Re: getopt reinvocation/reentrancy

[Gregory Pietsch <gpietsch at comcast dot net>]

Joel Sherrill wrote:
> Ralf Corsepius wrote:
> > On Fri, 2008-03-07 at 12:52 -0600, Joel Sherrill wrote:
> >  
> > > Jeff Johnston wrote:
> > >    
> > > > Ralf Corsepius wrote:
> > > >
> > > >      
> > > > > On Mon, 2008-03-03 at 15:07 -0500, Gregory Pietsch wrote:
> > > > >
> > > > >
> > > > >        
> > > > > > I got the definition of the GETOPT_DATA_INITIALIZER macro from 
> > > > > > that old
> > > > > > libc manual that Joel provided the link for:
> > > > > > http://sourceware.org/ml/libc-alpha/2004-03/msg00031/libc-manual.diff 
> > > > > > .
> > > > > >
> > > > > >
> > > > > >           
> > > > > Then Joel might want to recheck his docs.
> > > > >
> > > > >
> > > > >         
> > > Google turned up an old patch. :)
> > >    
> > > > > Current glibc doesn't have NO_ARG, REQUIRED_ARG, OPTIONAL_ARG nor
> > > > > GETOPT_DATA_INITIALIZER.
> > > > >
> > > > > FWIW: I removed these defines from the RTEMS newlib's sources.
> > > > >
> > > > >
> > > > >         
> > > And fixed the RTEMS source that used them I see. :)
> > > Unfortunately that break the code.
> > >
> > >   struct getopt_data getopt_reent;
> > >
> > >   while ( (option = getopt_r( argc, argv, "Aimfpcutv", &getopt_reent))
> > > != -1 ) {
> > >     
> >
> > All I did was to move the *_ARG defines from newlib's getopt.h to
> > getopt.c, i.e. to make these defines private to getopt and to adopt
> > newlib-cvs's getopt.h+getopt.c to rtems's newlib.
This doesn't make sense as those values should be in the interface (i.e. 
the header file).
> > => If these changes break your code, either this code is broken or
> > newlib's getopt_r is broken.
> >
> >  
> > > > Ok, here's what I did.  The newlib extensions to getopt.h have been
> > > > placed under the flag __need_getopt_newlib.  Applications ported from
> > > > glibc using getopt.h will be name-space equivalent (i.e. no NO_ARG or
> > > > GETOPT_DATA_INITIALIZER).  Applications needing the reentrant 
> > > > extensions
> > > > or preferring to use the old macros, may define __need_getopt_newlib
> > > > before including getopt.h.  getopt.c defines this flag.  I also 
> > > > added a
> > > > flag around the whole getopt.c because x86-linux has its own 
> > > > version of
> > > > getopt.h which obviously doesn't have the stuff needed to compile 
> > > > getopt.c.
> > > >
> > > >       
> > > I am ok with that.    The GETOPT_DATA_INITIALIZER is the
> > > only required one for the _r functions AFAIK though.
> > >     
> > I don't see any relationship between GETOPT_DATA_INITIALIZER and your
> > problem, because GETOPT_DATA_INITIALIZER is not used inside of newlib.
> >
> >   
> Greg should comment on this based upon the implementation.
> I suspect it is just a reflection that getopt.c passes through
> the getopt_reent structure passed into it.
What the GETOPT_DATA_INITIALIZER macro contains are the initial values 
for the reentrancy functions. The getopt() functions have to keep some 
state between calls; they do so in optarg, opterr, optind, optopt, and 
optwhere. The reentrant functions use values in the structure instead of 
global variables. GETOPT_DATA_INITIALIZER is the initializer macro for 
that structure. This should be in the interface as well.

Gregory
> > Probably, my changes broke your code, because it likely (bogusly) relies
> > on presence of GETOPT_DATA_INITIALIZER.
> >
> >   
> The getopt_reent structure is opaque to the caller and must
> be initialized somehow by the user or it is likely to contain
> random values from the stack.  This has to be either
> some type of initializer constant or a call to an init function.
> I modeled my suggestion after what was proposed to be glibc
> at one point.
>
> http://sources.redhat.com/ml/libc-alpha/2004-03/msg00031.html
>
> Temporarily I called memset to zero it out but that is also
> making assumptions about the default values.
>
> --joel
> > Ralf
> >
> > PS: Taking out Greg from the CC: because his rsp. his providers hostile
> > mailserver rejects mails from me.
> >