mp_serial.c

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/*
   //  PLP - An implementation of the PSION link protocol
   //
   //  The code in this file was written by Rudolf Koenig
   //  (rfkoenig@immd4.informatik.uni-erlangen.de). (from his p3nfs code)
   //  The Copyright remains his.
   //
   //  This program is free software; you can redistribute it and/or modify
   //  it under the terms of the GNU General Public License as published by
   //  the Free Software Foundation; either version 2 of the License, or
   //  (at your option) any later version.
   //
   //  This program is distributed in the hope that it will be useful,
   //  but WITHOUT ANY WARRANTY; without even the implied warranty of
   //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   //  GNU General Public License for more details.
   //
   //  You should have received a copy of the GNU General Public License along
   //  along with this program; if not, see <https://www.gnu.org/licenses/>.
   //
   //  e-mail philip.proudman@btinternet.com
 */
#include "config.h"
 
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>                /* for usleep() */
#include <string.h>                /* for bzero() */
#include <termios.h>
#if defined(linux) || defined(_IBMR2) || \
        (defined(__APPLE__) && defined(__MACH__)) || \
        defined(__NetBSD__) || defined(__FreeBSD__)
#include <sys/ioctl.h>                /* for ioctl() */
#endif
#include <errno.h>
#ifdef sun
#include <sys/ttold.h>                /* sun has TIOCEXCL there */
#endif
#include <stdlib.h>
 
#ifdef hpux
#include <sys/termiox.h>
#include <sys/modem.h>
#endif
 
#include "mp_serial.h"
 
 
#ifdef __sgi
#define CRTSCTS CNEW_RTSCTS
#endif
 
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
 
int
init_serial(const char *dev, int speed, int debug)
{
    int fd, baud;
    int uid, euid;
    struct termios ti;
#ifdef hpux
    struct termiox tx;
#endif
    static struct baud {
        int speed, baud;
    } btable[] = {
        { 9600, B9600 },
#ifdef B19200
        { 19200, B19200 },
#else
#ifdef EXTA
        { 19200, EXTA },
#endif
#endif
#ifdef B38400
        { 38400, B38400 },
#else
#ifdef EXTB
        { 38400, EXTB },
#endif
#endif
#ifdef B57600
        { 57600, B57600 },
#endif
#ifdef B115200
        { 115200, B115200 },
#endif
        { 4800, B4800 },
        { 2400, B2400 },
        { 1200, B1200 },
        { 300, B300 },
        { 75, B75 },
        { 50, B50 },
        { 0, 0 }
    }, *bptr;
 
    if (speed) {
        for (bptr = btable; bptr->speed; bptr++)
            if (bptr->speed == speed)
                break;
        if (!bptr->baud) {
            fprintf(stderr, "Cannot match selected speed %d\n", speed);
            exit(1);
        }
        baud = bptr->baud;
    } else
        baud = 0;
 
    if (debug)
        printf("using %s...\n", dev);
    euid = geteuid();
    uid = getuid();
 
#ifdef hpux
#define seteuid(a) setresuid(-1, a, -1)
#endif
 
    if (seteuid(uid)) {
        perror("seteuid");
        exit(1);
    }
 
    int options = O_RDWR | O_NOCTTY;
#if defined(__APPLE__) && defined(__MACH__)
    // On macOS 27, open seems to hang indefinitely when opened 'blocking' so we always open in non-blocking mode on
    // macOS. The Reconnect branch of plptools has opened the serial port non-blocking since its inception, so this
    // is well tested. Since DataLink is entirely select-based and does not rely on blocking reads, non-blocking should
    // be safe---even preferable---and we should probably enable this everywhere long-term.
    options |= O_NONBLOCK;
#endif
 
    if ((fd = open(dev, options, 0)) < 0) {
        perror(dev);
        exit(1);
    }
    if (seteuid(euid)) {
        perror("seteuid back");
        exit(1);
    }
    if (debug)
        printf("open done\n");
#ifdef TIOCEXCL
    ioctl(fd, TIOCEXCL, (char *) 0);        /* additional open() calls shall fail */
#else
    fprintf(stderr, "WARNING: opened %s non-exclusive!\n", dev);
#endif
 
    memset(&ti, 0, sizeof(struct termios));
    ti.c_cflag = CS8 | HUPCL | CLOCAL | CREAD;
#if defined(sun) || defined(linux) || defined(__sgi) || \
        (defined(__APPLE__) && defined(__MACH__)) || \
        defined(__NetBSD__) || defined(__FreeBSD__)
    ti.c_cflag |= CRTSCTS;
    ti.c_iflag = IGNBRK | IGNPAR;
    ti.c_cc[VMIN] = 1;
    ti.c_cc[VTIME] = 0;
#endif
    cfsetispeed(&ti, baud);
    cfsetospeed(&ti, baud);
 
    if (tcsetattr(fd, TCSADRAIN, &ti) < 0)
        perror("tcsetattr TCSADRAIN");
 
#ifdef hpux
    bzero(&tx, sizeof(struct termiox));
    tx.x_hflag = RTSXOFF | CTSXON;
    if (ioctl(fd, TCSETXW, &tx) < 0)
        perror("TCSETXW");
#endif
#if defined(_IBMR2)
    ioctl(fd, TXDELCD, "dtr");
    ioctl(fd, TXDELCD, "xon");
    ioctl(fd, TXADDCD, "rts");        /* That's how AIX does CRTSCTS */
#endif
 
    return fd;
}
 
void
ser_exit(int fd)
{
    struct termios ti;
 
#ifdef TIOCNXCL
    ioctl(fd, TIOCNXCL, (char *) 0);
#endif
    if (tcgetattr(fd, &ti) < 0)
        perror("tcgetattr");
    ti.c_cflag &= ~CRTSCTS;
    if (tcsetattr(fd, TCSANOW, &ti) < 0)
        perror("tcsetattr");
    (void) close(fd);
}