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To: zsh-workers@zsh.org
Subject: Re: [PATCH] GNU canonicalize_file_name can return a NULL pointer
References: <op.v9bnqmm2tyqwli@localhost.localdomain>
 <87r4y6e759.fsf@ft.bewatermyfriend.org>
Date: Tue, 07 Feb 2012 22:26:39 +0100
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From: "Timothy Redaelli" <timothy.redaelli@gmail.com>
Message-ID: <op.v9bu6pkotyqwli@localhost.localdomain>
In-Reply-To: <87r4y6e759.fsf@ft.bewatermyfriend.org>
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On Tue, 07 Feb 2012 21:10:58 +0100, Frank Terbeck <ft@bewatermyfriend.org>  
wrote:

> Timothy Redaelli wrote:
>> In Src/hist.c on line 1668 there is a NULL pointer dereference because
>> GNU canonicalize_file_name returns NULL on some errors.
>>
>> In attachment you will find a small patch that fixes that bug.
>
> Thanks!
>
> I've looked at the code and it bails out for a couple of errors in
> `errno'. I've looked at how canonicalize_file_name() is implemented by
> glibc, and it's just a short hand for "realpath(foo, NULL)". So at least
> on GNU systems the errors from realpath(3) apply to
> canonicalize_file_name(), too. Here's the current standard:
>
> <http://pubs.opengroup.org/onlinepubs/9699919799/functions/realpath.html>
>
> I don't know if it's worth checking all those or just go with bailing
> out if `real' is NULL.
>
> Both HAVE_REALPATH and HAVE_CANONICALIZE_FILE_NAME use a `real' pointer,
> so I think the "if (!null)" test should be in there unconditionally,
> without the `#ifdef'.
>
> Comments?

Hi,
in HAVE_REALPATH branch real it's not a point, but it's defined as  
real[PATH_MAX] so it cannot be NULL.
We can make the if unconditionally, but it's quite useless (because it's  
always false in the HAVE_REALPATH branch).