example_filesystem_test.go

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package http_test
     6  
     7  import (
     8  	"io/fs"
     9  	"log"
    10  	"net/http"
    11  	"strings"
    12  )
    13  
    14  // containsDotFile reports whether name contains a path element starting with a period.
    15  // The name is assumed to be a delimited by forward slashes, as guaranteed
    16  // by the http.FileSystem interface.
    17  func containsDotFile(name string) bool {
    18  	parts := strings.Split(name, "/")
    19  	for _, part := range parts {
    20  		if strings.HasPrefix(part, ".") {
    21  			return true
    22  		}
    23  	}
    24  	return false
    25  }
    26  
    27  // dotFileHidingFile is the http.File use in dotFileHidingFileSystem.
    28  // It is used to wrap the Readdir method of http.File so that we can
    29  // remove files and directories that start with a period from its output.
    30  type dotFileHidingFile struct {
    31  	http.File
    32  }
    33  
    34  // Readdir is a wrapper around the Readdir method of the embedded File
    35  // that filters out all files that start with a period in their name.
    36  func (f dotFileHidingFile) Readdir(n int) (fis []fs.FileInfo, err error) {
    37  	files, err := f.File.Readdir(n)
    38  	for _, file := range files { // Filters out the dot files
    39  		if !strings.HasPrefix(file.Name(), ".") {
    40  			fis = append(fis, file)
    41  		}
    42  	}
    43  	return
    44  }
    45  
    46  // dotFileHidingFileSystem is an http.FileSystem that hides
    47  // hidden "dot files" from being served.
    48  type dotFileHidingFileSystem struct {
    49  	http.FileSystem
    50  }
    51  
    52  // Open is a wrapper around the Open method of the embedded FileSystem
    53  // that serves a 403 permission error when name has a file or directory
    54  // with whose name starts with a period in its path.
    55  func (fsys dotFileHidingFileSystem) Open(name string) (http.File, error) {
    56  	if containsDotFile(name) { // If dot file, return 403 response
    57  		return nil, fs.ErrPermission
    58  	}
    59  
    60  	file, err := fsys.FileSystem.Open(name)
    61  	if err != nil {
    62  		return nil, err
    63  	}
    64  	return dotFileHidingFile{file}, err
    65  }
    66  
    67  func ExampleFileServer_dotFileHiding() {
    68  	fsys := dotFileHidingFileSystem{http.Dir(".")}
    69  	http.Handle("/", http.FileServer(fsys))
    70  	log.Fatal(http.ListenAndServe(":8080", nil))
    71  }
    72
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