regex: avoid glibc deadlock during configure glibc has a known bug where certain corruptions of the heap can cause malloc to default to printing a debug message that includes a backtrace, but the act of getting the backtrace uses dlopen which in turn calls into malloc, causing a recursive lock ending in deadlock. Thus, when configure is probing for a known glibc heap corruption bug, the overall configure would hang. The solution suggested by glibc developers is to force malloc to quit printing debug messages, which avoids recursive malloc. * m4/regex.m4 (gl_REGEX): Avoid recursive malloc deadlock when glibc bug 15078 in turn triggers bug 16159. Reported by Michal Privoznik. Signed-off-by: Eric Blake <eblake@redhat.com>

Description:
signbit() macro: Determine the sign bit of a floating-point number.

Files:
lib/signbitf.c
lib/signbitd.c
lib/signbitl.c
lib/float+.h
m4/signbit.m4

Depends-on:
math
float           [test $REPLACE_SIGNBIT = 1]
isnanf-nolibm   [test $REPLACE_SIGNBIT = 1]
isnand-nolibm   [test $REPLACE_SIGNBIT = 1]
isnanl-nolibm   [test $REPLACE_SIGNBIT = 1]
fpieee          [test $REPLACE_SIGNBIT = 1]
memcmp          [test $REPLACE_SIGNBIT = 1]

configure.ac:
gl_SIGNBIT
if test $REPLACE_SIGNBIT = 1; then
  AC_LIBOBJ([signbitf])
  AC_LIBOBJ([signbitd])
  AC_LIBOBJ([signbitl])
fi
gl_MATH_MODULE_INDICATOR([signbit])

Makefile.am:

Include:
<math.h>

License:
LGPL

Maintainer:
Bruno Haible