created hws module

hws/safefileserver.go

@@ -0,0 +1,52 @@
+package hws
+
+import (
+	"net/http"
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+// Wrapper for default FileSystem
+type justFilesFilesystem struct {
+	fs http.FileSystem
+}
+
+// Wrapper for default File
+type neuteredReaddirFile struct {
+	http.File
+}
+
+// Modifies the behavior of FileSystem.Open to return the neutered version of File
+func (fs justFilesFilesystem) Open(name string) (http.File, error) {
+	f, err := fs.fs.Open(name)
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if the requested path is a directory
+	// and explicitly return an error to trigger a 404
+	fileInfo, err := f.Stat()
+	if err != nil {
+		return nil, err
+	}
+	if fileInfo.IsDir() {
+		return nil, os.ErrNotExist
+	}
+
+	return neuteredReaddirFile{f}, nil
+}
+
+// Overrides the Readdir method of File to always return nil
+func (f neuteredReaddirFile) Readdir(count int) ([]os.FileInfo, error) {
+	return nil, nil
+}
+
+func SafeFileServer(fileSystem *http.FileSystem) (http.Handler, error) {
+	if fileSystem == nil {
+		return nil, errors.New("No file system provided")
+	}
+	nfs := justFilesFilesystem{*fileSystem}
+	fs := http.FileServer(nfs)
+	return fs, nil
+}