Introduce path Clean/Join helper functions, partially backport&refactor (#23495) (#23607)

Backport #23495, partially backport&refactor

The `modules/options` files are just copied from 1.20 to 1.19

modules/options/base.go

@@ -9,9 +9,52 @@ import (
 	"os"
 	"path/filepath"
 
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 )
 
+var directories = make(directorySet)
+
+// Locale reads the content of a specific locale from static/bindata or custom path.
+func Locale(name string) ([]byte, error) {
+	return fileFromOptionsDir("locale", name)
+}
+
+// Readme reads the content of a specific readme from static/bindata or custom path.
+func Readme(name string) ([]byte, error) {
+	return fileFromOptionsDir("readme", name)
+}
+
+// Gitignore reads the content of a gitignore locale from static/bindata or custom path.
+func Gitignore(name string) ([]byte, error) {
+	return fileFromOptionsDir("gitignore", name)
+}
+
+// License reads the content of a specific license from static/bindata or custom path.
+func License(name string) ([]byte, error) {
+	return fileFromOptionsDir("license", name)
+}
+
+// Labels reads the content of a specific labels from static/bindata or custom path.
+func Labels(name string) ([]byte, error) {
+	return fileFromOptionsDir("label", name)
+}
+
+// WalkLocales reads the content of a specific locale
+func WalkLocales(callback func(path, name string, d fs.DirEntry, err error) error) error {
+	if IsDynamic() {
+		if err := walkAssetDir(filepath.Join(setting.StaticRootPath, "options", "locale"), callback); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("failed to walk locales. Error: %w", err)
+		}
+	}
+
+	if err := walkAssetDir(filepath.Join(setting.CustomPath, "options", "locale"), callback); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to walk locales. Error: %w", err)
+	}
+	return nil
+}
+
 func walkAssetDir(root string, callback func(path, name string, d fs.DirEntry, err error) error) error {
 	if err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
 		// name is the path relative to the root
@@ -37,3 +80,55 @@ func walkAssetDir(root string, callback func(path, name string, d fs.DirEntry, e
 	}
 	return nil
 }
+
+// mustLocalPathAbs coverts a path to absolute path
+// FIXME: the old behavior (StaticRootPath might not be absolute), not ideal, just keep the same as before
+func mustLocalPathAbs(s string) string {
+	abs, err := filepath.Abs(s)
+	if err != nil {
+		// This should never happen in a real system. If it happens, the user must have already been in trouble: the system is not able to resolve its own paths.
+		log.Fatal("Unable to get absolute path for %q: %v", s, err)
+	}
+	return abs
+}
+
+func joinLocalPaths(baseDirs []string, subDir string, elems ...string) (paths []string) {
+	abs := make([]string, len(elems)+2)
+	abs[1] = subDir
+	copy(abs[2:], elems)
+	for _, baseDir := range baseDirs {
+		abs[0] = mustLocalPathAbs(baseDir)
+		paths = append(paths, util.FilePathJoinAbs(abs...))
+	}
+	return paths
+}
+
+func listLocalDirIfExist(baseDirs []string, subDir string, elems ...string) (files []string, err error) {
+	for _, localPath := range joinLocalPaths(baseDirs, subDir, elems...) {
+		isDir, err := util.IsDir(localPath)
+		if err != nil {
+			return nil, fmt.Errorf("unable to check if path %q is a directory. %w", localPath, err)
+		} else if !isDir {
+			continue
+		}
+
+		dirFiles, err := util.StatDir(localPath, true)
+		if err != nil {
+			return nil, fmt.Errorf("unable to read directory %q. %w", localPath, err)
+		}
+		files = append(files, dirFiles...)
+	}
+	return files, nil
+}
+
+func readLocalFile(baseDirs []string, subDir string, elems ...string) ([]byte, error) {
+	for _, localPath := range joinLocalPaths(baseDirs, subDir, elems...) {
+		data, err := os.ReadFile(localPath)
+		if err == nil {
+			return data, nil
+		} else if !os.IsNotExist(err) {
+			log.Error("Unable to read file %q. Error: %v", localPath, err)
+		}
+	}
+	return nil, os.ErrNotExist
+}