tusd/vendor/google.golang.org/appengine/blobstore/blobstore.go

277 lines
8.6 KiB
Go

// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
// Package blobstore provides a client for App Engine's persistent blob
// storage service.
package blobstore // import "google.golang.org/appengine/blobstore"
import (
"bufio"
"encoding/base64"
"fmt"
"io"
"io/ioutil"
"mime"
"mime/multipart"
"net/http"
"net/textproto"
"net/url"
"strconv"
"strings"
"time"
"github.com/golang/protobuf/proto"
"golang.org/x/net/context"
"google.golang.org/appengine"
"google.golang.org/appengine/datastore"
"google.golang.org/appengine/internal"
basepb "google.golang.org/appengine/internal/base"
blobpb "google.golang.org/appengine/internal/blobstore"
)
const (
blobInfoKind = "__BlobInfo__"
blobFileIndexKind = "__BlobFileIndex__"
zeroKey = appengine.BlobKey("")
)
// BlobInfo is the blob metadata that is stored in the datastore.
// Filename may be empty.
type BlobInfo struct {
BlobKey appengine.BlobKey
ContentType string `datastore:"content_type"`
CreationTime time.Time `datastore:"creation"`
Filename string `datastore:"filename"`
Size int64 `datastore:"size"`
MD5 string `datastore:"md5_hash"`
// ObjectName is the Google Cloud Storage name for this blob.
ObjectName string `datastore:"gs_object_name"`
}
// isErrFieldMismatch returns whether err is a datastore.ErrFieldMismatch.
//
// The blobstore stores blob metadata in the datastore. When loading that
// metadata, it may contain fields that we don't care about. datastore.Get will
// return datastore.ErrFieldMismatch in that case, so we ignore that specific
// error.
func isErrFieldMismatch(err error) bool {
_, ok := err.(*datastore.ErrFieldMismatch)
return ok
}
// Stat returns the BlobInfo for a provided blobKey. If no blob was found for
// that key, Stat returns datastore.ErrNoSuchEntity.
func Stat(c context.Context, blobKey appengine.BlobKey) (*BlobInfo, error) {
c, _ = appengine.Namespace(c, "") // Blobstore is always in the empty string namespace
dskey := datastore.NewKey(c, blobInfoKind, string(blobKey), 0, nil)
bi := &BlobInfo{
BlobKey: blobKey,
}
if err := datastore.Get(c, dskey, bi); err != nil && !isErrFieldMismatch(err) {
return nil, err
}
return bi, nil
}
// Send sets the headers on response to instruct App Engine to send a blob as
// the response body. This is more efficient than reading and writing it out
// manually and isn't subject to normal response size limits.
func Send(response http.ResponseWriter, blobKey appengine.BlobKey) {
hdr := response.Header()
hdr.Set("X-AppEngine-BlobKey", string(blobKey))
if hdr.Get("Content-Type") == "" {
// This value is known to dev_appserver to mean automatic.
// In production this is remapped to the empty value which
// means automatic.
hdr.Set("Content-Type", "application/vnd.google.appengine.auto")
}
}
// UploadURL creates an upload URL for the form that the user will
// fill out, passing the application path to load when the POST of the
// form is completed. These URLs expire and should not be reused. The
// opts parameter may be nil.
func UploadURL(c context.Context, successPath string, opts *UploadURLOptions) (*url.URL, error) {
req := &blobpb.CreateUploadURLRequest{
SuccessPath: proto.String(successPath),
}
if opts != nil {
if n := opts.MaxUploadBytes; n != 0 {
req.MaxUploadSizeBytes = &n
}
if n := opts.MaxUploadBytesPerBlob; n != 0 {
req.MaxUploadSizePerBlobBytes = &n
}
if s := opts.StorageBucket; s != "" {
req.GsBucketName = &s
}
}
res := &blobpb.CreateUploadURLResponse{}
if err := internal.Call(c, "blobstore", "CreateUploadURL", req, res); err != nil {
return nil, err
}
return url.Parse(*res.Url)
}
// UploadURLOptions are the options to create an upload URL.
type UploadURLOptions struct {
MaxUploadBytes int64 // optional
MaxUploadBytesPerBlob int64 // optional
// StorageBucket specifies the Google Cloud Storage bucket in which
// to store the blob.
// This is required if you use Cloud Storage instead of Blobstore.
// Your application must have permission to write to the bucket.
// You may optionally specify a bucket name and path in the format
// "bucket_name/path", in which case the included path will be the
// prefix of the uploaded object's name.
StorageBucket string
}
// Delete deletes a blob.
func Delete(c context.Context, blobKey appengine.BlobKey) error {
return DeleteMulti(c, []appengine.BlobKey{blobKey})
}
// DeleteMulti deletes multiple blobs.
func DeleteMulti(c context.Context, blobKey []appengine.BlobKey) error {
s := make([]string, len(blobKey))
for i, b := range blobKey {
s[i] = string(b)
}
req := &blobpb.DeleteBlobRequest{
BlobKey: s,
}
res := &basepb.VoidProto{}
if err := internal.Call(c, "blobstore", "DeleteBlob", req, res); err != nil {
return err
}
return nil
}
func errorf(format string, args ...interface{}) error {
return fmt.Errorf("blobstore: "+format, args...)
}
// ParseUpload parses the synthetic POST request that your app gets from
// App Engine after a user's successful upload of blobs. Given the request,
// ParseUpload returns a map of the blobs received (keyed by HTML form
// element name) and other non-blob POST parameters.
func ParseUpload(req *http.Request) (blobs map[string][]*BlobInfo, other url.Values, err error) {
_, params, err := mime.ParseMediaType(req.Header.Get("Content-Type"))
if err != nil {
return nil, nil, err
}
boundary := params["boundary"]
if boundary == "" {
return nil, nil, errorf("did not find MIME multipart boundary")
}
blobs = make(map[string][]*BlobInfo)
other = make(url.Values)
mreader := multipart.NewReader(io.MultiReader(req.Body, strings.NewReader("\r\n\r\n")), boundary)
for {
part, perr := mreader.NextPart()
if perr == io.EOF {
break
}
if perr != nil {
return nil, nil, errorf("error reading next mime part with boundary %q (len=%d): %v",
boundary, len(boundary), perr)
}
bi := &BlobInfo{}
ctype, params, err := mime.ParseMediaType(part.Header.Get("Content-Disposition"))
if err != nil {
return nil, nil, err
}
bi.Filename = params["filename"]
formKey := params["name"]
ctype, params, err = mime.ParseMediaType(part.Header.Get("Content-Type"))
if err != nil {
return nil, nil, err
}
bi.BlobKey = appengine.BlobKey(params["blob-key"])
if ctype != "message/external-body" || bi.BlobKey == "" {
if formKey != "" {
slurp, serr := ioutil.ReadAll(part)
if serr != nil {
return nil, nil, errorf("error reading %q MIME part", formKey)
}
other[formKey] = append(other[formKey], string(slurp))
}
continue
}
// App Engine sends a MIME header as the body of each MIME part.
tp := textproto.NewReader(bufio.NewReader(part))
header, mimeerr := tp.ReadMIMEHeader()
if mimeerr != nil {
return nil, nil, mimeerr
}
bi.Size, err = strconv.ParseInt(header.Get("Content-Length"), 10, 64)
if err != nil {
return nil, nil, err
}
bi.ContentType = header.Get("Content-Type")
// Parse the time from the MIME header like:
// X-AppEngine-Upload-Creation: 2011-03-15 21:38:34.712136
createDate := header.Get("X-AppEngine-Upload-Creation")
if createDate == "" {
return nil, nil, errorf("expected to find an X-AppEngine-Upload-Creation header")
}
bi.CreationTime, err = time.Parse("2006-01-02 15:04:05.000000", createDate)
if err != nil {
return nil, nil, errorf("error parsing X-AppEngine-Upload-Creation: %s", err)
}
if hdr := header.Get("Content-MD5"); hdr != "" {
md5, err := base64.URLEncoding.DecodeString(hdr)
if err != nil {
return nil, nil, errorf("bad Content-MD5 %q: %v", hdr, err)
}
bi.MD5 = string(md5)
}
// If the GCS object name was provided, record it.
bi.ObjectName = header.Get("X-AppEngine-Cloud-Storage-Object")
blobs[formKey] = append(blobs[formKey], bi)
}
return
}
// Reader is a blob reader.
type Reader interface {
io.Reader
io.ReaderAt
io.Seeker
}
// NewReader returns a reader for a blob. It always succeeds; if the blob does
// not exist then an error will be reported upon first read.
func NewReader(c context.Context, blobKey appengine.BlobKey) Reader {
return openBlob(c, blobKey)
}
// BlobKeyForFile returns a BlobKey for a Google Storage file.
// The filename should be of the form "/gs/bucket_name/object_name".
func BlobKeyForFile(c context.Context, filename string) (appengine.BlobKey, error) {
req := &blobpb.CreateEncodedGoogleStorageKeyRequest{
Filename: &filename,
}
res := &blobpb.CreateEncodedGoogleStorageKeyResponse{}
if err := internal.Call(c, "blobstore", "CreateEncodedGoogleStorageKey", req, res); err != nil {
return "", err
}
return appengine.BlobKey(*res.BlobKey), nil
}