07.08.2012 21:24, Alan Stern пишет:
On Tue, 7 Aug 2012, Pavel Vasilyev wrote:
06.08.2012 23:59, Alan Stern пишет:
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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