Re: lug-bg: AutoSlack 1.7 KeepAlive script

[vd@xxxxxxxxx (Vladimir Dzhuvinov)]

Zdravei,

On Fri, 25 May 2001, George Danchev wrote:

>neuspeshno , prosto tazi funkciq vse oste ne raboti) i sled kato izte4e 
>TIMEOUT parametura koito  mu se zadava (opitvah na nqkolko ftp servera s 
>mnogo golemi timeout stoinosti - ne resume-va )  autoslack prekratqwa rabota 
>. Trqbwa ru4no da se startira otnovo i zlopolu4niq package ste bude izteglen 
>otna4alo , za ve4e izteglinite nqma problemi - spool-nati sa v edin
>dir . Ta pri men taka 3 puti dropwashe na polovinata na glibc-2.2.2 (27MB) 
>... dialer-a (v moq slu4ai) reconnect-va , no autoslack ne iska da resume-ne 
>:(((.
Predpolagam, che tova e bilo mnogo nepriatno :-(

>Ta pitaneto mi e slednoto :
...
>Ta moje li nqkoi da nahvurlq suvsem grubo nqkolko red4eta na takuv keepalive 
>bash script koito da sledi i restartira : autoslack -opt1 -opt2 -optX
>( moje i na drug script ezik ) , a az posle ste si go "doumorq". 
Prastam ti edna cqla C programa, kompilira se s

        gcc -o keepalive keepalive.c

Sled tova pishesh

        ./keepalive command [arguments]

led koeto keepalive instalira SIGCHLD handler, fork-va command child,
i usleep(). Ako child command terminira, keepalive poluchava SIGCHLD,
sybuwda se, fork-va nov command child i pak zaspiva...

Edinstveniq nachin da prekratish tozi cikyl e da kill-nesh keepalive.

Predpolagam, che autoslack e konzolna programa, a pyk keepalive sym q
pisal s mnogo verbose prints, koito mogat da sa nepodhodiasti za teb,
zatova mojesh spokoino da iztriesh vsicko sto e printf() v keepalive.c

Razbira se, ne poemam nikakva garanciq za tazi programa.
Use at your own risk ;-))

Pozdravi,
Vladimir Dzhuvinov

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/* Vladimir Djouvinov, 12-2-1999
 * Forks out a child process and goes into sleep-wakeup cycle
 * If a SIGCHILD is received (child process died), 
 * a new instance of it is forked
*/



#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <sys/wait.h>


char* full_program_invocation_name;
char* command;
char** arguments;
pid_t child_pid;



int
start_process ()
{

	/* --- check for NULL function arguments --- */
	if (command == NULL)
		{
		fprintf(stderr, "%s: no process to start\n",
			full_program_invocation_name);
		return (1);
		}


	/* --- fork scan process --- */

	child_pid = fork();

	if(child_pid == -1)
		{
		/* fork() failed */
		fprintf(stderr, "%s: forking failed: %s\n",
				full_program_invocation_name,
				strerror(errno));
		return (1);
		}
		
	else if(child_pid == 0)
		{
		/* child */
		if ((execvp (command, arguments) )==-1)
			{
			fprintf(stderr, "%s: couldn't execute %s: %s\n",
					full_program_invocation_name, 
					command,
					strerror(errno));
			return (1);
			}

		/* exit child. note the use of _exit() instead of exit() */
		_exit(-1);
		}
	else
		/* parent */
		{
		printf ("%s: forked child process with pid %d\n",
			full_program_invocation_name,
			child_pid);
		}
			
	
	return (0);
}					


void
child_exit (int sig)
{
	
	int exit_status;
	
	puts("received SIGCHLD");
	
	if (waitpid(child_pid, &exit_status, WNOHANG | WUNTRACED) == -1)
		fprintf(stderr, "%s: couldn't get status of child process(pid=%d): %s\n",
			full_program_invocation_name, 
			child_pid, 
			strerror(errno));
			
	printf ("%s: child process(pid=%d) terminated with status %d, starting new process...\n",
		full_program_invocation_name,
		child_pid,
		WEXITSTATUS(exit_status));

	start_process();
	
		
}



int
main (int argc, char *argv[])
{

	int i;

	/* --- set the program invocation name for error reporting--- */
	full_program_invocation_name = argv[0];

	/* --- check input --- */
	if (argc == 1){
		printf ("%s: usage %s command [options...]\n",
			full_program_invocation_name,
			full_program_invocation_name);
		return (1);
	}

	/* --- install a signal handler for the child exit signal --- */
	if (signal (SIGCHLD, child_exit)==SIG_ERR) {
		printf ("%s: signal CHLD cannot be handled\n",
			full_program_invocation_name);
		return (1);
	}
	
	/* --- set the command of the process to be started --- */
	command = argv[1];
	printf ("command is %s\n", command);
	
	/* --- set the process arguments pointer --- */
	arguments = (char**)malloc(argc * sizeof(char*));
	for (i=0; i < argc; ++i) {
		arguments[i] = argv[i+1];
		printf ("ref. %d = %s\n", i, arguments[i]);
	}
	arguments[++i] == NULL;
	
	/* --- call fork wrapper --- */
	start_process();
	
	while (1)
		sleep(60);
	
	return (0);
	
}
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