X-Recipient: archive-cygwin@delorie.com X-SWARE-Spam-Status: No, hits=-0.7 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: sourceware.org MIME-Version: 1.0 In-Reply-To: <32663265.post@talk.nabble.com> References: <32663265.post@talk.nabble.com> Date: Sun, 16 Oct 2011 20:16:46 -0400 Message-ID: Subject: Re: /proc/*/cmdline corrupted From: Jon Clugston To: cygwin@cygwin.com Content-Type: text/plain; charset=ISO-8859-1 X-IsSubscribed: yes Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by delorie.com id p9H0HF3f014612 I've checked and on Linux (at least) xterm's command line is not corrupted. From looking at the xterm code, it would appear that the X libraries would have to be what is corrupting the command line. I didn't look into the X library (XmParseCommand). Jon On Sun, Oct 16, 2011 at 5:31 PM, jan.kolar wrote: > >> jc807j    2668     1  0 08:59 tty0     00:00:00 xterm -e ssh server > 80x72+285+0 -e ssh server >> jc807j    3004     1  0 08:59 tty0     00:00:00 xterm -e ssh server >> 80x72-8+0 -e ssh server >> jc807j    2928  5852  0 09:12 ?        00:00:00 xterm  20000 +tb > >> The actual command lines for the 3 xterm processes are: >> C:\cygwin\bin\xterm.exe -sl 20000 +tb -geometry 80x72+285+0 -e ssh server >> C:\cygwin\bin\xterm.exe -sl 20000 +tb -geometry 80x72-8+0 -e ssh server >> C:\cygwin\bin\xterm.exe -sl 20000 +tb > > xterm calls XrmParseCommand() that > "parses an (argc, argv) pair according to the specified option table ... and > modifies the (argc, argv) pair to remove all recognized options." > > Therefore >         "-sl 20000 +tb -geometry 80x72+285+0" > is properly removed > and "-e ssh server" is moved to __argv[1 .. 3]. > Then __argv[4] (respectively __argv[1] for the shorter command) is assigned > null pointer > which results in the second "\0" in the od-output below. > > > HOWEVER: > > Either XrmParseCommand() does not update argc > or the change does not propagate (how would that be possible?) to __argc. > Therefore the command lines appear corrupted this particular way. > > > /proc/*/cmdline  uses a copy of __argc named __argc_safe > which is hardly to be updated anyway. > "   for (int i = 0; i < __argc_safe; i++) " > > Funny enough, /proc/self/cmdline is likely to contain shortened version of > cmdline: > "     for (char **a = __argv; *a; a++) " > [ pinfo.cc from cygwin 1.7.9-1 ] > > > >> I have verified that the "/proc/*/cmdline" is the source of the >> corrupted information.  "cmdline" from PID 2928 is: >> >> jc807j@~>od -c /proc/2928/cmdline >> 0000000   x   t   e   r   m  \0  \0   2   0   0   0   0  \0   +   t   b >> 0000020  \0 >> 0000021 > > > > > > > ---- >  What does xterm on different platforms ? >  While concept of modifying own cmdline (In fact, __argv[0]) is used very >  often to signal the process state down to the user, >  I was never thinking of modifying argc: >     main (int argc, char **argv) >  :-) > > > JK > -- > View this message in context: http://old.nabble.com/-proc-*-cmdline-corrupted-tp32639066p32663265.html > Sent from the Cygwin list mailing list archive at Nabble.com. > > > -- > 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 > > -- 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