commands: Added MultiFileReader (read a File as multipart data)

commands/http/multifilereader.go

+package http
+
+import (
+	"bytes"
+	"io"
+	"mime/multipart"
+
+	cmds "github.com/jbenet/go-ipfs/commands"
+)
+
+type MultiFileReader struct {
+	io.Reader
+
+	files       cmds.File
+	currentFile cmds.File
+	buf         bytes.Buffer
+	mpWriter    *multipart.Writer
+	closed      bool
+}
+
+func NewMultiFileReader(file cmds.File) *MultiFileReader {
+	mfr := &MultiFileReader{
+		files: file,
+	}
+	mfr.mpWriter = multipart.NewWriter(&mfr.buf)
+
+	return mfr
+}
+
+func (mfr *MultiFileReader) Read(buf []byte) (written int, err error) {
+	// if we are closed, end reading
+	if mfr.closed && mfr.buf.Len() == 0 {
+		return 0, io.EOF
+	}
+
+	// if the current file isn't set, advance to the next file
+	if mfr.currentFile == nil {
+		mfr.currentFile, err = mfr.files.NextFile()
+		if err == io.EOF || (err == nil && mfr.currentFile == nil) {
+			mfr.mpWriter.Close()
+			mfr.closed = true
+		} else if err != nil {
+			return 0, err
+		}
+
+		if !mfr.closed {
+			_, err := mfr.mpWriter.CreateFormFile("file", mfr.currentFile.FileName())
+			if err != nil {
+				return 0, err
+			}
+		}
+	}
+
+	var reader io.Reader
+
+	if mfr.buf.Len() > 0 {
+		// if the buffer has something in it, read from it
+		reader = &mfr.buf
+
+	} else if mfr.currentFile != nil {
+		// otherwise, read from file data
+		reader = mfr.currentFile
+	}
+
+	written, err = reader.Read(buf)
+	if err == io.EOF && reader == mfr.currentFile {
+		mfr.currentFile = nil
+		return mfr.Read(buf)
+	}
+	return written, err
+}
+
+func (mfr *MultiFileReader) Boundary() string {
+	return mfr.mpWriter.Boundary()
+}