struct inode* pipe_new(struct inode* inode)
{
unsigned long page;
page = __get_free_page(GFP_USER);
if (!page)
return NULL;
inode->i_pipe = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
if (!inode->i_pipe)
goto fail_page;
init_waitqueue_head(PIPE_WAIT(*inode));
PIPE_BASE(*inode) = (char*) page;
PIPE_START(*inode) = PIPE_LEN(*inode) = 0;
PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 0;
PIPE_WAITING_READERS(*inode) = PIPE_WAITING_WRITERS(*inode) = 0;
PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1;
return inode;
fail_page:
free_page(page);
return NULL;
}
static int fifo_open(struct inode *inode, struct file *filp)
{
int ret;
ret = -ERESTARTSYS;
lock_kernel();
if (down_interruptible(PIPE_SEM(*inode)))
goto err_nolock_nocleanup;
if (!inode->i_pipe) {
ret = -ENOMEM;
if(!pipe_new(inode))
goto err_nocleanup;
}
filp->f_version = 0;
switch (filp->f_mode) {
case 1:
/*
* O_RDONLY
* POSIX.1 says that O_NONBLOCK means return with the FIFO
* opened, even when there is no process writing the FIFO.
*/
filp->f_op = &read_fifo_fops;
PIPE_RCOUNTER(*inode)++;
if (PIPE_READERS(*inode)++ == 0)
wake_up_partner(inode);
if (!PIPE_WRITERS(*inode)) {
if ((filp->f_flags & O_NONBLOCK)) {
/* suppress POLLHUP until we have
* seen a writer */
filp->f_version = PIPE_WCOUNTER(*inode);
} else
{
wait_for_partner(inode, &PIPE_WCOUNTER(*inode));
if(signal_pending(current))
goto err_rd;
}
}
break;
case 2:
/*
* O_WRONLY
* POSIX.1 says that O_NONBLOCK means return -1 with
* errno=ENXIO when there is no process reading the FIFO.
*/
ret = -ENXIO;
if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode))
goto err;
filp->f_op = &write_fifo_fops;
PIPE_WCOUNTER(*inode)++;
if (!PIPE_WRITERS(*inode)++)
wake_up_partner(inode);
if (!PIPE_READERS(*inode)) {
wait_for_partner(inode, &PIPE_RCOUNTER(*inode));
if (signal_pending(current))
goto err_wr;
}
break;
case 3:
/*
* O_RDWR
* POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
* This implementation will NEVER block on a O_RDWR open, since
* the process can at least talk to itself.
*/
filp->f_op = &rdwr_fifo_fops;
PIPE_READERS(*inode)++;
PIPE_WRITERS(*inode)++;
PIPE_RCOUNTER(*inode)++;
PIPE_WCOUNTER(*inode)++;
if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1)
wake_up_partner(inode);
break;
default:
ret = -EINVAL;
goto err;
}
/* Ok! */
up(PIPE_SEM(*inode));
unlock_kernel();
return 0;
err_rd:
if (!--PIPE_READERS(*inode))
wake_up_interruptible(PIPE_WAIT(*inode));
ret = -ERESTARTSYS;
goto err;
err_wr:
if (!--PIPE_WRITERS(*inode))
wake_up_interruptible(PIPE_WAIT(*inode));
ret = -ERESTARTSYS;
goto err;
err:
if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
struct pipe_inode_info *info = inode->i_pipe;
inode->i_pipe = NULL;
free_page((unsigned long)info->base);
kfree(info);
}
err_nocleanup:
up(PIPE_SEM(*inode));
err_nolock_nocleanup:
unlock_kernel();
return ret;
}
