cdctest.cpp

#include <iostream>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdexcept>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

using namespace std;

int main(int argc, char *argv[]) {
	if (argc != 2) {
		std::cout << "not enough parameters" << std::endl;
	}

	const std::string iface = argv[1];

	int fd = open(iface.c_str(), O_RDWR);
	if (fd < 0)
		throw std::runtime_error(
				std::string("Could not open device: ") + iface);

	//	close(fd);
	//	return 0;
	unsigned long writeCount = 0;

	char buffer[256];
	while (true) {

		struct timeval tv;
		tv.tv_sec = 0;
		tv.tv_usec = 20000;

		fd_set rfds;
		FD_ZERO(&rfds);
		FD_SET(fd, &rfds);

		fd_set wfds;
		FD_ZERO(&wfds);
		FD_SET(fd, &wfds);


		int retval = select(fd + 1, &rfds, &wfds, NULL, &tv);

		if (retval == -1)
			std::cout << "select error" << std::endl;
		else if (retval) {
			if( FD_ISSET(fd, &rfds)) {
				int readCount = read(fd, buffer, 256);
				if (readCount == -1) {
					std::cout << "Read Error: " << errno << " - " << strerror(errno)
										<< std::endl;
				}
				else {
					std::cout << "Read " << readCount << std::endl;
				}
			}
		} else {
			std::cout << "Timeout" << std::endl;
		}

		std::string writeData = "abcdefg";
		int writeRc = write(fd, writeData.c_str(), writeData.size());
		if (writeRc == -1) {
			std::cout << "Write Error: " << errno << " - " << strerror(errno)
							<< std::endl;
		} else
		{
			std::cout << "Write OK #" << writeCount++ << std::endl;
		}
	}
	return 0;
}