1 /* `struct termios' speed frobnication functions. Linux version. 2 Copyright (C) 1991-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #include <stddef.h> 20 #include <errno.h> 21 #include <termios.h> 22 #include <sysdep.h> 23 24 /* This is a gross hack around a kernel bug. If the cfsetispeed functions 25 is called with the SPEED argument set to zero this means use the same 26 speed as for output. But we don't have independent input and output 27 speeds and therefore cannot record this. 28 29 We use an unused bit in the `c_iflag' field to keep track of this 30 use of `cfsetispeed'. The value here must correspond to the one used 31 in `tcsetattr.c'. */ 32 #define IBAUD0 020000000000 33 34 35 /* Return the output baud rate stored in *TERMIOS_P. */ 36 speed_t cfgetospeed(const struct termios * termios_p)37cfgetospeed (const struct termios *termios_p) 38 { 39 return termios_p->c_cflag & (CBAUD | CBAUDEX); 40 } 41 42 /* Return the input baud rate stored in *TERMIOS_P. 43 Although for Linux there is no difference between input and output 44 speed, the numerical 0 is a special case for the input baud rate. It 45 should set the input baud rate to the output baud rate. */ 46 speed_t cfgetispeed(const struct termios * termios_p)47cfgetispeed (const struct termios *termios_p) 48 { 49 return ((termios_p->c_iflag & IBAUD0) 50 ? 0 : termios_p->c_cflag & (CBAUD | CBAUDEX)); 51 } 52 53 /* Set the output baud rate stored in *TERMIOS_P to SPEED. */ 54 int cfsetospeed(struct termios * termios_p,speed_t speed)55cfsetospeed (struct termios *termios_p, speed_t speed) 56 { 57 if ((speed & ~CBAUD) != 0 58 && (speed < B57600 || speed > __MAX_BAUD)) 59 return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); 60 61 #if _HAVE_STRUCT_TERMIOS_C_OSPEED 62 termios_p->c_ospeed = speed; 63 #endif 64 termios_p->c_cflag &= ~(CBAUD | CBAUDEX); 65 termios_p->c_cflag |= speed; 66 67 return 0; 68 } libc_hidden_def(cfsetospeed)69libc_hidden_def (cfsetospeed) 70 71 72 /* Set the input baud rate stored in *TERMIOS_P to SPEED. 73 Although for Linux there is no difference between input and output 74 speed, the numerical 0 is a special case for the input baud rate. It 75 should set the input baud rate to the output baud rate. */ 76 int 77 cfsetispeed (struct termios *termios_p, speed_t speed) 78 { 79 if ((speed & ~CBAUD) != 0 80 && (speed < B57600 || speed > __MAX_BAUD)) 81 return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); 82 83 #if _HAVE_STRUCT_TERMIOS_C_ISPEED 84 termios_p->c_ispeed = speed; 85 #endif 86 if (speed == 0) 87 termios_p->c_iflag |= IBAUD0; 88 else 89 { 90 termios_p->c_iflag &= ~IBAUD0; 91 termios_p->c_cflag &= ~(CBAUD | CBAUDEX); 92 termios_p->c_cflag |= speed; 93 } 94 95 return 0; 96 } 97 libc_hidden_def (cfsetispeed) 98