cfsetspeed(3POSIX)

NAME | SYNOPSIS | API RESTRICTIONS | FEATURES | DESCRIPTION | GETTING AND SETTING THE BAUD RATE | GETTING AND SETTING THE TERMIOS STATE | STANDARDS | RESTRICTIONS | ATTRIBUTES

NAME

tcsetattr, tcgetattr, cfgetispeed, cfsetispeed, cfgetospeed, cfsetospeed, cfsetspeed, cfmakeraw- manipulating the termios structure

SYNOPSIS

$(OS_DIR)/lib/libc.a
#include <termios.h>

speed_t cfgetispeed(struct termios * t);
int cfsetispeed(struct termios * t, speed_t speed);
speed_t cfgetospeed(struct termios * t);
int cfsetospeed(struct termios * t, speed_t speed);
int cfsetspeed(struct termios * t, speed_t speed);
void cfmakeraw(struct termios * t);
int tcgetattr(int fd, struct termios * t);
int tcsetattr(int fd, int action, struct termios * t);

API RESTRICTIONS

The function or functions documented here may not be used safely in all application contexts with all APIs provided in the ChorusOS 5.0 product.

See API(5FEA) for details.

FEATURES

VTTY

DESCRIPTION

The cfmakeraw() , tcgetattr() and tcsetattr() functions are provided for getting and setting the termios structure.

The cfgetispeed() , cfsetispeed() , cfgetospeed() , cfsetospeed() and 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 tcsetattr() function is called. Certain values for baud rates set in the termios structure and passed to tcsetattr() have special meanings. These are discussed in the portion of the man page that describes the tcsetattr() function.

GETTING AND SETTING THE BAUD RATE

The input and output baud rates are found in the termios structure. The unsigned integer speed_t is typdef ed in the include file <termios.h> . The value of the integer corresponds directly to the baud rate being represented, however, the following symbolic values are defined:

#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 */

The cfgetispeed() function returns the input baud rate in the termios structure referenced by t .

The cfsetispeed() function sets the input baud rate in the termios structure referenced by t to speed . The cfgetospeed() function returns the output baud rate in the termios structure referenced by t . The cfsetospeed() function sets the output baud rate in the termios structure referenced by t to speed .

The cfsetspeed() function sets both the input and output baud rate in the termios structure referenced by t to speed .

On successful completion, the functions cfsetispeed() , cfsetospeed() and cfsetspeed() return a value of 0 . Otherwise, a value of -1 is returned and the global variable errno is set to indicate the error.

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 will 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. See RESTRICTIONS below.

In all the functions, although 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.

The cfmakeraw() function sets the flags stored in the termios structure to a state disabling all input and output processing, giving a raw I/O path. Note that there is no function to reverse this effect, as a variety of processing options could be re-enabled. The correct method is for an application to snapshot the current terminal state using the tcgetattr() function, set raw mode using cfmakeraw() and the subsequent tcsetattr() , and then use another tcsetattr() with the saved state to revert to the previous terminal state.

The tcgetattr() function copies the parameters associated with the terminal referenced by fd in the termios structure referenced by t . This function is allowed from a background process (see RESTRICTIONS); however, the terminal attributes may subsequently be changed by a foreground process.

The tcsetattr() function sets the parameters associated with the terminal from the termios structure referenced by tp . The action field is created by or- ing the following values, as specified in the include file <termios.h> .

TCSANOW

The change occurs immediately.

TCSADRAIN

The change occurs after all output written to fd has been transmitted to the terminal. This value of action should be used when changing parameters that affect output.

TCSAFLUSH

The change occurs after all output written to fd has been transmitted to the terminal. In addition, any input that has been received but not read is discarded.

TCSASOFT

If this value is or'ed into the action value, the values of the c_cflag , c_ispeed , and c_ospeed fields are ignored.

The 0 baud rate is used to terminate the connection. If 0 is specified as the output speed to the function tcsetattr() , modem control will no longer be asserted on the terminal, disconnecting the terminal.

If 0 is specified as the input speed to the function tcsetattr() , the input baud rate will be set to the same value as that specified by the output baud rate.

If tcsetattr() is unable to make any of the requested changes, it returns -1 and sets errno . Otherwise, it makes all the requested changes that are possible. If the specified input and output baud rates differ and are a combination that is not supported, neither baud rate is changed.

On successful completion, the functions tcgetattr() and tcsetattr() return a value of 0 . Otherwise, they return -1 and the global variable errno is set to indicate one of the following error conditions:

[EBADF]

The fd argument to tcgetattr() or tcsetattr() was not a valid file descriptor.

[EINTR]

The tcsetattr() function was interrupted by a signal. See RESTRICTIONS below.

[EINVAL]

The action argument to the tcsetattr() function was not valid, or an attempt was made to change an attribute represented in the termios structure to an unsupported value.

[ENOTTY]

The file associated with the fd argument to tcgetattr() or tcsetattr() is not a terminal.

STANDARDS

The cfgetispeed() , cfsetispeed() , cfgetospeed() , cfsetospeed() , tcgetattr() and tcsetattr() functions are expected to be compliant with the POSIX 1003.1-88 specification. The cfmakeraw() and cfsetspeed() functions, as well as the TCSASOFT option to the tcsetattr() function are extensions to the POSIX 1003.1-88 specification.

RESTRICTIONS

Signals and signal management are not supported.

These library functions (in libbsd.a ) do not support multithreaded applications.

The background semantic is not supported.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving
MT-Level	Async-Signal-Safe

ChorusOS 5.0  Last Revised December 2001

NAME | SYNOPSIS | API RESTRICTIONS | FEATURES | DESCRIPTION | GETTING AND SETTING THE BAUD RATE | GETTING AND SETTING THE TERMIOS STATE | STANDARDS | RESTRICTIONS | ATTRIBUTES