m.Get("/languages", reqRepoReader(unit.TypeCode), repo.GetLanguages)
+				m.Get("/licenses", reqRepoReader(unit.TypeCode), repo.GetLicenses)
 				m.Get("/activities/feeds", repo.ListRepoActivityFeeds)
 				m.Get("/new_pin_allowed", repo.AreNewIssuePinsAllowed)
 				m.Group("/avatar", func() {

routers/api/v1/repo/license.go

@@ -0,0 +1,51 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"net/http"
+
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/services/context"
+)
+
+// GetLicenses returns licenses
+func GetLicenses(ctx *context.APIContext) {
+	// swagger:operation GET /repos/{owner}/{repo}/licenses repository repoGetLicenses
+	// ---
+	// summary: Get repo licenses
+	// produces:
+	//   - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// responses:
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "200":
+	//     "$ref": "#/responses/LicensesList"
+
+	licenses, err := repo_model.GetRepoLicenses(ctx, ctx.Repo.Repository)
+	if err != nil {
+		log.Error("GetRepoLicenses failed: %v", err)
+		ctx.InternalServerError(err)
+		return
+	}
+
+	resp := make([]string, len(licenses))
+	for i := range licenses {
+		resp[i] = licenses[i].License
+	}
+
+	ctx.JSON(http.StatusOK, resp)
+}

routers/api/v1/repo/repo.go

@@ -731,6 +731,7 @@ func updateBasicProperties(ctx *context.APIContext, opts api.EditRepoOption) err
 	}
 
 	// Default branch only updated if changed and exist or the repository is empty
+	updateRepoLicense := false
 	if opts.DefaultBranch != nil && repo.DefaultBranch != *opts.DefaultBranch && (repo.IsEmpty || ctx.Repo.GitRepo.IsBranchExist(*opts.DefaultBranch)) {
 		if !repo.IsEmpty {
 			if err := gitrepo.SetDefaultBranch(ctx, ctx.Repo.Repository, *opts.DefaultBranch); err != nil {
@@ -739,6 +740,7 @@ func updateBasicProperties(ctx *context.APIContext, opts api.EditRepoOption) err
 					return err
 				}
 			}
+			updateRepoLicense = true
 		}
 		repo.DefaultBranch = *opts.DefaultBranch
 	}
@@ -748,6 +750,15 @@ func updateBasicProperties(ctx *context.APIContext, opts api.EditRepoOption) err
 		return err
 	}
 
+	if updateRepoLicense {
+		if err := repo_service.AddRepoToLicenseUpdaterQueue(&repo_service.LicenseUpdaterOptions{
+			RepoID: ctx.Repo.Repository.ID,
+		}); err != nil {
+			ctx.Error(http.StatusInternalServerError, "AddRepoToLicenseUpdaterQueue", err)
+			return err
+		}
+	}
+
 	log.Trace("Repository basic settings updated: %s/%s", owner.Name, repo.Name)
 	return nil
 }

routers/api/v1/swagger/repo.go

@@ -359,6 +359,13 @@ type swaggerLanguageStatistics struct {
 	Body map[string]int64 `json:"body"`
 }
 
+// LicensesList
+// swagger:response LicensesList
+type swaggerLicensesList struct {
+	// in: body
+	Body []string `json:"body"`
+}
+
 // CombinedStatus
 // swagger:response CombinedStatus
 type swaggerCombinedStatus struct {

routers/init.go

@@ -172,6 +172,8 @@ func InitWebInstalled(ctx context.Context) {
 
 	actions_service.Init()
 
+	mustInit(repo_service.InitLicenseClassifier)
+
 	// Finally start up the cron
 	cron.NewContext(ctx)
 }

routers/private/default_branch.go

@@ -12,6 +12,7 @@ import (
 	"code.gitea.io/gitea/modules/gitrepo"
 	"code.gitea.io/gitea/modules/private"
 	gitea_context "code.gitea.io/gitea/services/context"
+	repo_service "code.gitea.io/gitea/services/repository"
 )
 
 // SetDefaultBranch updates the default branch
@@ -36,5 +37,15 @@ func SetDefaultBranch(ctx *gitea_context.PrivateContext) {
 		})
 		return
 	}
+
+	if err := repo_service.AddRepoToLicenseUpdaterQueue(&repo_service.LicenseUpdaterOptions{
+		RepoID: ctx.Repo.Repository.ID,
+	}); err != nil {
+		ctx.JSON(http.StatusInternalServerError, private.Response{
+			Err: fmt.Sprintf("Unable to set default branch on repository: %s/%s Error: %v", ownerName, repoName, err),
+		})
+		return
+	}
+
 	ctx.PlainText(http.StatusOK, "success")
 }

routers/private/hook_post_receive.go

@@ -278,11 +278,20 @@ func HookPostReceive(ctx *gitea_context.PrivateContext) {
 
 			branch := refFullName.BranchName()
 
+			if branch == baseRepo.DefaultBranch {
+				if err := repo_service.AddRepoToLicenseUpdaterQueue(&repo_service.LicenseUpdaterOptions{
+					RepoID: repo.ID,
+				}); err != nil {
+					ctx.JSON(http.StatusInternalServerError, private.Response{Err: err.Error()})
+					return
+				}
+
 				// If our branch is the default branch of an unforked repo - there's no PR to create or refer to
-			if !repo.IsFork && branch == baseRepo.DefaultBranch {
+				if !repo.IsFork {
 					results = append(results, private.HookPostReceiveBranchResult{})
 					continue
 				}
+			}
 
 			pr, err := issues_model.GetUnmergedPullRequest(ctx, repo.ID, baseRepo.ID, branch, baseRepo.DefaultBranch, issues_model.PullRequestFlowGithub)
 			if err != nil && !issues_model.IsErrPullRequestNotExist(err) {

routers/web/repo/branch.go

@@ -89,7 +89,7 @@ func Branches(ctx *context.Context) {
 	pager := context.NewPagination(int(branchesCount), pageSize, page, 5)
 	pager.SetDefaultParams(ctx)
 	ctx.Data["Page"] = pager
-
+	ctx.Data["LicenseFileName"] = repo_service.LicenseFileName
 	ctx.HTML(http.StatusOK, tplBranch)
 }
 

routers/web/repo/commit.go

@@ -29,7 +29,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/context"
 	"code.gitea.io/gitea/services/gitdiff"
-	git_service "code.gitea.io/gitea/services/repository"
+	repo_service "code.gitea.io/gitea/services/repository"
 )
 
 const (
@@ -101,7 +101,7 @@ func Commits(ctx *context.Context) {
 	pager := context.NewPagination(int(commitsCount), pageSize, page, 5)
 	pager.SetDefaultParams(ctx)
 	ctx.Data["Page"] = pager
-
+	ctx.Data["LicenseFileName"] = repo_service.LicenseFileName
 	ctx.HTML(http.StatusOK, tplCommits)
 }
 
@@ -218,6 +218,8 @@ func SearchCommits(ctx *context.Context) {
 	}
 	ctx.Data["Username"] = ctx.Repo.Owner.Name
 	ctx.Data["Reponame"] = ctx.Repo.Repository.Name
+	ctx.Data["RefName"] = ctx.Repo.RefName
+	ctx.Data["LicenseFileName"] = repo_service.LicenseFileName
 	ctx.HTML(http.StatusOK, tplCommits)
 }
 
@@ -263,12 +265,12 @@ func FileHistory(ctx *context.Context) {
 	pager := context.NewPagination(int(commitsCount), setting.Git.CommitsRangeSize, page, 5)
 	pager.SetDefaultParams(ctx)
 	ctx.Data["Page"] = pager
-
+	ctx.Data["LicenseFileName"] = repo_service.LicenseFileName
 	ctx.HTML(http.StatusOK, tplCommits)
 }
 
 func LoadBranchesAndTags(ctx *context.Context) {
-	response, err := git_service.LoadBranchesAndTags(ctx, ctx.Repo, ctx.PathParam("sha"))
+	response, err := repo_service.LoadBranchesAndTags(ctx, ctx.Repo, ctx.PathParam("sha"))
 	if err == nil {
 		ctx.JSON(http.StatusOK, response)
 		return

routers/web/repo/release.go

@@ -289,7 +289,6 @@ func releasesOrTagsFeed(ctx *context.Context, isReleasesOnly bool, formatType st
 // SingleRelease renders a single release's page
 func SingleRelease(ctx *context.Context) {
 	ctx.Data["PageIsReleaseList"] = true
-	ctx.Data["DefaultBranch"] = ctx.Repo.Repository.DefaultBranch
 
 	writeAccess := ctx.Repo.CanWrite(unit.TypeReleases)
 	ctx.Data["CanCreateRelease"] = writeAccess && !ctx.Repo.Repository.IsArchived

routers/web/repo/view.go

@@ -51,6 +51,7 @@ import (
 	"code.gitea.io/gitea/routers/web/feed"
 	"code.gitea.io/gitea/services/context"
 	issue_service "code.gitea.io/gitea/services/issue"
+	repo_service "code.gitea.io/gitea/services/repository"
 	files_service "code.gitea.io/gitea/services/repository/files"
 
 	"github.com/nektos/act/pkg/model"
@@ -1077,6 +1078,7 @@ func renderHomeCode(ctx *context.Context) {
 	ctx.Data["TreeLink"] = treeLink
 	ctx.Data["TreeNames"] = treeNames
 	ctx.Data["BranchLink"] = branchLink
+	ctx.Data["LicenseFileName"] = repo_service.LicenseFileName
 	ctx.HTML(http.StatusOK, tplRepoHome)
 }
 

services/context/repo.go

@@ -404,6 +404,13 @@ func repoAssignment(ctx *Context, repo *repo_model.Repository) {
 	ctx.Data["PushMirrors"] = pushMirrors
 	ctx.Data["RepoName"] = ctx.Repo.Repository.Name
 	ctx.Data["IsEmptyRepo"] = ctx.Repo.Repository.IsEmpty
+
+	repoLicenses, err := repo_model.GetRepoLicenses(ctx, ctx.Repo.Repository)
+	if err != nil {
+		ctx.ServerError("GetRepoLicenses", err)
+		return
+	}
+	ctx.Data["DetectedRepoLicenses"] = repoLicenses.StringList()
 }
 
 // RepoAssignment returns a middleware to handle repository assignment

services/convert/repository.go

@@ -175,6 +175,11 @@ func innerToRepo(ctx context.Context, repo *repo_model.Repository, permissionInR
 		language = repo.PrimaryLanguage.Language
 	}
 
+	repoLicenses, err := repo_model.GetRepoLicenses(ctx, repo)
+	if err != nil {
+		return nil
+	}
+
 	repoAPIURL := repo.APIURL()
 
 	return &api.Repository{
@@ -238,6 +243,7 @@ func innerToRepo(ctx context.Context, repo *repo_model.Repository, permissionInR
 		RepoTransfer:                  transfer,
 		Topics:                        repo.Topics,
 		ObjectFormatName:              repo.ObjectFormatName,
+		Licenses:                      repoLicenses.StringList(),
 	}
 }
 

services/cron/tasks_basic.go

@@ -156,6 +156,16 @@ func registerCleanupPackages() {
 	})
 }
 
+func registerSyncRepoLicenses() {
+	RegisterTaskFatal("sync_repo_licenses", &BaseConfig{
+		Enabled:    false,
+		RunAtStart: false,
+		Schedule:   "@annually",
+	}, func(ctx context.Context, _ *user_model.User, config Config) error {
+		return repo_service.SyncRepoLicenses(ctx)
+	})
+}
+
 func initBasicTasks() {
 	if setting.Mirror.Enabled {
 		registerUpdateMirrorTask()
@@ -172,4 +182,5 @@ func initBasicTasks() {
 	if setting.Packages.Enabled {
 		registerCleanupPackages()
 	}
+	registerSyncRepoLicenses()
 }

services/migrations/gitea_uploader_test.go

@@ -26,6 +26,7 @@ import (
 	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/test"
+	repo_service "code.gitea.io/gitea/services/repository"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -302,6 +303,8 @@ func TestGiteaUploadUpdateGitForPullRequest(t *testing.T) {
 	toRepoName := "migrated"
 	uploader := NewGiteaLocalUploader(context.Background(), fromRepoOwner, fromRepoOwner.Name, toRepoName)
 	uploader.gitServiceType = structs.GiteaService
+
+	assert.NoError(t, repo_service.Init(context.Background()))
 	assert.NoError(t, uploader.CreateRepo(&base.Repository{
 		Description: "description",
 		OriginalURL: fromRepo.RepoPath(),

services/mirror/mirror_pull.go

@@ -24,6 +24,7 @@ import (
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
 	notify_service "code.gitea.io/gitea/services/notify"
+	repo_service "code.gitea.io/gitea/services/repository"
 )
 
 // gitShortEmptySha Git short empty SHA
@@ -559,6 +560,14 @@ func SyncPullMirror(ctx context.Context, repoID int64) bool {
 		}
 	}
 
+	// Update License
+	if err = repo_service.AddRepoToLicenseUpdaterQueue(&repo_service.LicenseUpdaterOptions{
+		RepoID: m.Repo.ID,
+	}); err != nil {
+		log.Error("SyncMirrors [repo: %-v]: unable to add repo to license updater queue: %v", m.Repo, err)
+		return false
+	}
+
 	log.Trace("SyncMirrors [repo: %-v]: Successfully updated", m.Repo)
 
 	return true

services/repository/branch.go

@@ -612,6 +612,14 @@ func SetRepoDefaultBranch(ctx context.Context, repo *repo_model.Repository, gitR
 		return err
 	}
 
+	if !repo.IsEmpty {
+		if err := AddRepoToLicenseUpdaterQueue(&LicenseUpdaterOptions{
+			RepoID: repo.ID,
+		}); err != nil {
+			log.Error("AddRepoToLicenseUpdaterQueue: %v", err)
+		}
+	}
+
 	notify_service.ChangeDefaultBranch(ctx, repo)
 
 	return nil

services/repository/create.go

@@ -303,6 +303,25 @@ func CreateRepositoryDirectly(ctx context.Context, doer, u *user_model.User, opt
 			rollbackRepo.OwnerID = u.ID
 			return fmt.Errorf("CreateRepository(git update-server-info): %w", err)
 		}
+
+		// update licenses
+		var licenses []string
+		if len(opts.License) > 0 {
+			licenses = append(licenses, ConvertLicenseName(opts.License))
+
+			stdout, _, err := git.NewCommand(ctx, "rev-parse", "HEAD").
+				SetDescription(fmt.Sprintf("CreateRepository(git rev-parse HEAD): %s", repoPath)).
+				RunStdString(&git.RunOpts{Dir: repoPath})
+			if err != nil {
+				log.Error("CreateRepository(git rev-parse HEAD) in %v: Stdout: %s\nError: %v", repo, stdout, err)
+				rollbackRepo = repo
+				rollbackRepo.OwnerID = u.ID
+				return fmt.Errorf("CreateRepository(git rev-parse HEAD): %w", err)
+			}
+			if err := repo_model.UpdateRepoLicenses(ctx, repo, stdout, licenses); err != nil {
+				return err
+			}
+		}
 		return nil
 	}); err != nil {
 		if rollbackRepo != nil {

services/repository/delete.go

@@ -140,6 +140,7 @@ func DeleteRepositoryDirectly(ctx context.Context, doer *user_model.User, repoID
 		&git_model.Branch{RepoID: repoID},
 		&git_model.LFSLock{RepoID: repoID},
 		&repo_model.LanguageStat{RepoID: repoID},
+		&repo_model.RepoLicense{RepoID: repoID},
 		&issues_model.Milestone{RepoID: repoID},
 		&repo_model.Mirror{RepoID: repoID},
 		&activities_model.Notification{RepoID: repoID},

services/repository/fork.go

@@ -198,6 +198,9 @@ func ForkRepository(ctx context.Context, doer, owner *user_model.User, opts Fork
 	if err := repo_model.CopyLanguageStat(ctx, opts.BaseRepo, repo); err != nil {
 		log.Error("Copy language stat from oldRepo failed: %v", err)
 	}
+	if err := repo_model.CopyLicense(ctx, opts.BaseRepo, repo); err != nil {
+		return nil, err
+	}
 
 	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
 	if err != nil {

services/repository/license.go

@@ -0,0 +1,205 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repository
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/container"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/json"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/options"
+	"code.gitea.io/gitea/modules/queue"
+
+	licenseclassifier "github.com/google/licenseclassifier/v2"
+)
+
+var (
+	classifier      *licenseclassifier.Classifier
+	LicenseFileName = "LICENSE"
+	licenseAliases  map[string]string
+
+	// licenseUpdaterQueue represents a queue to handle update repo licenses
+	licenseUpdaterQueue *queue.WorkerPoolQueue[*LicenseUpdaterOptions]
+)
+
+func AddRepoToLicenseUpdaterQueue(opts *LicenseUpdaterOptions) error {
+	if opts == nil {
+		return nil
+	}
+	return licenseUpdaterQueue.Push(opts)
+}
+
+func loadLicenseAliases() error {
+	if licenseAliases != nil {
+		return nil
+	}
+
+	data, err := options.AssetFS().ReadFile("license", "etc", "license-aliases.json")
+	if err != nil {
+		return err
+	}
+	err = json.Unmarshal(data, &licenseAliases)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func ConvertLicenseName(name string) string {
+	if err := loadLicenseAliases(); err != nil {
+		return name
+	}
+
+	v, ok := licenseAliases[name]
+	if ok {
+		return v
+	}
+	return name
+}
+
+func InitLicenseClassifier() error {
+	// threshold should be 0.84~0.86 or the test will be failed
+	classifier = licenseclassifier.NewClassifier(.85)
+	licenseFiles, err := options.AssetFS().ListFiles("license", true)
+	if err != nil {
+		return err
+	}
+
+	existLicense := make(container.Set[string])
+	if len(licenseFiles) > 0 {
+		for _, licenseFile := range licenseFiles {
+			licenseName := ConvertLicenseName(licenseFile)
+			if existLicense.Contains(licenseName) {
+				continue
+			}
+			existLicense.Add(licenseName)
+			data, err := options.License(licenseFile)
+			if err != nil {
+				return err
+			}
+			classifier.AddContent("License", licenseFile, licenseName, data)
+		}
+	}
+	return nil
+}
+
+type LicenseUpdaterOptions struct {
+	RepoID int64
+}
+
+func repoLicenseUpdater(items ...*LicenseUpdaterOptions) []*LicenseUpdaterOptions {
+	ctx := graceful.GetManager().ShutdownContext()
+
+	for _, opts := range items {
+		repo, err := repo_model.GetRepositoryByID(ctx, opts.RepoID)
+		if err != nil {
+			log.Error("repoLicenseUpdater [%d] failed: GetRepositoryByID: %v", opts.RepoID, err)
+			continue
+		}
+		if repo.IsEmpty {
+			continue
+		}
+
+		gitRepo, err := gitrepo.OpenRepository(ctx, repo)
+		if err != nil {
+			log.Error("repoLicenseUpdater [%d] failed: OpenRepository: %v", opts.RepoID, err)
+			continue
+		}
+		defer gitRepo.Close()
+
+		commit, err := gitRepo.GetBranchCommit(repo.DefaultBranch)
+		if err != nil {
+			log.Error("repoLicenseUpdater [%d] failed: GetBranchCommit: %v", opts.RepoID, err)
+			continue
+		}
+		if err = UpdateRepoLicenses(ctx, repo, commit); err != nil {
+			log.Error("repoLicenseUpdater [%d] failed: updateRepoLicenses: %v", opts.RepoID, err)
+		}
+	}
+	return nil
+}
+
+func SyncRepoLicenses(ctx context.Context) error {
+	log.Trace("Doing: SyncRepoLicenses")
+
+	if err := db.Iterate(
+		ctx,
+		nil,
+		func(ctx context.Context, repo *repo_model.Repository) error {
+			select {
+			case <-ctx.Done():
+				return db.ErrCancelledf("before sync repo licenses for %s", repo.FullName())
+			default:
+			}
+			return AddRepoToLicenseUpdaterQueue(&LicenseUpdaterOptions{RepoID: repo.ID})
+		},
+	); err != nil {
+		log.Trace("Error: SyncRepoLicenses: %v", err)
+		return err
+	}
+
+	log.Trace("Finished: SyncReposLicenses")
+	return nil
+}
+
+// UpdateRepoLicenses will update repository licenses col if license file exists
+func UpdateRepoLicenses(ctx context.Context, repo *repo_model.Repository, commit *git.Commit) error {
+	if commit == nil {
+		return nil
+	}
+
+	b, err := commit.GetBlobByPath(LicenseFileName)
+	if err != nil && !git.IsErrNotExist(err) {
+		return fmt.Errorf("GetBlobByPath: %w", err)
+	}
+
+	if git.IsErrNotExist(err) {
+		return repo_model.CleanRepoLicenses(ctx, repo)
+	}
+
+	licenses := make([]string, 0)
+	if b != nil {
+		r, err := b.DataAsync()
+		if err != nil {
+			return err
+		}
+		defer r.Close()
+
+		licenses, err = detectLicense(r)
+		if err != nil {
+			return fmt.Errorf("detectLicense: %w", err)
+		}
+	}
+	return repo_model.UpdateRepoLicenses(ctx, repo, commit.ID.String(), licenses)
+}
+
+// detectLicense returns the licenses detected by the given content buff
+func detectLicense(r io.Reader) ([]string, error) {
+	if r == nil {
+		return nil, nil
+	}
+
+	matches, err := classifier.MatchFrom(r)
+	if err != nil {
+		return nil, err
+	}
+	if len(matches.Matches) > 0 {
+		results := make(container.Set[string], len(matches.Matches))
+		for _, r := range matches.Matches {
+			if r.MatchType == "License" && !results.Contains(r.Variant) {
+				results.Add(r.Variant)
+			}
+		}
+		return results.Values(), nil
+	}
+	return nil, nil
+}

services/repository/license_test.go

@@ -0,0 +1,73 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repository
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	repo_module "code.gitea.io/gitea/modules/repository"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_detectLicense(t *testing.T) {
+	type DetectLicenseTest struct {
+		name string
+		arg  string
+		want []string
+	}
+
+	tests := []DetectLicenseTest{
+		{
+			name: "empty",
+			arg:  "",
+			want: nil,
+		},
+		{
+			name: "no detected license",
+			arg:  "Copyright (c) 2023 Gitea",
+			want: nil,
+		},
+	}
+
+	repo_module.LoadRepoConfig()
+	err := loadLicenseAliases()
+	assert.NoError(t, err)
+	for _, licenseName := range repo_module.Licenses {
+		license, err := repo_module.GetLicense(licenseName, &repo_module.LicenseValues{
+			Owner: "Gitea",
+			Email: "teabot@gitea.io",
+			Repo:  "gitea",
+			Year:  "2024",
+		})
+		assert.NoError(t, err)
+
+		tests = append(tests, DetectLicenseTest{
+			name: fmt.Sprintf("single license test: %s", licenseName),
+			arg:  string(license),
+			want: []string{ConvertLicenseName(licenseName)},
+		})
+	}
+
+	err = InitLicenseClassifier()
+	assert.NoError(t, err)
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			license, err := detectLicense(strings.NewReader(tt.arg))
+			assert.NoError(t, err)
+			assert.Equal(t, tt.want, license)
+		})
+	}
+
+	result, err := detectLicense(strings.NewReader(tests[2].arg + tests[3].arg + tests[4].arg))
+	assert.NoError(t, err)
+	t.Run("multiple licenses test", func(t *testing.T) {
+		assert.Equal(t, 3, len(result))
+		assert.Contains(t, result, tests[2].want[0])
+		assert.Contains(t, result, tests[3].want[0])
+		assert.Contains(t, result, tests[4].want[0])
+	})
+}

services/repository/migrate.go

@@ -172,6 +172,11 @@ func MigrateRepositoryGitData(ctx context.Context, u *user_model.User,
 				return repo, fmt.Errorf("StoreMissingLfsObjectsInRepository: %w", err)
 			}
 		}
+
+		// Update repo license
+		if err := AddRepoToLicenseUpdaterQueue(&LicenseUpdaterOptions{RepoID: repo.ID}); err != nil {
+			log.Error("Failed to add repo to license updater queue: %v", err)
+		}
 	}
 
 	ctx, committer, err := db.TxContext(ctx)

services/repository/repository.go

@@ -18,6 +18,7 @@ import (
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/graceful"
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/queue"
 	repo_module "code.gitea.io/gitea/modules/repository"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/structs"
@@ -96,6 +97,12 @@ func PushCreateRepo(ctx context.Context, authUser, owner *user_model.User, repoN
 
 // Init start repository service
 func Init(ctx context.Context) error {
+	licenseUpdaterQueue = queue.CreateUniqueQueue(graceful.GetManager().ShutdownContext(), "repo_license_updater", repoLicenseUpdater)
+	if licenseUpdaterQueue == nil {
+		return fmt.Errorf("unable to create repo_license_updater queue")
+	}
+	go graceful.GetManager().RunWithCancel(licenseUpdaterQueue)
+
 	if err := repo_module.LoadRepoConfig(); err != nil {
 		return err
 	}

templates/repo/sub_menu.tmpl

@@ -13,7 +13,12 @@
 					{{svg "octicon-tag"}} <b>{{ctx.Locale.PrettyNumber .NumTags}}</b> {{ctx.Locale.TrN .NumTags "repo.tag" "repo.tags"}}
 				</a>
 			{{end}}
-			<span class="item not-mobile" {{if not (eq .Repository.Size 0)}}data-tooltip-content="{{.Repository.SizeDetailsString}}"{{end}}>
+			{{if .DetectedRepoLicenses}}
+				<a class="item muted" href="{{.RepoLink}}/src/{{.Repository.DefaultBranch}}/{{PathEscapeSegments .LicenseFileName}}" data-tooltip-placement="top" data-tooltip-content="{{StringUtils.Join .DetectedRepoLicenses ", "}}">
+					{{svg "octicon-law"}} <b>{{if eq (len .DetectedRepoLicenses) 1}}{{index .DetectedRepoLicenses 0}}{{else}}{{ctx.Locale.Tr "repo.multiple_licenses"}}{{end}}</b>
+				</a>
+			{{end}}
+			<span class="item not-mobile" {{if not (eq .Repository.Size 0)}}data-tooltip-placement="top" data-tooltip-content="{{.Repository.SizeDetailsString}}"{{end}}>
 				{{$fileSizeFormatted := FileSize .Repository.Size}}{{/* the formatted string is always "{val} {unit}" */}}
 				{{$fileSizeFields := StringUtils.Split $fileSizeFormatted " "}}
 				{{svg "octicon-database"}} <b>{{ctx.Locale.PrettyNumber (index $fileSizeFields 0)}}</b> {{index $fileSizeFields 1}}

templates/swagger/v1_json.tmpl

@@ -10640,6 +10640,42 @@
         }
       }
     },
+    "/repos/{owner}/{repo}/licenses": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "repository"
+        ],
+        "summary": "Get repo licenses",
+        "operationId": "repoGetLicenses",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/LicensesList"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          }
+        }
+      }
+    },
     "/repos/{owner}/{repo}/media/{filepath}": {
       "get": {
         "produces": [
@@ -24142,6 +24178,13 @@
           "type": "string",
           "x-go-name": "LanguagesURL"
         },
+        "licenses": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "x-go-name": "Licenses"
+        },
         "link": {
           "type": "string",
           "x-go-name": "Link"
@@ -25717,6 +25760,15 @@
         }
       }
     },
+    "LicensesList": {
+      "description": "LicensesList",
+      "schema": {
+        "type": "array",
+        "items": {
+          "type": "string"
+        }
+      }
+    },
     "MarkdownRender": {
       "description": "MarkdownRender is a rendered markdown document",
       "schema": {

tests/gitea-repositories-meta/user2/repo1.git/objects/90/c1019714259b24fb81711d4416ac0f18667dfa

@@ -0,0 +1,2 @@
+x
•ŽM
+Â0F]çÙ2“d&ñ*ù™`Á¶¶Æ…··Wð[>Þƒ¯®ó<
ëÐ<C3AB>Æ®j!Æ&=Õ*Êž1*¢@””TS*X3›WÞu–©cé.–êK<C3AA>Ð90E¦Äž”$h+µ„fòg<ÖÝ~_@ÞE{=,!€÷m»Ôu¾YŒ Ž„B´g8fz|ú_erkö9U]Þj~2]<¼

tests/gitea-repositories-meta/user2/repo1.git/refs/heads/DefaultBranch

@@ -1 +1 @@
-65f1bf27bc3bf70f64657658635e66094edbcb4d
+90c1019714259b24fb81711d4416ac0f18667dfa

tests/integration/api_admin_test.go

@@ -304,11 +304,11 @@ func TestAPICron(t *testing.T) {
 			AddTokenAuth(token)
 		resp := MakeRequest(t, req, http.StatusOK)
 
-		assert.Equal(t, "28", resp.Header().Get("X-Total-Count"))
+		assert.Equal(t, "29", resp.Header().Get("X-Total-Count"))
 
 		var crons []api.Cron
 		DecodeJSON(t, resp, &crons)
-		assert.Len(t, crons, 28)
+		assert.Len(t, crons, 29)
 	})
 
 	t.Run("Execute", func(t *testing.T) {

tests/integration/api_repo_license_test.go

@@ -0,0 +1,80 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"testing"
+	"time"
+
+	auth_model "code.gitea.io/gitea/models/auth"
+	api "code.gitea.io/gitea/modules/structs"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var testLicenseContent = `
+Copyright (c) 2024 Gitea 
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+`
+
+func TestAPIRepoLicense(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		session := loginUser(t, "user2")
+
+		// Request editor page
+		req := NewRequest(t, "GET", "/user2/repo1/_new/master/")
+		resp := session.MakeRequest(t, req, http.StatusOK)
+
+		doc := NewHTMLParser(t, resp.Body)
+		lastCommit := doc.GetInputValueByName("last_commit")
+		assert.NotEmpty(t, lastCommit)
+
+		// Save new file to master branch
+		req = NewRequestWithValues(t, "POST", "/user2/repo1/_new/master/", map[string]string{
+			"_csrf":         doc.GetCSRF(),
+			"last_commit":   lastCommit,
+			"tree_path":     "LICENSE",
+			"content":       testLicenseContent,
+			"commit_choice": "direct",
+		})
+		session.MakeRequest(t, req, http.StatusSeeOther)
+
+		// let gitea update repo license
+		time.Sleep(time.Second)
+		checkRepoLicense(t, "user2", "repo1", []string{"BSD-2-Clause"})
+
+		// Change default branch
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteRepository)
+		branchName := "DefaultBranch"
+		req = NewRequestWithJSON(t, "PATCH", "/api/v1/repos/user2/repo1", api.EditRepoOption{
+			DefaultBranch: &branchName,
+		}).AddTokenAuth(token)
+		session.MakeRequest(t, req, http.StatusOK)
+
+		// let gitea update repo license
+		time.Sleep(time.Second)
+		checkRepoLicense(t, "user2", "repo1", []string{"MIT"})
+	})
+}
+
+func checkRepoLicense(t *testing.T, owner, repo string, expected []string) {
+	reqURL := fmt.Sprintf("/api/v1/repos/%s/%s/licenses", owner, repo)
+	req := NewRequest(t, "GET", reqURL)
+	resp := MakeRequest(t, req, http.StatusOK)
+
+	var licenses []string
+	DecodeJSON(t, resp, &licenses)
+
+	assert.ElementsMatch(t, expected, licenses, 0)
+}