Refactor context flash msg and global variables (#33375)

1. add `GetSiteCookieFlashMessage` to help to parse flash message
2. clarify `handleRepoHomeFeed` logic
3. remove unnecessary global variables, use `sync.OnceValue` instead
4. add some tests for `IsUsableUsername` and `IsUsableRepoName`

models/db/name.go

@@ -11,8 +11,6 @@ import (
 	"code.gitea.io/gitea/modules/util"
 )
 
-var ErrNameEmpty = util.SilentWrap{Message: "name is empty", Err: util.ErrInvalidArgument}
-
 // ErrNameReserved represents a "reserved name" error.
 type ErrNameReserved struct {
 	Name string
@@ -79,7 +77,7 @@ func (err ErrNameCharsNotAllowed) Unwrap() error {
 func IsUsableName(reservedNames, reservedPatterns []string, name string) error {
 	name = strings.TrimSpace(strings.ToLower(name))
 	if utf8.RuneCountInString(name) == 0 {
-		return ErrNameEmpty
+		return util.SilentWrap{Message: "name is empty", Err: util.ErrInvalidArgument}
 	}
 
 	for i := range reservedNames {

models/repo/repo.go

@@ -14,6 +14,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/models/unit"
@@ -61,20 +62,30 @@ func (err ErrRepoIsArchived) Error() string {
 	return fmt.Sprintf("%s is archived", err.Repo.LogString())
 }
 
-var (
-	validRepoNamePattern   = regexp.MustCompile(`[-.\w]+`)
-	invalidRepoNamePattern = regexp.MustCompile(`[.]{2,}`)
-	reservedRepoNames      = []string{".", "..", "-"}
-	reservedRepoPatterns   = []string{"*.git", "*.wiki", "*.rss", "*.atom"}
-)
+type globalVarsStruct struct {
+	validRepoNamePattern   *regexp.Regexp
+	invalidRepoNamePattern *regexp.Regexp
+	reservedRepoNames      []string
+	reservedRepoPatterns   []string
+}
+
+var globalVars = sync.OnceValue(func() *globalVarsStruct {
+	return &globalVarsStruct{
+		validRepoNamePattern:   regexp.MustCompile(`[-.\w]+`),
+		invalidRepoNamePattern: regexp.MustCompile(`[.]{2,}`),
+		reservedRepoNames:      []string{".", "..", "-"},
+		reservedRepoPatterns:   []string{"*.git", "*.wiki", "*.rss", "*.atom"},
+	}
+})
 
 // IsUsableRepoName returns true when name is usable
 func IsUsableRepoName(name string) error {
-	if !validRepoNamePattern.MatchString(name) || invalidRepoNamePattern.MatchString(name) {
+	vars := globalVars()
+	if !vars.validRepoNamePattern.MatchString(name) || vars.invalidRepoNamePattern.MatchString(name) {
 		// Note: usually this error is normally caught up earlier in the UI
 		return db.ErrNameCharsNotAllowed{Name: name}
 	}
-	return db.IsUsableName(reservedRepoNames, reservedRepoPatterns, name)
+	return db.IsUsableName(vars.reservedRepoNames, vars.reservedRepoPatterns, name)
 }
 
 // TrustModelType defines the types of trust model for this repository

models/repo/repo_test.go

@@ -219,4 +219,5 @@ func TestIsUsableRepoName(t *testing.T) {
 	assert.Error(t, IsUsableRepoName("the..repo"))
 	assert.Error(t, IsUsableRepoName("foo.wiki"))
 	assert.Error(t, IsUsableRepoName("foo.git"))
+	assert.Error(t, IsUsableRepoName("foo.RSS"))
 }

models/user/user.go

@@ -502,10 +502,10 @@ func (u *User) IsMailable() bool {
 	return u.IsActive
 }
 
-// IsUserExist checks if given user name exist,
-// the user name should be noncased unique.
+// IsUserExist checks if given username exist,
+// the username should be non-cased unique.
 // If uid is presented, then check will rule out that one,
-// it is used when update a user name in settings page.
+// it is used when update a username in settings page.
 func IsUserExist(ctx context.Context, uid int64, name string) (bool, error) {
 	if len(name) == 0 {
 		return false, nil
@@ -515,7 +515,7 @@ func IsUserExist(ctx context.Context, uid int64, name string) (bool, error) {
 		Get(&User{LowerName: strings.ToLower(name)})
 }
 
-// Note: As of the beginning of 2022, it is recommended to use at least
+// SaltByteLength as of the beginning of 2022, it is recommended to use at least
 // 64 bits of salt, but NIST is already recommending to use to 128 bits.
 // (16 bytes = 16 * 8 = 128 bits)
 const SaltByteLength = 16

models/user/user_test.go

@@ -25,6 +25,21 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestIsUsableUsername(t *testing.T) {
+	assert.NoError(t, user_model.IsUsableUsername("a"))
+	assert.NoError(t, user_model.IsUsableUsername("foo.wiki"))
+	assert.NoError(t, user_model.IsUsableUsername("foo.git"))
+
+	assert.Error(t, user_model.IsUsableUsername("a--b"))
+	assert.Error(t, user_model.IsUsableUsername("-1_."))
+	assert.Error(t, user_model.IsUsableUsername(".profile"))
+	assert.Error(t, user_model.IsUsableUsername("-"))
+	assert.Error(t, user_model.IsUsableUsername("🌞"))
+	assert.Error(t, user_model.IsUsableUsername("the..repo"))
+	assert.Error(t, user_model.IsUsableUsername("foo.RSS"))
+	assert.Error(t, user_model.IsUsableUsername("foo.PnG"))
+}
+
 func TestOAuth2Application_LoadUser(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	app := unittest.AssertExistsAndLoadBean(t, &auth.OAuth2Application{ID: 1})