mach/devstream.c

   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) 1992-2017 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    <http://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
  26
  27 static ssize_t
  28 devstream_write (void *cookie, const char *buffer, size_t n)
  29 {
  30   const device_t dev = (device_t) cookie;
  31
  32   int write_some (const char *p, size_t to_write)
  33     {
  34       kern_return_t err;
  35       int wrote;
  36       int thiswrite;
  37
  38       while (to_write > 0)
  39         {
  40           thiswrite = to_write;
  41           if (thiswrite > IO_INBAND_MAX)
  42             thiswrite = IO_INBAND_MAX;
  43
  44           if (err = device_write_inband (dev, 0, 0, p, thiswrite, &wrote))
  45             {
  46               errno = err;
  47               return 0;
  48             }
  49           p += wrote;
  50           to_write -= wrote;
  51         }
  52       return 1;
  53     }
  54   int write_crlf (void)
  55     {
  56       static const char crlf[] = "\r\n";
  57       return write_some (crlf, 2);
  58     }
  59
  60   /* Search for newlines (LFs) in the buffer.  */
  61
  62   const char *start = buffer, *p;
  63   while ((p = memchr (start, '\n', n)) != NULL)
  64     {
  65       /* Found one.  Write out through the preceding character,
  66          and then write a CR/LF pair.  */
  67
  68       if ((p > start && !write_some (start, p - start))
  69           || !write_crlf ())
  70         return (start - buffer) ?: -1;
  71
  72       n -= p + 1 - start;
  73       start = p + 1;
  74     }
  75
  76   /* Write the remainder of the buffer.  */
  77   if (write_some (start, n))
  78     start += n;
  79   return (start - buffer) ?: -1;
  80 }
  81
  82 static ssize_t
  83 devstream_read (void *cookie, char *buffer, size_t to_read)
  84 {
  85   const device_t dev = (device_t) cookie;
  86
  87   kern_return_t err;
  88   mach_msg_type_number_t nread = to_read;
  89
  90   err = device_read_inband (dev, 0, 0, to_read, buffer, &nread);
  91   if (err)
  92     {
  93       errno = err;
  94       return -1;
  95     }
  96
  97   /* Translate CR to LF.  */
  98   {
  99     char *p;
 100     for (p = memchr (buffer, '\r', nread); p;
 101          p = memchr (p + 1, '\r', (buffer + nread) - (p + 1)))
 102       *p = '\n';
 103   }
 104
 105   /* Echo back what we read.  */
 106   (void) devstream_write (cookie, buffer, nread);
 107
 108   return nread;
 109 }
 110
 111 static int
 112 dealloc_ref (void *cookie)
 113 {
 114   if (mach_port_deallocate (mach_task_self (), (mach_port_t) cookie))
 115     {
 116       errno = EINVAL;
 117       return -1;
 118     }
 119   return 0;
 120 }
 121
 122 FILE *
 123 mach_open_devstream (mach_port_t dev, const char *mode)
 124 {
 125   FILE *stream;
 126
 127   if (mach_port_mod_refs (mach_task_self (), dev, MACH_PORT_RIGHT_SEND, 1))
 128     {
 129       errno = EINVAL;
 130       return NULL;
 131     }
 132
 133   stream = fopencookie ((void *) dev, mode,
 134                         (cookie_io_functions_t) { write: devstream_write,
 135                                                   read: devstream_read,
 136                                                   close: dealloc_ref });
 137   if (stream == NULL)
 138     {
 139       mach_port_deallocate (mach_task_self (), dev);
 140       return NULL;
 141     }
 142
 143   return stream;
 144 }