Re: [PATCH] Add simple versions of random() and srandom()

[Craig Howland <howland at LGSInnovations dot com>]

On 03/23/2016 03:36 PM, Yaakov Selkowitz wrote:
> On 2016-03-23 13:43, Joel Sherrill wrote:
> > On 3/23/2016 12:45 PM, Yaakov Selkowitz wrote:
> > > On 2016-03-23 12:38, Joel Sherrill wrote:
> > > > --- a/newlib/libc/include/stdlib.h
> > > > +++ b/newlib/libc/include/stdlib.h
> > > > @@ -226,6 +226,12 @@ unsigned short *
> > > >    _VOID  _EXFUN(srand48,(long));
> > > >    _VOID  _EXFUN(_srand48_r,(struct _reent *, long));
> > > >    #endif /* __SVID_VISIBLE || __XSI_VISIBLE */
> > > > +#if __SVID_VISIBLE || __XSI_VISIBLE >= 4 || __BSD_VISIBLE
> > >
> > > Please review my previous comment on this.
> >
> > Is this the desired guard?
> >
> > #if __MISC_VISIBLE || __XSI_VISIBLE >= 500
>
> MISC is right, but based on Craig's comment, it should be:
>
> #if __MISC_VISIBLE || __XSI_VISIBLE >= 4
>
> > > > +ANSI_SYNOPSIS
> > > > +    #define _XOPEN_SOURCE 500
> > > > +    #include <stdlib.h>
> > > > +    long int random(void);
> > > > +    void srandom(unsigned int <[seed]>);
> > >
> > > This doesn't match the header guard, nor does it account for the
> > > multiple options.
> >
> > So how is the || documented in this format?
>
> That hasn't been determined yet, but what about e.g.:
>
>     /* See PORTABILITY for feature test macros */
>     #include <stdlib.h>
>     long int random(void);
>     void srandom(unsigned int <[seed]>);
>
> Then mention the possibilities in PORTABILITY?
Two other possibilities for consideration (considering in PORTABILITY as #1, and 
only showing an abbreviated example without getting into the POSIX 4 extension 
complication, which would just add a line or 2):

2)  the way Linux man pages do it.  From Linux random(3):
"Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       random(), srandom(), initstate(), setstate(): _SVID_SOURCE ||
       _BSD_SOURCE || _XOPEN_SOURCE >= 500"

3)  Or perhaps something like:

#define _BSD_SOURCE    // one (or more) of these #defines is needed before the 
#include
#define _SVID_SOURCE
#define _XOPEN_SOURCE 500
#include <stdlib.h>

The Linux 'A || B' formula could be used under PORTABILITY.