From: Mitch Bradley <wmb@firmworks•com>
To: Scott Wood <scottwood@freescale•com>,
Kumar Gala <galak@kernel•crashing.org>,
linuxppc-dev@ozlabs•org, devicetree-discuss@ozlabs•org
Subject: Re: [PATCH v3] libfdt: Add support for using aliases in fdt_path_offset()
Date: Thu, 14 Aug 2008 15:51:05 -1000 [thread overview]
Message-ID: <48A4E109.2020506@firmworks.com> (raw)
In-Reply-To: <20080815013439.GB12327@yookeroo.seuss>
David Gibson wrote:
> On Thu, Aug 14, 2008 at 12:43:48PM -0500, Scott Wood wrote:
>
>> On Thu, Aug 14, 2008 at 08:28:19AM -0500, Kumar Gala wrote:
>>
>>> - if (*path != '/')
>>> - return -FDT_ERR_BADPATH;
>>> + /* see if we have an alias */
>>> + if (*path != '/') {
>>> + const char *q;
>>> + int aliasoffset = fdt_path_offset(fdt, "/aliases");
>>> +
>>> + if (aliasoffset < 0)
>>> + return -FDT_ERR_BADPATH;
>>> +
>>> + q = strchr(path, '/');
>>> + if (!q)
>>> + q = end;
>>> +
>>> + p = fdt_getprop_namelen(fdt, aliasoffset, path, q - p, NULL);
>>> + if (!p)
>>> + return -FDT_ERR_BADPATH;
>>> + offset = fdt_path_offset(fdt, p);
>>> +
>>> + p = q;
>>> + }
>>>
>> Can we limit the recursion depth to avoid falling off the stack if an
>> alias points to itself? Or if aliases pointing to aliases are
>> disallowed, check for a leading '/' before recursively calling
>> fdt_path_offset.
>>
>
> Hmm.. my reading of 1275 says that an alias pointing to another alias
> is not permitted, but I'm not terribly confident I'm not misreading
> it. Segher, do you know whether this is allowed?
>
The 1275 spec doesn't require multiple levels of aliasing, but my
current implementation allows it and uses it for things like components
of the network stack.
> If that's the case then, yes, we should not recurse if the alias value
> doesn't start with a /. In fact, if I factor out a fdt_get_alias()
> function, it should probably check the alias and return an error if
> it's not an absolute path.
>
>
next prev parent reply other threads:[~2008-08-15 1:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-14 13:28 [PATCH v3] libfdt: Add support for using aliases in fdt_path_offset() Kumar Gala
2008-08-14 13:36 ` David Gibson
2008-08-14 15:24 ` Jon Loeliger
2008-08-14 17:43 ` Scott Wood
2008-08-15 1:34 ` David Gibson
2008-08-15 1:51 ` Mitch Bradley [this message]
2008-08-16 6:51 ` Segher Boessenkool
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