Can I use -exec-interrupt to stop the inferior program?

Can I use -exec-interrupt to stop the inferior program?

[Nikolay Molchanov]

Hello!

I'm looking for a solution how to stop the inferior program,
which is running under gdb. I can stop it using ^C, but I
need a solution, that will work for the following case:

 Java application
       |   ^
 stdin |   | stdout
       v   |
 GDB debugger (gdb --i mi --tty /dev/pts/2 ...)
       |  ^
       v  |
 Inferior program  <--> External terminal (/dev/pts/28)


The action to stop the program is initiated by
Java application, which cannot send ^C to the
external terminal. So I have to use stdin to
tell gdb to stop the inferior program. But gdb
does not read the "-exec-interrupt" command,
until the program is stopped


sside-linux nikm/t1-exec-interrupt> gdb --i mi --tty /dev/pts/2 t2pl
~"GNU gdb 6.1\n"
~"Copyright 2004 Free Software Foundation, Inc.\n"
~"GDB is free software, covered by the GNU General Public License, and
you are\n"
~"welcome to change it and/or distribute copies of it under certain
conditions.\n"
~"Type \"show copying\" to see the conditions.\n"
~"There is absolutely no warranty for GDB.  Type \"show warranty\" for
details.\n"
~"This GDB was configured as \"x86_64-suse-linux\"..."
~"Using host libthread_db library \"/lib64/tls/libthread_db.so.1\".\n"
~"\n"
(gdb)
run
&"run\n"
-exec-interrupt
^done,reason="exited",exit-code="0100"
(gdb)
^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
(gdb)


Perhaps "-exec-interrupt" does not work in gdb 6.1?
If that's correct, can you tell me which version supports
"-exec-interrupt"?

Thanks in advance,
Nikolay Molchanov

Can I use -exec-interrupt to stop the inferior program?

[Nick Roberts]

 > (gdb)
 > run
 > &"run\n"
 > -exec-interrupt
 > ^done,reason="exited",exit-code="0100"
 > (gdb)
 > ^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
 > (gdb)
 > 
 > 
 > Perhaps "-exec-interrupt" does not work in gdb 6.1?
 > If that's correct, can you tell me which version supports
 > "-exec-interrupt"?

It doesn't currently works as you would like i.e. asynchronously, even in
CVS.

Can you get around the problem by using SIGTSTP instead of SIGINT to stop
the program?  Thats what Emacs does.

-- 
Nick                                           http://www.inet.net.nz/~nickrob

Re: Can I use -exec-interrupt to stop the inferior program?

[Carlos Eduardo Rodrigues de Almeida]

I had the same problem a while ago..
I wrote a driver in, C, that received "commands" from the java
application and performed actions in the GDB. There was only 2
"commands" CMD and SIG.
Explaining by example
If I send CMDlist my driver will remove the CMD and send list to GDB,
if I send SIG my driver will send a SIGINT to GDB... it should be
SIGsigno where signo is the number of the signal but not implemented
yet.
In java I have a class that encapsulate the driver and has 2 methods:
sendCommand(String command)
sendSignal(int signo)

If you want I can send you the driver and my java code.

The driver only work in linux


Eduardo

On 5/15/06, Nikolay Molchanov <Nikolay.Molchanov@sun.com> wrote:
> Hello!
>
> I'm looking for a solution how to stop the inferior program,
> which is running under gdb. I can stop it using ^C, but I
> need a solution, that will work for the following case:
>
>  Java application
>       |   ^
>  stdin |   | stdout
>       v   |
>  GDB debugger (gdb --i mi --tty /dev/pts/2 ...)
>       |  ^
>       v  |
>  Inferior program  <--> External terminal (/dev/pts/28)
>
>
> The action to stop the program is initiated by
> Java application, which cannot send ^C to the
> external terminal. So I have to use stdin to
> tell gdb to stop the inferior program. But gdb
> does not read the "-exec-interrupt" command,
> until the program is stopped
>
>
> sside-linux nikm/t1-exec-interrupt> gdb --i mi --tty /dev/pts/2 t2pl
> ~"GNU gdb 6.1\n"
> ~"Copyright 2004 Free Software Foundation, Inc.\n"
> ~"GDB is free software, covered by the GNU General Public License, and
> you are\n"
> ~"welcome to change it and/or distribute copies of it under certain
> conditions.\n"
> ~"Type \"show copying\" to see the conditions.\n"
> ~"There is absolutely no warranty for GDB.  Type \"show warranty\" for
> details.\n"
> ~"This GDB was configured as \"x86_64-suse-linux\"..."
> ~"Using host libthread_db library \"/lib64/tls/libthread_db.so.1\".\n"
> ~"\n"
> (gdb)
> run
> &"run\n"
> -exec-interrupt
> ^done,reason="exited",exit-code="0100"
> (gdb)
> ^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
> (gdb)
>
>
> Perhaps "-exec-interrupt" does not work in gdb 6.1?
> If that's correct, can you tell me which version supports
> "-exec-interrupt"?
>
> Thanks in advance,
> Nikolay Molchanov
>
>

Re: Can I use -exec-interrupt to stop the inferior program?

[Nikolay Molchanov]

Hello GDB developers and users!

I asked this question some time ago (in May 2006), and I implemented a 
solution
for Unix (it is based on signal), but I still cannot find a good 
solution for Windows.
Here is my original question:

I'm looking for a solution how to stop the inferior program,
which is running under gdb. I can stop it using ^C, but I
need a solution, that will work for the following case
on Windows (Cygwin):

 Java application
       |   ^
 stdin |   | stdout
       v   |
 GDB debugger (gdb --i mi --tty /dev/pts/2 ...)
       |  ^
       v  |
 Inferior program  <--> External terminal (/dev/pts/28)


The action to stop the program is initiated by
Java application, which cannot send ^C to the
external terminal.


Nick Roberts suggested to use signals to implement "interrupt" action,
and it really works very well on Unix (Solaris and Linux), but unfortunately
it does not work properly on Windows. If I send SIGTSTP, gdb does not
show that the program is stopped (and it really does not stop), so it looks
like this signal is ignored. If I send SIGINT, the program is really 
interrupted,
but it seems to cause SIGSEGV (Segmentation Fault), and there is no way
to continue the debugging. Here is a scenario (I use Cygwin):

Window 1: start debugging, set breakpoint, continue
===================================
$ gdb --i mi
~"GNU gdb 6.5.50.20060706-cvs (cygwin-special)\n"
~"Copyright (C) 2006 Free Software Foundation, Inc.\n"
~"GDB is free software, covered by the GNU General Public License, and 
you are\n"
~"welcome to change it and/or distribute copies of it under certain 
conditions.\n"
~"Type \"show copying\" to see the conditions.\n"
~"There is absolutely no warranty for GDB.  Type \"show warranty\" for 
details.\n"
~"This GDB was configured as \"i686-pc-cygwin\"."
~"\n"
(gdb)
-file-exec-and-symbols 
C:/tmp/nikm/samples/LongLoop1/dist/Debug/GNU-Windows/longloop1
^done
(gdb)
-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x004011b
5",func="main",file="main.cc",fullname="/cygdrive/c/tmp/nikm/samples/LongLoop1/m
ain.cc",line="33",times="0"}
(gdb)
-exec-run
^running
(gdb)
*stopped,reason="breakpoint-hit",bkptno="1",thread-id="1",frame={addr="0x004011b
5",func="main",args=[{name="argc",value="1"},{name="argv",value="0x6c1f50"}],fil
e="main.cc",fullname="/cygdrive/c/tmp/nikm/samples/LongLoop1/main.cc",line="33"}
(gdb)
-exec-continue
^running
(gdb)


Window 2: send signal
===============
$ ps
      PID    PPID    PGID     WINPID  TTY  UID    STIME COMMAND
     1520       1    1520       1520  con 1005 23:22:26 /usr/bin/bash
      884       1     884        884  con 1005 23:23:47 /usr/bin/bash
     1832    1520    1832       3880  con 1005 23:24:17 /usr/bin/gdb
     4036       1    4036       4036  con 1005 23:27:14 
/cygdrive/c/tmp/nikm/sam
ples/LongLoop1/dist/Debug/GNU-Windows/longloop1
     2380     884    2380       2336  con 1005 23:27:16 /usr/bin/ps

$ kill  -INT  4036


Window 1: caught signal
=================
~"\n"
~"[Switching to thread 4036.0x784]\n"
*stopped,reason="signal-received",signal-name="SIGSEGV",signal-meaning="Segmenta
tion fault",thread-id="2",frame={addr="0x000007d4",func="??",args=[]}
(gdb)

After that there is no way to continue:
=========================
-exec-continue
^running
(gdb)
*stopped,reason="signal-received",signal-name="SIGSEGV",signal-meaning="Segmenta
tion fault",thread-id="2",frame={addr="0x000007d4",func="??",args=[]}
(gdb)

Could you please tell me if there any other way to interrupt program on 
Windows,
so that gdb will show where it is stopped, and will allow to continue?

Thanks in advance,
Nikolay Molchanov

Re: Can I use -exec-interrupt to stop the inferior program?

[Daniel Jacobowitz]

On Tue, Oct 10, 2006 at 11:47:11PM -0700, Nikolay Molchanov wrote:
> Nick Roberts suggested to use signals to implement "interrupt" action,
> and it really works very well on Unix (Solaris and Linux), but unfortunately
> it does not work properly on Windows. If I send SIGTSTP, gdb does not
> show that the program is stopped (and it really does not stop), so it looks
> like this signal is ignored. If I send SIGINT, the program is really 
> interrupted,
> but it seems to cause SIGSEGV (Segmentation Fault), and there is no way
> to continue the debugging. Here is a scenario (I use Cygwin):

You should be using SIGINT for this, yes.  Windows SIGINT is funny, but
if you're dealing with Cygwin, it should be OK - in theory.  It doesn't
work for me either; I get the program exiting with code 01000, instead
of a segfault, but the result is equally useless.

Maybe this is a bug in Cygwin?

Eventually, you'll be able to do this properly in GDB.  Nick has been
working hard on asynchronous operation, and once that's ready, we can
implement the -exec-interrupt operation using Windows API calls.  In
the mean time, I have no idea.

-- 
Daniel Jacobowitz
CodeSourcery

Re: Can I use -exec-interrupt to stop the inferior program?

[Eli Zaretskii]

> Date: Wed, 11 Oct 2006 09:49:16 -0400
> From: Daniel Jacobowitz <drow@false.org>
> Cc: gdb@sourceware.org
> 
> Eventually, you'll be able to do this properly in GDB.  Nick has been
> working hard on asynchronous operation, and once that's ready, we can
> implement the -exec-interrupt operation using Windows API calls.

Yes, I think the best idea is to have a Windows-specific
implementation (alongside with a Posix one).  Signals is one of the
few areas where Windows is so different from Posix that no matter how
hard you try to disguise it, that difference will eventually stick
out.