#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <termios.h>

#include <errno.h>
#include <signal.h>

typedef void sigfunc_t(int);

void signal_handler(int param) {
	static int fd;
	unsigned char sig;

	if (fd && param==0) {
		close(fd);
		return;
	}
	
	if (param < 1) {
		fd = -param;
		return;
	}

	if (fd) {
		sig=param;
		while (-1 == write(fd, &sig, 1) && EINTR == errno)
			;
	}
}

sigfunc_t *connect_signal(int signo, sigfunc_t *func) {
	struct sigaction act, oact;

	act.sa_handler = func;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	if (sigaction(signo, &act, &oact) < 0)
		return SIG_ERR;
	return oact.sa_handler;
}

int open_signal_file(void) {
	int fd[2];
	
	pipe(fd);
	signal_handler(-fd[1]);    // hand off the write side of the pipe

	connect_signal(SIGHUP, signal_handler);
	connect_signal(SIGINT, signal_handler);
	connect_signal(SIGXFSZ, signal_handler);

	return fd[0];  //return the read side of the pipe
}

void close_signal_file(int fd) {
	signal_handler(0);
	close(fd);
}

int main(void) {
	fd_set read_fds;
	char buf[256], fname[]="log.0";
	int sigfd, fd, i;
	unsigned long long bytes_left=3ull * (1ull<<31) + 256ull;

	sigfd = open_signal_file();

	if (!sigfd)
		return 1;
	
	while (bytes_left) {
		int len;
		fd = creat(fname, S_IRUSR | S_IWUSR);
		if (fd == -1)
			return 2;
		
		len = 0x7fffffff;
		if (len > bytes_left)
			len = bytes_left;
		ftruncate(fd, len);
		bytes_left -= len;
		
		if (!bytes_left)
			break;
		
		lseek(fd, 0, SEEK_END);
		i = write(fd, buf, 256);

		if (i>0)
			bytes_left -= i;
		if (i<0)
			puts("write errored");
		
		FD_SET(sigfd, &read_fds);
		select(sigfd + 1, &read_fds, NULL, NULL, NULL);
		
		if (FD_ISSET(sigfd, &read_fds)) {
			int sigs = read(sigfd, buf, 256);
			if (sigs > 0)
				for (i=0; i<sigs; i++)
					switch(buf[i]) {
						case SIGINT:
							return 0;
						case SIGXFSZ:
							puts("seem to have gone overboard, switching to next log file...");
							break;
						default:
							break;
					}
		}
		
		close(fd);
		fname[4]++;
	}

	close_signal_file(sigfd);
	return 0;
}