Vendor dependencies for GCS

vendor/google.golang.org/api/gensupport/buffer.go

@@ -0,0 +1,77 @@
+// 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 (
+	"bytes"
+	"io"
+
+	"google.golang.org/api/googleapi"
+)
+
+// MediaBuffer buffers data from an io.Reader to support uploading media in retryable chunks.
+type MediaBuffer struct {
+	media io.Reader
+
+	chunk []byte // The current chunk which is pending upload.  The capacity is the chunk size.
+	err   error  // Any error generated when populating chunk by reading media.
+
+	// The absolute position of chunk in the underlying media.
+	off int64
+}
+
+func NewMediaBuffer(media io.Reader, chunkSize int) *MediaBuffer {
+	return &MediaBuffer{media: media, chunk: make([]byte, 0, chunkSize)}
+}
+
+// Chunk returns the current buffered chunk, the offset in the underlying media
+// from which the chunk is drawn, and the size of the chunk.
+// Successive calls to Chunk return the same chunk between calls to Next.
+func (mb *MediaBuffer) Chunk() (chunk io.Reader, off int64, size int, err error) {
+	// There may already be data in chunk if Next has not been called since the previous call to Chunk.
+	if mb.err == nil && len(mb.chunk) == 0 {
+		mb.err = mb.loadChunk()
+	}
+	return bytes.NewReader(mb.chunk), mb.off, len(mb.chunk), mb.err
+}
+
+// loadChunk will read from media into chunk, up to the capacity of chunk.
+func (mb *MediaBuffer) loadChunk() error {
+	bufSize := cap(mb.chunk)
+	mb.chunk = mb.chunk[:bufSize]
+
+	read := 0
+	var err error
+	for err == nil && read < bufSize {
+		var n int
+		n, err = mb.media.Read(mb.chunk[read:])
+		read += n
+	}
+	mb.chunk = mb.chunk[:read]
+	return err
+}
+
+// Next advances to the next chunk, which will be returned by the next call to Chunk.
+// Calls to Next without a corresponding prior call to Chunk will have no effect.
+func (mb *MediaBuffer) Next() {
+	mb.off += int64(len(mb.chunk))
+	mb.chunk = mb.chunk[0:0]
+}
+
+type readerTyper struct {
+	io.Reader
+	googleapi.ContentTyper
+}
+
+// ReaderAtToReader adapts a ReaderAt to be used as a Reader.
+// If ra implements googleapi.ContentTyper, then the returned reader
+// will also implement googleapi.ContentTyper, delegating to ra.
+func ReaderAtToReader(ra io.ReaderAt, size int64) io.Reader {
+	r := io.NewSectionReader(ra, 0, size)
+	if typer, ok := ra.(googleapi.ContentTyper); ok {
+		return readerTyper{r, typer}
+	}
+	return r
+}