Re: [PATCH] On linux require the libc to have large file support

[Felix Janda <felix.janda@posteo.de>]

Andrei Borzenkov wrote:
> В Sat, 17 Jan 2015 14:57:07 +0100
> Felix Janda <felix.janda@posteo.de> пишет:
> 
> > With this, support code in grub-core/osdep/unix/hostdisk.c
> > for old glibc releases could be removed.
> > ---
> > This patch tries to address the issues raised in
> > 
> > http://lists.gnu.org/archive/html/grub-devel/2014-12/msg00030.html
> > ---
> >  INSTALL                         |  1 +
> >  configure.ac                    |  5 +++++
> >  grub-core/osdep/unix/hostdisk.c | 25 -------------------------
> >  3 files changed, 6 insertions(+), 25 deletions(-)
> > 
> > diff --git a/INSTALL b/INSTALL
> > index b67cd7f..ac7c2aa 100644
> > --- a/INSTALL
> > +++ b/INSTALL
> > @@ -39,6 +39,7 @@ configuring the GRUB.
> >  On GNU/Linux, you also need:
> >  
> >  * libdevmapper 1.02.34 or later (recommended)
> > +* a libc with large file support (e.g. glibc 2.1 or later)
> >  
> >  For optional grub-emu features, you need:
> >  
> > diff --git a/configure.ac b/configure.ac
> > index 31d2b0b..bdaebb8 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -346,6 +346,11 @@ AC_GNU_SOURCE
> >  AM_GNU_GETTEXT([external])
> >  AC_SYS_LARGEFILE
> >  
> > +if test x"$host_kernel" = xlinux ; then
> 
> I wonder if we should do it unconditionally. Large files support is
> really presumed by current code.
> 
> Not for now, but something to keep in mind for next version.

Yes, the test is not ideal. But enabling it for everything would
break cygwin. (There sizeof(off_t)=4 and the windows hostdisk.c is
used.)

It was not obvious for me how to detect all architectures that
build grub-core/osdep/unix/hostdisk.c. It would also be possible
to put something like

int get_a_libc_with_lfs_support[sizeof(off_t)-8];

into grub-core/osdep/unix/hostdisk.c making at least the build fail
for the right architectures.

> > +  AC_CHECK_SIZEOF(off_t)
> > +  test x"$ac_cv_sizeof_off_t" = x8 || AC_MSG_ERROR([Large file support is required])
> > +fi
> > +
> >  # Identify characteristics of the host architecture.
> >  unset ac_cv_c_bigendian
> >  
> > [..]