sysdeps/unix/sysv/linux/tcsetattr.c

   1 /* Copyright (C) 1993-2022 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, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <string.h>
  20 #include <termios.h>
  21 #include <sys/ioctl.h>
  22 #include <sys/types.h>
  23 #include <sysdep.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 #define IBAUD0  020000000000
  40
  41
  42 /* Set the state of FD to *TERMIOS_P.  */
  43 int
  44 __tcsetattr (int fd, int optional_actions, const struct termios *termios_p)
  45 {
  46   struct __kernel_termios k_termios;
  47   unsigned long int cmd;
  48
  49   switch (optional_actions)
  50     {
  51     case TCSANOW:
  52       cmd = TCSETS;
  53       break;
  54     case TCSADRAIN:
  55       cmd = TCSETSW;
  56       break;
  57     case TCSAFLUSH:
  58       cmd = TCSETSF;
  59       break;
  60     default:
  61       return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
  62     }
  63
  64   k_termios.c_iflag = termios_p->c_iflag & ~IBAUD0;
  65   k_termios.c_oflag = termios_p->c_oflag;
  66   k_termios.c_cflag = termios_p->c_cflag;
  67   k_termios.c_lflag = termios_p->c_lflag;
  68   k_termios.c_line = termios_p->c_line;
  69 #if _HAVE_C_ISPEED && _HAVE_STRUCT_TERMIOS_C_ISPEED
  70   k_termios.c_ispeed = termios_p->c_ispeed;
  71 #endif
  72 #if _HAVE_C_OSPEED && _HAVE_STRUCT_TERMIOS_C_OSPEED
  73   k_termios.c_ospeed = termios_p->c_ospeed;
  74 #endif
  75   memcpy (&k_termios.c_cc[0], &termios_p->c_cc[0],
  76           __KERNEL_NCCS * sizeof (cc_t));
  77
  78   return INLINE_SYSCALL (ioctl, 3, fd, cmd, &k_termios);
  79 }
  80 weak_alias (__tcsetattr, tcsetattr)
  81 libc_hidden_def (tcsetattr)