The Linux Programming Interface

Terminals 1313

Listing 62-4: Demonstrating cbreak and raw modes

–––––––––––––––––––––––––––––––––––––––––––––––––– tty/test_tty_functions.c

#include <termios.h>

#include <signal.h>

#include <ctype.h>

#include "tty_functions.h" /* Declarations of ttySetCbreak()

and ttySetRaw() */

#include "tlpi_hdr.h"

qstatic struct termios userTermios;
/ Terminal settings as defined by user /

static void / General handler: restore tty settings and exit /
handler(int sig)
{
w if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &userTermios) == -1)
errExit("tcsetattr");
_exit(EXIT_SUCCESS);
}

static void / Handler for SIGTSTP /
etstpHandler(int sig)
{
struct termios ourTermios; / To save our tty settings /
sigset_t tstpMask, prevMask;
struct sigaction sa;
int savedErrno;

savedErrno = errno; /* We might change 'errno' here */

/* Save current terminal settings, restore terminal to

state at time of program startup */

r if (tcgetattr(STDIN_FILENO, &ourTermios) == -1)
errExit("tcgetattr");
t if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &userTermios) == -1)
errExit("tcsetattr");

/* Set the disposition of SIGTSTP to the default, raise the signal

once more, and then unblock it so that we actually stop */

if (signal(SIGTSTP, SIG_DFL) == SIG_ERR)

errExit("signal");

raise(SIGTSTP);

sigemptyset(&tstpMask);

sigaddset(&tstpMask, SIGTSTP);

if (sigprocmask(SIG_UNBLOCK, &tstpMask, &prevMask) == -1)

errExit("sigprocmask");

/* Execution resumes here after SIGCONT */

if (sigprocmask(SIG_SETMASK, &prevMask, NULL) == -1)

errExit("sigprocmask"); /* Reblock SIGTSTP */