Usenet 1994 October/usenetsourcesnewsgroupsinfomagicoctober1994disk2.iso/unix/volume15/modem-ctl/io.c

C/C++ Source or Header | 1988-05-24 | 5KB | 177 lines

/*
 * Copyright (c) Dave Settle, March 1987
 * Permission is granted to do anything with this program, except remove
 * this copyright notice, or sell it for profit.
 *
 *
 * io.c: routines to talk to the device directly.
 *
 * dread and dwrite act like read(2) and write(2), execpt that they always
 * either succeed or exit, so the caller doesn't have to check.
 *
 * hangup drops the DTR line to the modem, so that it will (hopefully) hang up
 * the phone line. It keeps it this way for 5 seconds.
 *
 * findspeed takes an ascii speed, and returns the corresponing baud rate.
 *
 * uuexit is a dodgy routine to make UUCP happy.
 */

#include <sys/errno.h>
#include <termio.h>
#include <fcntl.h>

#include "modem.h"

char *sys_errlist[];        /* error list        */
#define RETRY 5            /* retry failed writes    */
/*
 * dwrite: write some characters to the modem.
 * If your modem likes characters to be written s-l-o-w-l-y, define 'SLOW'
 */
dwrite(f, s, n)
int f;
unsigned n;
char *s;
{
    struct termio termio;
    int r, retry = 0, i = 0;
    static int error = 0;        /* error occurred on last call */
    while((i < n) && (retry < RETRY)) {
        if(locked()) uuexit(0);
        errno = 0;
        if(r = write(f, s + i, 1) == 1) i++;    /* Success! */
        else {
            retry++;
            fixline();
        }
#ifdef SLOW
        sleep(1);        /* Let the modem deal with it */
#endif
    }
    if(i != n) {
        ioctl(dev, TCGETA, &termio);
        printf("Tried %d times, still got %d/%d written. [error = %s]\n",
            retry, i, n, sys_errlist[errno]);
        printf("FAIL: dev %d, iflag %x, oflag %x, cflag %x, lflag %x, line %d\n",
            dev, termio.c_iflag,termio.c_oflag,termio.c_cflag,
            termio.c_lflag, termio.c_line);
        error = 1;
    }
    else if(retry > 1) printf("Write problem: fixed on retry %d\n", retry - 1);
    if(error && i == n) {
        ioctl(dev, TCGETA, &termio);
        printf("OK: iflag %x, oflag %x, cflag %x, lflag %x, line %d\n",
            termio.c_iflag,termio.c_oflag,termio.c_cflag,
            termio.c_lflag, termio.c_line);
    }
    if(i == n) error = 0;
    return(r);
}
/*
 * read one character at a time, checking before (and after) each read for
 * a lock file. If one exists, then exit.
 */
dread(f, s, n)
int f, n;
char *s;
{
    int i, w;
    for(i=0;i<n;i++, s++) {
        if(locked()) uuexit(0);
        while((w = read(f, s, 1)) < 1) {
            if(locked()) uuexit(0);
            if(w == -1) switch(errno) {
            case EINTR:
                break;
            default:
                perror("dread");
            }
        }
    }
}
/*
 * hangup(): hangup the phone, and close the device.
 * I've had problems with indefinate echoes from the modem when a connection
 * has closed - my modem transmits crap. This ought to hangup the phone and
 * prevent this.
 *
 * Oct 87: This problem should now be fixed, with the introduction of the
 * DCD control from the modem - we should now receive a hangup signal when
 * the line drops.
 */
hangup(device) {
    struct termio term;
    if(ioctl(device, TCGETA, &term) == -1) perror("hangup: TCGETA");
    term.c_lflag &= ~(ECHO | ECHOE | ECHOK);
    term.c_cflag &= ~CBAUD;
    term.c_cflag |= B0;        /* hangup */
    if(ioctl(device, TCSETA, &term) == -1) perror("hangup: TCSETA");
    if(ioctl(device, TCFLSH, 2) == -1) perror("hangup: TCFLSH");
    sleep(5);        /* 5 seconds with DTR down */
    return(0);
}
/*
 * findspeed: convert ascii baud rate into termio parameter.
 */
findspeed(s)
char *s;
{
    int baud = atoi(s);
    switch(baud) {
        case 110: baud = B110;
            break;
        case 300: baud = B300;
            break;
        case 1200: baud = B1200;
            break;
        case 2400: baud = B2400;
            break;
        default:
            printf("findspeed: unknown baud rate %s\n", s);
            baud = B1200;
    }
    return(baud);
}
/*
 * uuexit: make line useable by UUCP.
 * Because UUCP is pretty determined about using a "modem", it clears CLOCAL
 * which means that it can't write any characters at this point (modem not
 * online, so DCD not asserted). Not suprisingly, it doesn't work.
 * Solution: turn it on again, while UUCP isn't looking; this seems to work
 * fine, although I'm a little puzzled about the timing: this is a
 * definate "trial and error" solution.
 * This unfortunately also means that UUCP won't detect a line hangup,
 * so we have to rely on it's timeout facilities ...
 */
#define DIALTIME 5        /* time to continue to assert CLOCAL */
uuexit(code)
{
    struct termio term;
    register int i;
    for(i=0;i<DIALTIME;i++) {
        close(open(dname, O_RDONLY | O_NDELAY)); /* vital magic */
        if(ioctl(dev, TCGETA, &term) == -1) perror("qx TCGETA");
        term.c_cflag |= CLOCAL;
        if(ioctl(dev, TCSETA, &term) == -1) perror("qx TCSETA");
        close(open(dname, O_RDONLY | O_NDELAY)); /* vital magic */
        sleep(1);
    }
    exit(code);
}
/*
 * extensions for send & expect
 */
myread()
{
    char c;
    dread(dev, &c, 1);
    return(c);
}
void mywrite(s)
char *s;
{
    dwrite(dev, s, strlen(s));
}