79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/* Using kill for Communication
|
|
Copyright (C) 1991-2022 Free Software Foundation, Inc.
|
|
|
|
This program is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU General Public License
|
|
as published by the Free Software Foundation; either version 2
|
|
of the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, see <https://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
/*@group*/
|
|
#include <signal.h>
|
|
#include <stdio.h>
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
/*@end group*/
|
|
|
|
/* When a @code{SIGUSR1} signal arrives, set this variable. */
|
|
volatile sig_atomic_t usr_interrupt = 0;
|
|
|
|
void
|
|
synch_signal (int sig)
|
|
{
|
|
usr_interrupt = 1;
|
|
}
|
|
|
|
/* The child process executes this function. */
|
|
void
|
|
child_function (void)
|
|
{
|
|
/* Perform initialization. */
|
|
printf ("I'm here!!! My pid is %d.\n", (int) getpid ());
|
|
|
|
/* Let parent know you're done. */
|
|
kill (getppid (), SIGUSR1);
|
|
|
|
/* Continue with execution. */
|
|
puts ("Bye, now....");
|
|
exit (0);
|
|
}
|
|
|
|
int
|
|
main (void)
|
|
{
|
|
struct sigaction usr_action;
|
|
sigset_t block_mask;
|
|
pid_t child_id;
|
|
|
|
/* Establish the signal handler. */
|
|
sigfillset (&block_mask);
|
|
usr_action.sa_handler = synch_signal;
|
|
usr_action.sa_mask = block_mask;
|
|
usr_action.sa_flags = 0;
|
|
sigaction (SIGUSR1, &usr_action, NULL);
|
|
|
|
/* Create the child process. */
|
|
child_id = fork ();
|
|
if (child_id == 0)
|
|
child_function (); /* Does not return. */
|
|
|
|
/*@group*/
|
|
/* Busy wait for the child to send a signal. */
|
|
while (!usr_interrupt)
|
|
;
|
|
/*@end group*/
|
|
|
|
/* Now continue execution. */
|
|
puts ("That's all, folks!");
|
|
|
|
return 0;
|
|
}
|