#include "apue.h"#include <pthread.h>pthread_mutex_t lock1 = PTHREAD_MUTEX_INITIALIZER;pthread_mutex_t lock2 = PTHREAD_MUTEX_INITIALIZER;voidprepare(void){	printf("preparing locks...\n");	pthread_mutex_lock(&lock1);	pthread_mutex_lock(&lock2);}voidparent(void){	printf("parent unlocking locks...\n");	pthread_mutex_unlock(&lock1);	pthread_mutex_unlock(&lock2);}voidchild(void){	printf("child unlocking locks...\n");	pthread_mutex_unlock(&lock1);	pthread_mutex_unlock(&lock2);}void *thr_fn(void *arg){	printf("thread started...\n");	pause();	return(0);}intmain(void){	int			err;	pid_t		pid;	pthread_t	tid;#if defined(BSD) || defined(MACOS)	printf("pthread_atfork is unsupported\n");#else	if ((err = pthread_atfork(prepare, parent, child)) != 0)		err_exit(err, "can't install fork handlers");	err = pthread_create(&tid, NULL, thr_fn, 0);	if (err != 0)		err_exit(err, "can't create thread");	sleep(2);	printf("parent about to fork...\n");	if ((pid = fork()) < 0)		err_quit("fork failed");	else if (pid == 0)	/* child */		printf("child returned from fork\n");	else		/* parent */		printf("parent returned from fork\n");#endif	exit(0);}