mime: new package, use in http

R=rsc
CC=golang-dev
https://golang.org/cl/186160

src/pkg/Makefile

@@ -87,6 +87,7 @@ DIRS=\
 	json\
 	log\
 	math\
+	mime\
 	net\
 	once\
 	os\

src/pkg/http/fs.go

@@ -9,23 +9,13 @@ package http
 import (
 	"fmt"
 	"io"
+	"mime"
 	"os"
 	"path"
 	"strings"
 	"utf8"
 )
 
-// TODO this should be in a mime package somewhere
-var contentByExt = map[string]string{
-	".css": "text/css",
-	".gif": "image/gif",
-	".html": "text/html; charset=utf-8",
-	".jpg": "image/jpeg",
-	".js": "application/x-javascript",
-	".pdf": "application/pdf",
-	".png": "image/png",
-}
-
 // Heuristic: b is text if it is valid UTF-8 and doesn't
 // contain any unprintable ASCII or Unicode characters.
 func isText(b []byte) bool {
@@ -136,7 +126,7 @@ func serveFileInternal(c *Conn, r *Request, name string, redirect bool) {
 	// serve file
 	// use extension to find content type.
 	ext := path.Ext(name)
-	if ctype, ok := contentByExt[ext]; ok {
+	if ctype := mime.TypeByExtension(ext); ctype != "" {
 		c.SetHeader("Content-Type", ctype)
 	} else {
 		// read first chunk to decide between utf-8 text and binary

src/pkg/mime/Makefile

@@ -0,0 +1,11 @@
+# Copyright 2009 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.
+
+include ../../Make.$(GOARCH)
+
+TARG=mime
+GOFILES=\
+	type.go\
+
+include ../../Make.pkg

src/pkg/mime/mime_test.go

@@ -0,0 +1,27 @@
+// 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.
+
+// Tests for type.go
+
+package mime
+
+import "testing"
+
+var typeTests = map[string]string{
+	".t1": "application/test",
+	".t2": "text/test; charset=utf-8",
+	".png": "image/png",
+}
+
+func TestType(t *testing.T) {
+	typeFiles = []string{"test.types"}
+
+	for ext, want := range typeTests {
+		val := TypeByExtension(ext)
+		if val != want {
+			t.Errorf("TypeByExtension(%q) = %q, want %q", ext, val, want)
+		}
+
+	}
+}

src/pkg/mime/test.types

@@ -0,0 +1,8 @@
+# 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.
+
+
+ # mime package test
+application/test	t1	# Simple test
+text/test		t2	# Text test

src/pkg/mime/type.go

@@ -0,0 +1,83 @@
+// 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.
+
+// The mime package translates file name extensions to MIME types.
+// It consults the local system's mime.types file, which must be installed
+// under one of these names:
+//
+//   /etc/mime.types
+//   /etc/apache2/mime.types
+//   /etc/apache/mime.types
+//
+package mime
+
+import (
+	"bufio"
+	"once"
+	"os"
+	"strings"
+)
+
+var typeFiles = []string{
+	"/etc/mime.types",
+	"/etc/apache2/mime.types",
+	"/etc/apache/mime.types",
+}
+
+var mimeTypes = map[string]string{
+	".css": "text/css",
+	".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",
+}
+
+func loadMimeFile(filename string) {
+	f, err := os.Open(filename, os.O_RDONLY, 0666)
+	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
+		}
+		typename := fields[0]
+		if strings.HasPrefix(typename, "text/") {
+			typename += "; charset=utf-8"
+		}
+		for _, ext := range fields[1:] {
+			if ext[0] == '#' {
+				break
+			}
+			mimeTypes["."+ext] = typename
+		}
+	}
+}
+
+func initMime() {
+	for _, filename := range typeFiles {
+		loadMimeFile(filename)
+	}
+}
+
+// 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 "".
+func TypeByExtension(ext string) string {
+	once.Do(initMime)
+	typ, _ := mimeTypes[ext]
+	return typ
+}