1 /* @(#)sleep.c 4.2 (Berkeley) 06/10/83 */ 2 3 #include <signal.h> 4 #include <setjmp.h> 5 #include <time.h> 6 7 static jmp_buf jmp; 8 9 #define mask(s) (1<<((s)-1)) 10 #define setvec(vec, a) \ 11 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 12 13 sleep(n) 14 unsigned n; 15 { 16 int sleepx(), omask; 17 struct itimerval itv, oitv; 18 register struct itimerval *itp = &itv; 19 struct sigvec vec, ovec; 20 21 if (n == 0) 22 return; 23 timerclear(&itp->it_interval); 24 timerclear(&itp->it_value); 25 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 26 return; 27 setvec(ovec, SIG_DFL); 28 if (setjmp(jmp)) { 29 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 30 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 31 return; 32 } 33 omask = sigblock(0); 34 itp->it_value.tv_sec = n; 35 if (timerisset(&oitv.it_value)) { 36 if (timercmp(&oitv.it_value, &itp->it_value, >)) 37 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 38 else { 39 itp->it_value = oitv.it_value; 40 /* 41 * Set the reset value to the smallest possible, 42 * the system will round it to the clock resolution. 43 */ 44 oitv.it_value.tv_sec = 0; 45 oitv.it_value.tv_usec = 1; 46 } 47 } 48 setvec(vec, sleepx); 49 (void) sigvec(SIGALRM, &vec, &ovec); 50 if (setitimer(ITIMER_REAL, itp, (struct itimerval *)0) < 0) 51 longjmp(jmp, 1); 52 sigpause(omask &~ mask(SIGALRM)); 53 /*NOTREACHED*/ 54 } 55 56 static 57 sleepx() 58 { 59 60 longjmp(jmp, 1); 61 } 62