/* vi: set sw=4 ts=4: */
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <dirent.h>
#include <unistd.h>
#include <utime.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>

static const char *const app_name = "scopy";
static int intr_flag = 0;

static void verror_msg(const char *s, va_list p)
{
	fflush(stdout);
	fprintf(stderr, "%s: ", app_name);
	vfprintf(stderr, s, p);
}
static void vperror_msg(const char *s, va_list p)
{
	int err = errno;

	if (s == 0)
		s = "";
	verror_msg(s, p);
	if (*s)
		s = ": ";
	fprintf(stderr, "%s%s\n", s, strerror(err));
}

static void perror_msg_and_die(const char *s, ...)
{
	va_list p;

	va_start(p, s);
	vperror_msg(s, p);
	va_end(p);
	exit(EXIT_FAILURE);
}

static FILE *xfopen(const char *path, const char *mode)
{
	FILE *fp;

	if ((fp = fopen(path, mode)) == NULL)
		perror_msg_and_die("%s", path);
	return fp;
}

static void show_usage(void)
{
	fprintf(stderr, "Usage: scopy source dest\n");
	exit(EXIT_FAILURE);
}

static void sig_int(int signo)
{
	intr_flag = 1;
}

int main(int argc, char **argv)
{
	int status = 0;
	int opt;
	char *sname, *dname;
	fd_set rfds, wfds;
	FILE *source, *dest;
	int source_fd, dest_fd, n;
	ssize_t rsize = 0, wsize = 0;
	char buf[1024 * 1024];
	ssize_t bufsiz = sizeof(buf);
	struct timeval tv = { 0, 250000 };	/* 0.25 seconds */

	while ((opt = getopt(argc, argv, "adfipR")) != -1)
		switch (opt) {
		default:
			show_usage();
		}

	if (optind + 2 > argc)
		show_usage();

	/* If there are only two arguments and...  */
	if (optind + 2 != argc)
		show_usage();

	/* Store filenames for later use */
	sname = argv[optind++];
	dname = argv[optind];

	source = xfopen(sname, "r");
	dest = xfopen(dname, "w");
	source_fd = fileno(source);
	dest_fd = fileno(dest);

	/* Watch to see if things happen */
	FD_ZERO(&rfds);
	FD_ZERO(&wfds);
	n = (source_fd > dest_fd) ? source_fd + 1 : dest_fd + 1;

	if (fcntl(source_fd, F_SETFL, O_NONBLOCK) == -1)
		perror_msg_and_die("Setting O_NONBLOCK on %s", sname);
	if (fcntl(dest_fd, F_SETFL, O_NONBLOCK) == -1)
		perror_msg_and_die("Setting O_NONBLOCK on %s", dname);
	signal(SIGINT, sig_int);

	/* Ok, do the deed */
	while (1) {
		if (intr_flag) {
			printf("interrupted...  Please wait...\n");
			exit(EXIT_FAILURE);
		}
		FD_SET(fileno(source), &rfds);
		FD_SET(fileno(dest), &wfds);
		status = select(n, &rfds, &wfds, NULL, &tv);
		if (status < 0) {
			if (errno == EINTR) {
				printf("interrupted...  Please wait...\n");
				exit(EXIT_FAILURE);
			} else if (errno != EBADF) {
				perror_msg_and_die("select");
			}
		}

		if (FD_ISSET(source_fd, &rfds)) {
			rsize = read(source_fd, buf, bufsiz);
			if (rsize < 0)
				perror_msg_and_die("reading %d", sname);
			if (rsize == 0)
				exit(EXIT_SUCCESS);
		}
		if (FD_ISSET(dest_fd, &wfds)) {
			wsize = write(dest_fd, buf, rsize);
			if (wsize < 0)
				perror_msg_and_die("writing %s", dname);
			if (wsize == 0)
				exit(EXIT_SUCCESS);
		}

	}

	return 0;
}