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/*++
/* NAME
/* sigdelay 3
/* SUMMARY
/* delay/resume signal delivery
/* SYNOPSIS
/* #include <sigdelay.h>
/*
/* void sigdelay()
/*
/* void sigresume()
/* DESCRIPTION
/* sigdelay() delays delivery of signals. Signals that
/* arrive in the mean time will be queued.
/*
/* sigresume() resumes delivery of signals. Signals that have
/* arrived in the mean time will be delivered.
/* DIAGNOSTICS
/* All errors are fatal.
/* BUGS
/* The signal queue may be really short (as in: one per signal type).
/*
/* Some signals such as SIGKILL cannot be blocked.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <signal.h>
/* Utility library. */
#include "msg.h"
#include "posix_signals.h"
#include "sigdelay.h"
/* Application-specific. */
static sigset_t saved_sigmask;
static sigset_t block_sigmask;
static int suspending;
static int siginit_done;
/* siginit - compute signal mask only once */
static void siginit(void)
{
int sig;
siginit_done = 1;
sigemptyset(&block_sigmask);
for (sig = 1; sig < NSIG; sig++)
sigaddset(&block_sigmask, sig);
}
/* sigresume - deliver delayed signals and disable signal delay */
void sigresume(void)
{
if (suspending != 0) {
suspending = 0;
if (sigprocmask(SIG_SETMASK, &saved_sigmask, (sigset_t *) 0) < 0)
msg_fatal("sigresume: sigprocmask: %m");
}
}
/* sigdelay - save signal mask and block all signals */
void sigdelay(void)
{
if (siginit_done == 0)
siginit();
if (suspending == 0) {
suspending = 1;
if (sigprocmask(SIG_BLOCK, &block_sigmask, &saved_sigmask) < 0)
msg_fatal("sigdelay: sigprocmask: %m");
}
}
#ifdef TEST
/*
* Test program - press Ctrl-C twice while signal delivery is delayed, and
* see how many signals are delivered when signal delivery is resumed.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
static void gotsig(int sig)
{
printf("Got signal %d\n", sig);
}
int main(int unused_argc, char **unused_argv)
{
signal(SIGINT, gotsig);
signal(SIGQUIT, gotsig);
printf("Delaying signal delivery\n");
sigdelay();
sleep(5);
printf("Resuming signal delivery\n");
sigresume();
exit(0);
}
#endif
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