ttyopen.c

unix环境高级编程的源代码

#include    "calld.h"
#include    <fcntl.h>
#include    <termios.h>

/* Open the terminal line */

int
tty_open(char *class, char *line, enum parity parity, int modem)
{
    int                fd, baud;
    char            devname[100];
    struct termios    term;

            /* first open the device */
    strcpy(devname, "/dev/");
    strcat(devname, line);
    if ( (fd = open(devname, O_RDWR | O_NONBLOCK)) < 0) {
        sprintf(errmsg, "can't open %s: %s\n",
                                devname, strerror(errno));
        return(-1);
    }
    if (isatty(fd) == 0) {
        sprintf(errmsg, "%s is not a tty\n", devname);
        return(-1);
    }

            /* fetch then set modem's terminal status */
    if (tcgetattr(fd, &term) < 0)
        log_sys("tcgetattr error");

    if (parity == NONE)
        term.c_cflag = CS8;
    else if (parity == EVEN)
        term.c_cflag = CS7 | PARENB;
    else if (parity == ODD)
        term.c_cflag = CS7 | PARENB | PARODD;
    else
        log_quit("unknown parity");
    term.c_cflag |= CREAD |            /* enable receiver */
                    HUPCL;            /* lower modem lines on last close */
                                    /* 1 stop bit (since CSTOPB off) */
    if (modem == 0)
        term.c_cflag |= CLOCAL;        /* ignore modem status lines */

    term.c_oflag  = 0;                /* turn off all output processing */
    term.c_iflag  = IXON | IXOFF |    /* Xon/Xoff flow control (default) */
                    IGNBRK |        /* ignore breaks */
                    ISTRIP |        /* strip input to 7 bits */
                    IGNPAR;            /* ignore input parity errors */
    term.c_lflag  = 0;        /* everything off in local flag:
                               disables canonical mode, disables
                               signal generation, disables echo */
    term.c_cc[VMIN]  = 1;    /* 1 byte at a time, no timer */
    term.c_cc[VTIME] = 0;    /* (See {Fig call_read_counts}) */

    if      (strcmp(class, "38400") == 0)    baud = B38400;
    else if (strcmp(class, "19200") == 0)    baud = B19200;
    else if (strcmp(class, "9600") == 0)    baud = B9600;
    else if (strcmp(class, "4800") == 0)    baud = B4800;
    else if (strcmp(class, "2400") == 0)    baud = B2400;
    else if (strcmp(class, "1800") == 0)    baud = B1800;
    else if (strcmp(class, "1200") == 0)    baud = B1200;
    else if (strcmp(class, "600") == 0)        baud = B600;
    else if (strcmp(class, "300") == 0)        baud = B300;
    else if (strcmp(class, "200") == 0)        baud = B200;
    else if (strcmp(class, "150") == 0)        baud = B150;
    else if (strcmp(class, "134") == 0)        baud = B134;
    else if (strcmp(class, "110") == 0)        baud = B110;
    else if (strcmp(class, "75") == 0)        baud = B75;
    else if (strcmp(class, "50") == 0)        baud = B50;
    else {
        sprintf(errmsg, "invalid baud rate: %s\n", class);
        return(-1);
    }
    cfsetispeed(&term, baud);
    cfsetospeed(&term, baud);

    if (tcsetattr(fd, TCSANOW, &term) < 0)    /* set attributes */
        log_sys("tcsetattr error");

    DEBUG("tty open");
    clr_fl(fd, O_NONBLOCK);        /* turn off nonblocking */
    return(fd);
}