view m4/vararrays.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
line wrap: on
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# Check for variable-length arrays.

# serial 4

# From Paul Eggert

# Copyright (C) 2001, 2009-2013 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.

AC_DEFUN([AC_C_VARARRAYS],
[
  AC_CACHE_CHECK([for variable-length arrays],
    ac_cv_c_vararrays,
    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
         [],
         [[static int x; char a[++x]; a[sizeof a - 1] = 0; return a[0];]])],
       ac_cv_c_vararrays=yes,
       ac_cv_c_vararrays=no)])
  if test $ac_cv_c_vararrays = yes; then
    AC_DEFINE([HAVE_C_VARARRAYS], [1],
      [Define to 1 if C supports variable-length arrays.])
  fi
])