From bb620e09004e63699562c0533645bf8cfd865097 Mon Sep 17 00:00:00 2001
From: Ben Burwell <ben@benburwell.com>
Date: Wed, 31 Jul 2019 13:33:50 -0400
Subject: [PATCH] Include body MIME terminator in multipart messages

Before, the text/plain part of the multipart MIME message was not being
correctly terminated with its boundary. The multipart writer writes the
terminator when its Close is called, but since the call to Close() was
deferred, it was not being called until after the attachments were being
written resulting in the boundary not being included at all.
---
 widgets/compose.go | 53 ++++++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/widgets/compose.go b/widgets/compose.go
index 3dd569d..03b6586 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -335,14 +335,7 @@ func (c *Composer) WriteMessage(header *mail.Header, writer io.Writer) error {
 
 	if len(c.attachments) == 0 {
 		// don't create a multipart email if we only have text
-		header.SetContentType("text/plain", map[string]string{"charset": "UTF-8"})
-		w, err := mail.CreateSingleInlineWriter(writer, *header)
-		if err != nil {
-			return errors.Wrap(err, "CreateSingleInlineWriter")
-		}
-		defer w.Close()
-
-		return writeBody(body, w)
+		return writeInlineBody(header, body, writer)
 	}
 
 	// otherwise create a multipart email,
@@ -353,6 +346,34 @@ func (c *Composer) WriteMessage(header *mail.Header, writer io.Writer) error {
 	}
 	defer w.Close()
 
+	if err := writeMultipartBody(body, w); err != nil {
+		return errors.Wrap(err, "writeMultipartBody")
+	}
+
+	for _, a := range c.attachments {
+		if err := writeAttachment(a, w); err != nil {
+			return errors.Wrap(err, "writeAttachment")
+		}
+	}
+
+	return nil
+}
+
+func writeInlineBody(header *mail.Header, body io.Reader, writer io.Writer) error {
+	header.SetContentType("text/plain", map[string]string{"charset": "UTF-8"})
+	w, err := mail.CreateSingleInlineWriter(writer, *header)
+	if err != nil {
+		return errors.Wrap(err, "CreateSingleInlineWriter")
+	}
+	defer w.Close()
+	if _, err := io.Copy(w, body); err != nil {
+		return errors.Wrap(err, "io.Copy")
+	}
+	return nil
+}
+
+// write the message body to the multipart message
+func writeMultipartBody(body io.Reader, w *mail.Writer) error {
 	bh := mail.InlineHeader{}
 	bh.SetContentType("text/plain", map[string]string{"charset": "UTF-8"})
 
@@ -367,23 +388,9 @@ func (c *Composer) WriteMessage(header *mail.Header, writer io.Writer) error {
 		return errors.Wrap(err, "CreatePart")
 	}
 	defer bw.Close()
-
-	if err := writeBody(body, bw); err != nil {
-		return err
-	}
-
-	for _, a := range c.attachments {
-		writeAttachment(a, w)
-	}
-
-	return nil
-}
-
-func writeBody(body io.Reader, w io.Writer) error {
-	if _, err := io.Copy(w, body); err != nil {
+	if _, err := io.Copy(bw, body); err != nil {
 		return errors.Wrap(err, "io.Copy")
 	}
-
 	return nil
 }