Mercurial > gnulib
view m4/double-slash-root.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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# double-slash-root.m4 serial 4 -*- Autoconf -*- dnl Copyright (C) 2006, 2008-2013 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_DOUBLE_SLASH_ROOT], [ AC_REQUIRE([AC_CANONICAL_HOST]) AC_CACHE_CHECK([whether // is distinct from /], [gl_cv_double_slash_root], [ if test x"$cross_compiling" = xyes ; then # When cross-compiling, there is no way to tell whether // is special # short of a list of hosts. However, the only known hosts to date # that have a distinct // are Apollo DomainOS (too old to port to), # Cygwin, and z/OS. If anyone knows of another system for which // has # special semantics and is distinct from /, please report it to # <bug-gnulib@gnu.org>. case $host in *-cygwin | i370-ibm-openedition) gl_cv_double_slash_root=yes ;; *) # Be optimistic and assume that / and // are the same when we # don't know. gl_cv_double_slash_root='unknown, assuming no' ;; esac else set x `ls -di / // 2>/dev/null` if test "$[2]" = "$[4]" && wc //dev/null >/dev/null 2>&1; then gl_cv_double_slash_root=no else gl_cv_double_slash_root=yes fi fi]) if test "$gl_cv_double_slash_root" = yes; then AC_DEFINE([DOUBLE_SLASH_IS_DISTINCT_ROOT], [1], [Define to 1 if // is a file system root distinct from /.]) fi ])