From 3b0249153241ae0c16e9f5a0dd095dfe56eae1cf Mon Sep 17 00:00:00 2001
From: Eric Chen <eric@tron.network>
Date: Wed, 9 Oct 2019 16:37:36 -0700
Subject: [PATCH] Attach file size to each multipart file converted to http
 request. Read/set size for each Readerfile on parsing file.

---
 multifilereader.go |  9 +++++++--
 multipartfile.go   | 22 +++++++++++++++++++---
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/multifilereader.go b/multifilereader.go
index f6f225a..3bdc8fc 100644
--- a/multifilereader.go
+++ b/multifilereader.go
@@ -93,8 +93,6 @@ func (mfr *MultiFileReader) Read(buf []byte) (written int, err error) {
 				dispositionPrefix = "form-data; name=\"file\""
 			}
 
-			header.Set("Content-Disposition", fmt.Sprintf("%s; filename=\"%s\"", dispositionPrefix, filename))
-
 			var contentType string
 
 			switch f := entry.Node().(type) {
@@ -115,8 +113,15 @@ func (mfr *MultiFileReader) Read(buf []byte) (written int, err error) {
 			header.Set("Content-Type", contentType)
 			if rf, ok := entry.Node().(FileInfo); ok {
 				header.Set("abspath", rf.AbsPath())
+				// attach file size to content-disposition when available
+				// according to https://tools.ietf.org/html/rfc2183
+				if stat := rf.Stat(); stat != nil {
+					dispositionPrefix += fmt.Sprintf("; size=%d", stat.Size())
+				}
 			}
 
+			header.Set("Content-Disposition", fmt.Sprintf("%s; filename=\"%s\"", dispositionPrefix, filename))
+
 			_, err := mfr.mpWriter.CreatePart(header)
 			if err != nil {
 				return 0, err
diff --git a/multipartfile.go b/multipartfile.go
index d4593ad..d2480d5 100644
--- a/multipartfile.go
+++ b/multipartfile.go
@@ -7,6 +7,7 @@ import (
 	"mime/multipart"
 	"net/url"
 	"path"
+	"strconv"
 	"strings"
 )
 
@@ -18,7 +19,8 @@ const (
 	applicationSymlink   = "application/symlink"
 	applicationFile      = "application/octet-stream"
 
-	contentTypeHeader = "Content-Type"
+	contentTypeHeader        = "Content-Type"
+	contentDispositionHeader = "Content-Disposition"
 )
 
 type multipartDirectory struct {
@@ -101,10 +103,24 @@ func (w *multipartWalker) nextFile() (Node, error) {
 
 		return NewLinkFile(string(out), nil), nil
 	default:
-		return &ReaderFile{
+		rf := &ReaderFile{
 			reader:  part,
 			abspath: part.Header.Get("abspath"),
-		}, nil
+		}
+		cdh := part.Header.Get(contentDispositionHeader)
+		_, params, err := mime.ParseMediaType(cdh)
+		if err != nil {
+			return nil, err
+		}
+		// ignore if size is not available
+		if size, ok := params["size"]; ok {
+			fsize, err := strconv.ParseInt(size, 10, 64)
+			if err != nil {
+				return nil, err
+			}
+			rf.fsize = fsize
+		}
+		return rf, nil
 	}
 }