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// Copyright 2011 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 http
import (
"fmt"
"io"
)
// fileTransport implements RoundTripper for the 'file' protocol.
type fileTransport struct {
fh fileHandler
}
// NewFileTransport returns a new RoundTripper, serving the provided
// FileSystem. The returned RoundTripper ignores the URL host in its
// incoming requests, as well as most other properties of the
// request.
//
// The typical use case for NewFileTransport is to register the "file"
// protocol with a Transport, as in:
//
// t := &http.Transport{}
// t.RegisterProtocol("file", http.NewFileTransport(http.Dir("/")))
// c := &http.Client{Transport: t}
// res, err := c.Get("file:///etc/passwd")
// ...
func NewFileTransport(fs FileSystem) RoundTripper {
return fileTransport{fileHandler{fs}}
}
func (t fileTransport) RoundTrip(req *Request) (resp *Response, err error) {
// We start ServeHTTP in a goroutine, which may take a long
// time if the file is large. The newPopulateResponseWriter
// call returns a channel which either ServeHTTP or finish()
// sends our *Response on, once the *Response itself has been
// populated (even if the body itself is still being
// written to the res.Body, a pipe)
rw, resc := newPopulateResponseWriter()
go func() {
t.fh.ServeHTTP(rw, req)
rw.finish()
}()
return <-resc, nil
}
func newPopulateResponseWriter() (*populateResponse, <-chan *Response) {
pr, pw := io.Pipe()
rw := &populateResponse{
ch: make(chan *Response),
pw: pw,
res: &Response{
Proto: "HTTP/1.0",
ProtoMajor: 1,
Header: make(Header),
Close: true,
Body: pr,
},
}
return rw, rw.ch
}
// populateResponse is a ResponseWriter that populates the *Response
// in res, and writes its body to a pipe connected to the response
// body. Once writes begin or finish() is called, the response is sent
// on ch.
type populateResponse struct {
res *Response
ch chan *Response
wroteHeader bool
hasContent bool
sentResponse bool
pw *io.PipeWriter
}
func (pr *populateResponse) finish() {
if !pr.wroteHeader {
pr.WriteHeader(500)
}
if !pr.sentResponse {
pr.sendResponse()
}
pr.pw.Close()
}
func (pr *populateResponse) sendResponse() {
if pr.sentResponse {
return
}
pr.sentResponse = true
if pr.hasContent {
pr.res.ContentLength = -1
}
pr.ch <- pr.res
}
func (pr *populateResponse) Header() Header {
return pr.res.Header
}
func (pr *populateResponse) WriteHeader(code int) {
if pr.wroteHeader {
return
}
pr.wroteHeader = true
pr.res.StatusCode = code
pr.res.Status = fmt.Sprintf("%d %s", code, StatusText(code))
}
func (pr *populateResponse) Write(p []byte) (n int, err error) {
if !pr.wroteHeader {
pr.WriteHeader(StatusOK)
}
pr.hasContent = true
if !pr.sentResponse {
pr.sendResponse()
}
return pr.pw.Write(p)
}
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