usr/src/lib/libbc/libc/gen/4.2/sleep.c

   1 /*
   2  * copyright (c) 1980 Regents of the University of California.
   3  * All rights reserved.  The Berkeley software License Agreement
   4  * specifies the terms and conditions for redistribution.
   5  */
   6
   7 #pragma ident   "%Z%%M% %I%     %E% SMI"
   8
   9 #include <sys/time.h>
  10 #include <signal.h>
  11
  12 #define setvec(vec, a) \
  13         vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
  14
  15 static int ringring;
  16
  17 static void     sleepx(void);
  18
  19 void
  20 sleep(unsigned n)
  21 {
  22         int omask;
  23         struct itimerval itv, oitv;
  24         struct itimerval *itp = &itv;
  25         struct sigvec vec, ovec;
  26
  27         if (n == 0)
  28                 return;
  29         timerclear(&itp->it_interval);
  30         timerclear(&itp->it_value);
  31         if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
  32                 return;
  33         itp->it_value.tv_sec = n;
  34         if (timerisset(&oitv.it_value)) {
  35                 if (timercmp(&oitv.it_value, &itp->it_value, >))
  36                         oitv.it_value.tv_sec -= itp->it_value.tv_sec;
  37                 else {
  38                         itp->it_value = oitv.it_value;
  39                         /*
  40                          * This is a hack, but we must have time to
  41                          * return from the setitimer after the alarm
  42                          * or else it'll be restarted.  And, anyway,
  43                          * sleep never did anything more than this before.
  44                          */
  45                         oitv.it_value.tv_sec = 1;
  46                         oitv.it_value.tv_usec = 0;
  47                 }
  48         }
  49         setvec(vec, sleepx);
  50         (void) sigvec(SIGALRM, &vec, &ovec);
  51         omask = sigblock(sigmask(SIGALRM));
  52         ringring = 0;
  53         (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
  54         while (!ringring)
  55                 sigpause(omask &~ sigmask(SIGALRM));
  56         (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
  57         (void) sigsetmask(omask);
  58         (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
  59 }
  60
  61 static void
  62 sleepx(void)
  63 {
  64
  65         ringring = 1;
  66 }