mqnotifysig1.c

基于unix/linux 的消息队列编程；库采用POSIX 可做商业源代码用

#include	"unpipc.h"

mqd_t	mqd;
void	*buff;
struct mq_attr	attr;
struct sigevent	sigev;

static void	sig_usr1(int);

int
main(int argc, char **argv)
{
	if (argc != 2)
		err_quit("usage: mqnotifysig1 <name>");

		/* 4open queue, get attributes, allocate read buffer */
	mqd = Mq_open(argv[1], O_RDONLY);
	Mq_getattr(mqd, &attr);
	buff = Malloc(attr.mq_msgsize);

		/* 4establish signal handler, enable notification */
	Signal(SIGUSR1, sig_usr1);
	sigev.sigev_notify = SIGEV_SIGNAL;
	sigev.sigev_signo = SIGUSR1;
	Mq_notify(mqd, &sigev);

	for ( ; ; )
		pause();		/* signal handler does everything */
	exit(0);
}

static void
sig_usr1(int signo)
{
	ssize_t	n;

	Mq_notify(mqd, &sigev);			/* reregister first */
	n = Mq_receive(mqd, buff, attr.mq_msgsize, NULL);
	printf("SIGUSR1 received, read %ld bytes\n", (long) n);
	return;
}