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Re: Bug#401377: autoconf: AC_FUNC_FSEEKO does not make fseeko()/ftello()
Re: Bug#401377: autoconf: AC_FUNC_FSEEKO does not make fseeko()/ftello() visible
Mon, 04 Dec 2006 15:57:11 -0800
Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (gnu/linux)
Ralf Wildenhues <address@hidden> writes:
> This looks like a regression to me
Yup, me too. Thanks for reporting it.
> It seems the problematic bit here is this part of the change:
> | * lib/autoconf/functions.m4 (AC_FUNC_FSEEKO): Don't compile the
> | fseeko testing program twice; just use the earlier result.
I don't see why that is the problem. If the earlier compilation
thinks fseeko is present when it actually is absent, isn't that a bug?
(Please see a related question below.)
> - address@hidden:@include <stdio.h>],
> - [[return fseeko (stdin, 0, 0) && (fseeko) (stdin, 0, 0);]])
> + address@hidden:@include <stdio.h>], [typedef int (*fp);
> + fp p = (fp) fseeko;
> + return !p;])
This doesn't look right. It's the same as saying 'int *fp = (int *) fseeko;';
surely you meant a function type instead. But with that change, it's
a good idea.
> # We used to try defining _XOPEN_SOURCE=500 too, to work around a bug
> # in glibc 2.1.3, but that breaks too many other things.
> # If you want fseeko and ftello with glibc, upgrade to a fixed glibc.
> -if test $ac_cv_sys_largefile_source != unknown; then
> +AC_CACHE_CHECK([for fseeko], [ac_cv_func_fseeko],
> +[AC_LINK_IFELSE([AC_LANG_PROGRAM(address@hidden:@include <stdio.h>],
> + [[return fseeko (stdin, 0, 0);]])],
> + [ac_cv_func_fseeko=yes],
> + [ac_cv_func_fseeko=no])])
> +if test $ac_cv_func_fseeko = yes; then
> AC_DEFINE(HAVE_FSEEKO, 1,
> [Define to 1 if fseeko (and presumably ftello) exists and is declared.])
Sorry, I don't see why this part of the change is relevant. The
current code tries to link fseeko, so why would the second test report
anything differently from the first?
I installed the following, which implements the idea of the first part
of your patch, I hope in a better way.
2006-12-04 Paul Eggert <address@hidden>
* lib/autoconf/functions.m4 (AC_FUNC_FSEEKO): Check that fseeko
can be assigned to a function pointer. Problem reported by
Peter Palfrader in <http://bugs.debian.org/401377>. Based on
part of a patch by Ralf Wildenhues in that same bug report.
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/functions.m4,v
retrieving revision 1.116
diff -p -u -r1.116 functions.m4
--- lib/autoconf/functions.m4 28 Nov 2006 03:29:48 -0000 1.116
+++ lib/autoconf/functions.m4 4 Dec 2006 23:47:42 -0000
@@ -587,8 +587,10 @@ AC_DEFUN([AC_FUNC_FSEEKO],
[Define to 1 to make fseeko visible on some hosts (e.g. glibc 2.2).],
- address@hidden:@include <stdio.h>],
- [[return fseeko (stdin, 0, 0) && (fseeko) (stdin, 0, 0);]])
+ [[#include <sys/types.h> /* for off_t */
+ #include <stdio.h>]],
+ [[int (*fp) (FILE *, off_t, int) = fseeko;
+ return fseeko (stdin, 0, 0) && fp (stdin, 0, 0);]])
# We used to try defining _XOPEN_SOURCE=500 too, to work around a bug
# in glibc 2.1.3, but that breaks too many other things.