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/* GNU Mach Kernel Message Device.
Copyright (C) 1998, 1999, 2007 Free Software Foundation, Inc.
Written by OKUJI Yoshinori.
This is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This software is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the software; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* kmsg provides a stream interface. */
#include <sys/types.h>
#include <string.h>
#include <device/conf.h>
#include <device/ds_routines.h>
#include <device/io_req.h>
#include <mach/boolean.h>
#include <kern/lock.h>
#include <device/kmsg.h>
#define KMSGBUFSIZE (4096) /* XXX */
/* Simple array for buffering messages */
static char kmsg_buffer[KMSGBUFSIZE];
/* Point to the offset to write */
static int kmsg_write_offset;
/* Point to the offset to read */
static int kmsg_read_offset;
/* I/O request queue for blocking read */
static queue_head_t kmsg_read_queue;
/* Used for exclusive access to the device */
static boolean_t kmsg_in_use;
/* Used for exclusive access to the routines */
decl_simple_lock_data (static, kmsg_lock);
/* If already initialized or not */
static boolean_t kmsg_init_done = FALSE;
/* Kernel Message Initializer */
static void
kmsginit (void)
{
kmsg_write_offset = 0;
kmsg_read_offset = 0;
queue_init (&kmsg_read_queue);
kmsg_in_use = FALSE;
simple_lock_init (&kmsg_lock);
}
/* Kernel Message Open Handler */
io_return_t
kmsgopen (dev_t dev, int flag, const io_req_t ior)
{
simple_lock (&kmsg_lock);
if (kmsg_in_use)
{
simple_unlock (&kmsg_lock);
return D_ALREADY_OPEN;
}
kmsg_in_use = TRUE;
simple_unlock (&kmsg_lock);
return D_SUCCESS;
}
/* Kernel Message Close Handler */
void
kmsgclose (dev_t dev, int flag)
{
simple_lock (&kmsg_lock);
kmsg_in_use = FALSE;
simple_unlock (&kmsg_lock);
}
static boolean_t kmsg_read_done (io_req_t ior);
/* Kernel Message Read Handler */
io_return_t
kmsgread (dev_t dev, io_req_t ior)
{
int err;
int amt, len;
err = device_read_alloc (ior, ior->io_count);
if (err != KERN_SUCCESS)
return err;
simple_lock (&kmsg_lock);
if (kmsg_read_offset == kmsg_write_offset)
{
/* The queue is empty. */
if (ior->io_mode & D_NOWAIT)
{
simple_unlock (&kmsg_lock);
return D_WOULD_BLOCK;
}
ior->io_done = kmsg_read_done;
enqueue_tail (&kmsg_read_queue, (queue_entry_t) ior);
simple_unlock (&kmsg_lock);
return D_IO_QUEUED;
}
len = kmsg_write_offset - kmsg_read_offset;
if (len < 0)
len += KMSGBUFSIZE;
amt = ior->io_count;
if (amt > len)
amt = len;
if (kmsg_read_offset + amt <= KMSGBUFSIZE)
{
memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, amt);
}
else
{
int cnt;
cnt = KMSGBUFSIZE - kmsg_read_offset;
memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, cnt);
memcpy (ior->io_data + cnt, kmsg_buffer, amt - cnt);
}
kmsg_read_offset += amt;
if (kmsg_read_offset >= KMSGBUFSIZE)
kmsg_read_offset -= KMSGBUFSIZE;
ior->io_residual = ior->io_count - amt;
simple_unlock (&kmsg_lock);
return D_SUCCESS;
}
static boolean_t
kmsg_read_done (io_req_t ior)
{
int amt, len;
simple_lock (&kmsg_lock);
if (kmsg_read_offset == kmsg_write_offset)
{
/* The queue is empty. */
ior->io_done = kmsg_read_done;
enqueue_tail (&kmsg_read_queue, (queue_entry_t) ior);
simple_unlock (&kmsg_lock);
return FALSE;
}
len = kmsg_write_offset - kmsg_read_offset;
if (len < 0)
len += KMSGBUFSIZE;
amt = ior->io_count;
if (amt > len)
amt = len;
if (kmsg_read_offset + amt <= KMSGBUFSIZE)
{
memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, amt);
}
else
{
int cnt;
cnt = KMSGBUFSIZE - kmsg_read_offset;
memcpy (ior->io_data, kmsg_buffer + kmsg_read_offset, cnt);
memcpy (ior->io_data + cnt, kmsg_buffer, amt - cnt);
}
kmsg_read_offset += amt;
if (kmsg_read_offset >= KMSGBUFSIZE)
kmsg_read_offset -= KMSGBUFSIZE;
ior->io_residual = ior->io_count - amt;
simple_unlock (&kmsg_lock);
ds_read_done (ior);
return TRUE;
}
io_return_t
kmsggetstat (dev_t dev, dev_flavor_t flavor, dev_status_t data, mach_msg_type_number_t *count)
{
switch (flavor)
{
case DEV_GET_SIZE:
data[DEV_GET_SIZE_DEVICE_SIZE] = 0;
data[DEV_GET_SIZE_RECORD_SIZE] = 1;
*count = DEV_GET_SIZE_COUNT;
break;
default:
return D_INVALID_OPERATION;
}
return D_SUCCESS;
}
/* Write to Kernel Message Buffer */
void
kmsg_putchar (int c)
{
io_req_t ior;
int offset;
/* XXX: cninit is not called before cnputc is used. So call kmsginit
here if not initialized yet. */
if (!kmsg_init_done)
{
kmsginit ();
kmsg_init_done = TRUE;
}
simple_lock (&kmsg_lock);
offset = kmsg_write_offset + 1;
if (offset == KMSGBUFSIZE)
offset = 0;
if (offset == kmsg_read_offset)
{
/* Discard C. */
simple_unlock (&kmsg_lock);
return;
}
kmsg_buffer[kmsg_write_offset++] = c;
if (kmsg_write_offset == KMSGBUFSIZE)
kmsg_write_offset = 0;
while ((ior = (io_req_t) dequeue_head (&kmsg_read_queue)) != NULL)
iodone (ior);
simple_unlock (&kmsg_lock);
}
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