Re: [linux-pm] [PATCH] ACPI: replace strlen("string") with sizeof("string")-1

[Pavel Vasilyev]

07.08.2012 21:24, Alan Stern ÐÐÑÐÑ:
> On Tue, 7 Aug 2012, Pavel Vasilyev wrote:
>
> > 06.08.2012 23:59, Alan Stern ÐÐÑÐÑ:
> > > On Mon, 6 Aug 2012, Pavel Vasilyev wrote:
> > >
> > > > > > http://www.gossamer-threads.com/lists/engine?do=post_attachment;postatt_id=41157;list=linux
> > > > >
> > > > > Interestingly, many (all?) of the changes in that patch are wrong
> > > > > because they don't try to match the terminating '\0'.  As a result,
> > > > > they will match against extensions of the target string as well as the
> > > > > target string itself.
> > > >
> > > > strNcmp compare N bytes - http://lxr.linux.no/#linux+v3.5/lib/string.c#L270
> > > > memcmp compare N bytes  - http://lxr.linux.no/#linux+v3.5/lib/string.c#L651
> > >
> > > Yes.  So if s contains "abcde" then
> > >
> > > 	memcmp(s, "abc", 3) and strncmp(s, "abc", 3) will both return 0, and
> > > 	memcmp(s, "abc", 4) and strncmp(s, "abc", 4) will both return 1.
> >
> > No matter what is contained in *s, "abcde" or "abcxxx",
> > are important first N bytes. The second example, you see,
> > a little bit stupid, and devoid of logic. :)
>
> Maybe yes, maybe no.  It all depends on what you want.
>
> For example, if you're looking for "on" or "off", what should you do
> when the user writes "onoff"?  You could accept it as meaning the same
> as "on", but if you were being careful then you would want to reject it
> as a meaningless value.


The users should't be allowed to think!
There is "on" - the size of 2 bytes, or "off" - 3 bytes,
other variations - user error.

We do not create a kernel with artificial intelligence? ;)

--
                                                         Pavel.
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