linux-kernel - Re: memparse(), simple

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Date:	Tue, 20 Feb 2007 09:19:31 +0100
From:	"Francis Moreau" <francis.moro@...il.com>
To:	"Avi Kivity" <avi@...o.co.il>
Cc:	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: memparse(), simple_strtoul() prototypes...

On 2/19/07, Avi Kivity <avi@...o.co.il> wrote:
> Francis Moreau wrote:
> >> > unsigned long simple_strtoul(const char *cp, char **endp,unsigned
> >> int base)
> >
> > hm, I don't get your point. I understand why we cast 'cp' into a (char
> > *) but that's not my point. My point is why aren't all function
> > parameters are not const ?
> >
>
> 'cp' can be passed as const, because simple_strtoul() does not modify
> it. 'endp' cannot be passed as const, because simple_strtoul() cannot
> know whether the caller would want to modify the string or not.
>
> Whichever way it is written, it is broken.  If changed to 'const', it
> would preclude the caller from modifying the string if one has a
> non-const string.  As written, it can silently convert a const string to
> a non-const string.  However, as written it is (a) standard conforming,
> and (b) more useful.
>

ok I think I finally got it and I agree that both ways are broken.

Maybe changing simple_strtoul() prototype as follow would be better ?

int simple_strtoul(const char *cp,  unsigned long *value, unsigned base)

the function would return the number of parsed char, and 'value' would
be the result.
-- 
Francis
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