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Commit | Line | Data |
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d9a17c07 | 1 | /* Using kill for Communication |
d4697bc9 | 2 | Copyright (C) 1991-2014 Free Software Foundation, Inc. |
d9a17c07 RM |
3 | |
4 | This program is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU General Public License | |
6 | as published by the Free Software Foundation; either version 2 | |
7 | of the License, or (at your option) any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program; if not, if not, see <http://www.gnu.org/licenses/>. | |
16 | */ | |
17 | ||
28f540f4 RM |
18 | /*@group*/ |
19 | #include <signal.h> | |
20 | #include <stdio.h> | |
21 | #include <sys/types.h> | |
22 | #include <unistd.h> | |
23 | /*@end group*/ | |
24 | ||
25 | /* When a @code{SIGUSR1} signal arrives, set this variable. */ | |
26 | volatile sig_atomic_t usr_interrupt = 0; | |
27 | ||
d9a17c07 | 28 | void |
28f540f4 RM |
29 | synch_signal (int sig) |
30 | { | |
31 | usr_interrupt = 1; | |
32 | } | |
33 | ||
34 | /* The child process executes this function. */ | |
d9a17c07 | 35 | void |
28f540f4 RM |
36 | child_function (void) |
37 | { | |
38 | /* Perform initialization. */ | |
39 | printf ("I'm here!!! My pid is %d.\n", (int) getpid ()); | |
40 | ||
41 | /* Let parent know you're done. */ | |
42 | kill (getppid (), SIGUSR1); | |
43 | ||
44 | /* Continue with execution. */ | |
45 | puts ("Bye, now...."); | |
46 | exit (0); | |
47 | } | |
48 | ||
49 | int | |
50 | main (void) | |
51 | { | |
52 | struct sigaction usr_action; | |
53 | sigset_t block_mask; | |
54 | pid_t child_id; | |
55 | ||
56 | /* Establish the signal handler. */ | |
57 | sigfillset (&block_mask); | |
58 | usr_action.sa_handler = synch_signal; | |
59 | usr_action.sa_mask = block_mask; | |
60 | usr_action.sa_flags = 0; | |
61 | sigaction (SIGUSR1, &usr_action, NULL); | |
62 | ||
63 | /* Create the child process. */ | |
64 | child_id = fork (); | |
65 | if (child_id == 0) | |
66 | child_function (); /* Does not return. */ | |
67 | ||
68 | /*@group*/ | |
69 | /* Busy wait for the child to send a signal. */ | |
70 | while (!usr_interrupt) | |
71 | ; | |
72 | /*@end group*/ | |
73 | ||
74 | /* Now continue execution. */ | |
75 | puts ("That's all, folks!"); | |
76 | ||
77 | return 0; | |
78 | } |