Ubuntu
glibc package

tanf causes FPE

Bug #65998 reported by Juanjo Garcia-Ripoll
2
Affects Status Importance Assigned to Milestone
glibc (Ubuntu)
Confirmed
Medium
Unassigned

Bug Description

Binary package hint: libc6-amd64

When one sets the floating point environment to trap exceptions and uses tanf with a value that should not produce singularities, an exception is sometimes signalled.

To reproduce: store the following piece of code in a file foo.c and build using gcc -o foo foo.c -lm When you execute the program, it will give rise to an exception

What should have happened: The program should have output the value 1

#define _GNU_SOURCE
#include <math.h>
#include <fenv.h>
#include <stdio.h>

int main()
{
  int bits = FE_UNDERFLOW;
  feenableexcept(bits);

  printf("%d", tanf((float)(M_PI/4)));

  return 0;
}

Revision history for this message
Matthias Klose (doko) wrote :

confirmed with glibc-2.5, amd64; works on i386

Changed in glibc:
importance: Undecided → Medium
status: Unconfirmed → Confirmed
Revision history for this message
Juanjo Garcia-Ripoll (worm) wrote :

2006-10-13 and we are at 2008-08-03. Seriously, is this such a difficult bug?

Revision history for this message
Matthias Klose (doko) wrote :

> 2006-10-13 and we are at 2008-08-03. Seriously, is this such a difficult bug?

no. care to recheck with 8.04 and 8.10 (development)?

Changed in glibc:
status: Confirmed → Incomplete
Revision history for this message
Daniel T Chen (crimsun) wrote :

Using 4:4.2.3-1ubuntu6 (hardy-proposed) on amd64, I receive an FPE.

Using 4:4.3.1-1ubuntu2 (intrepid chroot) on amd64, I receive 85028072.

Changed in glibc:
status: Incomplete → Confirmed
Revision history for this message
Daniel T Chen (crimsun) wrote :

To clarify the previous comment, for hardy-proposed:

gcc-4.2:
  Installed: 4.2.4-1ubuntu1
  Candidate: 4.2.4-1ubuntu1
  Version table:
 *** 4.2.4-1ubuntu1 0
        500 http://us.archive.ubuntu.com hardy-proposed/main Packages
        100 /var/lib/dpkg/status
     4.2.3-2ubuntu7 0
        500 http://us.archive.ubuntu.com hardy/main Packages

Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.2.4 (Ubuntu 4.2.4-1ubuntu1)

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