From owner-freebsd-fs@FreeBSD.ORG  Mon Aug 11 22:08:46 2008
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 235521065672
	for <freebsd-fs@freebsd.org>; Mon, 11 Aug 2008 22:08:46 +0000 (UTC)
	(envelope-from nejc@skoberne.net)
Received: from delusion.skoberne.net
	(lk.84.20.249.154.dc.cable.static.lj-kabel.net [84.20.249.154])
	by mx1.freebsd.org (Postfix) with ESMTP id CC89B8FC08
	for <freebsd-fs@freebsd.org>; Mon, 11 Aug 2008 22:08:45 +0000 (UTC)
	(envelope-from nejc@skoberne.net)
Received: from localhost (localhost [127.0.0.1])
	by delusion.skoberne.net (Postfix) with ESMTP id DC4A022884;
	Tue, 12 Aug 2008 00:02:16 +0200 (CEST)
Received: from delusion.skoberne.net ([127.0.0.1])
	by localhost (delusion.skoberne.net [127.0.0.1]) (amavisd-maia,
	port 10024)
	with ESMTP id 39035-07; Tue, 12 Aug 2008 00:02:13 +0200 (CEST)
Received: from [192.168.15.2] (simian.skoberne.local [192.168.15.1])
	(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
	(No client certificate requested)
	(Authenticated sender: nejkopejko@skoberne.net)
	by delusion.skoberne.net (Postfix) with ESMTP id B268722883;
	Tue, 12 Aug 2008 00:02:13 +0200 (CEST)
Message-ID: <48A0B6E5.3000000@skoberne.net>
Date: Tue, 12 Aug 2008 00:02:13 +0200
From: =?ISO-8859-2?Q?Nejc_=A9koberne?= <nejc@skoberne.net>
User-Agent: Thunderbird 2.0.0.16 (Windows/20080708)
MIME-Version: 1.0
To: freebsd-fs@freebsd.org
X-Enigmail-Version: 0.95.6
Content-Type: text/plain; charset=ISO-8859-2; format=flowed
Content-Transfer-Encoding: 7bit
X-Virus-Scanned: Maia Mailguard
Cc: Mitar <mitar@tnode.com>, Weiss <weiss@druga.org>
Subject: fchroot on unionfs
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 11 Aug 2008 22:08:46 -0000

Hi,

I have a strange problem with Apache not seeing the lower layer of unionfs. Using
ktrace on Apache I have written this C code:

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

int main() {
         int fd;
         char buf[512];

	/* This is what apache does */
         fd=open(".",O_RDONLY,0);
         fchdir(fd);
         close(fd);

	/* This is how Apache calls open */
         fd=open("/etc/hosts",O_RDONLY,0x1b6);
         if(fd < 0) {
                 printf("error %d,%d\n",fd,errno);
                 perror(NULL);
                 exit(-1);
         }
         read(fd, buf, 511);
         buf[511]=0;
         printf("%s",buf);
         close(fd);
         return(0);
}

So without fchdir() call this program just displays (first 511 bytes) of /etc/hosts.
If I uncomment fchdir() call with precedent open(".",...) call, I get this:

root@web:~# ./a
No such file or directory
error -1,2

and also if I list the /etc directory with a php script, I see only those files in
/etc which are on the upper layer of unionfs.

I stumbled upon this problem while trying to figure out why apache can't resolve
hostnames I have defined in /etc/hosts. I have this:

FreeBSD web.jail 7.0-STABLE FreeBSD 7.0-STABLE #5: Sun Aug 10 09:54:42 CEST 2008
root@server.domain.com:/usr/src/sys/amd64/compile/SERVER  amd64

So I am running a jail on a unionfs. Everything works now (after MFCing the unix
sockets patch from HEAD to the 7-STABLE (MySQL didn't work)), so I currently have
only this problem.

I also tried to grep the Apache source code for fchdir, but the call seems to be
made implicitely somehow (grep returned no matches).

Thanks,
Nejc