[balsa] Try to recover from parser failure

[Peter Bloomfield <peterb src gnome org>]

commit 9df15e65e086d94c236402050255152e4ce1e2f3
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Thu May 4 10:21:44 2017 -0400

    Try to recover from parser failure
    
        * libbalsa/mailbox_mbox.c (parse_mailbox): try to recover when
        the GMimeParser returns a NULL GMimeMessage.

 ChangeLog               |    5 +++++
 libbalsa/mailbox_mbox.c |   19 ++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index f4ebf84..04718aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2017-05-04  Peter Bloomfield  <pbloomfield bellsouth net>
 
+       * libbalsa/mailbox_mbox.c (parse_mailbox): try to recover when
+       the GMimeParser returns a NULL GMimeMessage.
+
+2017-05-04  Peter Bloomfield  <pbloomfield bellsouth net>
+
        * libbalsa/mailbox_pop3.c (message_cb): reset the GMimeStream
          before passing it to libbalsa_mailbox_add_message.
 
diff --git a/libbalsa/mailbox_mbox.c b/libbalsa/mailbox_mbox.c
index ac4cd3f..ff5ecbb 100644
--- a/libbalsa/mailbox_mbox.c
+++ b/libbalsa/mailbox_mbox.c
@@ -487,8 +487,25 @@ parse_mailbox(LibBalsaMailboxMbox * mbox)
 
         msg_info.status = msg_info.x_status = msg_info.mime_version = -1;
         mime_message   = g_mime_parser_construct_message(gmime_parser);
-        if (!mime_message)
+        if (mime_message == NULL) {
+            /* Skip to the next message, if any */
+            GMimeStream *mbox_stream;
+
+            mbox_stream = mbox->gmime_stream;
+            while (!g_mime_stream_eos(mbox_stream)) {
+                gchar c;
+
+                while (g_mime_stream_read(mbox_stream, &c, 1) == 1)
+                    if (c == '\n')
+                        break;
+
+                if (lbm_mbox_stream_seek_to_message(mbox_stream,
+                                                    g_mime_stream_tell(mbox_stream)))
+                    break;
+            }
+            g_mime_parser_init_with_stream(gmime_parser, mbox_stream);
             continue;
+        }
         msg_info.start = g_mime_parser_get_from_offset(gmime_parser);
         msg_info.end   = g_mime_parser_tell(gmime_parser);
         if (msg_info.end <= msg_info.start