Mercurial > gnulib
view m4/modff.m4 @ 37246:5cfb3a67238d
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>
author | Eric Blake <eblake@redhat.com> |
---|---|
date | Tue, 03 Dec 2013 10:34:13 -0700 |
parents | c741bc27922a |
children | 344018b6e5d7 |
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# modff.m4 serial 5 dnl Copyright (C) 2011-2013 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_FUNC_MODFF], [ m4_divert_text([DEFAULTS], [gl_modff_required=plain]) AC_REQUIRE([gl_MATH_H_DEFAULTS]) AC_REQUIRE([gl_FUNC_MODF]) dnl Persuade glibc <math.h> to declare modff(). AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) dnl Test whether modff() exists. We cannot assume that modff(), if it dnl exists, is defined in the same library as modf(). This is not the case dnl on FreeBSD, NetBSD, OpenBSD. gl_MATHFUNC([modff], [float], [(float, float *)]) if test $gl_cv_func_modff_no_libm = yes \ || test $gl_cv_func_modff_in_libm = yes; then : m4_ifdef([gl_FUNC_MODFF_IEEE], [ if test $gl_modff_required = ieee && test $REPLACE_MODFF = 0; then AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_CACHE_CHECK([whether modff works according to ISO C 99 with IEC 60559], [gl_cv_func_modff_ieee], [ save_LIBS="$LIBS" LIBS="$LIBS $MODFF_LIBM" AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include <math.h> ]gl_FLOAT_MINUS_ZERO_CODE[ ]gl_FLOAT_SIGNBIT_CODE[ /* Compare two numbers with ==. This is a separate function because IRIX 6.5 "cc -O" miscompiles an 'x == x' test. */ static int numeric_equal (float x, float y) { return x == y; } static float dummy (float x, float *iptr) { return 0; } float zero; float minus_one = - 1.0f; int main (int argc, char *argv[]) { float (*my_modff) (float, float *) = argc ? modff : dummy; int result = 0; float i; float f; /* Test modff(NaN,...). This test fails on NetBSD 5.1, OpenBSD 4.9, Solaris 9, Cygwin. */ f = my_modff (zero / zero, &i); if (numeric_equal (f, f)) result |= 1; /* Test modff(-Inf,...). This test fails on IRIX 6.5, OSF/1 5.1, mingw. */ f = my_modff (minus_one / zero, &i); if (!(f == 0.0f) || (signbitf (minus_zerof) && !signbitf (f))) result |= 2; return result; } ]])], [gl_cv_func_modff_ieee=yes], [gl_cv_func_modff_ieee=no], [case "$host_os" in # Guess yes on glibc systems. *-gnu*) gl_cv_func_modff_ieee="guessing yes" ;; # If we don't know, assume the worst. *) gl_cv_func_modff_ieee="guessing no" ;; esac ]) LIBS="$save_LIBS" ]) case "$gl_cv_func_modff_ieee" in *yes) ;; *) REPLACE_MODFF=1 ;; esac fi ]) else HAVE_MODFF=0 fi if test $HAVE_MODFF = 0 || test $REPLACE_MODFF = 1; then dnl Find libraries needed to link lib/modff.c. MODFF_LIBM="$MODF_LIBM" fi AC_SUBST([MODFF_LIBM]) ])