Advanced Programming in the UNIX® Environment

ptg10805159

Section 12.4 Synchronization Attributes 437

void *to_arg; /* argument */

struct timespec to_wait; /* time to wait */

};

#define SECTONSEC 1000000000 /* seconds to nanoseconds */

#if !defined(CLOCK_REALTIME) || defined(BSD)

#define clock_nanosleep(ID, FL, REQ, REM) nanosleep((REQ), (REM))

#endif

#ifndef CLOCK_REALTIME

#define CLOCK_REALTIME 0

#define USECTONSEC 1000 /* microseconds to nanoseconds */

void

clock_gettime(int id, struct timespec *tsp)

{

struct timeval tv;

gettimeofday(&tv, NULL);

tsp->tv_sec = tv.tv_sec;

tsp->tv_nsec = tv.tv_usec * USECTONSEC;

}

#endif

void *

timeout_helper(void *arg)

{

struct to_info *tip;

tip = (struct to_info *)arg;

clock_nanosleep(CLOCK_REALTIME, 0, &tip->to_wait, NULL);

(*tip->to_fn)(tip->to_arg);

free(arg);

return(0);

}

void

timeout(const struct timespec *when, void (*func)(void *), void *arg)

{

struct timespec now;

struct to_info *tip;

int err;

clock_gettime(CLOCK_REALTIME, &now);

if ((when->tv_sec > now.tv_sec) ||

(when->tv_sec == now.tv_sec && when->tv_nsec > now.tv_nsec)) {

tip = malloc(sizeof(struct to_info));

if (tip != NULL) {

tip->to_fn = func;

tip->to_arg = arg;

tip->to_wait.tv_sec = when->tv_sec - now.tv_sec;

if (when->tv_nsec >= now.tv_nsec) {

tip->to_wait.tv_nsec = when->tv_nsec - now.tv_nsec;

}else {