#include	<setjmp.h>#include	<signal.h>#include	<unistd.h>static jmp_buf	env_alrm;static voidsig_alrm(int signo){	longjmp(env_alrm, 1);}unsigned intsleep2(unsigned int nsecs){	if (signal(SIGALRM, sig_alrm) == SIG_ERR)		return(nsecs);	if (setjmp(env_alrm) == 0) {		alarm(nsecs);		/* start the timer */		pause();			/* next caught signal wakes us up */	}	return(alarm(0));		/* turn off timer, return unslept time */}