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Re: [PATCH] GNU canonicalize_file_name can return a NULL pointer

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From: "Timothy Redaelli" <timothy.redaelli@xxxxxxxxx>
To: zsh-workers@xxxxxxx
Subject: Re: [PATCH] GNU canonicalize_file_name can return a NULL pointer
Date: Tue, 07 Feb 2012 22:26:39 +0100
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On Tue, 07 Feb 2012 21:10:58 +0100, Frank Terbeck <ft@xxxxxxxxxxxxxxxxxxx>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 asreal[PATH_MAX] so it cannot be NULL.We can make the if unconditionally, but it's quite useless (because it'salways false in the HAVE_REALPATH branch).

References:
- [PATCH] GNU canonicalize_file_name can return a NULL pointer
  - From: Timothy Redaelli
- Re: [PATCH] GNU canonicalize_file_name can return a NULL pointer
  - From: Frank Terbeck

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