Re: Port insserv to kfreebsd?

[Petr Salinger <Petr.Salinger@seznam.cz>]

> > [Petter Reinholdtsen]
> > > Hi.  I notice that the latest insserv package fail to build on
> > > kfreebsd, because several posix_fadvise() arguments are unknown.  The
> > > code in question is protected with #ifdefs like this:
> > >
> > >   #if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 600
> > >     else if ((dfd = dirfd(rcdir)) != 0) {
> > >         (void)posix_fadvise(dfd, 0, 0, POSIX_FADV_WILLNEED);
> > >         (void)posix_fadvise(dfd, 0, 0, POSIX_FADV_SEQUENTIAL);
> > >     }
> > >   #endif
> > >
> > > Why is this test not sufficient on kfreebsd?  Can any of you provide
> > > patches to get insserv working on kfreebsd?  I hope to make
> > > dependency based boot sequencing a core part of the boot system in
> > > Debian and then insserv should work on all archs.
> >
> > I made this patch based on the changes done to startpar in sysvinit,
> > but fail to understand why this is needed.  Can anyone confirm that
> > this work on kfreebsd?
> >
> > --- insserv-1.12.0.orig/insserv.c
> > +++ insserv-1.12.0/insserv.c
> > @@ -40,6 +40,13 @@
> >  #endif /* USE_RPMLIB */
> >  #include "listing.h"
> >
> > +#if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 600
> > +/* kfreebsd fail to provide working posix_fadvise
> > +#  ifndef POSIX_FADV_SEQUENTIAL
> > +#    define posix_fadvise(fd, off, len, adv)        (-1)
> > +#  endif
> > +#endif
> > +
> >  #ifdef SUSE
> >  # define DEFAULT_START_LVL     "3 5"
> >  # define DEFAULT_STOP_LVL      "3 5"
>
> posix_fadvise is optional per POSIX, so checking that that builds if
> you use autoconf or for the macro is better.

See 
http://www.opengroup.org/onlinepubs/9699919799/functions/posix_fadvise.html

APPLICATION USAGE

    The posix_fadvise() function is part of the Advisory Information
    option and need not be provided on all implementations.

> You should also probably return ENOSYS instead.

Well, to be 100% correct, errno should be set to ENOSYS and return -1.
The eventually implemented posix_fadvise() could only provide hint
to the kernel memory and io management.
The result of posix_fadvise() is not checked anyway.

The proper upstream way should be to guard all usage
of posix_fadvise() by something like
"#if USE_FADVISE" instead of current
"#if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 600"

and either check by autoconf for presence of function and macros
or put at the begin of insserv.c light variant like

#if defined(POSIX_FADV_SEQUENTIAL)
#define USE_FADVISE 1
#endif

The "#define posix_fadvise(fd, off, len, adv) (-1)" is sufficient
for GNU/kFreeBSD build.

Petr