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googleapi.go
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googleapi.go
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// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package googleapi contains the common code shared by all Google API
// libraries.
package googleapi
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"mime/multipart"
"net/http"
"net/textproto"
"net/url"
"regexp"
"strconv"
"strings"
"sync"
"time"
"golang.org/x/net/context"
"google.golang.org/api/googleapi/internal/uritemplates"
)
// ContentTyper is an interface for Readers which know (or would like
// to override) their Content-Type. If a media body doesn't implement
// ContentTyper, the type is sniffed from the content using
// http.DetectContentType.
type ContentTyper interface {
ContentType() string
}
// A SizeReaderAt is a ReaderAt with a Size method.
// An io.SectionReader implements SizeReaderAt.
type SizeReaderAt interface {
io.ReaderAt
Size() int64
}
const (
Version = "0.5"
// statusResumeIncomplete is the code returned by the Google uploader when the transfer is not yet complete.
statusResumeIncomplete = 308
// UserAgent is the header string used to identify this package.
UserAgent = "google-api-go-client/" + Version
// uploadPause determines the delay between failed upload attempts
uploadPause = 1 * time.Second
)
// Error contains an error response from the server.
type Error struct {
// Code is the HTTP response status code and will always be populated.
Code int `json:"code"`
// Message is the server response message and is only populated when
// explicitly referenced by the JSON server response.
Message string `json:"message"`
// Body is the raw response returned by the server.
// It is often but not always JSON, depending on how the request fails.
Body string
Errors []ErrorItem
}
// ErrorItem is a detailed error code & message from the Google API frontend.
type ErrorItem struct {
// Reason is the typed error code. For example: "some_example".
Reason string `json:"reason"`
// Message is the human-readable description of the error.
Message string `json:"message"`
}
func (e *Error) Error() string {
if len(e.Errors) == 0 && e.Message == "" {
return fmt.Sprintf("googleapi: got HTTP response code %d with body: %v", e.Code, e.Body)
}
var buf bytes.Buffer
fmt.Fprintf(&buf, "googleapi: Error %d: ", e.Code)
if e.Message != "" {
fmt.Fprintf(&buf, "%s", e.Message)
}
if len(e.Errors) == 0 {
return strings.TrimSpace(buf.String())
}
if len(e.Errors) == 1 && e.Errors[0].Message == e.Message {
fmt.Fprintf(&buf, ", %s", e.Errors[0].Reason)
return buf.String()
}
fmt.Fprintln(&buf, "\nMore details:")
for _, v := range e.Errors {
fmt.Fprintf(&buf, "Reason: %s, Message: %s\n", v.Reason, v.Message)
}
return buf.String()
}
type errorReply struct {
Error *Error `json:"error"`
}
// CheckResponse returns an error (of type *Error) if the response
// status code is not 2xx.
func CheckResponse(res *http.Response) error {
if res.StatusCode >= 200 && res.StatusCode <= 299 {
return nil
}
slurp, err := ioutil.ReadAll(res.Body)
if err == nil {
jerr := new(errorReply)
err = json.Unmarshal(slurp, jerr)
if err == nil && jerr.Error != nil {
if jerr.Error.Code == 0 {
jerr.Error.Code = res.StatusCode
}
jerr.Error.Body = string(slurp)
return jerr.Error
}
}
return &Error{
Code: res.StatusCode,
Body: string(slurp),
}
}
// CheckMediaResponse returns an error (of type *Error) if the response
// status code is not 2xx. Unlike CheckResponse it does not assume the
// body is a JSON error document.
func CheckMediaResponse(res *http.Response) error {
if res.StatusCode >= 200 && res.StatusCode <= 299 {
return nil
}
slurp, _ := ioutil.ReadAll(io.LimitReader(res.Body, 1<<20))
res.Body.Close()
return &Error{
Code: res.StatusCode,
Body: string(slurp),
}
}
type MarshalStyle bool
var WithDataWrapper = MarshalStyle(true)
var WithoutDataWrapper = MarshalStyle(false)
func (wrap MarshalStyle) JSONReader(v interface{}) (io.Reader, error) {
buf := new(bytes.Buffer)
if wrap {
buf.Write([]byte(`{"data": `))
}
err := json.NewEncoder(buf).Encode(v)
if err != nil {
return nil, err
}
if wrap {
buf.Write([]byte(`}`))
}
return buf, nil
}
func getMediaType(media io.Reader) (io.Reader, string) {
if typer, ok := media.(ContentTyper); ok {
return media, typer.ContentType()
}
pr, pw := io.Pipe()
typ := "application/octet-stream"
buf, err := ioutil.ReadAll(io.LimitReader(media, 512))
if err != nil {
pw.CloseWithError(fmt.Errorf("error reading media: %v", err))
return pr, typ
}
typ = http.DetectContentType(buf)
mr := io.MultiReader(bytes.NewReader(buf), media)
go func() {
_, err = io.Copy(pw, mr)
if err != nil {
pw.CloseWithError(fmt.Errorf("error reading media: %v", err))
return
}
pw.Close()
}()
return pr, typ
}
// DetectMediaType detects and returns the content type of the provided media.
// If the type can not be determined, "application/octet-stream" is returned.
func DetectMediaType(media io.ReaderAt) string {
if typer, ok := media.(ContentTyper); ok {
return typer.ContentType()
}
typ := "application/octet-stream"
buf := make([]byte, 1024)
n, err := media.ReadAt(buf, 0)
buf = buf[:n]
if err == nil || err == io.EOF {
typ = http.DetectContentType(buf)
}
return typ
}
type Lengther interface {
Len() int
}
// endingWithErrorReader from r until it returns an error. If the
// final error from r is io.EOF and e is non-nil, e is used instead.
type endingWithErrorReader struct {
r io.Reader
e error
}
func (er endingWithErrorReader) Read(p []byte) (n int, err error) {
n, err = er.r.Read(p)
if err == io.EOF && er.e != nil {
err = er.e
}
return
}
func typeHeader(contentType string) textproto.MIMEHeader {
h := make(textproto.MIMEHeader)
h.Set("Content-Type", contentType)
return h
}
// countingWriter counts the number of bytes it receives to write, but
// discards them.
type countingWriter struct {
n *int64
}
func (w countingWriter) Write(p []byte) (int, error) {
*w.n += int64(len(p))
return len(p), nil
}
// ConditionallyIncludeMedia does nothing if media is nil.
//
// bodyp is an in/out parameter. It should initially point to the
// reader of the application/json (or whatever) payload to send in the
// API request. It's updated to point to the multipart body reader.
//
// ctypep is an in/out parameter. It should initially point to the
// content type of the bodyp, usually "application/json". It's updated
// to the "multipart/related" content type, with random boundary.
//
// The return value is the content-length of the entire multpart body.
func ConditionallyIncludeMedia(media io.Reader, bodyp *io.Reader, ctypep *string) (cancel func(), ok bool) {
if media == nil {
return
}
// Get the media type, which might return a different reader instance.
var mediaType string
media, mediaType = getMediaType(media)
body, bodyType := *bodyp, *ctypep
pr, pw := io.Pipe()
mpw := multipart.NewWriter(pw)
*bodyp = pr
*ctypep = "multipart/related; boundary=" + mpw.Boundary()
go func() {
w, err := mpw.CreatePart(typeHeader(bodyType))
if err != nil {
mpw.Close()
pw.CloseWithError(fmt.Errorf("googleapi: body CreatePart failed: %v", err))
return
}
_, err = io.Copy(w, body)
if err != nil {
mpw.Close()
pw.CloseWithError(fmt.Errorf("googleapi: body Copy failed: %v", err))
return
}
w, err = mpw.CreatePart(typeHeader(mediaType))
if err != nil {
mpw.Close()
pw.CloseWithError(fmt.Errorf("googleapi: media CreatePart failed: %v", err))
return
}
_, err = io.Copy(w, media)
if err != nil {
mpw.Close()
pw.CloseWithError(fmt.Errorf("googleapi: media Copy failed: %v", err))
return
}
mpw.Close()
pw.Close()
}()
cancel = func() { pw.CloseWithError(errAborted) }
return cancel, true
}
var errAborted = errors.New("googleapi: upload aborted")
// ProgressUpdater is a function that is called upon every progress update of a resumable upload.
// This is the only part of a resumable upload (from googleapi) that is usable by the developer.
// The remaining usable pieces of resumable uploads is exposed in each auto-generated API.
type ProgressUpdater func(current, total int64)
// ResumableUpload is used by the generated APIs to provide resumable uploads.
// It is not used by developers directly.
type ResumableUpload struct {
Client *http.Client
// URI is the resumable resource destination provided by the server after specifying "&uploadType=resumable".
URI string
UserAgent string // User-Agent for header of the request
// Media is the object being uploaded.
Media io.ReaderAt
// MediaType defines the media type, e.g. "image/jpeg".
MediaType string
// ContentLength is the full size of the object being uploaded.
ContentLength int64
mu sync.Mutex // guards progress
progress int64 // number of bytes uploaded so far
started bool // whether the upload has been started
// Callback is an optional function that will be called upon every progress update.
Callback ProgressUpdater
}
var (
// rangeRE matches the transfer status response from the server. $1 is the last byte index uploaded.
rangeRE = regexp.MustCompile(`^bytes=0\-(\d+)$`)
// chunkSize is the size of the chunks created during a resumable upload and should be a power of two.
// 1<<18 is the minimum size supported by the Google uploader, and there is no maximum.
chunkSize int64 = 1 << 18
)
// Progress returns the number of bytes uploaded at this point.
func (rx *ResumableUpload) Progress() int64 {
rx.mu.Lock()
defer rx.mu.Unlock()
return rx.progress
}
func (rx *ResumableUpload) transferStatus() (int64, *http.Response, error) {
req, _ := http.NewRequest("POST", rx.URI, nil)
req.ContentLength = 0
req.Header.Set("User-Agent", rx.UserAgent)
req.Header.Set("Content-Range", fmt.Sprintf("bytes */%v", rx.ContentLength))
res, err := rx.Client.Do(req)
if err != nil || res.StatusCode != statusResumeIncomplete {
return 0, res, err
}
var start int64
if m := rangeRE.FindStringSubmatch(res.Header.Get("Range")); len(m) == 2 {
start, err = strconv.ParseInt(m[1], 10, 64)
if err != nil {
return 0, nil, fmt.Errorf("unable to parse range size %v", m[1])
}
start += 1 // Start at the next byte
}
return start, res, nil
}
type chunk struct {
body io.Reader
size int64
err error
}
func (rx *ResumableUpload) transferChunks(ctx context.Context) (*http.Response, error) {
var start int64
var err error
res := &http.Response{}
if rx.started {
start, res, err = rx.transferStatus()
if err != nil || res.StatusCode != statusResumeIncomplete {
return res, err
}
}
rx.started = true
for {
select { // Check for cancellation
case <-ctx.Done():
res.StatusCode = http.StatusRequestTimeout
return res, ctx.Err()
default:
}
reqSize := rx.ContentLength - start
if reqSize > chunkSize {
reqSize = chunkSize
}
r := io.NewSectionReader(rx.Media, start, reqSize)
req, _ := http.NewRequest("POST", rx.URI, r)
req.ContentLength = reqSize
req.Header.Set("Content-Range", fmt.Sprintf("bytes %v-%v/%v", start, start+reqSize-1, rx.ContentLength))
req.Header.Set("Content-Type", rx.MediaType)
req.Header.Set("User-Agent", rx.UserAgent)
res, err = rx.Client.Do(req)
start += reqSize
if err == nil && (res.StatusCode == statusResumeIncomplete || res.StatusCode == http.StatusOK) {
rx.mu.Lock()
rx.progress = start // keep track of number of bytes sent so far
rx.mu.Unlock()
if rx.Callback != nil {
rx.Callback(start, rx.ContentLength)
}
}
if err != nil || res.StatusCode != statusResumeIncomplete {
break
}
}
return res, err
}
var sleep = time.Sleep // override in unit tests
// Upload starts the process of a resumable upload with a cancellable context.
// It retries indefinitely (with a pause of uploadPause between attempts) until cancelled.
// It is called from the auto-generated API code and is not visible to the user.
// rx is private to the auto-generated API code.
func (rx *ResumableUpload) Upload(ctx context.Context) (*http.Response, error) {
var res *http.Response
var err error
for {
res, err = rx.transferChunks(ctx)
if err != nil || res.StatusCode == http.StatusCreated || res.StatusCode == http.StatusOK {
return res, err
}
select { // Check for cancellation
case <-ctx.Done():
res.StatusCode = http.StatusRequestTimeout
return res, ctx.Err()
default:
}
sleep(uploadPause)
}
return res, err
}
func ResolveRelative(basestr, relstr string) string {
u, _ := url.Parse(basestr)
rel, _ := url.Parse(relstr)
u = u.ResolveReference(rel)
us := u.String()
us = strings.Replace(us, "%7B", "{", -1)
us = strings.Replace(us, "%7D", "}", -1)
return us
}
// has4860Fix is whether this Go environment contains the fix for
// http://golang.org/issue/4860
var has4860Fix bool
// init initializes has4860Fix by checking the behavior of the net/http package.
func init() {
r := http.Request{
URL: &url.URL{
Scheme: "http",
Opaque: "//opaque",
},
}
b := &bytes.Buffer{}
r.Write(b)
has4860Fix = bytes.HasPrefix(b.Bytes(), []byte("GET http"))
}
// SetOpaque sets u.Opaque from u.Path such that HTTP requests to it
// don't alter any hex-escaped characters in u.Path.
func SetOpaque(u *url.URL) {
u.Opaque = "//" + u.Host + u.Path
if !has4860Fix {
u.Opaque = u.Scheme + ":" + u.Opaque
}
}
// Expand subsitutes any {encoded} strings in the URL passed in using
// the map supplied.
//
// This calls SetOpaque to avoid encoding of the parameters in the URL path.
func Expand(u *url.URL, expansions map[string]string) {
expanded, err := uritemplates.Expand(u.Path, expansions)
if err == nil {
u.Path = expanded
SetOpaque(u)
}
}
// CloseBody is used to close res.Body.
// Prior to calling Close, it also tries to Read a small amount to see an EOF.
// Not seeing an EOF can prevent HTTP Transports from reusing connections.
func CloseBody(res *http.Response) {
if res == nil || res.Body == nil {
return
}
// Justification for 3 byte reads: two for up to "\r\n" after
// a JSON/XML document, and then 1 to see EOF if we haven't yet.
// TODO(bradfitz): detect Go 1.3+ and skip these reads.
// See https://codereview.appspot.com/58240043
// and https://codereview.appspot.com/49570044
buf := make([]byte, 1)
for i := 0; i < 3; i++ {
_, err := res.Body.Read(buf)
if err != nil {
break
}
}
res.Body.Close()
}
// VariantType returns the type name of the given variant.
// If the map doesn't contain the named key or the value is not a []interface{}, "" is returned.
// This is used to support "variant" APIs that can return one of a number of different types.
func VariantType(t map[string]interface{}) string {
s, _ := t["type"].(string)
return s
}
// ConvertVariant uses the JSON encoder/decoder to fill in the struct 'dst' with the fields found in variant 'v'.
// This is used to support "variant" APIs that can return one of a number of different types.
// It reports whether the conversion was successful.
func ConvertVariant(v map[string]interface{}, dst interface{}) bool {
var buf bytes.Buffer
err := json.NewEncoder(&buf).Encode(v)
if err != nil {
return false
}
return json.Unmarshal(buf.Bytes(), dst) == nil
}
// A Field names a field to be retrieved with a partial response.
// See https://developers.google.com/gdata/docs/2.0/basics#PartialResponse
//
// Partial responses can dramatically reduce the amount of data that must be sent to your application.
// In order to request partial responses, you can specify the full list of fields
// that your application needs by adding the Fields option to your request.
//
// Field strings use camelCase with leading lower-case characters to identify fields within the response.
//
// For example, if your response has a "NextPageToken" and a slice of "Items" with "Id" fields,
// you could request just those fields like this:
//
// svc.Events.List().Fields("nextPageToken", "items/id").Do()
//
// or if you were also interested in each Item's "Updated" field, you can combine them like this:
//
// svc.Events.List().Fields("nextPageToken", "items(id,updated)").Do()
//
// More information about field formatting can be found here:
// https://developers.google.com/+/api/#fields-syntax
//
// Another way to find field names is through the Google API explorer:
// https://developers.google.com/apis-explorer/#p/
type Field string
// CombineFields combines fields into a single string.
func CombineFields(s []Field) string {
r := make([]string, len(s))
for i, v := range s {
r[i] = string(v)
}
return strings.Join(r, ",")
}