sysdeps/unix/sysv/linux/tcsetattr.c

   1 /* Copyright (C) 1993, 1996, 1997, 1998 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <string.h>
  21 #include <termios.h>
  22 #include <sys/ioctl.h>
  23 #include <sys/types.h>
  24
  25 /* The difference here is that the termios structure used in the
  26    kernel is not the same as we use in the libc.  Therefore we must
  27    translate it here.  */
  28 #include <kernel_termios.h>
  29
  30
  31 /* This is a gross hack around a kernel bug.  If the cfsetispeed functions
  32    is called with the SPEED argument set to zero this means use the same
  33    speed as for output.  But we don't have independent input and output
  34    speeds and therefore cannot record this.
  35
  36    We use an unused bit in the `c_iflag' field to keep track of this
  37    use of `cfsetispeed'.  The value here must correspond to the one used
  38    in `speed.c'.  */
  39 #if !defined _HAVE_C_ISPEED || !defined _HAVE_C_OSPEED
  40 # define IBAUD0 020000000000
  41 #else
  42 /* If we have separate values for input and output speed don't bother
  43    with this.  Define the value as zero so the compiler sees we don't
  44    have to do the AND below.  */
  45 # define IBAUD0 0
  46 #endif
  47
  48
  49 /* Set the state of FD to *TERMIOS_P.  */
  50 int
  51 tcsetattr (fd, optional_actions, termios_p)
  52      int fd;
  53      int optional_actions;
  54      const struct termios *termios_p;
  55 {
  56   struct __kernel_termios k_termios;
  57   unsigned long int cmd;
  58   int retval;
  59
  60   switch (optional_actions)
  61     {
  62     case TCSANOW:
  63       cmd = TCSETS;
  64       break;
  65     case TCSADRAIN:
  66       cmd = TCSETSW;
  67       break;
  68     case TCSAFLUSH:
  69       cmd = TCSETSF;
  70       break;
  71     default:
  72       __set_errno (EINVAL);
  73       return -1;
  74     }
  75
  76   k_termios.c_iflag = termios_p->c_iflag & ~IBAUD0;
  77   k_termios.c_oflag = termios_p->c_oflag;
  78   k_termios.c_cflag = termios_p->c_cflag;
  79   k_termios.c_lflag = termios_p->c_lflag;
  80   k_termios.c_line = termios_p->c_line;
  81 #ifdef _HAVE_C_ISPEED
  82   k_termios.c_ispeed = termios_p->c_ispeed;
  83 #endif
  84 #ifdef _HAVE_C_OSPEED
  85   k_termios.c_ospeed = termios_p->c_ospeed;
  86 #endif
  87   memcpy (&k_termios.c_cc[0], &termios_p->c_cc[0],
  88           __KERNEL_NCCS * sizeof (cc_t));
  89
  90   retval = __ioctl (fd, cmd, &k_termios);
  91
  92   if (retval == 0 && cmd == TCSETS)
  93     {
  94       /* The Linux kernel has a bug which silently ignore the invalid
  95          c_cflag on pty. We have to check it here. */
  96       int save = errno;
  97       retval = __ioctl (fd, TCGETS, &k_termios);
  98       if (retval)
  99         {
 100           /* We cannot verify if the setting is ok. We don't return
 101              an error (?). */
 102           __set_errno (save);
 103           retval = 0;
 104         }
 105       else if ((termios_p->c_cflag & (PARENB | CREAD))
 106                != (k_termios.c_cflag & (PARENB | CREAD))
 107                || ((termios_p->c_cflag & CSIZE)
 108                    && ((termios_p->c_cflag & CSIZE)
 109                        != (k_termios.c_cflag & CSIZE))))
 110         {
 111           /* It looks like the Linux kernel silently changed the
 112              PARENB/CREAD/CSIZE bits in c_cflag. Report it as an
 113              error. */
 114           __set_errno (EINVAL);
 115           retval = -1;
 116         }
 117     }
 118
 119   return retval;
 120 }