/* stdio on a Mach device port.
   Translates \n to \r\n on output, echos and translates \r to \n on input.
   Copyright (C) 1992,93,94,96,97,2000,2011 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <stdio.h>
#include <mach.h>
#include <device/device.h>
#include <errno.h>
#include <string.h>


static ssize_t
devstream_write (void *cookie, const char *buffer, size_t n)
{
  const device_t dev = (device_t) cookie;

  int write_some (const char *p, size_t to_write)
    {
      kern_return_t err;
      int wrote;
      int thiswrite;

      while (to_write > 0)
	{
	  thiswrite = to_write;
	  if (thiswrite > IO_INBAND_MAX)
	    thiswrite = IO_INBAND_MAX;

	  if (err = device_write_inband (dev, 0, 0, p, thiswrite, &wrote))
	    {
	      errno = err;
	      return 0;
	    }
	  p += wrote;
	  to_write -= wrote;
	}
      return 1;
    }
  int write_crlf (void)
    {
      static const char crlf[] = "\r\n";
      return write_some (crlf, 2);
    }

  /* Search for newlines (LFs) in the buffer.  */

  const char *start = buffer, *p;
  while ((p = memchr (start, '\n', n)) != NULL)
    {
      /* Found one.  Write out through the preceding character,
	 and then write a CR/LF pair.  */

      if ((p > start && !write_some (start, p - start))
	  || !write_crlf ())
	return (start - buffer) ?: -1;

      n -= p + 1 - start;
      start = p + 1;
    }

  /* Write the remainder of the buffer.  */
  if (write_some (start, n))
    start += n;
  return (start - buffer) ?: -1;
}

static ssize_t
devstream_read (void *cookie, char *buffer, size_t to_read)
{
  const device_t dev = (device_t) cookie;

  kern_return_t err;
  mach_msg_type_number_t nread = to_read;

  err = device_read_inband (dev, 0, 0, to_read, buffer, &nread);
  if (err)
    {
      errno = err;
      return -1;
    }

  /* Translate CR to LF.  */
  {
    char *p;
    for (p = memchr (buffer, '\r', nread); p;
	 p = memchr (p + 1, '\r', (buffer + nread) - (p + 1)))
      *p = '\n';
  }

  /* Echo back what we read.  */
  (void) devstream_write (cookie, buffer, nread);

  return nread;
}

static int
dealloc_ref (void *cookie)
{
  if (mach_port_deallocate (mach_task_self (), (mach_port_t) cookie))
    {
      errno = EINVAL;
      return -1;
    }
  return 0;
}

#define cookie_io_functions_t __io_functions
#define write __write
#define read __read
#define close __close

FILE *
mach_open_devstream (mach_port_t dev, const char *mode)
{
  FILE *stream;

  if (mach_port_mod_refs (mach_task_self (), dev, MACH_PORT_RIGHT_SEND, 1))
    {
      errno = EINVAL;
      return NULL;
    }

  stream = fopencookie ((void *) dev, mode,
			(cookie_io_functions_t) { write: devstream_write,
						  read: devstream_read,
						  close: dealloc_ref });
  if (stream == NULL)
    {
      mach_port_deallocate (mach_task_self (), dev);
      return NULL;
    }

  return stream;
}