[geary: 1/2] Geary.RFC822.Message: Handle 0 size of body and header in from_parts().

[Michael Gratton <mjog src gnome org>]

commit 0bffbd2c5ddbeb7b0df5d31dd12f39df5ce5116e
Author: Marek Benc <dusxmt gmx com>
Date:   Sun Feb 14 16:07:47 2021 +0100

    Geary.RFC822.Message: Handle 0 size of body and header in from_parts().
    
    Fixes #1137

 src/engine/rfc822/rfc822-message.vala | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/src/engine/rfc822/rfc822-message.vala b/src/engine/rfc822/rfc822-message.vala
index e6cc17a40..521058dea 100644
--- a/src/engine/rfc822/rfc822-message.vala
+++ b/src/engine/rfc822/rfc822-message.vala
@@ -194,8 +194,15 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
     public Message.from_parts(Header header, Text body)
         throws Error {
         GMime.StreamCat stream_cat = new GMime.StreamCat();
-        stream_cat.add_source(new GMime.StreamMem.with_buffer(header.buffer.get_bytes().get_data()));
-        stream_cat.add_source(new GMime.StreamMem.with_buffer(body.buffer.get_bytes().get_data()));
+
+        if (header.buffer.size != 0) {
+            stream_cat.add_source(new GMime.StreamMem.with_buffer(header.buffer.get_bytes().get_data()));
+        } else {
+            throw new Error.INVALID("Missing header in RFC 822 message");
+        }
+        if (body.buffer.size != 0) {
+            stream_cat.add_source(new GMime.StreamMem.with_buffer(body.buffer.get_bytes().get_data()));
+        }
 
         GMime.Parser parser = new GMime.Parser.with_stream(stream_cat);
         var message = parser.construct_message(Geary.RFC822.get_parser_options());