Date: Mon, 25 Jul 2005 16:35:20 +0400 (MSD) From: "Felix-KM" <Felix-KM@yandex.ru> To: freebsd-hackers@freebsd.org Subject: how to use the function copyout() Message-ID: <42E4DC88.000006.21996@camay.yandex.ru>
next in thread | raw e-mail | index | archive | help
I can't understand how to use the function copyout().
It is necessary to write the data from a device driver to the
array defined in user program.
I do it this way:
#define IOCTL_GET_B _IOWR("F", 127, 0x4)
---- driver ----
struct my_softc {
...
short unsigned int B;
};
...
static int
my_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag,
struct thread *td)
{
struct my_softc *my_sc;
int unit, error;
unit = minor(dev);
my_sc = (struct my_softc *)devclass_get_softc(my_devclass, unit);
if (my_sc == NULL)
return (ENXIO);
switch(cmd)
{
...
case IOCTL_GET_B:
error = copyout(&my_sc->B, data, sizeof(my_sc->B));
switch (error)
{
case 0:
printf(" IOCTL_GET_B: %d\n", my_sc->B);
break;
case EFAULT:
printf("EFAULT\n");
break;
case EIO:
printf("EIO\n");
break;
case ENOMEM:
printf("ENOMEM\n");
break;
case ENOSPC:
printf("ENOSPC\n");
break;
}
break;
default:
break;
}
return 0;
}
---user program ----------------------
...
short unsigned int Data[32768];
int
main(int argc, char *argv[])
{ ...
if (ioctl(fd0, IOCTL_GET_B, Data) == -1)
err(1, "IOCTL_GET_B");
...
}
-------
Here I get EFAULT.
What have I done wrong? How can I do it correctly?
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?42E4DC88.000006.21996>