9ff56c9570
From-SVN: r173931
271 lines
6.2 KiB
Go
271 lines
6.2 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// HTTP file system request handler
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package http
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import (
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"fmt"
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"io"
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"mime"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"time"
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"utf8"
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)
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// Heuristic: b is text if it is valid UTF-8 and doesn't
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// contain any unprintable ASCII or Unicode characters.
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func isText(b []byte) bool {
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for len(b) > 0 && utf8.FullRune(b) {
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rune, size := utf8.DecodeRune(b)
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if size == 1 && rune == utf8.RuneError {
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// decoding error
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return false
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}
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if 0x7F <= rune && rune <= 0x9F {
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return false
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}
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if rune < ' ' {
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switch rune {
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case '\n', '\r', '\t':
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// okay
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default:
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// binary garbage
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return false
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}
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}
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b = b[size:]
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}
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return true
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}
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func dirList(w ResponseWriter, f *os.File) {
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fmt.Fprintf(w, "<pre>\n")
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for {
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dirs, err := f.Readdir(100)
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if err != nil || len(dirs) == 0 {
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break
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}
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for _, d := range dirs {
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name := d.Name
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if d.IsDirectory() {
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name += "/"
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}
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// TODO htmlescape
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fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", name, name)
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}
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}
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fmt.Fprintf(w, "</pre>\n")
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}
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func serveFile(w ResponseWriter, r *Request, name string, redirect bool) {
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const indexPage = "/index.html"
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// redirect .../index.html to .../
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if strings.HasSuffix(r.URL.Path, indexPage) {
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Redirect(w, r, r.URL.Path[0:len(r.URL.Path)-len(indexPage)+1], StatusMovedPermanently)
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return
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}
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f, err := os.Open(name)
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if err != nil {
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// TODO expose actual error?
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NotFound(w, r)
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return
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}
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defer f.Close()
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d, err1 := f.Stat()
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if err1 != nil {
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// TODO expose actual error?
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NotFound(w, r)
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return
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}
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if redirect {
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// redirect to canonical path: / at end of directory url
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// r.URL.Path always begins with /
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url := r.URL.Path
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if d.IsDirectory() {
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if url[len(url)-1] != '/' {
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Redirect(w, r, url+"/", StatusMovedPermanently)
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return
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}
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} else {
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if url[len(url)-1] == '/' {
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Redirect(w, r, url[0:len(url)-1], StatusMovedPermanently)
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return
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}
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}
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}
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if t, _ := time.Parse(TimeFormat, r.Header.Get("If-Modified-Since")); t != nil && d.Mtime_ns/1e9 <= t.Seconds() {
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w.WriteHeader(StatusNotModified)
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return
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}
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w.Header().Set("Last-Modified", time.SecondsToUTC(d.Mtime_ns/1e9).Format(TimeFormat))
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// use contents of index.html for directory, if present
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if d.IsDirectory() {
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index := name + filepath.FromSlash(indexPage)
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ff, err := os.Open(index)
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if err == nil {
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defer ff.Close()
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dd, err := ff.Stat()
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if err == nil {
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name = index
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d = dd
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f = ff
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}
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}
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}
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if d.IsDirectory() {
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dirList(w, f)
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return
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}
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// serve file
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size := d.Size
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code := StatusOK
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// If Content-Type isn't set, use the file's extension to find it.
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if w.Header().Get("Content-Type") == "" {
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ctype := mime.TypeByExtension(filepath.Ext(name))
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if ctype == "" {
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// read a chunk to decide between utf-8 text and binary
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var buf [1024]byte
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n, _ := io.ReadFull(f, buf[:])
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b := buf[:n]
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if isText(b) {
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ctype = "text/plain; charset=utf-8"
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} else {
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// generic binary
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ctype = "application/octet-stream"
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}
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f.Seek(0, os.SEEK_SET) // rewind to output whole file
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}
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w.Header().Set("Content-Type", ctype)
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}
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// handle Content-Range header.
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// TODO(adg): handle multiple ranges
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ranges, err := parseRange(r.Header.Get("Range"), size)
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if err == nil && len(ranges) > 1 {
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err = os.ErrorString("multiple ranges not supported")
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}
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if err != nil {
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Error(w, err.String(), StatusRequestedRangeNotSatisfiable)
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return
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}
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if len(ranges) == 1 {
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ra := ranges[0]
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if _, err := f.Seek(ra.start, os.SEEK_SET); err != nil {
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Error(w, err.String(), StatusRequestedRangeNotSatisfiable)
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return
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}
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size = ra.length
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code = StatusPartialContent
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w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size))
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}
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w.Header().Set("Accept-Ranges", "bytes")
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w.Header().Set("Content-Length", strconv.Itoa64(size))
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w.WriteHeader(code)
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if r.Method != "HEAD" {
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io.Copyn(w, f, size)
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}
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}
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// ServeFile replies to the request with the contents of the named file or directory.
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func ServeFile(w ResponseWriter, r *Request, name string) {
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serveFile(w, r, name, false)
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}
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type fileHandler struct {
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root string
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prefix string
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}
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// FileServer returns a handler that serves HTTP requests
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// with the contents of the file system rooted at root.
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// It strips prefix from the incoming requests before
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// looking up the file name in the file system.
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func FileServer(root, prefix string) Handler { return &fileHandler{root, prefix} }
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func (f *fileHandler) ServeHTTP(w ResponseWriter, r *Request) {
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path := r.URL.Path
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if !strings.HasPrefix(path, f.prefix) {
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NotFound(w, r)
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return
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}
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path = path[len(f.prefix):]
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serveFile(w, r, filepath.Join(f.root, filepath.FromSlash(path)), true)
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}
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// httpRange specifies the byte range to be sent to the client.
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type httpRange struct {
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start, length int64
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}
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// parseRange parses a Range header string as per RFC 2616.
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func parseRange(s string, size int64) ([]httpRange, os.Error) {
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if s == "" {
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return nil, nil // header not present
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}
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const b = "bytes="
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if !strings.HasPrefix(s, b) {
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return nil, os.NewError("invalid range")
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}
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var ranges []httpRange
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for _, ra := range strings.Split(s[len(b):], ",", -1) {
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i := strings.Index(ra, "-")
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if i < 0 {
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return nil, os.NewError("invalid range")
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}
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start, end := ra[:i], ra[i+1:]
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var r httpRange
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if start == "" {
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// If no start is specified, end specifies the
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// range start relative to the end of the file.
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i, err := strconv.Atoi64(end)
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if err != nil {
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return nil, os.NewError("invalid range")
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}
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if i > size {
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i = size
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}
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r.start = size - i
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r.length = size - r.start
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} else {
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i, err := strconv.Atoi64(start)
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if err != nil || i > size || i < 0 {
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return nil, os.NewError("invalid range")
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}
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r.start = i
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if end == "" {
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// If no end is specified, range extends to end of the file.
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r.length = size - r.start
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} else {
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i, err := strconv.Atoi64(end)
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if err != nil || r.start > i {
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return nil, os.NewError("invalid range")
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}
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if i >= size {
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i = size - 1
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}
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r.length = i - r.start + 1
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}
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}
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ranges = append(ranges, r)
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}
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return ranges, nil
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}
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