70 lines
1.8 KiB
C
Executable file
70 lines
1.8 KiB
C
Executable file
/* sleep() - Sleep for a number of seconds. Author: Kees J. Bot
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* 24 Apr 2000
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* (Inspired by the Minix-vmd version of same, except that
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* this implementation doesn't bother to check if all the signal
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* functions succeed. Under Minix that is no problem.)
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*/
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#include <lib.h>
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#define sleep _sleep
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#include <signal.h>
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#include <unistd.h>
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#include <time.h>
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static void handler(int sig)
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{
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/* Dummy signal handler. */
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}
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unsigned sleep(unsigned sleep_seconds)
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{
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sigset_t ss_full, ss_orig, ss_alarm;
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struct sigaction action_alarm, action_orig;
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unsigned alarm_seconds, nap_seconds;
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if (sleep_seconds == 0) return 0; /* No rest for the wicked */
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/* Mask all signals. */
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sigfillset(&ss_full);
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sigprocmask(SIG_BLOCK, &ss_full, &ss_orig);
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/* Cancel currently running alarm. */
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alarm_seconds= alarm(0);
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/* How long can we nap without interruptions? */
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nap_seconds= sleep_seconds;
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if (alarm_seconds != 0 && alarm_seconds < sleep_seconds) {
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nap_seconds= alarm_seconds;
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}
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/* Now sleep. */
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action_alarm.sa_handler= handler;
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sigemptyset(&action_alarm.sa_mask);
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action_alarm.sa_flags= 0;
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sigaction(SIGALRM, &action_alarm, &action_orig);
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alarm(nap_seconds);
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/* Wait for a wakeup call, either our alarm, or some other signal. */
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ss_alarm= ss_orig;
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sigdelset(&ss_alarm, SIGALRM);
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sigsuspend(&ss_alarm);
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/* Cancel alarm, set mask and stuff back to normal. */
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nap_seconds -= alarm(0);
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sigaction(SIGALRM, &action_orig, NULL);
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sigprocmask(SIG_SETMASK, &ss_orig, NULL);
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/* Restore alarm counter to the time remaining. */
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if (alarm_seconds != 0 && alarm_seconds >= nap_seconds) {
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alarm_seconds -= nap_seconds;
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if (alarm_seconds == 0) {
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raise(SIGALRM); /* Alarm expires now! */
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} else {
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alarm(alarm_seconds); /* Count time remaining. */
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}
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}
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/* Return time not slept. */
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return sleep_seconds - nap_seconds;
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}
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