Bug 6797

Summary: lround() and llround() do not set errno on domain error
Product: glibc Reporter: Michael Kerrisk <mtk.manpages>
Component: mathAssignee: Not yet assigned to anyone <unassigned>
Status: NEW ---    
Severity: normal CC: glibc-bugs
Priority: P2 Flags: fweimer: security-
Version: unspecified   
Target Milestone: ---   
Host: Target:
Build: Last reconfirmed:
Attachments: test program
test program

Description Michael Kerrisk 2008-07-31 10:12:32 UTC
On a domain error, lround() and llround() correctly raise an exception, but do
not set errno.  They should set errno to EDOM.


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).
Comment 1 Michael Kerrisk 2008-07-31 10:13:11 UTC
Created attachment 2859 [details]
test program
Comment 2 Michael Kerrisk 2008-07-31 10:14:13 UTC
Created attachment 2860 [details]
test program

Sample runs demonstrating the problem:

$ /tmp/mt_lround inf
errno == 0
fetestexcept() says:  FE_INVALID
lround(inf)=-2147483648
0 FE_INVALID normal

$ /tmp/mt_llround inf
errno == 0
fetestexcept() says:  FE_INVALID
llround(inf)=-9223372036854775808
0 FE_INVALID normal

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

$ /tmp/mt_llround nan
errno == 0
fetestexcept() says:  FE_INVALID
llround(nan)=-9223372036854775808
0 FE_INVALID normal
Comment 3 Michael Kerrisk 2008-07-31 10:17:22 UTC
See also http://sourceware.org/bugzilla/show_bug.cgi?id=6798
Comment 4 Joseph Myers 2012-03-01 16:40:51 UTC
Confirmed with current sources on x86 and x86_64.