Messages in this thread | | | Subject | Re: [PATCH][RFC] Extend "memparse" to allow a NULL return pointer value. | Date | Sun, 23 Sep 2007 22:52:08 +0200 | From | Oleg Verych <> |
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* 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/
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