Add an option to allow empty root in the fsHandler (#1299)

* Add an option to allow empty root in the fsHandler

this is necessary to restore the capabilities before the commit c7576cc
and to allow further functionality to be docked from the outside which is not affected by setting the root dir afterwards

gofiber/fiber#1882 (comment)

* Add an option to allow empty root in the fsHandler

this is necessary to restore the capabilities before the commit c7576cc
and to allow further functionality to be docked from the outside which is not affected by setting the root dir afterwards

gofiber/fiber#1882 (comment)

* Update fs.go

Co-authored-by: Erik Dubbelboer <erik@dubbelboer.com>

* Update fs.go

Co-authored-by: Erik Dubbelboer <erik@dubbelboer.com>

Co-authored-by: Erik Dubbelboer <erik@dubbelboer.com>

fs.go

@@ -128,6 +128,7 @@ var (
 	rootFSOnce sync.Once
 	rootFS     = &FS{
 		Root:               "",
+		AllowEmptyRoot:     true,
 		GenerateIndexPages: true,
 		Compress:           true,
 		CompressBrotli:     true,
@@ -229,6 +230,12 @@ type FS struct {
 	// Path to the root directory to serve files from.
 	Root string
 
+	// AllowEmptyRoot controls what happens when Root is empty. When false (default) it will default to the
+	// current working directory. An empty root is mostly useful when you want to use absolute paths
+	// on windows that are on different filesystems. On linux setting your Root to "/" already allows you to use
+	// absolute paths on any filesystem.
+	AllowEmptyRoot bool
+
 	// List of index file names to try opening during directory access.
 	//
 	// For example:
@@ -384,19 +391,16 @@ func (fs *FS) NewRequestHandler() RequestHandler {
 func (fs *FS) initRequestHandler() {
 	root := fs.Root
 
-	// rootFS' handleRequest will do special treatment of absolute and relative paths
-	if fs != rootFS {
-		// serve files from the current working directory if root is empty
-		if len(root) == 0 || !filepath.IsAbs(root) {
-			path, err := os.Getwd()
-			if err != nil {
-				path = "."
-			}
-			root = path + "/" + root
+	// Serve files from the current working directory if Root is empty or if Root is a relative path.
+	if (!fs.AllowEmptyRoot && len(root) == 0) || (len(root) > 0 && !filepath.IsAbs(root)) {
+		path, err := os.Getwd()
+		if err != nil {
+			path = "."
 		}
-		// convert the root directory slashes to the native format
-		root = filepath.FromSlash(root)
+		root = path + "/" + root
 	}
+	// convert the root directory slashes to the native format
+	root = filepath.FromSlash(root)
 
 	// strip trailing slashes from the root path
 	for len(root) > 0 && root[len(root)-1] == os.PathSeparator {

go.sum

@@ -19,7 +19,6 @@ golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9 h1:nhht2DYV/Sn3qOayu8lM+cU1i
 golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=