X-Recipient:	archive-cygwin AT delorie DOT com
X-SWARE-Spam-Status:	No, hits=-0.3 required=5.0 tests=AWL,BAYES_00,DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED,RCVD_NUMERIC_HELO,RP_MATCHES_RCVD,SPF_HELO_PASS,TW_DB,TW_YG,T_TO_NO_BRKTS_FREEMAIL
X-Spam-Check-By:	sourceware.org
To:	cygwin AT cygwin DOT com
From:	jojelino <jojelino AT gmail DOT com>
Subject:	Re: debugging SIGSEV on pclose
Date:	Thu, 08 Sep 2011 09:44:28 +0900
Lines:	63
Message-ID:	<j4934t$gv9$1@dough.gmane.org>
References:	<4E64BE96 DOT 5020107 AT gmail DOT com> <j42imm$ecj$1 AT dough DOT gmane DOT org> <4E64D638 DOT 4030507 AT gmail DOT com>
Mime-Version:	1.0
User-Agent:	Mozilla/5.0 (Windows NT 5.2; rv:8.0a2) Gecko/20110907 Thunderbird/8.0a2
In-Reply-To:	<4E64D638.4030507@gmail.com>
X-IsSubscribed:	yes
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Unsubscribe:	<mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT 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 2011-09-05 PM 11:01, Marco atzeri wrote:
> Hi jojelino,
> gs is unlikely crashing as the fltk.png is correctly produced.
>  From strace I know that octave crashes before gs complete its output.
>
i'm sorry. mine was not the case.
and after some digging, it is found that fd[6] is *closed* before pclose.

warning: print.m: epstool binary is not available.
Some output formats are not available.
Hardware watchpoint 3: cygheap->fdtab.fds[6]

Old value = (fhandler_base *) 0x0
New value = (fhandler_pipe *) 0x612dbb8c
_pipe (filedes=0x22b370, psize=0x10000, mode=0x10000)
     at /tmp/winsup/winsup/cygwin/pipe.cc:382
382           filedes[0] = fdin;
(gdb) b _sigfe_fclose
Breakpoint 6 at 0x610f080b
(gdb) c
Continuing.
[New Thread 1684.0xf98]

Breakpoint 6, 0x610f080b in _sigfe_fclose ()
    from /cygdrive/d/cygwin/bin/cygwin1.dll
(gdb) bt
#0  0x610f080b in _sigfe_fclose () from /cygdrive/d/cygwin/bin/cygwin1.dll
#1  0x66f6a41f in 
cygoctinterp-0!_ZN13glps_renderer4drawERK15graphics_object ()
    from /cygdrive/d/cygwin/bin/cygoctinterp-0.dll
#2  0x6ec0ff2f in _init_fltk__-0!_ZN11OpenGL_fltk4drawEv ()
    from D:/cygwin/lib/octave/3.4.2/oct/i686-pc-cygwin/__init_fltk__.oct
#3  0x6dab19ef in cygfltk_gl-1!_ZN12Fl_Gl_Window5flushEv ()
    from /cygdrive/d/cygwin/bin/cygfltk_gl-1.1.dll
#4  0x6dae2a0f in cygfltk-1!_ZN2Fl5flushEv ()
    from /cygdrive/d/cygwin/bin/cygfltk-1.1.dll
#5  0x6dae2c28 in cygfltk-1!_ZN2Fl4waitEd ()
    from /cygdrive/d/cygwin/bin/cygfltk-1.1.dll
#6  0x6ec21272 in 
_init_fltk__-0!_ZNK21fltk_graphics_toolkit12print_figureERK15graphics_objectRKSsS4_bS4_ 
()
    from D:/cygwin/lib/octave/3.4.2/oct/i686-pc-cygwin/__init_fltk__.oct
#7  0x66ffc52b in cygoctinterp-0!_Z8FdrawnowRK17octave_value_listi ()
    from /cygdrive/d/cygwin/bin/cygoctinterp-0.dll
#8  0x67159266 in 
cygoctinterp-0!_ZN14octave_builtin17do_multi_index_opEiRK17octave_value_listPKSt4listI13octave_lvalueSaIS4_EE 
()
    from /cygdrive/d/cygwin/bin/cygoctinterp-0.dll
#9  0x67158397 in 
cygoctinterp-0!_ZN14octave_builtin7subsrefERKSsRKSt4listI17octave_value_listSaIS3_EEiPKS2_I13octave_lvalueSaIS8_EE 
()
    from /cygdrive/d/cygwin/bin/cygoctinterp-0.dll
#10 0x67159066 in 
cygoctinterp-0!_ZN14octave_builtin7subsrefERKSsRKSt4listI17oct---Type 
<return> to continue, or q <return> to quit---q
Quit
(gdb)

i think fltk have bad behavior which use fclose to close pipe fd, but it 
should have used pclose. so closing disposed fd yields sigsegv.
http://pubs.opengroup.org/onlinepubs/009695399/functions/pclose.html
we should inspect fltk's glps_renderer::draw(graphics_object const&) for 
this strange behavior.


--
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

- Raw text -