/* stdio on a Mach device port.

   Translates \n to \r\n on output, echos and translates \r to \n on input.

   Copyright (C) 1992-2018 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>

#include <libioP.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;

}

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 = _IO_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;

}