SerialController.cpp

/*
 *   Copyright (C) 2002-2004,2007-2011,2013,2014-2017 by Jonathan Naylor G4KLX
 *   Copyright (C) 1999-2001 by Thomas Sailor HB9JNX
 *
 *   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 with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "SerialController.h"
#include "Log.h"

#include <cstring>
#include <cassert>

#include <sys/ioctl.h>
#include <sys/stat.h>
#include <cerrno>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <termios.h>

CSerialController::CSerialController(const std::string& device, SERIAL_SPEED speed, bool assertRTS) :
m_device(device),
m_speed(speed),
m_assertRTS(assertRTS),
m_fd(-1)
{
	assert(!device.empty());
	LogInitialise("/tmp","MMDVModem", 1, 1);
}

CSerialController::CSerialController()
{
}

CSerialController::~CSerialController()
{
}

bool CSerialController::open()
{
	assert(m_fd == -1);

	m_fd = ::open(m_device.c_str(), O_RDWR | O_NOCTTY | O_NDELAY, 0);
	if (m_fd < 0) {
		LogError("Cannot open device - %s", m_device.c_str());
		return false;
	}

	if (::isatty(m_fd) == 0) {
		LogError("%s is not a TTY device", m_device.c_str());
		::close(m_fd);
		return false;
	}

	// socat replacement code
	// TODO: add error checks

	grantpt(m_fd);
    	unlockpt(m_fd);

        char cwdpath[256];
        getcwd(cwdpath, 256);

    	char* pts_name = ptsname(m_fd);
    	LogMessage("virtual pts: %s <> %s/ttyMMDVM0", pts_name, cwdpath);

    	unlink("ttyMMDVM0");

    	if ((symlink(pts_name, "ttyMMDVM0")) == -1) {	// creating symlink in local dir - /dev requires suid :(	
        	LogError("error creating symlink from %s to ttyMMDVM0", pts_name);
        	return false;
    	}

    	// end 


	termios termios;
	if (::tcgetattr(m_fd, &termios) < 0) {
		LogError("Cannot get the attributes for %s", m_device.c_str());
		::close(m_fd);
		return false;
	}

	termios.c_lflag    &= ~(ECHO | ECHOE | ICANON | IEXTEN | ISIG);
	termios.c_iflag    &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON | IXOFF | IXANY);
	termios.c_cflag    &= ~(CSIZE | CSTOPB | PARENB | CRTSCTS);
	termios.c_cflag    |= CS8;
	termios.c_oflag    &= ~(OPOST);
	termios.c_cc[VMIN]  = 0;
	termios.c_cc[VTIME] = 10;

	switch (m_speed) {
		case SERIAL_1200:
			::cfsetospeed(&termios, B1200);
			::cfsetispeed(&termios, B1200);
			break;
		case SERIAL_2400:
			::cfsetospeed(&termios, B2400);
			::cfsetispeed(&termios, B2400);
			break;
		case SERIAL_4800:
			::cfsetospeed(&termios, B4800);
			::cfsetispeed(&termios, B4800);
			break;
		case SERIAL_9600:
			::cfsetospeed(&termios, B9600);
			::cfsetispeed(&termios, B9600);
			break;
		case SERIAL_19200:
			::cfsetospeed(&termios, B19200);
			::cfsetispeed(&termios, B19200);
			break;
		case SERIAL_38400:
			::cfsetospeed(&termios, B38400);
			::cfsetispeed(&termios, B38400);
			break;
		case SERIAL_115200:
			::cfsetospeed(&termios, B115200);
			::cfsetispeed(&termios, B115200);
			break;
		case SERIAL_230400:
			::cfsetospeed(&termios, B230400);
			::cfsetispeed(&termios, B230400);
			break;
		default:
			LogError("Unsupported serial port speed - %d", int(m_speed));
			::close(m_fd);
			return false;
	}

	if (::tcsetattr(m_fd, TCSANOW, &termios) < 0) {
		LogError("Cannot set the attributes for %s", m_device.c_str());
		::close(m_fd);
		return false;
	}

	if (m_assertRTS) {
		unsigned int y;
		if (::ioctl(m_fd, TIOCMGET, &y) < 0) {
			LogError("Cannot get the control attributes for %s", m_device.c_str());
			::close(m_fd);
			return false;
		}

		y |= TIOCM_RTS;
                                                                                
		if (::ioctl(m_fd, TIOCMSET, &y) < 0) {
			LogError("Cannot set the control attributes for %s", m_device.c_str());
			::close(m_fd);
			return false;
		}
	}

	return true;
}

int CSerialController::read(unsigned char* buffer, unsigned int length)
{
	assert(buffer != NULL);
	assert(m_fd != -1);

	if (length == 0U)
		return 0;

	unsigned int offset = 0U;

	while (offset < length) 
	{
		fd_set fds;
		FD_ZERO(&fds);
		FD_SET(m_fd, &fds);
		int n;
		if (offset == 0U) {
			struct timeval tv;
			tv.tv_sec  = 0;
			tv.tv_usec = 0;
			n = ::select(m_fd + 1, &fds, NULL, NULL, &tv);
			if (n == 0)
				return 0;
		} else {
			n = ::select(m_fd + 1, &fds, NULL, NULL, NULL);
		}

		if (n < 0) {
			LogError("Error from select(), errno=%d", errno);
			return -1;
		}

		if (n > 0) {
			ssize_t len = ::read(m_fd, buffer + offset, length - offset);
			
			if (len < 0) {
				if (errno != EAGAIN) {
					//LogError("Error from read(), errno=%d", errno);
					return 0;
				}
			}

			if (len > 0)
			{
				//LogDebug("Read byte, len:%d", len);

				offset += len;
			}
		}
	}

	return length;
}

bool CSerialController::canWrite(){
	return true;
}

int CSerialController::write(const unsigned char* buffer, unsigned int length)
{
	assert(buffer != NULL);
	assert(m_fd != -1);

	if (length == 0U)
		return 0;

	unsigned int ptr = 0U;
	while (ptr < length) {
		ssize_t n = 0U;
		if (canWrite())
			n = ::write(m_fd, buffer + ptr, length - ptr);
		if (n < 0) {
			if (errno != EAGAIN) {
				LogError("Error returned from write(), errno=%d", errno);
				return -1;
			}
		}

		if (n > 0)
		{
			//LogDebug("Write byte, len:%d", n);
			ptr += n;
		}
	}

	return length;
}

void CSerialController::close()
{
	assert(m_fd != -1);

	::close(m_fd);
	m_fd = -1;
}