Segfault with weird Message-ID

[Mike Hommey <mh+notmuch@glandium.org>]

Hi,

I got a segfault when importing my maildir. It happened because of an
old weird email, where the message-id is the following:
Message-ID: <000022b17a1f$00004fbe$00000550@myrop (ew6.southwind.net [216.53.98.70]) by onyx.southwind.net from homepage.com (114.230.197.216) by newmail.spectraweb.ch from default (m202.2-25.warwick.net [
218.242.202.80]) by host.warwick.net (8.10.0.Beta10/8.10.0.Beta10) with SMTP id e9GKEKk19201>

I have absolutely no idea how it got this value, but the mail being
an archived 8 years old spam, I'm not exactly sure if anyone would 
still expect such message id to occur.

Anyways, the stack dump is the following:
#0  0x00007ffff6d1e598 in Xapian::Document::add_term(std::string const&, unsigned int) () from /usr/lib/libxapian.so.15
#1  0x000000000040f5ff in _notmuch_message_add_term (message=0x0, prefix_name=0x41ad7f "tag", value=0x4191b0 "inbox") at lib/message.cc:587
#2  0x000000000040f827 in notmuch_message_add_tag (message=0x0, tag=0x4191b0 "inbox") at lib/message.cc:668
#3  0x0000000000407bc8 in tag_inbox_and_unread (message=0x0) at notmuch-new.c:44
#4  0x0000000000407f63 in add_files_recursive (notmuch=0x62cc20, path=0x832e90 "/home/mh/Maildir/saved-messages/cur", st=0x7fffffffe000, state=0x7fffffffe240) at notmuch-new.c:185
#5  0x0000000000408036 in add_files_recursive (notmuch=0x62cc20, path=0x832de0 "/home/mh/Maildir/saved-messages", st=0x7fffffffe000, state=0x7fffffffe240) at notmuch-new.c:223
#6  0x0000000000408036 in add_files_recursive (notmuch=0x62cc20, path=0x62c920 "/home/mh/Maildir", st=0x7fffffffe000, state=0x7fffffffe240) at notmuch-new.c:223
#7  0x0000000000408245 in add_files (notmuch=0x62cc20, path=0x62c920 "/home/mh/Maildir", state=0x7fffffffe240) at notmuch-new.c:287
#8  0x0000000000408704 in notmuch_new_command (ctx=0x61f140, argc=0, argv=0x7fffffffe3e8) at notmuch-new.c:431
#9  0x0000000000406ea8 in main (argc=2, argv=0x7fffffffe3d8) at notmuch.c:400

And the most likely problem is that message is NULL.

Now, looking at the code, there seems to me there actually 3 problems:
- _notmuch_message_create_for_message_id can return NULL, and while
  there is a test for it in notmuch_database_add_message, the function
  still returns a success code
- things are still going on even when message is NULL in
  add_files_recursive
- for some reason, xapian doesn't want to add the document corresponding
  to this old spam message: notmuch->xapian_db->add_document throws an
  exception.

I can provide the spam if necessary, or can continue debugging the issue
with some guidance.

Cheers,

Mike