Re: Infinite loop in cascade_filter_fn()

From: Carlos Martín Nieto <cmn@elego.de>
Date: Nov 25, 2011, 15:53 UTC
Message-ID: <20111125155301.GC10417@beez.lab.cmartin.tk>
In-Reply-To: <Pine.GSO.4.63.1111251629500.22588@shipon.roxen.com>

On Fri, Nov 25, 2011 at 04:43:41PM +0100, Henrik Grubbström wrote:

Show 20 quoted lines

> On Wed, 23 Nov 2011, Henrik Grubbström wrote:
> 
> >Hi.
> >
> >My git repository walker just got bitten by what seems to be a
> >reasonably new bug in convert.c:cascade_filter_fn() (git 1.7.8.rc3
> >(gentoo)).
> 
> After some tracing, the problem is triggered by the variable "remaining"
> being set to 1 in the beginning of the cascade_filter_fn() loop,
> which causes filter "two" to be called with an output buffer size of
> 1.
> Filter "two" in this case is lf_to_crlf_filter_fn(), and the next
> input character is a "\n". lf_to_crlf_filter_fn() wants to convert
> this to "\r\n", but that doesn't fit into the buffer, so it breaks
> out and returns zero. Upon seing the zero cascade_filter_fn() thinks
> all is well, even though nothing has happened, and loops.
> 
> The bug is probably that lf_to_crlf_filter_fn() should return
> non-zero in this case (ie o and/or i being zero).

non-zero? That would cause the filter to abort, which definitely not what we want. Have you seen my other e-mails regarding this? I'm trying to figure out which is the best way to go about this. The solution is to keep track of the fact that we're missing a LF in the output buffer.

cmn