Re: [PATCH] Introduce the 'usertemp' filesystem type

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

On Oct 21 20:23, Corinna Vinschen wrote:
> On Oct 20 13:47, Johannes Schindelin wrote:
> > On Tue, 20 Oct 2015, Corinna Vinschen wrote:
> > > On Sep 16 09:35, Johannes Schindelin wrote:
> > [...]
> > > > +          char mb_tmp[len = sys_wcstombs (NULL, 0, tmp)];
> > > 
> > > - len = sys_wcstombs() + 1
> > 
> > Whoops. I always get that wrong.
> > 
> > But... actually... Did you know that `sys_wcstombs()` returns something
> > different than advertised? The documentation says:
> > 
> > 	- dst == NULL; len is ignored, the return value is the number
> > 	  of bytes required for the string without the trailing NUL, just
> > 	  like the return value of the wcstombs function.
> > 
> > But when I call
> > 
> > 	small_printf("len of 1: %d\n", sys_wcstombs(NULL, 0, L"1"));
> > 
> > it prints "len of 1: 2", i.e. the number of bytes requires for the string
> > *with* the trailing NUL, disagreeing with the comment in strfuncs.cc.
> 
> Drat.  You're right.  As usual I wonder why nobody ever noticed this.
> As soon as the nwc parameter is larger than the number of non-0 wchars
> in the source string, sys_cp_wcstombs returns the length including the
> trailing NUL.
> 
> And looking through the Cygwin sources the usage is rather erratic,
> sometimes with, sometimes without + 1 :(
> 
> > How do you want to proceed from here? Should I fix sys_wcstombs() when the
> > fourth parameter is -1? Or is this not a fix, but I would rather break
> > things?
> 
> No, this needs fixing, but it also would break things.  I have to take
> a stab at fixing this throughout Cygwin first.

I just pushed a patch to the git repo supposed to fix sys_cp_wcstombs
return value inconsistency.  It should now always return the length of
the string without the trailing NUL.  Please give it a try.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat