sysdeps/unix/sysv/linux/tcsetattr.c

   1 /* Copyright (C) 1993,1996,1997,1998,2002,2003 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 #include <sysdep.h>
  25
  26 /* The difference here is that the termios structure used in the
  27    kernel is not the same as we use in the libc.  Therefore we must
  28    translate it here.  */
  29 #include <kernel_termios.h>
  30
  31
  32 /* This is a gross hack around a kernel bug.  If the cfsetispeed functions
  33    is called with the SPEED argument set to zero this means use the same
  34    speed as for output.  But we don't have independent input and output
  35    speeds and therefore cannot record this.
  36
  37    We use an unused bit in the `c_iflag' field to keep track of this
  38    use of `cfsetispeed'.  The value here must correspond to the one used
  39    in `speed.c'.  */
  40 #define IBAUD0  020000000000
  41
  42
  43 /* Set the state of FD to *TERMIOS_P.  */
  44 int
  45 tcsetattr (fd, optional_actions, termios_p)
  46      int fd;
  47      int optional_actions;
  48      const struct termios *termios_p;
  49 {
  50   struct __kernel_termios k_termios;
  51   unsigned long int cmd;
  52   int retval;
  53
  54   switch (optional_actions)
  55     {
  56     case TCSANOW:
  57       cmd = TCSETS;
  58       break;
  59     case TCSADRAIN:
  60       cmd = TCSETSW;
  61       break;
  62     case TCSAFLUSH:
  63       cmd = TCSETSF;
  64       break;
  65     default:
  66       __set_errno (EINVAL);
  67       return -1;
  68     }
  69
  70   k_termios.c_iflag = termios_p->c_iflag & ~IBAUD0;
  71   k_termios.c_oflag = termios_p->c_oflag;
  72   k_termios.c_cflag = termios_p->c_cflag;
  73   k_termios.c_lflag = termios_p->c_lflag;
  74   k_termios.c_line = termios_p->c_line;
  75 #if defined _HAVE_C_ISPEED && defined _HAVE_STRUCT_TERMIOS_C_ISPEED
  76   k_termios.c_ispeed = termios_p->c_ispeed;
  77 #endif
  78 #if defined _HAVE_C_OSPEED && defined _HAVE_STRUCT_TERMIOS_C_OSPEED
  79   k_termios.c_ospeed = termios_p->c_ospeed;
  80 #endif
  81   memcpy (&k_termios.c_cc[0], &termios_p->c_cc[0],
  82           __KERNEL_NCCS * sizeof (cc_t));
  83
  84   retval = INLINE_SYSCALL (ioctl, 3, fd, cmd, &k_termios);
  85
  86   if (retval == 0 && cmd == TCSETS)
  87     {
  88       /* The Linux kernel has a bug which silently ignore the invalid
  89         c_cflag on pty. We have to check it here. */
  90       int save = errno;
  91       retval = INLINE_SYSCALL (ioctl, 3, fd, TCGETS, &k_termios);
  92       if (retval)
  93        {
  94          /* We cannot verify if the setting is ok. We don't return
  95             an error (?). */
  96          __set_errno (save);
  97          retval = 0;
  98        }
  99       else if ((termios_p->c_cflag & (PARENB | CREAD))
 100               != (k_termios.c_cflag & (PARENB | CREAD))
 101               || ((termios_p->c_cflag & CSIZE)
 102                   && ((termios_p->c_cflag & CSIZE)
 103                       != (k_termios.c_cflag & CSIZE))))
 104        {
 105          /* It looks like the Linux kernel silently changed the
 106             PARENB/CREAD/CSIZE bits in c_cflag. Report it as an
 107             error. */
 108          __set_errno (EINVAL);
 109          retval = -1;
 110        }
 111     }
 112
 113   return retval;
 114 }
 115 libc_hidden_def (tcsetattr)