| 1 | /* sleep() - Sleep for a number of seconds. Author: Kees J. Bot
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| 2 | * 24 Apr 2000
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| 3 | * (Inspired by the Minix-vmd version of same, except that
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| 4 | * this implementation doesn't bother to check if all the signal
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| 5 | * functions succeed. Under Minix that is no problem.)
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| 6 | */
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| 7 |
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| 8 | #include <lib.h>
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| 9 | #define sleep _sleep
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| 10 | #include <signal.h>
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| 11 | #include <unistd.h>
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| 12 | #include <time.h>
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| 13 |
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| 14 | static void handler(int sig)
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| 15 | {
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| 16 | /* Dummy signal handler. */
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| 17 | }
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| 18 |
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| 19 | unsigned sleep(unsigned sleep_seconds)
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| 20 | {
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| 21 | sigset_t ss_full, ss_orig, ss_alarm;
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| 22 | struct sigaction action_alarm, action_orig;
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| 23 | unsigned alarm_seconds, nap_seconds;
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| 24 |
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| 25 | if (sleep_seconds == 0) return 0; /* No rest for the wicked */
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| 26 |
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| 27 | /* Mask all signals. */
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| 28 | sigfillset(&ss_full);
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| 29 | sigprocmask(SIG_BLOCK, &ss_full, &ss_orig);
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| 30 |
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| 31 | /* Cancel currently running alarm. */
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| 32 | alarm_seconds= alarm(0);
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| 33 |
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| 34 | /* How long can we nap without interruptions? */
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| 35 | nap_seconds= sleep_seconds;
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| 36 | if (alarm_seconds != 0 && alarm_seconds < sleep_seconds) {
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| 37 | nap_seconds= alarm_seconds;
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| 38 | }
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| 39 |
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| 40 | /* Now sleep. */
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| 41 | action_alarm.sa_handler= handler;
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| 42 | sigemptyset(&action_alarm.sa_mask);
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| 43 | action_alarm.sa_flags= 0;
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| 44 | sigaction(SIGALRM, &action_alarm, &action_orig);
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| 45 | alarm(nap_seconds);
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| 46 |
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| 47 | /* Wait for a wakeup call, either our alarm, or some other signal. */
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| 48 | ss_alarm= ss_orig;
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| 49 | sigdelset(&ss_alarm, SIGALRM);
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| 50 | sigsuspend(&ss_alarm);
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| 51 |
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| 52 | /* Cancel alarm, set mask and stuff back to normal. */
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| 53 | nap_seconds -= alarm(0);
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| 54 | sigaction(SIGALRM, &action_orig, NULL);
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| 55 | sigprocmask(SIG_SETMASK, &ss_orig, NULL);
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| 56 |
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| 57 | /* Restore alarm counter to the time remaining. */
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| 58 | if (alarm_seconds != 0 && alarm_seconds >= nap_seconds) {
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| 59 | alarm_seconds -= nap_seconds;
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| 60 | if (alarm_seconds == 0) {
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| 61 | raise(SIGALRM); /* Alarm expires now! */
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| 62 | } else {
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| 63 | alarm(alarm_seconds); /* Count time remaining. */
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| 64 | }
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| 65 | }
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| 66 |
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| 67 | /* Return time not slept. */
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| 68 | return sleep_seconds - nap_seconds;
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| 69 | }
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