sysdeps/unix/bsd/tcflow.c

   1 /* Copyright (C) 1991, 1992, 1996 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 Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <errno.h>
  20 #include <stddef.h>
  21 #include <termios.h>
  22 #include <unistd.h>
  23
  24 #include "bsdtty.h"
  25
  26 /* Suspend or restart transmission on FD.  */
  27 int
  28 tcflow (fd, action)
  29      int fd;
  30      int action;
  31 {
  32   switch (action)
  33     {
  34     case TCOOFF:
  35       return __ioctl (fd, TIOCSTOP, (void *) NULL);
  36     case TCOON:
  37       return __ioctl (fd, TIOCSTART, (void *) NULL);
  38
  39     case TCIOFF:
  40     case TCION:
  41       {
  42         /* This just writes the START or STOP character with
  43            `write'.  Is there another way to do this?  */
  44         struct termios attr;
  45         unsigned char c;
  46         if (tcgetattr (fd, &attr) < 0)
  47           return -1;
  48         c = attr.c_cc[action == TCIOFF ? VSTOP : VSTART];
  49         if (c != _POSIX_VDISABLE && write (fd, &c, 1) < 1)
  50           return -1;
  51         return 0;
  52       }
  53
  54     default:
  55       __set_errno (EINVAL);
  56       return -1;
  57     }
  58 }