Hi Paul,
On 2025-03-23 11:17:52 +0100, Paul Gevers wrote:
> Hi Vincent,
>
> On Fri, 15 Dec 2023 04:53:51 +0100 Vincent Lefevre <vinc...@vinc17.net>
> wrote:
> > On 2023-12-03 22:13:03 +0100, Vincent Lefevre wrote:
> > > I've reported the following bug in the MPFR mailing-list. I think
> > > I've fixed the issues on the MPFR side in master, but MPFR is still
> > > affected by the bug on the GMP side (gmp_vasprintf):
> > > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1057344
> >
> > The gmp_vasprintf function is actually correct (but its documentation
> > is not; and it is gmp_sprintf that is incorrect, which is not a
> > problem for MPFR). I've fixed the remaining bugs in MPFR.
>
> In which version is this fixed? 4.2.2?
Yes, it is fixed in 4.2.2, but this assumes that GMP does not use
its buggy vsnprintf replacement (i.e. it uses either the system
vsnprintf function or the replacement that was patched one year
ago in the development branch). I suppose that for Debian, the
system vsnprintf function is used on all platforms (this is decided
at GMP build time, after some tests for C conformance in GMP's
configure script).
If the buggy vsnprintf replacement is used, the MPFR testsuite would
fail. I've put the following section in the INSTALL file about such
a failure:
------------------------------------------------------------------------
tfprintf and tsprintf failures in check_null
--------------------------------------------
If you get the failures
$ ./tfprintf
Error in test #40: mpfr_vfprintf printed 1 characters instead of 4
$ ./tsprintf
Error in check_null, i = 0
expected r = 1, s = { 0, 0, 1 }
got r = 0, s = { 0, 1, 1 }
the cause is probably that GMP uses a buggy vsnprintf replacement.
The reason GMP uses its own vsnprintf replacement is that during
configure, it detected that the vsnprintf function from the C library
is buggy. But the replacement from GMP 6.3.0 and below also has its own
bugs. This means that using the formatted output functions with %c and
the value 0 will yield an erratic behavior.
For the above issue, this is fixed in the GMP development branch:
https://gmplib.org/repo/gmp/rev/4ac76064639e
You can have details at
https://gmplib.org/list-archives/gmp-bugs/2023-December/005420.html
https://gitlab.inria.fr/mpfr/mpfr/-/commit/390e51ef85
These tests can be skipped by defining the MPFR_TESTS_SKIP_CHECK_NULL macro,
but you should rather get a fixed vsnprintf replacement.
------------------------------------------------------------------------
--
Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)
