Mercurial > gnulib
view lib/getdtablesize.c @ 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 | ae8079a89eec |
children | 344018b6e5d7 |
line wrap: on
line source
/* getdtablesize() function for platforms that don't have it. Copyright (C) 2008-2013 Free Software Foundation, Inc. Written by Bruno Haible <bruno@clisp.org>, 2008. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <config.h> /* Specification. */ #include <unistd.h> #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ # include <stdio.h> # include "msvc-inval.h" # if HAVE_MSVC_INVALID_PARAMETER_HANDLER static int _setmaxstdio_nothrow (int newmax) { int result; TRY_MSVC_INVAL { result = _setmaxstdio (newmax); } CATCH_MSVC_INVAL { result = -1; } DONE_MSVC_INVAL; return result; } # define _setmaxstdio _setmaxstdio_nothrow # endif /* Cache for the previous getdtablesize () result. Safe to cache because Windows also lacks setrlimit. */ static int dtablesize; int getdtablesize (void) { if (dtablesize == 0) { /* We are looking for the number N such that the valid file descriptors are 0..N-1. It can be obtained through a loop as follows: { int fd; for (fd = 3; fd < 65536; fd++) if (dup2 (0, fd) == -1) break; return fd; } On Windows XP, the result is 2048. The drawback of this loop is that it allocates memory for a libc internal array that is never freed. The number N can also be obtained as the upper bound for _getmaxstdio (). _getmaxstdio () returns the maximum number of open FILE objects. The sanity check in _setmaxstdio reveals the maximum number of file descriptors. This too allocates memory, but it is freed when we call _setmaxstdio with the original value. */ int orig_max_stdio = _getmaxstdio (); unsigned int bound; for (bound = 0x10000; _setmaxstdio (bound) < 0; bound = bound / 2) ; _setmaxstdio (orig_max_stdio); dtablesize = bound; } return dtablesize; } #elif HAVE_GETDTABLESIZE # include <sys/resource.h> # undef getdtablesize int rpl_getdtablesize(void) { /* To date, this replacement is only compiled for Cygwin 1.7.25, which auto-increased the RLIMIT_NOFILE soft limit until it hits the compile-time constant hard limit of 3200. Although that version of cygwin supported a child process inheriting a smaller soft limit, the smaller limit is not enforced, so we might as well just report the hard limit. */ struct rlimit lim; if (!getrlimit (RLIMIT_NOFILE, &lim) && lim.rlim_max != RLIM_INFINITY) return lim.rlim_max; return getdtablesize (); } #endif