Use fs.FS in MergeFS implementation

server/nativeapi/translations.go

@@ -4,8 +4,9 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"io/fs"
 	"io/ioutil"
-	"net/http"
+	"os"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -30,10 +31,10 @@ var (
 )
 
 func newTranslationRepository(context.Context) rest.Repository {
-	dir := utils.NewMergeFS(
-		http.FS(resources.FS),
-		http.Dir(filepath.Join(conf.Server.DataFolder, "resources")),
-	)
+	dir := utils.MergeFS{
+		Base:    resources.FS,
+		Overlay: os.DirFS(filepath.Join(conf.Server.DataFolder, "resources")),
+	}
 	if err := loadTranslations(dir); err != nil {
 		log.Error("Error loading translation files", err)
 	}
@@ -72,22 +73,22 @@ func (r *translationRepository) NewInstance() interface{} {
 	return &translation{}
 }
 
-func loadTranslations(fs http.FileSystem) (loadError error) {
+func loadTranslations(fsys fs.FS) (loadError error) {
 	once.Do(func() {
 		translations = make(map[string]translation)
-		dir, err := fs.Open(consts.I18nFolder)
+		dir, err := fsys.Open(consts.I18nFolder)
 		if err != nil {
 			loadError = err
 			return
 		}
-		files, err := dir.Readdir(0)
+		files, err := dir.(fs.ReadDirFile).ReadDir(-1)
 		if err != nil {
 			loadError = err
 			return
 		}
 		var languages []string
 		for _, f := range files {
-			t, err := loadTranslation(fs, f.Name())
+			t, err := loadTranslation(fsys, f.Name())
 			if err != nil {
 				log.Error("Error loading translation file", "file", f.Name(), err)
 				continue
@@ -100,14 +101,14 @@ func loadTranslations(fs http.FileSystem) (loadError error) {
 	return
 }
 
-func loadTranslation(fs http.FileSystem, fileName string) (translation translation, err error) {
+func loadTranslation(fsys fs.FS, fileName string) (translation translation, err error) {
 	// Get id and full path
 	name := filepath.Base(fileName)
 	id := strings.TrimSuffix(name, filepath.Ext(name))
 	filePath := filepath.Join(consts.I18nFolder, name)
 
 	// Load translation from json file
-	file, err := fs.Open(filePath)
+	file, err := fsys.Open(filePath)
 	if err != nil {
 		return
 	}

server/nativeapi/translations_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"path/filepath"
 
 	"github.com/navidrome/navidrome/consts"
@@ -37,7 +38,7 @@ var _ = Describe("Translations", func() {
 
 	Describe("loadTranslation", func() {
 		It("loads a translation file correctly", func() {
-			fs := http.Dir("ui/src")
+			fs := os.DirFS("ui/src")
 			tr, err := loadTranslation(fs, "en.json")
 			Expect(err).To(BeNil())
 			Expect(tr.ID).To(Equal("en"))

utils/merge_fs.go

@@ -1,64 +1,58 @@
 package utils
 
 import (
-	"fmt"
+	"errors"
 	"io"
-	"net/http"
-	"os"
+	"io/fs"
 	"sort"
 )
 
-// NewMergeFS returns a simple implementation of a merged FS (http.FileSystem), that can combine a base FS with a
-// overlay FS. The semantics are:
-// - Files from the overlay FS will override file s with the same name in the base FS
-// - Directories are combined, with priority for the overlay FS over the base FS for files with matching names
-// TODO Replace http.FileSystem with new fs.FS interface
-func NewMergeFS(base, overlay http.FileSystem) http.FileSystem {
-	return &mergeFS{
-		base:    base,
-		overlay: overlay,
-	}
+// MergeFS implements a simple merged fs.FS, that can combine a Base FS with an Overlay FS. The semantics are:
+// - Files from the Overlay FS will override files with the same name in the Base FS
+// - Directories are combined, with priority for the Overlay FS over the Base FS for files with matching names
+type MergeFS struct {
+	Base    fs.FS
+	Overlay fs.FS
 }
 
-type mergeFS struct {
-	base    http.FileSystem
-	overlay http.FileSystem
-}
-
-func (m mergeFS) Open(name string) (http.File, error) {
-	f, err := m.overlay.Open(name)
+func (m MergeFS) Open(name string) (fs.File, error) {
+	file, err := m.Overlay.Open(name)
 	if err != nil {
-		return m.base.Open(name)
+		return m.Base.Open(name)
 	}
 
-	info, err := f.Stat()
+	info, err := file.Stat()
 	if err != nil {
-		_ = f.Close()
-		return m.base.Open(name)
+		_ = file.Close()
+		return nil, err
+	}
+	overlayDirFile, ok := file.(fs.ReadDirFile)
+	if !info.IsDir() || !ok {
+		return file, nil
 	}
 
-	if !info.IsDir() {
-		return f, nil
-	}
-
-	baseDir, _ := m.base.Open(name)
+	baseDir, _ := m.Base.Open(name)
 	defer func() {
 		_ = baseDir.Close()
-		_ = f.Close()
+		_ = file.Close()
 	}()
-	return m.mergeDirs(name, info, baseDir, f)
+	baseDirFile, ok := baseDir.(fs.ReadDirFile)
+	if !ok {
+		return nil, fs.ErrInvalid
+	}
+	return m.mergeDirs(name, info, baseDirFile, overlayDirFile)
 }
 
-func (m mergeFS) mergeDirs(name string, info os.FileInfo, baseDir http.File, overlayDir http.File) (http.File, error) {
-	merged := map[string]os.FileInfo{}
+func (m MergeFS) mergeDirs(name string, info fs.FileInfo, baseDir fs.ReadDirFile, overlayDir fs.ReadDirFile) (fs.File, error) {
+	merged := map[string]fs.DirEntry{}
 
-	baseFiles, err := baseDir.Readdir(-1)
+	baseFiles, err := baseDir.ReadDir(-1)
 	if err != nil {
 		return nil, err
 	}
 	sort.Slice(baseFiles, func(i, j int) bool { return baseFiles[i].Name() < baseFiles[j].Name() })
 
-	overlayFiles, err := overlayDir.Readdir(-1)
+	overlayFiles, err := overlayDir.ReadDir(-1)
 	if err != nil {
 		overlayFiles = nil
 	}
@@ -71,7 +65,7 @@ func (m mergeFS) mergeDirs(name string, info os.FileInfo, baseDir http.File, ove
 		merged[f.Name()] = f
 	}
 
-	var entries []os.FileInfo
+	var entries []fs.DirEntry
 	for _, i := range merged {
 		entries = append(entries, i)
 	}
@@ -86,32 +80,27 @@ func (m mergeFS) mergeDirs(name string, info os.FileInfo, baseDir http.File, ove
 
 type mergedDir struct {
 	name    string
-	info    os.FileInfo
-	entries []os.FileInfo
+	info    fs.FileInfo
+	entries []fs.DirEntry
 	pos     int
 }
 
-func (d *mergedDir) Readdir(count int) ([]os.FileInfo, error) {
+var _ fs.ReadDirFile = (*mergedDir)(nil)
+
+func (d *mergedDir) ReadDir(count int) ([]fs.DirEntry, error) {
 	if d.pos >= len(d.entries) && count > 0 {
 		return nil, io.EOF
 	}
 	if count <= 0 || count > len(d.entries)-d.pos {
 		count = len(d.entries) - d.pos
 	}
-	e := d.entries[d.pos : d.pos+count]
+	entries := d.entries[d.pos : d.pos+count]
 	d.pos += count
-	return e, nil
+	return entries, nil
 }
 
 func (d *mergedDir) Close() error               { return nil }
-func (d *mergedDir) Stat() (os.FileInfo, error) { return d.info, nil }
-func (d *mergedDir) Read(p []byte) (n int, err error) {
-	return 0, fmt.Errorf("cannot Read from directory %s", d.name)
-}
-func (d *mergedDir) Seek(offset int64, whence int) (int64, error) {
-	if offset == 0 && whence == io.SeekStart {
-		d.pos = 0
-		return 0, nil
-	}
-	return 0, fmt.Errorf("unsupported Seek in directory %s", d.name)
+func (d *mergedDir) Stat() (fs.FileInfo, error) { return d.info, nil }
+func (d *mergedDir) Read([]byte) (n int, err error) {
+	return 0, &fs.PathError{Op: "read", Path: d.name, Err: errors.New("is a directory")}
 }

utils/merge_fs_test.go

@@ -1,9 +1,8 @@
 package utils_test
 
 import (
-	"io"
+	"io/fs"
 	"io/ioutil"
-	"net/http"
 	"os"
 	"path/filepath"
 
@@ -12,19 +11,19 @@ import (
 	. "github.com/onsi/gomega"
 )
 
-var _ = Describe("mergeFS", func() {
+var _ = Describe("MergeFS", func() {
 	var baseName, overlayName string
-	var baseDir, overlayDir, mergedDir http.FileSystem
+	var baseDir, overlayDir, mergedDir fs.FS
 
 	BeforeEach(func() {
 		baseName, _ = ioutil.TempDir("", "merge_fs_base_test")
 		overlayName, _ = ioutil.TempDir("", "merge_fs_overlay_test")
-		baseDir = http.Dir(baseName)
-		overlayDir = http.Dir(overlayName)
-		mergedDir = utils.NewMergeFS(baseDir, overlayDir)
+		baseDir = os.DirFS(baseName)
+		overlayDir = os.DirFS(overlayName)
+		mergedDir = utils.MergeFS{Base: baseDir, Overlay: overlayDir}
 	})
 
-	It("reads from base dir if not found in overlay", func() {
+	It("reads from Base dir if not found in Overlay", func() {
 		_f(baseName, "a.json")
 		file, err := mergedDir.Open("a.json")
 		Expect(err).To(BeNil())
@@ -47,13 +46,13 @@ var _ = Describe("mergeFS", func() {
 		Expect(string(content)).To(Equal("overridden"))
 	})
 
-	It("reads only files from base if overlay is empty", func() {
+	It("reads only files from Base if Overlay is empty", func() {
 		_f(baseName, "test.txt")
 
 		dir, err := mergedDir.Open(".")
 		Expect(err).To(BeNil())
 
-		list, err := dir.Readdir(-1)
+		list, err := dir.(fs.ReadDirFile).ReadDir(-1)
 		Expect(err).To(BeNil())
 
 		Expect(list).To(HaveLen(1))
@@ -67,7 +66,7 @@ var _ = Describe("mergeFS", func() {
 		dir, err := mergedDir.Open(".")
 		Expect(err).To(BeNil())
 
-		list, err := dir.Readdir(-1)
+		list, err := dir.(fs.ReadDirFile).ReadDir(-1)
 		Expect(err).To(BeNil())
 
 		Expect(list).To(HaveLen(2))
@@ -83,17 +82,14 @@ var _ = Describe("mergeFS", func() {
 		dir, err := mergedDir.Open(".")
 		Expect(err).To(BeNil())
 
-		list, _ := dir.Readdir(2)
+		list, _ := dir.(fs.ReadDirFile).ReadDir(2)
 		Expect(list).To(HaveLen(2))
 		Expect(list[0].Name()).To(Equal("1111"))
 		Expect(list[1].Name()).To(Equal("2222"))
 
-		Expect(dir.Seek(0, io.SeekStart)).To(Equal(int64(0)))
-
-		list, _ = dir.Readdir(2)
-		Expect(list).To(HaveLen(2))
-		Expect(list[0].Name()).To(Equal("1111"))
-		Expect(list[1].Name()).To(Equal("2222"))
+		list, _ = dir.(fs.ReadDirFile).ReadDir(2)
+		Expect(list).To(HaveLen(1))
+		Expect(list[0].Name()).To(Equal("3333"))
 	})
 })