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Date: Thu, 18 Jul 2013 14:26:24 -0500
From: Richard Todd <rmtodd@servalan.servalan.com>
To: George Hartzell <hartzell@alerce.com>
Subject: Re: Help with filing a [maybe] ZFS/mmap bug.
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On Thu, Jul 18, 2013 at 11:40:51AM -0700, George Hartzell wrote:
> Removing the mmap support from those two routines seems to avoid the
> issue.

Aha. 

>  > If so, then the issue is triggered by one or both of those two routines;
>  > hack them to print out the exact offsets used on each call and use that to 
>  > try and code up a simple C++ test case.  
>  > [...]
> 
> Your test case doesn't use mmap, I assume that you've offered it up as
> a hint, not as something that's nearly done.  The shell script in
> particular seems useful.

Um, go look at gen4.cpp again.  It uses mmap().  The insert_bytes and
delete_bytes functions should work the same way as the (mmap-using path of)
the functions of the same name in py-mutagen. 

				
> In my case I'd want to find a particular set of file size, offset, and
> insertion size that triggers the problem and code up a c/c++ equiv. of
> the mmap calls that py-mutagen does.  Right?

Yeah.