[Bug math/6794] New: ilogb() does not raise exceptions or set errno on domain errors

[Bug math/6794] New: ilogb() does not raise exceptions or set errno on domain errors

[mtk dot manpages at gmail dot com]

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The POSIX.1 specification of ilogb() says:

==
Domain Error
    The x argument is zero, NaN, or ±Inf, or the correct value is not
representable as an integer.

    If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [EDOM]. If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be
raised
==

However, in all of the above cases, errno is not set on error, and in some of
the cases, no exceptions is raised.  In all cases errno should be set to EDOM
and an FE_INVALID exception should be raised.


Background: 
On error, many glibc math functions both set errno and raise an exception
(fetestexcept(3)).  For example, the following  function all do this: acos(),
asin(), cosh(), sinh(), acosh(), asinh(), exp(), exp2(), ldexp(), log(),
log10(), log2().  However, there is much inconsistency.  Some functions raise an
exception, but don't set errno.  Some functions set errno for some errors, but
not others.  A few set errno, but don't raise an exception.  This series of bug
reports documents deviations from what I consider the ideal: all functions
should BOTH set errno AND raise an exception for all errors.

All of these reports relate to tests on glibc 2.8 (as provided by SUSE 11.0).

-- 
           Summary: ilogb() does not raise exceptions or set errno on domain
                    errors
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: mtk dot manpages at gmail dot com
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6794

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[Bug math/6794] ilogb() does not raise exceptions or set errno on domain errors

[mtk dot manpages at gmail dot com]

------- Additional Comments From mtk dot manpages at gmail dot com  2008-07-31 09:48 -------
Created an attachment (id=2856)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=2856&action=view)
test program

Sample runs demonstrating problem.  In no case is errno set.  For the Inf and
-Inf cases, no exception is raised.

$ /tmp/mt_ilogb 0
errno == 0
fetestexcept() says:  FE_INVALID FE_DIVBYZERO
ilogb(0.00000000000000000e+00)=-2147483648
0 FE_DIVBYZERO normal

$ /tmp/mt_ilogb nan
errno == 0
fetestexcept() says:  FE_INVALID
ilogb(nan)=-2147483648
0 FE_INVALID normal

$ /tmp/mt_ilogb inf
errno == 0
fetestexcept() says:
ilogb(inf)=2147483647
0 0 normal

$ /tmp/mt_ilogb -- -inf
errno == 0
fetestexcept() says:
ilogb(-inf)=2147483647
0 0 normal


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6794

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[Bug math/6794] ilogb() does not raise exceptions or set errno on domain errors

[mtk dot manpages at gmail dot com]

------- Additional Comments From mtk dot manpages at gmail dot com  2008-07-31 09:50 -------
Also, it is worth noting that log(), log2(), log10() do set errno and raise an
exception for the 0 and --inf cases.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6794

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[Bug math/6794] ilogb() does not raise exceptions or set errno on domain errors

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=6794

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|aj at suse dot de           |unassigned at sourceware
                   |                            |dot org

--- Comment #3 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-03-01 02:25:35 UTC ---
Confirmed with current sources on x86.  On x86_64, none of these cases raise
exceptions or set errno at all (whereas on x86 some at least do raise
exceptions).

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[Bug math/6794] ilogb() does not raise exceptions or set errno on domain errors

[aj at suse dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=6794

Andreas Jaeger <aj at suse dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |aj at suse dot de
         Resolution|                            |FIXED

--- Comment #4 from Andreas Jaeger <aj at suse dot de> 2012-04-17 20:14:59 UTC ---
Thanks for the report, this is fixed now in glibc for glibc 2.16 thanks to
Adhemerval Zanella .

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