1 /* $NetBSD: sigdelay.c,v 1.1.1.1 2009/06/23 10:09:00 tron Exp $ */
2
3 /*++
4 /* NAME
5 /* sigdelay 3
6 /* SUMMARY
7 /* delay/resume signal delivery
8 /* SYNOPSIS
9 /* #include <sigdelay.h>
10 /*
11 /* void sigdelay()
12 /*
13 /* void sigresume()
14 /* DESCRIPTION
15 /* sigdelay() delays delivery of signals. Signals that
16 /* arrive in the mean time will be queued.
17 /*
18 /* sigresume() resumes delivery of signals. Signals that have
19 /* arrived in the mean time will be delivered.
20 /* DIAGNOSTICS
21 /* All errors are fatal.
22 /* BUGS
23 /* The signal queue may be really short (as in: one per signal type).
24 /*
25 /* Some signals such as SIGKILL cannot be blocked.
26 /* LICENSE
27 /* .ad
28 /* .fi
29 /* The Secure Mailer license must be distributed with this software.
30 /* AUTHOR(S)
31 /* Wietse Venema
32 /* IBM T.J. Watson Research
33 /* P.O. Box 704
34 /* Yorktown Heights, NY 10598, USA
35 /*--*/
36
37 /* System library. */
38
39 #include <sys_defs.h>
40 #include <signal.h>
41
42 /* Utility library. */
43
44 #include "msg.h"
45 #include "posix_signals.h"
46 #include "sigdelay.h"
47
48 /* Application-specific. */
49
50 static sigset_t saved_sigmask;
51 static sigset_t block_sigmask;
52 static int suspending;
53 static int siginit_done;
54
55 /* siginit - compute signal mask only once */
56
siginit(void)57 static void siginit(void)
58 {
59 int sig;
60
61 siginit_done = 1;
62 sigemptyset(&block_sigmask);
63 for (sig = 1; sig < NSIG; sig++)
64 sigaddset(&block_sigmask, sig);
65 }
66
67 /* sigresume - deliver delayed signals and disable signal delay */
68
sigresume(void)69 void sigresume(void)
70 {
71 if (suspending != 0) {
72 suspending = 0;
73 if (sigprocmask(SIG_SETMASK, &saved_sigmask, (sigset_t *) 0) < 0)
74 msg_fatal("sigresume: sigprocmask: %m");
75 }
76 }
77
78 /* sigdelay - save signal mask and block all signals */
79
sigdelay(void)80 void sigdelay(void)
81 {
82 if (siginit_done == 0)
83 siginit();
84 if (suspending == 0) {
85 suspending = 1;
86 if (sigprocmask(SIG_BLOCK, &block_sigmask, &saved_sigmask) < 0)
87 msg_fatal("sigdelay: sigprocmask: %m");
88 }
89 }
90
91 #ifdef TEST
92
93 /*
94 * Test program - press Ctrl-C twice while signal delivery is delayed, and
95 * see how many signals are delivered when signal delivery is resumed.
96 */
97
98 #include <stdio.h>
99 #include <unistd.h>
100 #include <stdlib.h>
101
gotsig(int sig)102 static void gotsig(int sig)
103 {
104 printf("Got signal %d\n", sig);
105 }
106
main(int unused_argc,char ** unused_argv)107 int main(int unused_argc, char **unused_argv)
108 {
109 signal(SIGINT, gotsig);
110 signal(SIGQUIT, gotsig);
111
112 printf("Delaying signal delivery\n");
113 sigdelay();
114 sleep(5);
115 printf("Resuming signal delivery\n");
116 sigresume();
117 exit(0);
118 }
119
120 #endif
121