| /*@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; |
| } |