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/*
* 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/malloc.h>
static int fifo_open(struct inode *inode, struct file *filp)
{
int ret;
ret = -ERESTARTSYS;
if (down_interruptible(PIPE_SEM(*inode)))
goto err_nolock_nocleanup;
if (! inode->i_pipe) {
unsigned long page;
struct pipe_inode_info *info;
info = kmalloc(sizeof(struct pipe_inode_info),GFP_KERNEL);
ret = -ENOMEM;
if (!info)
goto err_nocleanup;
page = __get_free_page(GFP_KERNEL);
if (!page) {
kfree(info);
goto err_nocleanup;
}
inode->i_pipe = info;
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;
}
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 = &connecting_fifo_fops;
if (PIPE_READERS(*inode)++ == 0)
wake_up_interruptible(PIPE_WAIT(*inode));
if (!(filp->f_flags & O_NONBLOCK)) {
while (!PIPE_WRITERS(*inode)) {
if (signal_pending(current))
goto err_rd;
up(PIPE_SEM(*inode));
interruptible_sleep_on(PIPE_WAIT(*inode));
/* Note that using down_interruptible here
and similar places below is pointless,
since we have to acquire the lock to clean
up properly. */
down(PIPE_SEM(*inode));
}
}
if (PIPE_WRITERS(*inode))
filp->f_op = &read_fifo_fops;
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;
if (!PIPE_WRITERS(*inode)++)
wake_up_interruptible(PIPE_WAIT(*inode));
while (!PIPE_READERS(*inode)) {
if (signal_pending(current))
goto err_wr;
up(PIPE_SEM(*inode));
interruptible_sleep_on(PIPE_WAIT(*inode));
down(PIPE_SEM(*inode));
}
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)++;
if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1)
wake_up_interruptible(PIPE_WAIT(*inode));
break;
default:
ret = -EINVAL;
goto err;
}
/* Ok! */
up(PIPE_SEM(*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)) {
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:
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...
*/
static struct file_operations def_fifo_fops = {
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
fifo_open, /* will set read or write pipe_fops */
NULL,
NULL,
NULL,
NULL
};
struct inode_operations fifo_inode_operations = {
&def_fifo_fops, /* default file operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
NULL, /* readlink */
NULL, /* follow_link */
NULL, /* get_block */
NULL, /* readpage */
NULL, /* writepage */
NULL, /* flushpage */
NULL, /* truncate */
NULL, /* permission */
NULL, /* smap */
NULL /* revalidate */
};
/* Goner. Filesystems do not use it anymore. */
void init_fifo(struct inode * inode)
{
inode->i_op = &fifo_inode_operations;
}
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