asyn_io_signal.c

vxworks中信号量同步的一个小程序 本程序用c语言开发

/* aioExSig.c - example code for using signals with asynchronous I/O */

/* includes */
#include "vxWorks.h"
#include "aio.h"
#include "errno.h"

/* defines */
#define BUFFER_SIZE 200
#define LIST_SIZE 1
#define EXAMPLE_SIG_NO 25 /* signal number */

/* forward declarations */
void mySigHandler (int sig, struct siginfo * info, void * pContext);

/************************************************************************
* aioExampleSig - use AIO library.
*
* This example shows the basic functions of the AIO library.
* Note if this is run from the shell it must be spawned. Use:
* -> sp aioExampleSig
*
* RETURNS: OK if successful, otherwise ERROR.
*/
STATUS aioExampleSig (void)
{
	int fd;
	static char exFile [] = "/pipe/1stPipe";
	struct aiocb aiocb_read; /* read aiocb */
	static struct aiocb aiocb_write; /* write aiocb */
	struct sigaction action; /* signal info */
	static char * test_string = "testing 1 2 3";
	char buffer [BUFFER_SIZE]; /* aiocb read buffer */
	pipeDevCreate (exFile, 50, 100);
	if ((fd = open (exFile, O_CREAT | O_TRUNC| O_RDWR, 0666)) == ERROR)
		{
			printf ("aioExample: cannot open %s errno 0x%x\n", exFile, errno);
			return (ERROR);
		}
	printf ("aioExampleSig: Example file = %s\tFile descriptor = %d\n", exFile, fd);

	/* set up signal handler for EXAMPLE_SIG_NO */
	action.sa_sigaction = mySigHandler;
	action.sa_flags = SA_SIGINFO;
	sigemptyset (&action.sa_mask);
	sigaction (EXAMPLE_SIG_NO, &action, NULL);

	/* initialize read and write aiocbs */
	bzero ((char *) &aiocb_read, sizeof (struct aiocb));
	bzero ((char *) buffer, sizeof (buffer));
	aiocb_read.aio_fildes = fd;
	aiocb_read.aio_buf = buffer;
	aiocb_read.aio_nbytes = BUFFER_SIZE;
	aiocb_read.aio_reqprio = 0;
	bzero ((char *) &aiocb_write, sizeof (struct aiocb));
	aiocb_write.aio_fildes = fd;
	aiocb_write.aio_buf = test_string;
	aiocb_write.aio_nbytes = strlen (test_string);
	aiocb_write.aio_reqprio = 0;

	/* set up signal info */
	aiocb_write.aio_sigevent.sigev_signo = EXAMPLE_SIG_NO;
	aiocb_write.aio_sigevent.sigev_notify = SIGEV_SIGNAL;
	aiocb_write.aio_sigevent.sigev_value.sival_ptr = (void *) &aiocb_write;

	/* initiate the read */
	if (aio_read (&aiocb_read) == -1)
		printf ("aioExampleSig: aio_read failed\n");

	/* verify that it is in progress */
	if (aio_error (&aiocb_read) == EINPROGRESS)
		printf ("aioExampleSig: read is still in progress\n");

	/* write to pipe - the read should be able to complete */
	printf ("aioExampleSig: getting ready to initiate the write\n");
	if (aio_write (&aiocb_write) == -1)
		printf ("aioExampleSig: aio_write failed\n");

	/* clean up */
	if (aio_return (&aiocb_read) == -1)
		printf ("aioExampleSig: aio_return for aiocb_read failed\n");
	else
		printf ("aioExampleSig: aio read message = %s\n", aiocb_read.aio_buf);

	close (fd);
	return (OK);
}

void mySigHandler
(
	int sig,
	struct siginfo * info,
	void * pContext
)
{
	/* print out what was read */
	printf ("mySigHandler: Got signal for aio write\n");
	/* write is complete so let’s do cleanup for it here */
	if (aio_return (info->si_value.sival_ptr) == -1)
		{
			printf ("mySigHandler: aio_return for aiocb_write failed\n");
			printErrno (0);
		}
}