Vendor aws-sdk-go (dep ensure) (#178)

vendor/github.com/aws/aws-sdk-go/service/s3/s3crypto/helper.go

@@ -0,0 +1,70 @@
+package s3crypto
+
+import (
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/aws/aws-sdk-go/aws/request"
+)
+
+func getWriterStore(req *request.Request, path string, useTempFile bool) (io.ReadWriteSeeker, error) {
+	if !useTempFile {
+		return &bytesReadWriteSeeker{}, nil
+	}
+	// Create temp file to be used later for calculating the SHA256 header
+	f, err := ioutil.TempFile(path, "")
+	if err != nil {
+		return nil, err
+	}
+
+	req.Handlers.Send.PushBack(func(r *request.Request) {
+		// Close the temp file and cleanup
+		f.Close()
+		fpath := filepath.Join(path, f.Name())
+		os.Remove(fpath)
+	})
+	return f, nil
+}
+
+type bytesReadWriteSeeker struct {
+	buf []byte
+	i   int64
+}
+
+// Copied from Go stdlib bytes.Reader
+func (ws *bytesReadWriteSeeker) Read(b []byte) (int, error) {
+	if ws.i >= int64(len(ws.buf)) {
+		return 0, io.EOF
+	}
+	n := copy(b, ws.buf[ws.i:])
+	ws.i += int64(n)
+	return n, nil
+}
+
+func (ws *bytesReadWriteSeeker) Write(b []byte) (int, error) {
+	ws.buf = append(ws.buf, b...)
+	return len(b), nil
+}
+
+// Copied from Go stdlib bytes.Reader
+func (ws *bytesReadWriteSeeker) Seek(offset int64, whence int) (int64, error) {
+	var abs int64
+	switch whence {
+	case 0:
+		abs = offset
+	case 1:
+		abs = int64(ws.i) + offset
+	case 2:
+		abs = int64(len(ws.buf)) + offset
+	default:
+		return 0, errors.New("bytes.Reader.Seek: invalid whence")
+	}
+	if abs < 0 {
+		return 0, errors.New("bytes.Reader.Seek: negative position")
+	}
+	ws.i = abs
+	return abs, nil
+}