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Revision 1.13, Mon Mar 22 19:30:55 2010 UTC (10 years, 3 months ago) by joerg
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.\" $NetBSD: tcsetattr.3,v 1.13 2010/03/22 19:30:55 joerg Exp $ .\" .\" Copyright (c) 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)tcsetattr.3 8.3 (Berkeley) 1/2/94 .\" .Dd May 1, 2004 .Dt TCSETATTR 3 .Os .Sh NAME .Nm cfgetispeed , .Nm cfsetispeed , .Nm cfgetospeed , .Nm cfsetospeed , .Nm cfsetspeed , .Nm cfmakeraw , .Nm tcgetattr , .Nm tcsetattr .Nd manipulating the termios structure .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In termios.h .Ft speed_t .Fn cfgetispeed "const struct termios *t" .Ft int .Fn cfsetispeed "struct termios *t" "speed_t speed" .Ft speed_t .Fn cfgetospeed "const struct termios *t" .Ft int .Fn cfsetospeed "struct termios *t" "speed_t speed" .Ft int .Fn cfsetspeed "struct termios *t" "speed_t speed" .Ft void .Fn cfmakeraw "struct termios *t" .Ft int .Fn tcgetattr "int fd" "struct termios *t" .Ft int .Fn tcsetattr "int fd" "int action" "const struct termios *t" .Sh DESCRIPTION The .Nm cfmakeraw , .Nm tcgetattr and .Nm tcsetattr functions are provided for getting and setting the termios structure. .Pp The .Nm cfgetispeed , .Nm cfsetispeed , .Nm cfgetospeed , .Nm cfsetospeed and .Nm cfsetspeed functions are provided for getting and setting the baud rate values in the termios structure. The effects of the functions on the terminal as described below do not become effective, nor are all errors detected, until the .Nm tcsetattr function is called. Certain values for baud rates set in the termios structure and passed to .Nm tcsetattr have special meanings. These are discussed in the portion of the manual page that describes the .Nm tcsetattr function. .Sh GETTING AND SETTING THE BAUD RATE The input and output baud rates are found in the termios structure. The unsigned integer .Li speed_t is typdef'd in the include file .In termios.h . The value of the integer corresponds directly to the baud rate being represented, however, the following symbolic values are defined. .Bd -literal #define B0 0 #define B50 50 #define B75 75 #define B110 110 #define B134 134 #define B150 150 #define B200 200 #define B300 300 #define B600 600 #define B1200 1200 #define B1800 1800 #define B2400 2400 #define B4800 4800 #define B9600 9600 #define B19200 19200 #define B38400 38400 #ifndef _POSIX_SOURCE #define EXTA 19200 #define EXTB 38400 #endif /*_POSIX_SOURCE */ .Ed .Pp The .Nm cfgetispeed function returns the input baud rate in the termios structure referenced by .Fa tp . .Pp The .Nm cfsetispeed function sets the input baud rate in the termios structure referenced by .Fa tp to .Fa speed . .Pp The .Nm cfgetospeed function returns the output baud rate in the termios structure referenced by .Fa tp . .Pp The .Nm cfsetospeed function sets the output baud rate in the termios structure referenced by .Fa tp to .Fa speed . .Pp The .Nm cfsetspeed function sets both the input and output baud rate in the termios structure referenced by .Fa tp to .Fa speed . .Pp Upon successful completion, the functions .Nm cfsetispeed , .Nm cfsetospeed , and .Nm cfsetspeed return a value of 0. Otherwise, a value of -1 is returned and the global variable .Va errno is set to indicate the error. .Sh GETTING AND SETTING THE TERMIOS STATE This section describes the functions that are used to control the general terminal interface. Unless otherwise noted for a specific command, these functions are restricted from use by background processes. Attempts to perform these operations shall cause the process group to be sent a SIGTTOU signal. If the calling process is blocking or ignoring SIGTTOU signals, the process is allowed to perform the operation and the SIGTTOU signal is not sent. .Pp In all the functions, although .Fa fd is an open file descriptor, the functions affect the underlying terminal file, not just the open file description associated with the particular file descriptor. .Pp The .Nm cfmakeraw function sets the flags stored in the termios structure (initialized by .Nm tcgetattr ) to a state disabling all input and output processing, giving a .Dq raw I/O path . It should be noted that there is no function to reverse this effect. This is because there are a variety of processing options that could be re-enabled and the correct method is for an application to snapshot the current terminal state using the function .Nm tcgetattr , setting raw mode with .Nm cfmakeraw and the subsequent .Nm tcsetattr , and then using another .Nm tcsetattr with the saved state to revert to the previous terminal state. .Pp The .Nm tcgetattr function copies the parameters associated with the terminal referenced by .Fa fd to the termios structure referenced by .Fa tp . This function is allowed from a background process, however, the terminal attributes may be subsequently changed by a foreground process. .Pp The .Nm tcsetattr function sets the parameters associated with the terminal from the termios structure referenced by .Fa tp . The .Fa action field is created by .Em or Ns 'ing the following values, as specified in the include file .In termios.h . .Bl -tag -width "TCSADRAIN" .It Fa TCSANOW The change occurs immediately. .It Fa TCSADRAIN The change occurs after all output written to .Fa fd has been transmitted to the terminal. This value of .Fa action should be used when changing parameters that affect output. .It Fa TCSAFLUSH The change occurs after all output written to .Fa fd has been transmitted to the terminal. Additionally, any input that has been received but not read is discarded. .It Fa TCSASOFT If this value is .Em or Ns 'ed into the .Fa action value, the values of the .Em c_cflag , .Em c_ispeed , and .Em c_ospeed fields are ignored. .El .Pp The 0 baud rate is used to terminate the connection. If 0 is specified as the output speed to the function .Nm tcsetattr , modem control will no longer be asserted on the terminal, disconnecting the terminal. .Pp If zero is specified as the input speed to the function .Nm tcsetattr , the input baud rate will be set to the same value as that specified by the output baud rate. .Sh RETURN VALUES If .Nm tcsetattr is unable to make any of the requested changes, it returns -1 and sets errno. Otherwise, it makes all of the requested changes it can. If the specified input and output baud rates differ and are a combination that is not supported, neither baud rate is changed. .Pp Upon successful completion, the functions .Nm tcgetattr and .Nm tcsetattr return a value of 0. Otherwise, they return -1 and the global variable .Va errno is set to indicate the error, as follows: .Bl -tag -width Er .It Bq Er EBADF The .Fa fd argument to .Nm tcgetattr or .Nm tcsetattr was not a valid file descriptor. .It Bq Er EINTR The .Nm tcsetattr function was interrupted by a signal. .It Bq Er EINVAL The .Fa action argument to the .Nm tcsetattr function was not valid, or an attempt was made to change an attribute represented in the termios structure to an unsupported value. .It Bq Er ENOTTY The file associated with the .Fa fd argument to .Nm tcgetattr or .Nm tcsetattr is not a terminal. .El .Sh SEE ALSO .Xr tcsendbreak 3 , .Xr termios 4 .Sh STANDARDS The .Nm cfgetispeed , .Nm cfsetispeed , .Nm cfgetospeed , .Nm cfsetospeed , .Nm tcgetattr and .Nm tcsetattr functions are expected to be compliant with the .St -p1003.1-88 specification. The .Nm cfmakeraw and .Nm cfsetspeed functions, as well as the .Li TCSASOFT option to the .Nm tcsetattr function are extensions to the .St -p1003.1-88 specification.