1  /* stdio on a Mach device port.
       2     Translates \n to \r\n on output, echos and translates \r to \n on input.
       3     Copyright (C) 1992-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #include <stdio.h>
      21  #include <mach.h>
      22  #include <device/device.h>
      23  #include <errno.h>
      24  #include <string.h>
      25  #include <libioP.h>
      26  
      27  
      28  static ssize_t
      29  devstream_write (void *cookie, const char *buffer, size_t n)
      30  {
      31    const device_t dev = (device_t) (uintptr_t) cookie;
      32  
      33    int write_some (const char *p, size_t to_write)
      34      {
      35        kern_return_t err;
      36        int wrote;
      37        int thiswrite;
      38  
      39        while (to_write > 0)
      40  	{
      41  	  thiswrite = to_write;
      42  	  if (thiswrite > IO_INBAND_MAX)
      43  	    thiswrite = IO_INBAND_MAX;
      44  
      45  	  if (err = device_write_inband (dev, 0, 0, p, thiswrite, &wrote))
      46  	    {
      47  	      errno = err;
      48  	      return 0;
      49  	    }
      50  	  p += wrote;
      51  	  to_write -= wrote;
      52  	}
      53        return 1;
      54      }
      55    int write_crlf (void)
      56      {
      57        static const char crlf[] = "\r\n";
      58        return write_some (crlf, 2);
      59      }
      60  
      61    /* Search for newlines (LFs) in the buffer.  */
      62  
      63    const char *start = buffer, *p;
      64    while ((p = memchr (start, '\n', n)) != NULL)
      65      {
      66        /* Found one.  Write out through the preceding character,
      67  	 and then write a CR/LF pair.  */
      68  
      69        if ((p > start && !write_some (start, p - start))
      70  	  || !write_crlf ())
      71  	return (start - buffer) ?: -1;
      72  
      73        n -= p + 1 - start;
      74        start = p + 1;
      75      }
      76  
      77    /* Write the remainder of the buffer.  */
      78    if (write_some (start, n))
      79      start += n;
      80    return (start - buffer) ?: -1;
      81  }
      82  
      83  static ssize_t
      84  devstream_read (void *cookie, char *buffer, size_t to_read)
      85  {
      86    const device_t dev = (device_t) (uintptr_t) cookie;
      87  
      88    kern_return_t err;
      89    mach_msg_type_number_t nread = to_read;
      90  
      91    err = device_read_inband (dev, 0, 0, to_read, buffer, &nread);
      92    if (err)
      93      {
      94        errno = err;
      95        return -1;
      96      }
      97  
      98    /* Translate CR to LF.  */
      99    {
     100      char *p;
     101      for (p = memchr (buffer, '\r', nread); p;
     102  	 p = memchr (p + 1, '\r', (buffer + nread) - (p + 1)))
     103        *p = '\n';
     104    }
     105  
     106    /* Echo back what we read.  */
     107    (void) devstream_write (cookie, buffer, nread);
     108  
     109    return nread;
     110  }
     111  
     112  static int
     113  dealloc_ref (void *cookie)
     114  {
     115    const device_t dev = (device_t) (uintptr_t) cookie;
     116    if (__mach_port_deallocate (mach_task_self (), dev))
     117      {
     118        errno = EINVAL;
     119        return -1;
     120      }
     121    return 0;
     122  }
     123  
     124  FILE *
     125  mach_open_devstream (mach_port_t dev, const char *mode)
     126  {
     127    FILE *stream;
     128  
     129    if (mach_port_mod_refs (mach_task_self (), dev, MACH_PORT_RIGHT_SEND, 1))
     130      {
     131        errno = EINVAL;
     132        return NULL;
     133      }
     134  
     135    stream = _IO_fopencookie ((void *) (uintptr_t) dev, mode,
     136  			    (cookie_io_functions_t) { write: devstream_write,
     137  						      read: devstream_read,
     138  						      close: dealloc_ref });
     139    if (stream == NULL)
     140      {
     141        __mach_port_deallocate (mach_task_self (), dev);
     142        return NULL;
     143      }
     144  
     145    return stream;
     146  }