1 /* Copyright (C) 1991-2021 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 <stddef.h>
20 #include <termios.h>
21 #include <unistd.h>
22 
23 #include "bsdtty.h"
24 
25 /* Suspend or restart transmission on FD.  */
26 int
tcflow(int fd,int action)27 tcflow (int fd, int action)
28 {
29   switch (action)
30     {
31     case TCOOFF:
32       return __ioctl (fd, TIOCSTOP, (void *) NULL);
33     case TCOON:
34       return __ioctl (fd, TIOCSTART, (void *) NULL);
35 
36     case TCIOFF:
37     case TCION:
38       {
39 	/* This just writes the START or STOP character with
40 	   `write'.  Is there another way to do this?  */
41 	struct termios attr;
42 	unsigned char c;
43 	if (__tcgetattr (fd, &attr) < 0)
44 	  return -1;
45 	c = attr.c_cc[action == TCIOFF ? VSTOP : VSTART];
46 	if (c != _POSIX_VDISABLE && write (fd, &c, 1) < 1)
47 	  return -1;
48 	return 0;
49       }
50 
51     default:
52       __set_errno (EINVAL);
53       return -1;
54     }
55 }
56