Mercurial > gnulib
view m4/flexmember.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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# serial 3 # Check for flexible array member support. # Copyright (C) 2006, 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. # Written by Paul Eggert. AC_DEFUN([AC_C_FLEXIBLE_ARRAY_MEMBER], [ AC_CACHE_CHECK([for flexible array member], ac_cv_c_flexmember, [AC_COMPILE_IFELSE( [AC_LANG_PROGRAM( [[#include <stdlib.h> #include <stdio.h> #include <stddef.h> struct s { int n; double d[]; };]], [[int m = getchar (); struct s *p = malloc (offsetof (struct s, d) + m * sizeof (double)); p->d[0] = 0.0; return p->d != (double *) NULL;]])], [ac_cv_c_flexmember=yes], [ac_cv_c_flexmember=no])]) if test $ac_cv_c_flexmember = yes; then AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [], [Define to nothing if C supports flexible array members, and to 1 if it does not. That way, with a declaration like 'struct s { int n; double d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack can be used with pre-C99 compilers. When computing the size of such an object, don't use 'sizeof (struct s)' as it overestimates the size. Use 'offsetof (struct s, d)' instead. Don't use 'offsetof (struct s, d@<:@0@:>@)', as this doesn't work with MSVC and with C++ compilers.]) else AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [1]) fi ])