[PATCH setxkbmap; 2nd try] Consistent handling of memory allocation errors.

[Van de Bugger]

Got it. See the next version.

On Fri, 2011-02-25 at 14:50 -0800, Alan Coopersmith wrote:
> On 02/25/11 11:43 AM, Van de Bugger wrote:
> > Macro `OOM' ("Out of memory") introduced for checking and reporting
> > memory allocation errors. The same macro is used in all the cases.
> > 
> > One check was missed in original source; fixed.
> > 
> > Signed-off-by: Van de Bugger <van.de.bugger at gmail.com>
> > ---
> >  setxkbmap.c |   27 +++++++++------------------
> >  1 files changed, 9 insertions(+), 18 deletions(-)
> > 
> > diff --git a/setxkbmap.c b/setxkbmap.c
> > index f7dbade..7aa56f7 100644
> > --- a/setxkbmap.c
> > +++ b/setxkbmap.c
> > @@ -170,6 +170,8 @@ static int deviceSpec = XkbUseCoreKbd;
> >  #define ERR2(s,a,b)     fprintf(stderr,s,a,b)
> >  #define ERR3(s,a,b,c)   fprintf(stderr,s,a,b,c)
> >  
> > +#define OOM(ptr)        { if ((ptr) == NULL) { ERR("Out of memory.\n"); abort(); }; }
> 
> There's an extra ; between the last two }'s there.   Also, you probably want to
> stick with the original exit(-1), not force a core dump with abort();
> 
> The idiom normally used in the X code (and much C code in fact) for a
> compound statement in a macro like this you want to make look like a
> function call is:
> 
> #define OOM(ptr) \
>     do { if ((ptr) == NULL) { ERR("Out of memory.\n"); abort(); } } while (0)
> 
> The do { ... } while(0) allows OOM(); to end with a ; without any compiler
> warnings about empty statements or without causing any issues in breaking
> other blocks, like if/else pairs, that you may wind up adjacent to.
> 
> For more complete explanations, see:
> 	http://kernelnewbies.org/FAQ/DoWhile0
> 	http://www.rtems.com/ml/rtems-users/2001/august/msg00086.html
> 	http://stackoverflow.com/questions/923822/whats-the-use-of-do-while0-when-we-define-a-macro
>