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Date: Fri, 28 Dec 2007 19:56:27 +0100
From: Werner Baumann <werner.baumann@onlinehome.de>
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To: dev@httpd.apache.org
Subject: Re: time for 1.3.40 and 2.2.7 ?
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Nick Kew wrote (concerning bug 38034):
> A quick look at the reports shows a lot of competing patches, and a
> lot of inconclusive discussion.  So it doesn't look like a simple
> matter just to apply patches and close bug.
> 
> If you're telling us it is a simple matter, perhaps you could post
> a summary here, as a startingpoint for reviewing what you propose.
> 
Don't try to get me flaming again. But I don't see a lot of competing 
patches. What I see is a lot of effort from outside apache to provide a 
patch for a five year old bug, with almost no response from apache 
developers, at least from no one, who would be able or willing to commit 
a patch.

Although I think, I explained it on 
http://issues.apache.org/bugzilla/show_bug.cgi?id=38034, here is a 
summary again. But note: it is up to you, to look at the proposed 
patched, decide and do the real commit. And please don't try to start 
another *inconlusive discussion*, if you are not willing to commit a bug 
fix, that proves to work.

The bug
-------
It's really two bugs:
1. mod_dav does not get the Etag and provide it to ap_meets_conditions.
    So ap_meets_conditions works with no or the wrong Etag, so decisions
    involving the Etag can't be correct.
2. ap_meets_conditions does not and cannot know, whether the resource
    exists. This knowledge is needed for decisions about "If-Match: *"
    and "If-None-Match: *". That's why these go wrong.

How two fix the bugs:
---------------------
There are two alternatives: fix only for mod_dav (it is very important) 
or fix in general (would be nice).

Fix for mod_dav only:
There are two patches (as far as I can see):
http://issues.apache.org/bugzilla/attachment.cgi?id=20552 (from me)
and
http://mail-archives.apache.org/mod_mbox/httpd-dev/200710.mbox/%3c1b4c87db0710111756h650c4856r4642c0365e074120@mail.gmail.com%3e
(from Paritosh Shah)
These two patches are not competing. They do fundamentaly the same, but 
the second one (from Paritosh) is the cleaner one.

Fix it in general:
Even a general solution will still have to fix the bug in mod_dav. There 
is a patch from Paritosh
http://mail-archives.apache.org/mod_mbox/httpd-dev/200710.mbox/raw/%3C1b4c87db0710191345y61c22370v5f15c5959768597f@mail.gmail.com%3E/3

To fix the problem with ap_meets_conditions in general, a change in its 
interface is necessary, to provide ap_meets_conditions with information 
about the existence of the file. There has been some discussion about 
how to do this interface change.
In my opinion, the best solution is suggested by Paritosh in
http://mail-archives.apache.org/mod_mbox/httpd-dev/200711.mbox/%3c1b4c87db0711190838v69dd7593l15c0ceb4e4755b01@mail.gmail.com%3e
The changes of the code in ap_meets_conditions(2?) should be exactly the 
ones in
http://mail-archives.apache.org/mod_mbox/httpd-dev/200710.mbox/raw/%3C1b4c87db0710191345y61c22370v5f15c5959768597f@mail.gmail.com%3E/2
But editorial changes are necessary, depending on how the interface will 
be changed exactly.

As I understand, Paritosh would be willing, to provide a complete 
working patch for the general solution. But I also understand, that Tim 
Olsen would not be fond of wasting time on creating fine patches, that 
will be ignored anyway.

My Proposal:
------------
Use the mod_dav-only patch as an intermediate solution, because it is 
urgent. This solution will not touch anything but mod_dav and can be 
removed without side effects as soon as a general solution is available.
Take the time to consider how to change the interface of 
ap_meets_conditions (there might be more issues related to this) and 
include a clean general solution in 2.2.8.

Competing Patches
-----------------
The only competing patch I know of is
http://issues.apache.org/bugzilla/attachment.cgi?id=21295
It just does not work, because it ignores half of the bugs and relies on 
assumptions that are most probably wrong.

Werner