[linux.git] / fs / fifo.c

/*
 *  linux/fs/fifo.c
 *
 *  written by Paul H. Hargrove
 *
 *  Fixes:
 *	10-06-1999, AV: fixed OOM handling in fifo_open(), moved
 *			initialization there, switched to external
 *			allocation of pipe_inode_info.
 */

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/pipe_fs_i.h>

static void wait_for_partner(struct inode* inode, unsigned int* cnt)
{
	int cur = *cnt;	
	while(cur == *cnt) {
		pipe_wait(inode);
		if(signal_pending(current))
			break;
	}
}

static void wake_up_partner(struct inode* inode)
{
	wake_up_interruptible(PIPE_WAIT(*inode));
}

static int fifo_open(struct inode *inode, struct file *filp)
{
	int ret;

	mutex_lock(PIPE_MUTEX(*inode));
	if (!inode->i_pipe) {
		ret = -ENOMEM;
		if(!pipe_new(inode))
			goto err_nocleanup;
	}
	filp->f_version = 0;

	/* We can only do regular read/write on fifos */
	filp->f_mode &= (FMODE_READ | FMODE_WRITE);

	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! */
	mutex_unlock(PIPE_MUTEX(*inode));
	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))
		free_pipe_info(inode);

err_nocleanup:
	mutex_unlock(PIPE_MUTEX(*inode));
	return ret;
}

/*
 * Dummy default file-operations: the only thing this does
 * is contain the open that then fills in the correct operations
 * depending on the access mode of the file...
 */
struct file_operations def_fifo_fops = {
	.open		= fifo_open,	/* will set read or write pipe_fops */
};
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/fifo.c
	3	*
	4	* written by Paul H. Hargrove
	5	*
	6	* Fixes:
	7	* 10-06-1999, AV: fixed OOM handling in fifo_open(), moved
	8	* initialization there, switched to external
	9	* allocation of pipe_inode_info.
	10	*/
	11
	12	#include <linux/mm.h>
	13	#include <linux/slab.h>
	14	#include <linux/smp_lock.h>
	15	#include <linux/fs.h>
	16	#include <linux/pipe_fs_i.h>
	17
	18	static void wait_for_partner(struct inode* inode, unsigned int* cnt)
	19	{
	20	int cur = *cnt;
	21	while(cur == *cnt) {
	22	pipe_wait(inode);
	23	if(signal_pending(current))
	24	break;
	25	}
	26	}
	27
	28	static void wake_up_partner(struct inode* inode)
	29	{
	30	wake_up_interruptible(PIPE_WAIT(*inode));
	31	}
	32
	33	static int fifo_open(struct inode inode, struct file filp)
	34	{
	35	int ret;
	36
d19e9974	37	mutex_lock(PIPE_MUTEX(*inode));
1da177e4 LT	38	if (!inode->i_pipe) {
	39	ret = -ENOMEM;
	40	if(!pipe_new(inode))
	41	goto err_nocleanup;
	42	}
	43	filp->f_version = 0;
	44
	45	/* We can only do regular read/write on fifos */
	46	filp->f_mode &= (FMODE_READ \| FMODE_WRITE);
	47
	48	switch (filp->f_mode) {
	49	case 1:
	50	/*
	51	* O_RDONLY
	52	* POSIX.1 says that O_NONBLOCK means return with the FIFO
	53	* opened, even when there is no process writing the FIFO.
	54	*/
	55	filp->f_op = &read_fifo_fops;
	56	PIPE_RCOUNTER(*inode)++;
	57	if (PIPE_READERS(*inode)++ == 0)
	58	wake_up_partner(inode);
	59
	60	if (!PIPE_WRITERS(*inode)) {
	61	if ((filp->f_flags & O_NONBLOCK)) {
	62	/* suppress POLLHUP until we have
	63	* seen a writer */
	64	filp->f_version = PIPE_WCOUNTER(*inode);
	65	} else
	66	{
	67	wait_for_partner(inode, &PIPE_WCOUNTER(*inode));
	68	if(signal_pending(current))
	69	goto err_rd;
	70	}
	71	}
	72	break;
	73
	74	case 2:
	75	/*
	76	* O_WRONLY
	77	* POSIX.1 says that O_NONBLOCK means return -1 with
	78	* errno=ENXIO when there is no process reading the FIFO.
	79	*/
	80	ret = -ENXIO;
	81	if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode))
	82	goto err;
	83
	84	filp->f_op = &write_fifo_fops;
	85	PIPE_WCOUNTER(*inode)++;
	86	if (!PIPE_WRITERS(*inode)++)
	87	wake_up_partner(inode);
	88
	89	if (!PIPE_READERS(*inode)) {
	90	wait_for_partner(inode, &PIPE_RCOUNTER(*inode));
	91	if (signal_pending(current))
	92	goto err_wr;
	93	}
	94	break;
	95
	96	case 3:
	97	/*
	98	* O_RDWR
	99	* POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
	100	* This implementation will NEVER block on a O_RDWR open, since
	101	* the process can at least talk to itself.
102	*/
103	filp->f_op = &rdwr_fifo_fops;
104
105	PIPE_READERS(*inode)++;
106	PIPE_WRITERS(*inode)++;
107	PIPE_RCOUNTER(*inode)++;
108	PIPE_WCOUNTER(*inode)++;
109	if (PIPE_READERS(inode) == 1 \|\| PIPE_WRITERS(inode) == 1)
110	wake_up_partner(inode);
111	break;
112
113	default:
114	ret = -EINVAL;
115	goto err;
116	}
117
118	/* Ok! */
1b1dcc1b	119	mutex_unlock(PIPE_MUTEX(*inode));
1da177e4 LT	120	return 0;
	121
	122	err_rd:
	123	if (!--PIPE_READERS(*inode))
	124	wake_up_interruptible(PIPE_WAIT(*inode));
	125	ret = -ERESTARTSYS;
	126	goto err;
	127
	128	err_wr:
	129	if (!--PIPE_WRITERS(*inode))
	130	wake_up_interruptible(PIPE_WAIT(*inode));
	131	ret = -ERESTARTSYS;
	132	goto err;
	133
	134	err:
	135	if (!PIPE_READERS(inode) && !PIPE_WRITERS(inode))
	136	free_pipe_info(inode);
	137
	138	err_nocleanup:
1b1dcc1b	139	mutex_unlock(PIPE_MUTEX(*inode));
1da177e4 LT	140	return ret;
	141	}
	142
	143	/*
	144	* Dummy default file-operations: the only thing this does
	145	* is contain the open that then fills in the correct operations
	146	* depending on the access mode of the file...
	147	*/
	148	struct file_operations def_fifo_fops = {
	149	.open = fifo_open, /* will set read or write pipe_fops */
	150	};