Eric Blake <eblake@redhat.com> wrote on 09/28/2010 03:26:48 PM:
[image removed]
Re: [libvirt] [PATCH v2 3/5] Extend nwfilter schema to accept comment attributes
Eric Blake
to:
Stefan Berger
09/28/2010 03:27 PM
Cc:
libvir-list
On 09/28/2010 04:28 AM, Stefan Berger wrote:
okay. It also leaves out 8-bit bytes - could that be a problem for i18n
where people want comments with native-language accented characters? That is, are we being too strict here? Maybe a better pattern would be to reject specific non-printing ASCII bytes we want to avoid, assuing you can use escape sequences like [^\001]?
Looking at
I should probably include 0x20-0x7E and 128-175, 224-238 - maybe even more? So the regex then becomes
[ -~€-¯à-î]{0,256}
True ASCII is strictly 7-bit; any locale where isprint() returns true on
8-bit bytes is a superset single-byte encoding, such as ISO-8859-1, or 'extended ascii' from the URL you posted above. But I'm also thinking about multi-byte encodings, like UTF-8, where we cannot a priori write a
regex that will accept all valid Unicode printable characters, in part because you have to look at more than one byte at a time to determine if
you have a printable character. Which goes back to my suggestion of an inverse charset - rejecting bytes that are known to be non-printable ASCII, and letting everything else whether or not it is is a printable byte sequence in the current locale. So what about this idea: exclude control characters except for tab, and let space and everything after through (I don't know if it needs to be adjusted to also reject �):
[^- - ]{0,256}
Fine by me. We may just give the impression of accepting unicode while the code does not handle it. Stefan