Re: Use PATH_MAX for pathname char arrays.

Re: Use PATH_MAX for pathname char arrays.

[Samuel Thibault]

Hello,

Using PATH_MAX is not a good idea: POSIX says that that definition
is facultative, in case the system does not impose any limit on path
length.  Some systems may also set PATH_MAX to a quite high value, and
we would hence consume a lot of stack.

Samuel

Re: Re: Use PATH_MAX for pathname char arrays.

[Keir Fraser]

If there are better alternatives I'd be happy to use them instead. But we
already use PATH_MAX elsewhere in the tools, so this might be a
wider-ranging cleanup than you think. The original impetus for this change
was due to bugchecks applied in some cases by glibc's realpath()
implementation. But actually is realpath() deprecated anyway?

 -- Keir

On 4/4/08 15:17, "Samuel Thibault" <samuel.thibault@eu.citrix.com> wrote:

> Hello,
> 
> Using PATH_MAX is not a good idea: POSIX says that that definition
> is facultative, in case the system does not impose any limit on path
> length.  Some systems may also set PATH_MAX to a quite high value, and
> we would hence consume a lot of stack.
> 
> Samuel
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Re: Re: Use PATH_MAX for pathname char arrays.

[Samuel Thibault]

Keir Fraser, le Fri 04 Apr 2008 15:30:52 +0100, a écrit :
> If there are better alternatives I'd be happy to use them instead. But we
> already use PATH_MAX elsewhere in the tools, so this might be a
> wider-ranging cleanup than you think.

That's possible indeed, I'm just making sure we try to avoid adding
others :)

> The original impetus for this change was due to bugchecks applied in
> some cases by glibc's realpath() implementation.
> But actually is realpath() deprecated anyway?

Ah, right, realpath has a bad semantic indeed.  The intent of SUS is to
have it allocate the string if NULL is given, but that's not necessarily
implemented yet.  In the wild, I only know GNU/Hurd which doesn't have
any PATH_MAX limit, and it happens that that one has the allocation
behavior.

Samuel