Re: [Qemu-devel] Use of PATH_MAX

[Anthony Liguori <anthony@codemonkey.ws>]

Ian Jackson wrote:
> There are a couple of places where we use PATH_MAX.  I don't think
> this is right.  PATH_MAX is a #define specified by POSIX, SuSv3 etc.
> But it isn't guaranteed to be defined or necessarily very useful.
>
> In particular, it may be defined to a very large value (larger than a
> practical static buffer).  Or on systems where the maximum pathname
> length varies (for example, it depends on the underlying filesystem)
> it may be not defined at all and applications which really need to
> know are supposed to use pathconf.
>
> I think it would be better to invent a new name for the maximum path
> length supported by qemu's statically-sized buffers.  This would
> replace both the uses of PATH_MAX (in block.c, linux-user/path.c, and
> block-vvfat.c) but also direct use of (eg) 1024 in many places.
>   

It would be far better to get rid of instances of PATH_MAX and replace 
them with dynamically allocated buffers.   The use of static sized 
buffers for filenames is just asking for subtle bugs (and possibly even 
security problems.

Regards,

Anthony Liguori