Re: AC_SYS_LARGEFILE macro

[Paul Eggert]

> From: "Andrej Borsenkow" <address@hidden>
> Date: Thu, 28 Jun 2001 13:58:35 +0400
> 
> It checks only for specific option for IRIX and _FILE_OFFSET_BITS and
> _LARGE_FILES macros. That is not enough; e.g. on our system:
> 
> address@hidden getconf LFS_CFLAGS
> -D_FILE_OFFSET_BITS=64 -D_LONGLONG -Kll64

This wouldn't be Reliant UNIX, would it?  (If it makes you jump
through silly hoops like that just to access large files, no wonder
the operating system is so rarely used.  :-)

Anyway, can you suggest a simple test for this problem, and suggest
what flags should be added for that OS?  We could add a special case
for it, just as there is already a special case for IRIX 6.2.

> why AC_SYS_LARGEFILE does not use getconf that is the
> sdtandard interface to obtain {C,LD}FLAGS needed to compile program with LFS
> support?

I used that method originally, but it was a miserable failure in
practice.  For example, that method fails for Bash 2.04 on Reliant
Unix with GCC; see
<http://mail.gnu.org/pipermail/bug-bash/2001-March/001571.html>.

And you can't easily cross-compile once you invoke getconf.

I used to recommend `getconf LFS_CFLAGS', but I don't do it any more;
in practice, it causes more trouble than it cures.  Also, `getconf
LFS_CFLAGS' will not be included in the next POSIX standard.


> Additionally, if package is using ftello/fseeko it is expected to
> set _LARGEFILE_SOURCE ... granted, it is independent of off_t size
> but still related.

They used to be the same macro, but this caused problems in practice,
so we separated them.  The problem was that some systems (notably
glibc 2.1.3 x86) supported large files but not ftello; when there was
just a single macro, large files were disabled on those systems as
they were not fully supported.