src/pkg/http/fs.go - go - Git at Google

 // 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.

 // HTTP file system request handler

 package http

 import (
 	"fmt"
 	"io"
 	"mime"
 	"os"
 	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
 	"utf8"
 )

 // A Dir implements http.FileSystem using the native file
 // system restricted to a specific directory tree.
 type Dir string

 func (d Dir) Open(name string) (File, os.Error) {
 	if filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0 {
 		return nil, os.NewError("http: invalid character in file path")
 	}
 	f, err := os.Open(filepath.Join(string(d), filepath.FromSlash(path.Clean("/"+name))))
 	if err != nil {
 		return nil, err
 	}
 	return f, nil
 }

 // A FileSystem implements access to a collection of named files.
 // The elements in a file path are separated by slash ('/', U+002F)
 // characters, regardless of host operating system convention.
 type FileSystem interface {
 	Open(name string) (File, os.Error)
 }

 // A File is returned by a FileSystem's Open method and can be
 // served by the FileServer implementation.
 type File interface {
 	Close() os.Error
 	Stat() (*os.FileInfo, os.Error)
 	Readdir(count int) ([]os.FileInfo, os.Error)
 	Read([]byte) (int, os.Error)
 	Seek(offset int64, whence int) (int64, os.Error)
 }

 // 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 {
 	for len(b) > 0 && utf8.FullRune(b) {
 		rune, size := utf8.DecodeRune(b)
 		if size == 1 && rune == utf8.RuneError {
 			// decoding error
 			return false
 		}
 		if 0x7F <= rune && rune <= 0x9F {
 			return false
 		}
 		if rune < ' ' {
 			switch rune {
 			case '\n', '\r', '\t':
 				// okay
 			default:
 				// binary garbage
 				return false
 			}
 		}
 		b = b[size:]
 	}
 	return true
 }

 func dirList(w ResponseWriter, f File) {
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
 	fmt.Fprintf(w, "<pre>\n")
 	for {
 		dirs, err := f.Readdir(100)
 		if err != nil || len(dirs) == 0 {
 			break
 		}
 		for _, d := range dirs {
 			name := d.Name
 			if d.IsDirectory() {
 				name += "/"
 			}
 			// TODO htmlescape
 			fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", name, name)
 		}
 	}
 	fmt.Fprintf(w, "</pre>\n")
 }

 // name is '/'-separated, not filepath.Separator.
 func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirect bool) {
 	const indexPage = "/index.html"

 	// redirect .../index.html to .../
 	// can't use Redirect() because that would make the path absolute,
 	// which would be a problem running under StripPrefix
 	if strings.HasSuffix(r.URL.Path, indexPage) {
 		localRedirect(w, r, "./")
 		return
 	}

 	f, err := fs.Open(name)
 	if err != nil {
 		// TODO expose actual error?
 		NotFound(w, r)
 		return
 	}
 	defer f.Close()

 	d, err1 := f.Stat()
 	if err1 != nil {
 		// TODO expose actual error?
 		NotFound(w, r)
 		return
 	}

 	if redirect {
 		// redirect to canonical path: / at end of directory url
 		// r.URL.Path always begins with /
 		url := r.URL.Path
 		if d.IsDirectory() {
 			if url[len(url)-1] != '/' {
 				localRedirect(w, r, path.Base(url)+"/")
 				return
 			}
 		} else {
 			if url[len(url)-1] == '/' {
 				localRedirect(w, r, "../"+path.Base(url))
 				return
 			}
 		}
 	}

 	if t, _ := time.Parse(TimeFormat, r.Header.Get("If-Modified-Since")); t != nil && d.Mtime_ns/1e9 <= t.Seconds() {
 		w.WriteHeader(StatusNotModified)
 		return
 	}
 	w.Header().Set("Last-Modified", time.SecondsToUTC(d.Mtime_ns/1e9).Format(TimeFormat))

 	// use contents of index.html for directory, if present
 	if d.IsDirectory() {
 		index := name + indexPage
 		ff, err := fs.Open(index)
 		if err == nil {
 			defer ff.Close()
 			dd, err := ff.Stat()
 			if err == nil {
 				name = index
 				d = dd
 				f = ff
 			}
 		}
 	}

 	if d.IsDirectory() {
 		dirList(w, f)
 		return
 	}

 	// serve file
 	size := d.Size
 	code := StatusOK

 	// If Content-Type isn't set, use the file's extension to find it.
 	if w.Header().Get("Content-Type") == "" {
 		ctype := mime.TypeByExtension(filepath.Ext(name))
 		if ctype == "" {
 			// read a chunk to decide between utf-8 text and binary
 			var buf [1024]byte
 			n, _ := io.ReadFull(f, buf[:])
 			b := buf[:n]
 			if isText(b) {
 				ctype = "text/plain; charset=utf-8"
 			} else {
 				// generic binary
 				ctype = "application/octet-stream"
 			}
 			f.Seek(0, os.SEEK_SET) // rewind to output whole file
 		}
 		w.Header().Set("Content-Type", ctype)
 	}

 	// handle Content-Range header.
 	// TODO(adg): handle multiple ranges
 	ranges, err := parseRange(r.Header.Get("Range"), size)
 	if err == nil && len(ranges) > 1 {
 		err = os.NewError("multiple ranges not supported")
 	}
 	if err != nil {
 		Error(w, err.String(), StatusRequestedRangeNotSatisfiable)
 		return
 	}
 	if len(ranges) == 1 {
 		ra := ranges[0]
 		if _, err := f.Seek(ra.start, os.SEEK_SET); err != nil {
 			Error(w, err.String(), StatusRequestedRangeNotSatisfiable)
 			return
 		}
 		size = ra.length
 		code = StatusPartialContent
 		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size))
 	}

 	w.Header().Set("Accept-Ranges", "bytes")
 	if w.Header().Get("Content-Encoding") == "" {
 		w.Header().Set("Content-Length", strconv.Itoa64(size))
 	}

 	w.WriteHeader(code)

 	if r.Method != "HEAD" {
 		io.CopyN(w, f, size)
 	}
 }

 // localRedirect gives a Moved Permanently response.
 // It does not convert relative paths to absolute paths like Redirect does.
 func localRedirect(w ResponseWriter, r *Request, newPath string) {
 	if q := r.URL.RawQuery; q != "" {
 		newPath += "?" + q
 	}
 	w.Header().Set("Location", newPath)
 	w.WriteHeader(StatusMovedPermanently)
 }

 // ServeFile replies to the request with the contents of the named file or directory.
 func ServeFile(w ResponseWriter, r *Request, name string) {
 	dir, file := filepath.Split(name)
 	serveFile(w, r, Dir(dir), file, false)
 }

 type fileHandler struct {
 	root FileSystem
 }

 // FileServer returns a handler that serves HTTP requests
 // with the contents of the file system rooted at root.
 //
 // To use the operating system's file system implementation,
 // use http.Dir:
 //
 //     http.Handle("/", http.FileServer(http.Dir("/tmp")))
 func FileServer(root FileSystem) Handler {
 	return &fileHandler{root}
 }

 func (f *fileHandler) ServeHTTP(w ResponseWriter, r *Request) {
 	upath := r.URL.Path
 	if !strings.HasPrefix(upath, "/") {
 		upath = "/" + upath
 		r.URL.Path = upath
 	}
 	serveFile(w, r, f.root, path.Clean(upath), true)
 }

 // httpRange specifies the byte range to be sent to the client.
 type httpRange struct {
 	start, length int64
 }

 // parseRange parses a Range header string as per RFC 2616.
 func parseRange(s string, size int64) ([]httpRange, os.Error) {
 	if s == "" {
 		return nil, nil // header not present
 	}
 	const b = "bytes="
 	if !strings.HasPrefix(s, b) {
 		return nil, os.NewError("invalid range")
 	}
 	var ranges []httpRange
 	for _, ra := range strings.Split(s[len(b):], ",") {
 		i := strings.Index(ra, "-")
 		if i < 0 {
 			return nil, os.NewError("invalid range")
 		}
 		start, end := ra[:i], ra[i+1:]
 		var r httpRange
 		if start == "" {
 			// If no start is specified, end specifies the
 			// range start relative to the end of the file.
 			i, err := strconv.Atoi64(end)
 			if err != nil {
 				return nil, os.NewError("invalid range")
 			}
 			if i > size {
 				i = size
 			}
 			r.start = size - i
 			r.length = size - r.start
 		} else {
 			i, err := strconv.Atoi64(start)
 			if err != nil || i > size || i < 0 {
 				return nil, os.NewError("invalid range")
 			}
 			r.start = i
 			if end == "" {
 				// If no end is specified, range extends to end of the file.
 				r.length = size - r.start
 			} else {
 				i, err := strconv.Atoi64(end)
 				if err != nil || r.start > i {
 					return nil, os.NewError("invalid range")
 				}
 				if i >= size {
 					i = size - 1
 				}
 				r.length = i - r.start + 1
 			}
 		}
 		ranges = append(ranges, r)
 	}
 	return ranges, nil
 }
	// 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.

	// HTTP file system request handler

	package http

	import (
	"fmt"
	"io"
	"mime"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"time"
	"utf8"
	)

	// A Dir implements http.FileSystem using the native file
	// system restricted to a specific directory tree.
	type Dir string

	func (d Dir) Open(name string) (File, os.Error) {
	if filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0 {
	return nil, os.NewError("http: invalid character in file path")
	}
	f, err := os.Open(filepath.Join(string(d), filepath.FromSlash(path.Clean("/"+name))))
	if err != nil {
	return nil, err
	}
	return f, nil
	}

	// A FileSystem implements access to a collection of named files.
	// The elements in a file path are separated by slash ('/', U+002F)
	// characters, regardless of host operating system convention.
	type FileSystem interface {
	Open(name string) (File, os.Error)
	}

	// A File is returned by a FileSystem's Open method and can be
	// served by the FileServer implementation.
	type File interface {
	Close() os.Error
	Stat() (*os.FileInfo, os.Error)
	Readdir(count int) ([]os.FileInfo, os.Error)
	Read([]byte) (int, os.Error)
	Seek(offset int64, whence int) (int64, os.Error)
	}

	// 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 {
	for len(b) > 0 && utf8.FullRune(b) {
	rune, size := utf8.DecodeRune(b)
	if size == 1 && rune == utf8.RuneError {
	// decoding error
	return false
	}
	if 0x7F <= rune && rune <= 0x9F {
	return false
	}
	if rune < ' ' {
	switch rune {
	case '\n', '\r', '\t':
	// okay
	default:
	// binary garbage
	return false
	}
	}
	b = b[size:]
	}
	return true
	}

	func dirList(w ResponseWriter, f File) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	fmt.Fprintf(w, "<pre>\n")
	for {
	dirs, err := f.Readdir(100)
	if err != nil \|\| len(dirs) == 0 {
	break
	}
	for _, d := range dirs {
	name := d.Name
	if d.IsDirectory() {
	name += "/"
	}
	// TODO htmlescape
	fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", name, name)
	}
	}
	fmt.Fprintf(w, "</pre>\n")
	}

	// name is '/'-separated, not filepath.Separator.
	func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirect bool) {
	const indexPage = "/index.html"

	// redirect .../index.html to .../
	// can't use Redirect() because that would make the path absolute,
	// which would be a problem running under StripPrefix
	if strings.HasSuffix(r.URL.Path, indexPage) {
	localRedirect(w, r, "./")
	return
	}

	f, err := fs.Open(name)
	if err != nil {
	// TODO expose actual error?
	NotFound(w, r)
	return
	}
	defer f.Close()

	d, err1 := f.Stat()
	if err1 != nil {
	// TODO expose actual error?
	NotFound(w, r)
	return
	}

	if redirect {
	// redirect to canonical path: / at end of directory url
	// r.URL.Path always begins with /
	url := r.URL.Path
	if d.IsDirectory() {
	if url[len(url)-1] != '/' {
	localRedirect(w, r, path.Base(url)+"/")
	return
	}
	} else {
	if url[len(url)-1] == '/' {
	localRedirect(w, r, "../"+path.Base(url))
	return
	}
	}
	}

	if t, _ := time.Parse(TimeFormat, r.Header.Get("If-Modified-Since")); t != nil && d.Mtime_ns/1e9 <= t.Seconds() {
	w.WriteHeader(StatusNotModified)
	return
	}
	w.Header().Set("Last-Modified", time.SecondsToUTC(d.Mtime_ns/1e9).Format(TimeFormat))

	// use contents of index.html for directory, if present
	if d.IsDirectory() {
	index := name + indexPage
	ff, err := fs.Open(index)
	if err == nil {
	defer ff.Close()
	dd, err := ff.Stat()
	if err == nil {
	name = index
	d = dd
	f = ff
	}
	}
	}

	if d.IsDirectory() {
	dirList(w, f)
	return
	}

	// serve file
	size := d.Size
	code := StatusOK

	// If Content-Type isn't set, use the file's extension to find it.
	if w.Header().Get("Content-Type") == "" {
	ctype := mime.TypeByExtension(filepath.Ext(name))
	if ctype == "" {
	// read a chunk to decide between utf-8 text and binary
	var buf [1024]byte
	n, _ := io.ReadFull(f, buf[:])
	b := buf[:n]
	if isText(b) {
	ctype = "text/plain; charset=utf-8"
	} else {
	// generic binary
	ctype = "application/octet-stream"
	}
	f.Seek(0, os.SEEK_SET) // rewind to output whole file
	}
	w.Header().Set("Content-Type", ctype)
	}

	// handle Content-Range header.
	// TODO(adg): handle multiple ranges
	ranges, err := parseRange(r.Header.Get("Range"), size)
	if err == nil && len(ranges) > 1 {
	err = os.NewError("multiple ranges not supported")
	}
	if err != nil {
	Error(w, err.String(), StatusRequestedRangeNotSatisfiable)
	return
	}
	if len(ranges) == 1 {
	ra := ranges[0]
	if _, err := f.Seek(ra.start, os.SEEK_SET); err != nil {
	Error(w, err.String(), StatusRequestedRangeNotSatisfiable)
	return
	}
	size = ra.length
	code = StatusPartialContent
	w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size))
	}

	w.Header().Set("Accept-Ranges", "bytes")
	if w.Header().Get("Content-Encoding") == "" {
	w.Header().Set("Content-Length", strconv.Itoa64(size))
	}

	w.WriteHeader(code)

	if r.Method != "HEAD" {
	io.CopyN(w, f, size)
	}
	}

	// localRedirect gives a Moved Permanently response.
	// It does not convert relative paths to absolute paths like Redirect does.
	func localRedirect(w ResponseWriter, r *Request, newPath string) {
	if q := r.URL.RawQuery; q != "" {
	newPath += "?" + q
	}
	w.Header().Set("Location", newPath)
	w.WriteHeader(StatusMovedPermanently)
	}

	// ServeFile replies to the request with the contents of the named file or directory.
	func ServeFile(w ResponseWriter, r *Request, name string) {
	dir, file := filepath.Split(name)
	serveFile(w, r, Dir(dir), file, false)
	}

	type fileHandler struct {
	root FileSystem
	}

	// FileServer returns a handler that serves HTTP requests
	// with the contents of the file system rooted at root.
	//
	// To use the operating system's file system implementation,
	// use http.Dir:
	//
	// http.Handle("/", http.FileServer(http.Dir("/tmp")))
	func FileServer(root FileSystem) Handler {
	return &fileHandler{root}
	}

	func (f fileHandler) ServeHTTP(w ResponseWriter, r Request) {
	upath := r.URL.Path
	if !strings.HasPrefix(upath, "/") {
	upath = "/" + upath
	r.URL.Path = upath
	}
	serveFile(w, r, f.root, path.Clean(upath), true)
	}

	// httpRange specifies the byte range to be sent to the client.
	type httpRange struct {
	start, length int64
	}

	// parseRange parses a Range header string as per RFC 2616.
	func parseRange(s string, size int64) ([]httpRange, os.Error) {
	if s == "" {
	return nil, nil // header not present
	}
	const b = "bytes="
	if !strings.HasPrefix(s, b) {
	return nil, os.NewError("invalid range")
	}
	var ranges []httpRange
	for _, ra := range strings.Split(s[len(b):], ",") {
	i := strings.Index(ra, "-")
	if i < 0 {
	return nil, os.NewError("invalid range")
	}
	start, end := ra[:i], ra[i+1:]
	var r httpRange
	if start == "" {
	// If no start is specified, end specifies the
	// range start relative to the end of the file.
	i, err := strconv.Atoi64(end)
	if err != nil {
	return nil, os.NewError("invalid range")
	}
	if i > size {
	i = size
	}
	r.start = size - i
	r.length = size - r.start
	} else {
	i, err := strconv.Atoi64(start)
	if err != nil \|\| i > size \|\| i < 0 {
	return nil, os.NewError("invalid range")
	}
	r.start = i
	if end == "" {
	// If no end is specified, range extends to end of the file.
	r.length = size - r.start
	} else {
	i, err := strconv.Atoi64(end)
	if err != nil \|\| r.start > i {
	return nil, os.NewError("invalid range")
	}
	if i >= size {
	i = size - 1
	}
	r.length = i - r.start + 1
	}
	}
	ranges = append(ranges, r)
	}
	return ranges, nil
	}