RE: Question!

["Mariano Moreyra" <moremari@aca.org.ar>]

-----Mensaje original-----
De: linux-c-programming-owner@vger.kernel.org
[mailto:linux-c-programming-owner@vger.kernel.org]En nombre de Jorge
Opaso Pazos
Enviado el: Viernes, 05 de Septiembre de 2003 01:17
Para: linux-c-programming@vger.kernel.org
Asunto: Re: Question!


Mariano Moreyra wrote:
> The problem is that the child is waiting for the script to finish (the one
> that start mysqld) so the child sends a response to the client telling him
> that the script finished ok (or not).
> So, if I close the socket, the child can't send the response.
> I tried to find a solution to this situation, but the client needs to know
> the exit status of the script.
> The parent process has his own socket listening for incoming connections
and
> forks the childs. These childs accepts the connections on his own sockets,
> so  childs doesn't inherit the parent's socket.
> It's ok to do that?? Or I'm doing something wrong with the sockets??
> Thanks a lot to all of you for your answers!!
>
> -----Mensaje original-----
> De: linux-c-programming-owner@vger.kernel.org
> [mailto:linux-c-programming-owner@vger.kernel.org]En nombre de Luciano
> Miguel Ferreira Rocha
> Enviado el: Jueves, 04 de Septiembre de 2003 14:54
> Para: Jorge Opaso Pazos
> CC: linux-c-programming@vger.kernel.org
> Asunto: Re: Question!
>
>
> On Thu, Sep 04, 2003 at 12:04:43PM -0400, Jorge Opaso Pazos wrote:
>
>>Mariano Moreyra wrote:
>>
>>>Hola!
>>>Te mando la seccion del programa que ejecuta el script en si.
>>>
>>>Este proceso lo unico que espera del script es que el mismo conteste con
>
> un
>
>>>"-" si hubo algun error o con un "+" si salio todo bien
>>>
>>>----------------------------------------------------------
>>>   if(err==0) {
>>>     pipe_in = popen(shell_cmd,"r");
>>>     fgets(response,5,pipe_in);
>>>
>>>     if(response[0]=='-') {
>>>       err=1;
>>>     } else if(response[0]=='+') {
>>>       err=0;
>>>     };
>>>     while(fgets(response,5,pipe_in)) {
>>>     };
>>>     pclose(pipe_in);
>>>   };
>>>-----------------------------------------------------------
>>>
>>>El script lo unico que hace es copiar algunos archivos y luego leventar
>
> el
>
>>>MySQL con el
>>>safe_mysqld
>>>
>>>Espero que esto sirva! Muchas gracias!!
>>>Saludos!!
>>>
>>>
>>>
>>>-----Mensaje original-----
>>>De: linux-c-programming-owner@vger.kernel.org
>>>[mailto:linux-c-programming-owner@vger.kernel.org]En nombre de Jorge
>>>Opaso Pazos
>>>Enviado el: Miércoles, 03 de Septiembre de 2003 18:09
>>>Para: linux-c-programming@vger.kernel.org
>>>Asunto: Re: Question!
>>>
>>>
>>>Mariano Moreyra wrote:
>>>
>>>
>>>>Hi!!
>>>>First...I'd like to know if there is any kind of digest on this list to
>>>
>>>see
>>>
>>>
>>>>old submited messages.
>>>>
>>>>Now...I have a little problem.
>>>>I have a process that is listening for incoming connections on a socket.
>>>>That process waits for a command and then
>>>>forks a child to run a bash script.
>>>>The problems is:
>>>>	- When the bash script runs the safe_mysql script to run MySql
>>>>	engine,
>>>
>>>it's
>>>
>>>
>>>>like the child process never ends.
>>>>	  And because of that, the parent can't close the connection with the
>>>>client socket.
>>>>	- But if the bash script doesn't run the safe_mysql script...the
>>>>	child
>>>>process dies successfully and everything end
>>>>	  Ok
>>>>
>>>>Sorry about my english, but I hope that I made my self clear....
>>>>Bye!
>>>>
>>>>-
>>>>To unsubscribe from this list: send the line "unsubscribe
>>>
>>>linux-c-programming" in
>>>
>>>
>>>>the body of a message to majordomo@vger.kernel.org
>>>>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>
>>>
>>>
>>>envíame el script.
>>>
>>>-
>>>To unsubscribe from this list: send the line "unsubscribe
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>>>
>>
>>English: I suspect that the problem is that safe_mysqld don't return
>>until mysqld ends.
>>Try to execute safe_mysqld in background in the shellscript:
>>
>>	if ! pgrep mysqld
>>	then
>>		/usr/bin/safe_mysqld &
>>	fi
>
> As the socket is inherited, the remote client will never exit.
> If the popen is after a fork(), then it doesn't matter if safe_mysql
doesn't
> end, as the parent wouldn't be waiting on it.
>
> My bet is in the socket not being closed, either in the parent, child, or
> both, or before the execution of safe_mysql. (If mysqld inherits the
socket,
> then the connection won't close until mysqld does.)
>
>
>>Castellano: El problema debe ser que no termina safe_mydqld hasta que no
>>termina mysqld. Se podría solucionar llamando a safe_mysqld en
>>"background" de la forma anterior.
>
>
> Portugues: AH! that would be something :)
>
> Regards,
> Luciano Rocha
> -
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>

>Hi Mariano, hi Luciano.

>When we make a concurrent server (a server that spawn a child process
>when accept return) always the parent have to close de socket returned
>by accept and the child have to close the socket that the server use to
>call accept (server socket).

I have to check if I'm closing the sockets in the right way...

>I you have to inform the client about the exit status of the script, the
>better way (I think) is to execute the script in the child with
>system(3), because you need the exit status of the script, not the
>output.

I tried to execute the script with system, but I don't know why I didn't
recieve the right  exit status from the script. That's why i'm using popen
and getting the output.

> About the safe_mysqld, you must send it to bg.
The script is running safe_mysqld on bg, but that seems to be the problem.
Actually, if I'm connected to my linux box, via SecureCRT and run
safe_mysqld on background, when I exit from the console, with the exit
command or Ctrl-D, the SecureCRT connection never ends.
That's why I don't know if my problem really has a solution hehe  :)
But I'll keep trying all your recomendations to see what happens.
Thanks again!!

>Luciano, I've never heard the lsof command, thanks.
About lsof ... I don't know if it comes with all Linux distributions, but in
my case it does (Linux Redhat 7.2)

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