Re: [Xen-devel] [PATCH v1 1/6] docs: add feature document for Xen hypervisor sysfs-like support

[Jürgen Groß <jgross@xxxxxxxx>]

On 30.09.19 10:57, Jan Beulich wrote:
> On 30.09.2019 10:17, Jürgen Groß wrote:
> > On 27.09.19 17:19, Ian Jackson wrote:
> > > Jürgen Groß writes ("Re: [PATCH v1 1/6] docs: add feature document for Xen 
> > > hypervisor sysfs-like support"):
> > > > On 27.09.19 15:37, Ian Jackson wrote:
> > > > > I think this is ASCII printing characters with the exception of
> > > > >      ! " ` $ % ^ & * = + { } ' ~ < > / \ |
> > > > >
> > > > > I struggle to find a principled explanation for this particular
> > > > > exclusion set (apart from /), considering that following are
> > > > > included:
> > > > >      - @ _ . : ( ) [ ] # , ;
> > > > >
> > > > > Could we borrow some existing permitted character set ?  If we are
> > > > > permitting shell metacharacters why not just permit all printable
> > > > > ASCII except / ?
> > > > Hmm, maybe we should allow just the "Posix portable file name character
> > > > set"? That would be [-._0-9A-Za-z]. And we should explicitly not allow
> > > > the key names "." and "..".
> > > I agree about "." and "..".
> > >
> > > I'm not sure the "Posix portable file name character set" is a very
> > > good guide.  Posix will be pretty restricted there.  What is the legal
> > > set in a Linux sysfs filename ?
> > Everything but "/" and "\0".
> >
> > > > > Do you mean "any 7-bit byte", or octet values 32-126 (0x20-0x7e)
> > > > > inclusive, or something else ?
> > > > :-)
> > > >
> > > > As I'd like to support e.g. the .config file contents of the hypervisor
> > > > build I guess I need (0x01-0xff) inclusive, right?
> > > The .config file I have here does not seem to contain any control
> > > characters.  If it did surely that would be a bug?  If you want this
> > > you obviously do need to permit newlines and spaces and perhaps tabs
> > > too.
> > .config can contain user supplied strings. While not making much sense
> > to have unprintable characters in there I don't see how to prevent them.
> Does / can't kconfig reject them?
Right now it doesn't.

I tested that by manually modifying my .config and then doing a make.
The (wrong) .config was accepted and the hypervisor built with it.


Juergen


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel