chore: refactor rest file server (#4851)

Signed-off-by: kevin <wanjunfeng@gmail.com>

rest/internal/fileserver/filehandler.go

@@ -2,16 +2,16 @@ package fileserver
 
 import (
 	"net/http"
-	pathpkg "path"
+	"path"
 	"strings"
 	"sync"
 )
 
 // Middleware returns a middleware that serves files from the given file system.
-func Middleware(path string, fs http.FileSystem) func(http.HandlerFunc) http.HandlerFunc {
+func Middleware(upath string, fs http.FileSystem) func(http.HandlerFunc) http.HandlerFunc {
 	fileServer := http.FileServer(fs)
-	pathWithoutTrailSlash := ensureNoTrailingSlash(path)
-	canServe := createServeChecker(path, fs)
+	pathWithoutTrailSlash := ensureNoTrailingSlash(upath)
+	canServe := createServeChecker(upath, fs)
 
 	return func(next http.HandlerFunc) http.HandlerFunc {
 		return func(w http.ResponseWriter, r *http.Request) {
@@ -29,7 +29,7 @@ func createFileChecker(fs http.FileSystem) func(string) bool {
 	var lock sync.RWMutex
 	fileChecker := make(map[string]bool)
 
-	return func(path string) bool {
+	return func(upath string) bool {
 		// Emulate http.Dir.Open’s path normalization for embed.FS.Open.
 		// http.FileServer redirects any request ending in "/index.html"
 		// to the same path without the final "index.html".
@@ -37,13 +37,14 @@ func createFileChecker(fs http.FileSystem) func(string) bool {
 		// http.Dir.Open uses this logic to clean the path,
 		// correctly handling those two cases.
 		// embed.FS doesn’t perform this normalization, so we apply the same logic here.
-		path = pathpkg.Clean("/" + path)[1:]
-		if path == "" {
-			path = "."
+		upath = path.Clean("/" + upath)[1:]
+		if len(upath) == 0 {
+			// if the path is empty, we use "." to open the current directory
+			upath = "."
 		}
 
 		lock.RLock()
-		exist, ok := fileChecker[path]
+		exist, ok := fileChecker[upath]
 		lock.RUnlock()
 		if ok {
 			return exist
@@ -52,9 +53,9 @@ func createFileChecker(fs http.FileSystem) func(string) bool {
 		lock.Lock()
 		defer lock.Unlock()
 
-		file, err := fs.Open(path)
+		file, err := fs.Open(upath)
 		exist = err == nil
-		fileChecker[path] = exist
+		fileChecker[upath] = exist
 		if err != nil {
 			return false
 		}
@@ -64,8 +65,8 @@ func createFileChecker(fs http.FileSystem) func(string) bool {
 	}
 }
 
-func createServeChecker(path string, fs http.FileSystem) func(r *http.Request) bool {
-	pathWithTrailSlash := ensureTrailingSlash(path)
+func createServeChecker(upath string, fs http.FileSystem) func(r *http.Request) bool {
+	pathWithTrailSlash := ensureTrailingSlash(upath)
 	fileChecker := createFileChecker(fs)
 
 	return func(r *http.Request) bool {
@@ -75,18 +76,18 @@ func createServeChecker(path string, fs http.FileSystem) func(r *http.Request) b
 	}
 }
 
-func ensureTrailingSlash(path string) string {
-	if strings.HasSuffix(path, "/") {
-		return path
+func ensureTrailingSlash(upath string) string {
+	if strings.HasSuffix(upath, "/") {
+		return upath
 	}
 
-	return path + "/"
+	return upath + "/"
 }
 
-func ensureNoTrailingSlash(path string) string {
-	if strings.HasSuffix(path, "/") {
-		return path[:len(path)-1]
+func ensureNoTrailingSlash(upath string) string {
+	if strings.HasSuffix(upath, "/") {
+		return upath[:len(upath)-1]
 	}
 
-	return path
+	return upath
 }