blob: 39bf40ee89aa99e16f2e3e1c0a8d3f9e8e6589bd [file] [log] [blame]
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package mime implements parts of the MIME spec.
package mime
import (
"bufio"
"fmt"
"os"
"strings"
"sync"
)
var typeFiles = []string{
"/etc/mime.types",
"/etc/apache2/mime.types",
"/etc/apache/mime.types",
}
var mimeTypes = map[string]string{
".css": "text/css; charset=utf-8",
".gif": "image/gif",
".htm": "text/html; charset=utf-8",
".html": "text/html; charset=utf-8",
".jpg": "image/jpeg",
".js": "application/x-javascript",
".pdf": "application/pdf",
".png": "image/png",
".xml": "text/xml; charset=utf-8",
}
var mimeLock sync.RWMutex
func loadMimeFile(filename string) {
f, err := os.Open(filename)
if err != nil {
return
}
reader := bufio.NewReader(f)
for {
line, err := reader.ReadString('\n')
if err != nil {
f.Close()
return
}
fields := strings.Fields(line)
if len(fields) <= 1 || fields[0][0] == '#' {
continue
}
mimeType := fields[0]
for _, ext := range fields[1:] {
if ext[0] == '#' {
break
}
setExtensionType("."+ext, mimeType)
}
}
}
func initMime() {
for _, filename := range typeFiles {
loadMimeFile(filename)
}
}
var once sync.Once
// TypeByExtension returns the MIME type associated with the file extension ext.
// The extension ext should begin with a leading dot, as in ".html".
// When ext has no associated type, TypeByExtension returns "".
//
// The built-in table is small but is is augmented by the local
// system's mime.types file(s) if available under one or more of these
// names:
//
// /etc/mime.types
// /etc/apache2/mime.types
// /etc/apache/mime.types
//
// Text types have the charset parameter set to "utf-8" by default.
func TypeByExtension(ext string) string {
once.Do(initMime)
mimeLock.RLock()
typename := mimeTypes[ext]
mimeLock.RUnlock()
return typename
}
// AddExtensionType sets the MIME type associated with
// the extension ext to typ. The extension should begin with
// a leading dot, as in ".html".
func AddExtensionType(ext, typ string) os.Error {
if ext == "" || ext[0] != '.' {
return fmt.Errorf(`mime: extension "%s" misses dot`, ext)
}
once.Do(initMime)
return setExtensionType(ext, typ)
}
func setExtensionType(extension, mimeType string) os.Error {
full, param, err := ParseMediaType(mimeType)
if err != nil {
return err
}
if split := strings.Index(full, "/"); split < 0 {
return fmt.Errorf(`mime: malformed MIME type "%s"`, mimeType)
} else {
main := full[:split]
sub := full[split+1:]
if main == "text" && param["charset"] == "" {
param["charset"] = "utf-8"
}
mimeType = FormatMediaType(main, sub, param)
}
mimeLock.Lock()
mimeTypes[extension] = mimeType
mimeLock.Unlock()
return nil
}