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From: Dmitry Kurochkin <dmitry.kurochkin@gmail.com>
To: Sebastian Spaeth <Sebastian@SSpaeth.de>,
	Patrick Totzke <patricktotzke@googlemail.com>
Subject: Re: [python] segfaults at Message.get_date
In-Reply-To: <87hb7n300m.fsf@SSpaeth.de>
References: <20110616215439.GA26997@brick> <87boxxq833.fsf@SSpaeth.de>
	<20110617161024.GA8154@optimusprime> <87hb7n300m.fsf@SSpaeth.de>
User-Agent: Notmuch/0.5-237-gf6d8cdb (http://notmuchmail.org) Emacs/23.3.1
	(x86_64-pc-linux-gnu)
Date: Sun, 19 Jun 2011 13:45:07 +0400
Message-ID: <87hb7m5f4s.fsf@gmail.com>
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Cc: notmuch@notmuchmail.org
Precedence: list

Hi Sebastian, Patrick.

On Sat, 18 Jun 2011 12:30:01 +0200, Sebastian Spaeth <Sebastian@SSpaeth.de> wrote:
> On Fri, 17 Jun 2011 17:10:24 +0100, Patrick Totzke :
> > #0  0x006eb87d in Xapian::Document::Internal::get_value(unsigned int) const () from /usr/lib/sse2/libxapian.so.22
> > #1  0x006eb952 in Xapian::Document::get_value(unsigned int) const () from /usr/lib/sse2/libxapian.so.22
> > #2  0x00523963 in notmuch_message_get_date () from /usr/local/lib/libnotmuch.so.1
> 
> One question, what type is libnotmuch really returning here? The code:
> 
> 
> time_t
> notmuch_message_get_date (notmuch_message_t *message)
> {   ...
>     return Xapian::sortable_unserialise (value);
> }
> 
> But Xapian API says that sortable_unserialise() returns floating type "double"
> 
> http://xapian.org/docs/apidoc/html/namespaceXapian.html#326fe2d6b0ee59ac9536f3960e8fd99b
> "Convert a string encoded using sortable_serialise back to a floating
> point number."
> 
> But time_t is usually a (signed) long and not floating point. Obviously
> things have worked just fine so far, but is libnotmuch really returning
> the right type here? Sorry, I expose my total lack of basic C++ knowledge
> here...
> 

Converting double to time_t does not look good.  Notmuch converts
between time_t and double both when setting and getting the date.  I
guess it should work good in most cases at least.  Perhaps Carl knows
better that it is safe.

This is not relevant to the segfault.  The failure happens in:

  value = message->doc.get_value (NOTMUCH_VALUE_TIMESTAMP);

before conversion from double to time_t.

Sebastian, are you able to reproduce the issue?  A python script that
triggers the bug, perhaps?  I would look at this if I can reproduce the
problem.

Patrick, can you install debugging symbols for libxapian and get the
backtrace again?  On Debian you need to install libxapian22-dbg.

Regards,
  Dmitry

> Sebastian
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