blob: 5a1a405eb72fadde21617d5f55db90b8d4b89363 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
/* Using kill for Communication
Copyright (C) 1991-2014 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, if not, see <http://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;
}
|
