X-Recipient: archive-cygwin AT delorie DOT com
X-SWARE-Spam-Status: No, hits=0.1 required=5.0	tests=AWL,BAYES_40,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,FRT_APPROV,RCVD_IN_DNSWL_LOW,TW_CG,T_TO_NO_BRKTS_FREEMAIL
X-Spam-Check-By: sourceware.org
Message-ID: <4E68EB4A.5040406@gmail.com>
Date: Thu, 08 Sep 2011 18:20:26 +0200
From: Marco atzeri <marco DOT atzeri AT gmail DOT com>
User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:6.0.1) Gecko/20110830 Thunderbird/6.0.1
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Re: debugging SIGSEV on pclose
References: <4E64BE96 DOT 5020107 AT gmail DOT com> <4E68CE13 DOT 6010106 AT gmail DOT com> <20110908142702 DOT GA28918 AT ednor DOT casa DOT cgf DOT cx> <4E68DB48 DOT 3050906 AT gmail DOT com>
In-Reply-To: <4E68DB48.3050906@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-IsSubscribed: yes
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

On 9/8/2011 5:12 PM, Marco atzeri wrote:
> On 9/8/2011 4:27 PM, Christopher Faylor wrote:
>> On Thu, Sep 08, 2011 at 04:15:47PM +0200, Marco atzeri wrote:
>
>>> Question:
>>> is a mistake in pclose to assume that fh could be invalid
>>
>> I'm not sure what you're asking here. It's not a mistake to assume that
>> pclose is being passed a valid fp. Linux also crashes if the fp is
>> closed twice.
>
> Just as I noticed earlier on syscall.cc a defensive approuch
>
> -----------------------------------------------
> close_all_files (bool norelease)
> {
> cygheap->fdtab.lock ();
>
> semaphore::terminate ();
>
> fhandler_base *fh;
> HANDLE h = NULL;
>
> for (int i = 0; i < (int) cygheap->fdtab.size; i++)
> if ((fh = cygheap->fdtab[i]) != NULL)
> {
> ------------------------------------------------

using the same defensive approuch on pclose,
I see no more SEGFAULT, just some lost popen childs
that are closed on octave exit.

--- syscalls.cc~        2011-08-02 20:19:18.000000000 +0200
+++ syscalls.cc 2011-09-08 16:31:03.109375000 +0200
@@ -4023,7 +4023,7 @@
  {
    fhandler_pipe *fh = (fhandler_pipe *) cygheap->fdtab[fileno(fp)];

-  if (fh->get_device () != FH_PIPEW && fh->get_device () != FH_PIPER)
+  if ( !fh ||(fh->get_device () != FH_PIPEW && fh->get_device () != 
FH_PIPER))
      {
        set_errno (EBADF);
        return -1;


Does it make sense ?

>
>>
>>> or something is just trashing cygheap->fdtab ?
>>
>> Who knows? strace should show if the fp is closed twice.
>>
>> cgf
>
> correct, it looks I have two close in excess for fd 5 and 6
>
> Thanks
> Marco
>
>

too fast, the mismatch are the pipe closure,
that are reported differently as opening

I see a double pipe closure

$ grep 'pipe:\[5\]'  octave.strace
    24     595 [main] sh 2840 fhandler_base::fixup_after_exec: here for 
'/dev/fd/pipe:[5]'
    35 103396815 [main] octave-3.4.2 3664 fhandler_base::close: closing 
'/dev/fd/pipe:[5]' handle 0x46C
    37     896 [main] gs 2840 fhandler_base::fixup_after_exec: here for 
'/dev/fd/pipe:[5]'
    48   93072 [main] sh 2840! fhandler_base::close: closing 
'/dev/fd/pipe:[5]' handle 0x46C
    31 2358333 [main] gs 2840 fhandler_base::close: closing 
'/dev/fd/pipe:[5]' handle 0x46C

but I guess they are the two sides of the pipe


spawn_guts: 2840 = spawn_guts (/bin/sh, E:\cygwin2\bin\sh.exe -c 
"/usr/bin/gs -dQUIET -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m 
-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -r150x150 -dEPSCrop 
-sOutputFile=plot.png -")


Marco


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple