| // 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 ( |
| "fmt" |
| "strings" |
| "sync" |
| ) |
| |
| 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 |
| |
| 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 on unix it 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 |
| // |
| // Windows system mime types are extracted from registry. |
| // |
| // 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) 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) error { |
| _, param, err := ParseMediaType(mimeType) |
| if err != nil { |
| return err |
| } |
| if strings.HasPrefix(mimeType, "text/") && param["charset"] == "" { |
| param["charset"] = "utf-8" |
| mimeType = FormatMediaType(mimeType, param) |
| } |
| mimeLock.Lock() |
| mimeTypes[extension] = mimeType |
| mimeLock.Unlock() |
| return nil |
| } |