mirror of
https://github.com/letic/terraform-provider-google.git
synced 2024-09-07 09:36:44 +00:00
200 lines
6.0 KiB
Go
200 lines
6.0 KiB
Go
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// Copyright 2016 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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package gensupport
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import (
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"fmt"
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"io"
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"io/ioutil"
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"mime/multipart"
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"net/http"
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"net/textproto"
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"google.golang.org/api/googleapi"
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)
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const sniffBuffSize = 512
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func newContentSniffer(r io.Reader) *contentSniffer {
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return &contentSniffer{r: r}
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}
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// contentSniffer wraps a Reader, and reports the content type determined by sniffing up to 512 bytes from the Reader.
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type contentSniffer struct {
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r io.Reader
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start []byte // buffer for the sniffed bytes.
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err error // set to any error encountered while reading bytes to be sniffed.
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ctype string // set on first sniff.
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sniffed bool // set to true on first sniff.
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}
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func (cs *contentSniffer) Read(p []byte) (n int, err error) {
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// Ensure that the content type is sniffed before any data is consumed from Reader.
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_, _ = cs.ContentType()
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if len(cs.start) > 0 {
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n := copy(p, cs.start)
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cs.start = cs.start[n:]
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return n, nil
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}
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// We may have read some bytes into start while sniffing, even if the read ended in an error.
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// We should first return those bytes, then the error.
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if cs.err != nil {
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return 0, cs.err
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}
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// Now we have handled all bytes that were buffered while sniffing. Now just delegate to the underlying reader.
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return cs.r.Read(p)
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}
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// ContentType returns the sniffed content type, and whether the content type was succesfully sniffed.
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func (cs *contentSniffer) ContentType() (string, bool) {
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if cs.sniffed {
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return cs.ctype, cs.ctype != ""
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}
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cs.sniffed = true
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// If ReadAll hits EOF, it returns err==nil.
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cs.start, cs.err = ioutil.ReadAll(io.LimitReader(cs.r, sniffBuffSize))
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// Don't try to detect the content type based on possibly incomplete data.
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if cs.err != nil {
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return "", false
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}
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cs.ctype = http.DetectContentType(cs.start)
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return cs.ctype, true
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}
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// DetermineContentType determines the content type of the supplied reader.
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// If the content type is already known, it can be specified via ctype.
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// Otherwise, the content of media will be sniffed to determine the content type.
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// If media implements googleapi.ContentTyper (deprecated), this will be used
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// instead of sniffing the content.
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// After calling DetectContentType the caller must not perform further reads on
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// media, but rather read from the Reader that is returned.
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func DetermineContentType(media io.Reader, ctype string) (io.Reader, string) {
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// Note: callers could avoid calling DetectContentType if ctype != "",
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// but doing the check inside this function reduces the amount of
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// generated code.
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if ctype != "" {
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return media, ctype
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}
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// For backwards compatability, allow clients to set content
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// type by providing a ContentTyper for media.
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if typer, ok := media.(googleapi.ContentTyper); ok {
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return media, typer.ContentType()
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}
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sniffer := newContentSniffer(media)
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if ctype, ok := sniffer.ContentType(); ok {
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return sniffer, ctype
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}
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// If content type could not be sniffed, reads from sniffer will eventually fail with an error.
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return sniffer, ""
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}
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type typeReader struct {
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io.Reader
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typ string
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}
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// multipartReader combines the contents of multiple readers to creat a multipart/related HTTP body.
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// Close must be called if reads from the multipartReader are abandoned before reaching EOF.
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type multipartReader struct {
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pr *io.PipeReader
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pipeOpen bool
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ctype string
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}
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func newMultipartReader(parts []typeReader) *multipartReader {
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mp := &multipartReader{pipeOpen: true}
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var pw *io.PipeWriter
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mp.pr, pw = io.Pipe()
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mpw := multipart.NewWriter(pw)
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mp.ctype = "multipart/related; boundary=" + mpw.Boundary()
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go func() {
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for _, part := range parts {
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w, err := mpw.CreatePart(typeHeader(part.typ))
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if err != nil {
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mpw.Close()
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pw.CloseWithError(fmt.Errorf("googleapi: CreatePart failed: %v", err))
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return
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}
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_, err = io.Copy(w, part.Reader)
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if err != nil {
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mpw.Close()
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pw.CloseWithError(fmt.Errorf("googleapi: Copy failed: %v", err))
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return
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}
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}
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mpw.Close()
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pw.Close()
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}()
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return mp
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}
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func (mp *multipartReader) Read(data []byte) (n int, err error) {
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return mp.pr.Read(data)
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}
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func (mp *multipartReader) Close() error {
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if !mp.pipeOpen {
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return nil
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}
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mp.pipeOpen = false
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return mp.pr.Close()
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}
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// CombineBodyMedia combines a json body with media content to create a multipart/related HTTP body.
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// It returns a ReadCloser containing the combined body, and the overall "multipart/related" content type, with random boundary.
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//
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// The caller must call Close on the returned ReadCloser if reads are abandoned before reaching EOF.
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func CombineBodyMedia(body io.Reader, bodyContentType string, media io.Reader, mediaContentType string) (io.ReadCloser, string) {
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mp := newMultipartReader([]typeReader{
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{body, bodyContentType},
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{media, mediaContentType},
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})
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return mp, mp.ctype
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}
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func typeHeader(contentType string) textproto.MIMEHeader {
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h := make(textproto.MIMEHeader)
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if contentType != "" {
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h.Set("Content-Type", contentType)
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}
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return h
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}
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// PrepareUpload determines whether the data in the supplied reader should be
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// uploaded in a single request, or in sequential chunks.
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// chunkSize is the size of the chunk that media should be split into.
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// If chunkSize is non-zero and the contents of media do not fit in a single
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// chunk (or there is an error reading media), then media will be returned as a
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// MediaBuffer. Otherwise, media will be returned as a Reader.
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//
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// After PrepareUpload has been called, media should no longer be used: the
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// media content should be accessed via one of the return values.
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func PrepareUpload(media io.Reader, chunkSize int) (io.Reader, *MediaBuffer) {
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if chunkSize == 0 { // do not chunk
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return media, nil
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}
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mb := NewMediaBuffer(media, chunkSize)
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rdr, _, _, err := mb.Chunk()
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if err == io.EOF { // we can upload this in a single request
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return rdr, nil
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}
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// err might be a non-EOF error. If it is, the next call to mb.Chunk will
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// return the same error. Returning a MediaBuffer ensures that this error
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// will be handled at some point.
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return nil, mb
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}
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