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:
log2f() function: base 2 logarithm.

Files:
lib/log2f.c
m4/log2f.m4

Depends-on:
math
extensions
log2            [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1]
isnanf          [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1]
frexpf          [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1]
logf            [test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1]

configure.ac:
gl_FUNC_LOG2F
if test $HAVE_LOG2F = 0 || test $REPLACE_LOG2F = 1; then
  AC_LIBOBJ([log2f])
fi
gl_MATH_MODULE_INDICATOR([log2f])

Makefile.am:

Include:
<math.h>

Link:
$(LOG2F_LIBM)

License:
LGPL

Maintainer:
Bruno Haible