1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
// Copyright 2016 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 gensupport
import (
"fmt"
"io"
"io/ioutil"
"mime/multipart"
"net/http"
"net/textproto"
"google.golang.org/api/googleapi"
)
const sniffBuffSize = 512
func newContentSniffer(r io.Reader) *contentSniffer {
return &contentSniffer{r: r}
}
// contentSniffer wraps a Reader, and reports the content type determined by sniffing up to 512 bytes from the Reader.
type contentSniffer struct {
r io.Reader
start []byte // buffer for the sniffed bytes.
err error // set to any error encountered while reading bytes to be sniffed.
ctype string // set on first sniff.
sniffed bool // set to true on first sniff.
}
func (cs *contentSniffer) Read(p []byte) (n int, err error) {
// Ensure that the content type is sniffed before any data is consumed from Reader.
_, _ = cs.ContentType()
if len(cs.start) > 0 {
n := copy(p, cs.start)
cs.start = cs.start[n:]
return n, nil
}
// We may have read some bytes into start while sniffing, even if the read ended in an error.
// We should first return those bytes, then the error.
if cs.err != nil {
return 0, cs.err
}
// Now we have handled all bytes that were buffered while sniffing. Now just delegate to the underlying reader.
return cs.r.Read(p)
}
// ContentType returns the sniffed content type, and whether the content type was succesfully sniffed.
func (cs *contentSniffer) ContentType() (string, bool) {
if cs.sniffed {
return cs.ctype, cs.ctype != ""
}
cs.sniffed = true
// If ReadAll hits EOF, it returns err==nil.
cs.start, cs.err = ioutil.ReadAll(io.LimitReader(cs.r, sniffBuffSize))
// Don't try to detect the content type based on possibly incomplete data.
if cs.err != nil {
return "", false
}
cs.ctype = http.DetectContentType(cs.start)
return cs.ctype, true
}
// DetermineContentType determines the content type of the supplied reader.
// If the content type is already known, it can be specified via ctype.
// Otherwise, the content of media will be sniffed to determine the content type.
// If media implements googleapi.ContentTyper (deprecated), this will be used
// instead of sniffing the content.
// After calling DetectContentType the caller must not perform further reads on
// media, but rather read from the Reader that is returned.
func DetermineContentType(media io.Reader, ctype string) (io.Reader, string) {
// Note: callers could avoid calling DetectContentType if ctype != "",
// but doing the check inside this function reduces the amount of
// generated code.
if ctype != "" {
return media, ctype
}
// For backwards compatability, allow clients to set content
// type by providing a ContentTyper for media.
if typer, ok := media.(googleapi.ContentTyper); ok {
return media, typer.ContentType()
}
sniffer := newContentSniffer(media)
if ctype, ok := sniffer.ContentType(); ok {
return sniffer, ctype
}
// If content type could not be sniffed, reads from sniffer will eventually fail with an error.
return sniffer, ""
}
type typeReader struct {
io.Reader
typ string
}
// multipartReader combines the contents of multiple readers to creat a multipart/related HTTP body.
// Close must be called if reads from the multipartReader are abandoned before reaching EOF.
type multipartReader struct {
pr *io.PipeReader
pipeOpen bool
ctype string
}
func newMultipartReader(parts []typeReader) *multipartReader {
mp := &multipartReader{pipeOpen: true}
var pw *io.PipeWriter
mp.pr, pw = io.Pipe()
mpw := multipart.NewWriter(pw)
mp.ctype = "multipart/related; boundary=" + mpw.Boundary()
go func() {
for _, part := range parts {
w, err := mpw.CreatePart(typeHeader(part.typ))
if err != nil {
mpw.Close()
pw.CloseWithError(fmt.Errorf("googleapi: CreatePart failed: %v", err))
return
}
_, err = io.Copy(w, part.Reader)
if err != nil {
mpw.Close()
pw.CloseWithError(fmt.Errorf("googleapi: Copy failed: %v", err))
return
}
}
mpw.Close()
pw.Close()
}()
return mp
}
func (mp *multipartReader) Read(data []byte) (n int, err error) {
return mp.pr.Read(data)
}
func (mp *multipartReader) Close() error {
if !mp.pipeOpen {
return nil
}
mp.pipeOpen = false
return mp.pr.Close()
}
// CombineBodyMedia combines a json body with media content to create a multipart/related HTTP body.
// It returns a ReadCloser containing the combined body, and the overall "multipart/related" content type, with random boundary.
//
// The caller must call Close on the returned ReadCloser if reads are abandoned before reaching EOF.
func CombineBodyMedia(body io.Reader, bodyContentType string, media io.Reader, mediaContentType string) (io.ReadCloser, string) {
mp := newMultipartReader([]typeReader{
{body, bodyContentType},
{media, mediaContentType},
})
return mp, mp.ctype
}
func typeHeader(contentType string) textproto.MIMEHeader {
h := make(textproto.MIMEHeader)
if contentType != "" {
h.Set("Content-Type", contentType)
}
return h
}
// PrepareUpload determines whether the data in the supplied reader should be
// uploaded in a single request, or in sequential chunks.
// chunkSize is the size of the chunk that media should be split into.
// If chunkSize is non-zero and the contents of media do not fit in a single
// chunk (or there is an error reading media), then media will be returned as a
// MediaBuffer. Otherwise, media will be returned as a Reader.
//
// After PrepareUpload has been called, media should no longer be used: the
// media content should be accessed via one of the return values.
func PrepareUpload(media io.Reader, chunkSize int) (io.Reader, *MediaBuffer) {
if chunkSize == 0 { // do not chunk
return media, nil
}
mb := NewMediaBuffer(media, chunkSize)
rdr, _, _, err := mb.Chunk()
if err == io.EOF { // we can upload this in a single request
return rdr, nil
}
// err might be a non-EOF error. If it is, the next call to mb.Chunk will
// return the same error. Returning a MediaBuffer ensures that this error
// will be handled at some point.
return nil, mb
}
|
