libgo/go/http/fs.go

   1 // Copyright 2009 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 // HTTP file system request handler
   6
   7 package http
   8
   9 import (
  10         "fmt"
  11         "io"
  12         "mime"
  13         "os"
  14         "path"
  15         "strings"
  16         "time"
  17         "utf8"
  18 )
  19
  20 // Heuristic: b is text if it is valid UTF-8 and doesn't
  21 // contain any unprintable ASCII or Unicode characters.
  22 func isText(b []byte) bool {
  23         for len(b) > 0 && utf8.FullRune(b) {
  24                 rune, size := utf8.DecodeRune(b)
  25                 if size == 1 && rune == utf8.RuneError {
  26                         // decoding error
  27                         return false
  28                 }
  29                 if 0x80 <= rune && rune <= 0x9F {
  30                         return false
  31                 }
  32                 if rune < ' ' {
  33                         switch rune {
  34                         case '\n', '\r', '\t':
  35                                 // okay
  36                         default:
  37                                 // binary garbage
  38                                 return false
  39                         }
  40                 }
  41                 b = b[size:]
  42         }
  43         return true
  44 }
  45
  46 func dirList(w ResponseWriter, f *os.File) {
  47         fmt.Fprintf(w, "<pre>\n")
  48         for {
  49                 dirs, err := f.Readdir(100)
  50                 if err != nil || len(dirs) == 0 {
  51                         break
  52                 }
  53                 for _, d := range dirs {
  54                         name := d.Name
  55                         if d.IsDirectory() {
  56                                 name += "/"
  57                         }
  58                         // TODO htmlescape
  59                         fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", name, name)
  60                 }
  61         }
  62         fmt.Fprintf(w, "</pre>\n")
  63 }
  64
  65 func serveFile(w ResponseWriter, r *Request, name string, redirect bool) {
  66         const indexPage = "/index.html"
  67
  68         // redirect .../index.html to .../
  69         if strings.HasSuffix(r.URL.Path, indexPage) {
  70                 Redirect(w, r, r.URL.Path[0:len(r.URL.Path)-len(indexPage)+1], StatusMovedPermanently)
  71                 return
  72         }
  73
  74         f, err := os.Open(name, os.O_RDONLY, 0)
  75         if err != nil {
  76                 // TODO expose actual error?
  77                 NotFound(w, r)
  78                 return
  79         }
  80         defer f.Close()
  81
  82         d, err1 := f.Stat()
  83         if err1 != nil {
  84                 // TODO expose actual error?
  85                 NotFound(w, r)
  86                 return
  87         }
  88
  89         if redirect {
  90                 // redirect to canonical path: / at end of directory url
  91                 // r.URL.Path always begins with /
  92                 url := r.URL.Path
  93                 if d.IsDirectory() {
  94                         if url[len(url)-1] != '/' {
  95                                 Redirect(w, r, url+"/", StatusMovedPermanently)
  96                                 return
  97                         }
  98                 } else {
  99                         if url[len(url)-1] == '/' {
 100                                 Redirect(w, r, url[0:len(url)-1], StatusMovedPermanently)
 101                                 return
 102                         }
 103                 }
 104         }
 105
 106         if t, _ := time.Parse(TimeFormat, r.Header["If-Modified-Since"]); t != nil && d.Mtime_ns/1e9 <= t.Seconds() {
 107                 w.WriteHeader(StatusNotModified)
 108                 return
 109         }
 110         w.SetHeader("Last-Modified", time.SecondsToUTC(d.Mtime_ns/1e9).Format(TimeFormat))
 111
 112         // use contents of index.html for directory, if present
 113         if d.IsDirectory() {
 114                 index := name + indexPage
 115                 ff, err := os.Open(index, os.O_RDONLY, 0)
 116                 if err == nil {
 117                         defer ff.Close()
 118                         dd, err := ff.Stat()
 119                         if err == nil {
 120                                 name = index
 121                                 d = dd
 122                                 f = ff
 123                         }
 124                 }
 125         }
 126
 127         if d.IsDirectory() {
 128                 dirList(w, f)
 129                 return
 130         }
 131
 132         // serve file
 133         // use extension to find content type.
 134         ext := path.Ext(name)
 135         if ctype := mime.TypeByExtension(ext); ctype != "" {
 136                 w.SetHeader("Content-Type", ctype)
 137         } else {
 138                 // read first chunk to decide between utf-8 text and binary
 139                 var buf [1024]byte
 140                 n, _ := io.ReadFull(f, buf[0:])
 141                 b := buf[0:n]
 142                 if isText(b) {
 143                         w.SetHeader("Content-Type", "text-plain; charset=utf-8")
 144                 } else {
 145                         w.SetHeader("Content-Type", "application/octet-stream") // generic binary
 146                 }
 147                 w.Write(b)
 148         }
 149         io.Copy(w, f)
 150 }
 151
 152 // ServeFile replies to the request with the contents of the named file or directory.
 153 func ServeFile(w ResponseWriter, r *Request, name string) {
 154         serveFile(w, r, name, false)
 155 }
 156
 157 type fileHandler struct {
 158         root   string
 159         prefix string
 160 }
 161
 162 // FileServer returns a handler that serves HTTP requests
 163 // with the contents of the file system rooted at root.
 164 // It strips prefix from the incoming requests before
 165 // looking up the file name in the file system.
 166 func FileServer(root, prefix string) Handler { return &fileHandler{root, prefix} }
 167
 168 func (f *fileHandler) ServeHTTP(w ResponseWriter, r *Request) {
 169         path := r.URL.Path
 170         if !strings.HasPrefix(path, f.prefix) {
 171                 NotFound(w, r)
 172                 return
 173         }
 174         path = path[len(f.prefix):]
 175         serveFile(w, r, f.root+"/"+path, true)
 176 }