proper usage of "-exec-interrupt"

proper usage of "-exec-interrupt"

[Alexander Petukhov]

Hi,
I'm writing a GDB plugin for an IDE and I'm using async target in MI mode
to allow user to alter breakpoints while debugging.
As I learned I have to use "-exec-interrupt" command to stop a debugger but
when I'm doing so a process that spawns GDB, i.e. an IDE receives SIGINT 
and exits accordingly.
Unfortunately I wasn't able to intercept a signal in IDE as it's written 
with GTK and signal functions do not work for some reason.
The other way I've found is to send SIGINT directly to a GDB process and 
it worked for me but
recently another developer reported that he has problem with finishing 
the whole X session when trying to interrupt GDB in this way, looks like 
SIGINT reached X session manager...

Whay does this signal come to parent process and can I avoid this somehow?

Thanks, Alexander

Re: proper usage of "-exec-interrupt"

[Joel Brobecker]

> Whay does this signal come to parent process and can I avoid this
> somehow?

This is a bit of a guess, since I don't remember all the details,
but I think it might be a question of process group. To implement
the interrupt, many targets simply send a SIGINT signal to the
inferior process group. If you spawned GDB within the same process
group as GDB, and both GDB and the program being debugged share
the same process group as well, the interrupt will cause SIGINT
to be received by your IDE as well. So, try spawning GDB in its
own process group.

-- 
Joel

Re: proper usage of "-exec-interrupt"

[Alexander Petukhov]

On 9/17/11 11:06 PM, Joel Brobecker wrote:
>> Whay does this signal come to parent process and can I avoid this
>> somehow?
> This is a bit of a guess, since I don't remember all the details,
> but I think it might be a question of process group. To implement
> the interrupt, many targets simply send a SIGINT signal to the
> inferior process group. If you spawned GDB within the same process
> group as GDB, and both GDB and the program being debugged share
> the same process group as well, the interrupt will cause SIGINT
> to be received by your IDE as well. So, try spawning GDB in its
> own process group.
>
I tried to move gdb into a distinct group with "setpgid(gdb_pid, 0)", 
right after spawning it with "g_spawn_async_with_pipes".
If I do so SIGINT doesn't come to IDE but a program being debugged quits 
right after executing "-exec-interrupt".
The gdb output is:

^done
(gdb)
&"Quit\n"
=thread-exited, .....
=thread-group-exited,....
*stopped,reason="exited-normally"

I also tried to do all this executing gdb from a terminal window and a 
program had stopped correctly with stop reason="signal-received", no 
quits...

Can't it be a bug, I've found several discussions with suggestions to 
send SIGINT or SIGTSTP directly to a process being debugged instead of 
using "-exec-interrupt" ?