/*
 * Rump block driver support
 *
 * Copyright (C) 2019 Free Software Foundation
 *
 * This program 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 program 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 this program; if not, write to the Free Software
 * Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <ctype.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>

#include "mach_U.h"

#include <mach.h>
#include <hurd.h>
#include <hurd/ports.h>

#define MACH_INCLUDE

#include "libmachdev/machdev.h"
#include "device_reply_U.h"

#include <rump/rump.h>
#include <rump/rump_syscalls.h>
#include <rump/rumperrno2host.h>

#include "ioccom-rump.h"
#define DIOCGMEDIASIZE  _IOR('d', 132, off_t)
#define DIOCGSECTORSIZE _IOR('d', 133, unsigned int)

#define DISK_NAME_LEN 32

/* One of these is associated with each open instance of a device.  */
struct block_data
{
  struct port_info port;	/* device port */
  struct machdev_emul_device device;	/* generic device structure */
  dev_mode_t mode;		/* r/w etc */
  int rump_fd;			/* block device fd handle */
  char name[DISK_NAME_LEN];	/* eg /dev/wd0 */
  off_t media_size;		/* total block device size */
  uint32_t block_size;		/* size in bytes of 1 sector */
  bool taken;			/* simple refcount */
  struct block_data *next;
};

/* Return a send right associated with network device ND.  */
static mach_port_t
dev_to_port (void *nd)
{
  return (nd ? ports_get_send_right (nd) : MACH_PORT_NULL);
}

static struct block_data *block_head;
static struct machdev_device_emulation_ops rump_block_emulation_ops;

static struct block_data *
search_bd (char *name)
{
  struct block_data *bd = block_head;

  while (bd)
    {
      if (!strcmp (bd->name, name))
	return bd;
      bd = bd->next;
    }
  return NULL;
}

/* BSD name of whole disk device is /dev/wdXd
 * but we will receive /dev/wdX as the name */
static void
translate_name (char *output, int len, char *name)
{
  snprintf (output, len, "%sd", name);
}

static int
dev_mode_to_rump_mode (const dev_mode_t mode)
{
  int ret = 0;
  if (mode & D_READ)
    {
      if (mode & D_WRITE)
	ret = RUMP_O_RDWR;
      else
	ret = RUMP_O_RDONLY;
    }
  else
    {
      if (mode & D_WRITE)
	ret = RUMP_O_WRONLY;
    }
  return ret;
}

static void
device_init (void)
{
  rump_init ();
}

static io_return_t
device_close (void *d)
{
  struct block_data *bd = d;

  return rump_errno2host (rump_sys_close (bd->rump_fd));
}

static void
device_dealloc (void *d)
{
  rump_sys_reboot (0, NULL);
}

static io_return_t
device_open (mach_port_t reply_port, mach_msg_type_name_t reply_port_type,
	     dev_mode_t mode, char *name, device_t * devp,
	     mach_msg_type_name_t * devicePoly)
{
  io_return_t err = D_SUCCESS;
  struct block_data *bd = NULL;
  char dev_name[DISK_NAME_LEN];
  off_t media_size;
  uint32_t block_size;

  translate_name (dev_name, DISK_NAME_LEN, name);

  /* Find previous device or open if new */
  bd = search_bd (name);
  if (!bd)
    {
      err = machdev_create_device_port (sizeof (*bd), &bd);

      snprintf (bd->name, DISK_NAME_LEN, "%s", name);
      bd->mode = mode;
      bd->device.emul_data = bd;
      bd->device.emul_ops = &rump_block_emulation_ops;

      err = rump_sys_open (dev_name, dev_mode_to_rump_mode (bd->mode));
      if (err < 0)
	{
	  err = rump_errno2host (errno);
	  goto out;
	}
      bd->rump_fd = err;

      err = rump_sys_ioctl (bd->rump_fd, DIOCGMEDIASIZE, &media_size);
      if (err < 0)
	{
	  mach_print ("DIOCGMEDIASIZE ioctl fails\n");
	  err = D_NO_SUCH_DEVICE;
	  goto out;
	}

      err = rump_sys_ioctl (bd->rump_fd, DIOCGSECTORSIZE, &block_size);
      if (err < 0)
	{
	  mach_print ("DIOCGSECTORSIZE ioctl fails\n");
	  err = D_NO_SUCH_DEVICE;
	  goto out;
	}
      bd->media_size = media_size;
      bd->block_size = block_size;

      err = D_SUCCESS;
    }

out:
  if (err)
    {
      if (bd)
	{
	  ports_port_deref (bd);
	  ports_destroy_right (bd);
	  bd = NULL;
	}
    }

  if (bd)
    {
      bd->next = block_head;
      block_head = bd;
      *devp = ports_get_right (bd);
      *devicePoly = MACH_MSG_TYPE_MAKE_SEND;
    }
  return err;
}

static io_return_t
device_write (void *d, mach_port_t reply_port,
	      mach_msg_type_name_t reply_port_type, dev_mode_t mode,
	      recnum_t bn, io_buf_ptr_t data, unsigned int count,
	      int *bytes_written)
{
  struct block_data *bd = d;
  int64_t written = 0;

  if ((bd->mode & D_WRITE) == 0)
    return D_INVALID_OPERATION;

  if (rump_sys_lseek (bd->rump_fd, (off_t) bn * bd->block_size, SEEK_SET) < 0)
    {
      *bytes_written = 0;
      return EIO;
    }

  written = rump_sys_write (bd->rump_fd, data, count);
  if (written < 0)
    {
      *bytes_written = 0;
      return EIO;
    }
  else
    {
      *bytes_written = (int)written;
      return D_SUCCESS;
    }
}

static io_return_t
device_read (void *d, mach_port_t reply_port,
	     mach_msg_type_name_t reply_port_type, dev_mode_t mode,
	     recnum_t bn, int count, io_buf_ptr_t * data,
	     unsigned *bytes_read)
{
  struct block_data *bd = d;
  char *buf;
  int pagesize = sysconf (_SC_PAGE_SIZE);
  int npages = (count + pagesize - 1) / pagesize;
  io_return_t err = D_SUCCESS;

  if ((bd->mode & D_READ) == 0)
    return D_INVALID_OPERATION;

  if (count == 0)
    return D_SUCCESS;

  *data = 0;
  buf = mmap (NULL, npages * pagesize, PROT_READ | PROT_WRITE,
	      MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
  if (buf == MAP_FAILED)
    return errno;

  if (rump_sys_lseek (bd->rump_fd, (off_t) bn * bd->block_size, SEEK_SET) < 0)
    {
      *bytes_read = 0;
      return EIO;
    }

  err = rump_sys_read (bd->rump_fd, buf, count);
  if (err < 0)
    {
      *bytes_read = 0;
      munmap (buf, npages * pagesize);
      return EIO;
    }
  else
    {
      *bytes_read = err;
      *data = buf;
      return D_SUCCESS;
    }
}

static io_return_t
device_get_status (void *d, dev_flavor_t flavor, dev_status_t status,
		   mach_msg_type_number_t * count)
{
  struct block_data *bd = d;

  switch (flavor)
    {
    case DEV_GET_SIZE:
      status[DEV_GET_SIZE_RECORD_SIZE] = bd->block_size;
      status[DEV_GET_SIZE_DEVICE_SIZE] = bd->media_size;
      *count = 2;
      break;
    case DEV_GET_RECORDS:
      status[DEV_GET_RECORDS_RECORD_SIZE] = bd->block_size;
      status[DEV_GET_RECORDS_DEVICE_RECORDS] =
	bd->media_size / (unsigned long long) bd->block_size;
      *count = 2;
      break;
    default:
      return D_INVALID_OPERATION;
      break;
    }
  return D_SUCCESS;
}

/* FIXME:
 * Short term strategy:
 *
 * Use rump_sys_pread/pwrite instead of rump_sys_lseek + rump_sys_read/write.
 * Make device_read/write multithreaded.
 *
 * Long term strategy:
 *
 * Call rump_sys_aio_read/write and return MIG_NO_REPLY from
 * device_read/write, and send the mig reply once the aio request has
 * completed. That way, only the aio request will be kept in rumpdisk
 * memory instead of a whole thread structure.
 */
static struct machdev_device_emulation_ops rump_block_emulation_ops = {
  device_init,
  NULL,
  device_dealloc,
  dev_to_port,
  device_open,
  device_close,
  device_write, /* FIXME: make multithreaded */
  NULL,
  device_read, /* FIXME: make multithreaded */
  NULL,
  NULL,
  device_get_status,
  NULL,
  NULL,
  NULL,
  NULL,
  NULL
};

void
rump_register_block (void)
{
  machdev_register (&rump_block_emulation_ops);
}