lkml.org 
[lkml]   [2007]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH][RFC] Extend "memparse" to allow a NULL return pointer value.
Date
From
* Sat, 15 Sep 2007 12:27:07 -0400 (EDT)

> Extend the memparse() routine to allow a caller to use NULL as the
> second parameter value if he has no interest in that returned value.

(not `he', but `it', even if `he', then better `callers' + `they')

> ---
>
> there appear to be quite a number of calls to "memparse" which have
> no use for the value returned in the second parameter (the current
> pointer after the successful parse), but which are still forced to
> supply a valid char** address since they have no choice but to accept
> that value coming back. in many cases, that value is accepted just
> before the end of the calling function, making it clear that the value
> is ignored entirely, anyway.

A posteriori value, stored in this pointer serves very important role: it
validates returned result. Caller must do this. But if programmer doesn't
know problems (see below), `must' melts down to `may'.

If you take a look at simple_strtoull(), it already doesn't care if this
pointer is NULL or not. (So patch is NULL :)

But take closer look. If it returns `0' (zero), it is not clear if this
zero was parsed or not, unless you can compare `ptr' and `retptr'.
Another case if entire string have no valid number to parse (see
strtol(3)).

This is problem of this particular function, that is copied form
ordinary C. For instance see <http://bugs.debian.org/431320>.
--
-o--=O`C
#oo'L O
<___=E M
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-09-23 22:39    [W:0.046 / U:0.184 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site