feat(serverHandler): add WSL 1 fix

`http.ServeContent` does not work well in WSL 1. The downloaded file
content may corrupt.

Apply a workaround fix if in WSL 1.

See also: golang/go#27128

Author: marjune163

src/app/main.go

@@ -4,10 +4,12 @@ import (
 	"../goVirtualHost"
 	"../param"
 	"../serverErrHandler"
+	"../serverHandler"
 	"../serverLog"
 	"../tpl"
 	"../util"
 	"../vhostHandler"
+	"fmt"
 	"os"
 	"path/filepath"
 )
@@ -34,6 +36,14 @@ func (app *App) ReOpenLog() {
 }
 
 func NewApp(params []*param.Param) *App {
+	verbose := !util.GetBoolEnv("GHFS_QUIET")
+
+	if serverHandler.TryEnableWSL1Fix() && verbose {
+		ttyFile, teardownTtyFile := util.GetTTYFile()
+		fmt.Fprintln(ttyFile, "WSL 1 compatible mode enabled")
+		teardownTtyFile()
+	}
+
 	vhSvc := goVirtualHost.NewService()
 	vhHandlers := make([]*vhostHandler.VhostHandler, 0, len(params))
 	logFileMan := serverLog.NewFileMan()
@@ -95,7 +105,7 @@ func NewApp(params []*param.Param) *App {
 		}
 	}
 
-	if !util.GetBoolEnv("GHFS_QUIET") {
+	if verbose {
 		go printAccessibleURLs(vhSvc)
 	}
 

src/serverHandler/content.go

@@ -3,10 +3,15 @@ package serverHandler
 import (
 	"../util"
 	"net/http"
+	"os"
 	"strconv"
 	"time"
 )
 
+var serveContent = func(h *handler, w http.ResponseWriter, r *http.Request, info os.FileInfo, file *os.File) {
+	http.ServeContent(w, r, info.Name(), info.ModTime(), file)
+}
+
 func (h *handler) content(w http.ResponseWriter, r *http.Request, data *responseData) {
 	header := w.Header()
 	header.Set("X-Content-Type-Options", "nosniff")
@@ -18,7 +23,7 @@ func (h *handler) content(w http.ResponseWriter, r *http.Request, data *response
 	file := data.File
 
 	if needResponseBody(r.Method) {
-		http.ServeContent(w, r, item.Name(), item.ModTime(), file)
+		serveContent(h, w, r, item, file)
 		return
 	}
 

src/serverHandler/handler.go

@@ -11,6 +11,8 @@ import (
 	"strings"
 )
 
+var createFileServer func(root string) http.Handler
+
 type handler struct {
 	root        string
 	emptyRoot   bool
@@ -58,6 +60,8 @@ type handler struct {
 	hideFiles *regexp.Regexp
 	theme     tpl.Theme
 
+	fileServer http.Handler
+
 	logger     *serverLog.Logger
 	errHandler *serverErrHandler.ErrHandler
 }
@@ -156,6 +160,11 @@ func newHandler(
 		}
 	}
 
+	var fileServer http.Handler
+	if !emptyRoot && createFileServer != nil { // for WSL 1 fix
+		fileServer = createFileServer(root)
+	}
+
 	h := &handler{
 		root:        root,
 		emptyRoot:   emptyRoot,
@@ -203,6 +212,8 @@ func newHandler(
 		hideFiles: p.HideFiles,
 		theme:     theme,
 
+		fileServer: fileServer,
+
 		logger:     logger,
 		errHandler: errHandler,
 	}

src/serverHandler/wsl1.go

@@ -0,0 +1,41 @@
+package serverHandler
+
+import (
+	"net/http"
+	"os"
+	"runtime"
+)
+
+type wrappedHttpFile struct {
+	http.File
+}
+
+func (f wrappedHttpFile) Readdir(n int) (items []os.FileInfo, err error) {
+	return f.File.Readdir(n)
+}
+
+type wrappedHttpFileSystem struct {
+	http.FileSystem
+}
+
+func (fs wrappedHttpFileSystem) Open(name string) (http.File, error) {
+	file, err := fs.FileSystem.Open(name)
+	return wrappedHttpFile{file}, err
+}
+
+func createFsFileServer(root string) http.Handler {
+	return http.FileServer(wrappedHttpFileSystem{http.Dir(root)})
+}
+
+func serveFsContent(h *handler, w http.ResponseWriter, r *http.Request, info os.FileInfo, file *os.File) {
+	h.fileServer.ServeHTTP(w, r)
+}
+
+func TryEnableWSL1Fix() bool {
+	if runtime.GOOS == "linux" && len(os.Getenv("WSL_DISTRO_NAME")) > 0 && len(os.Getenv("WSL_INTEROP")) == 0 {
+		createFileServer = createFsFileServer
+		serveContent = serveFsContent
+		return true
+	}
+	return false
+}