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

#ifndef lint
static char rcsid[] = "@(#) $Id: dcp.c,v 1.4 1997/06/09 15:35:59 wpaul Exp $";
#endif

/*
 * This program copies data from one file to another, ignoring
 * read errors. It is useful for performing disk copies where the
 * original disk drive has some unrecoverable errors but still
 * contains a large amount of undamaged data.
 *
 * Note that you must compile this program with the SGI C compiler
 * in order for it to work correctly (gcc doesn't seem to handle
 * 64-bit offsets correctly on IRIX yet):
 *
 *  % cc -D_SGI_SOURCE -o dcp dcp.c
 */

int main(argc, argv)
	int		argc;
	char		*argv[];
{

	char 		cbuf[419200];
	char		*cptr;
	int		in, out;
	off_t		cnt = 0;
	off_t		rpos = 0, wpos = 0;

	if (argc < 3) {
		fprintf(stderr, "%s: infile outfile\n", argv[0]);
		exit(1);
	}

	/*
	 * Align to 32-bit boundary.
	 */
	cptr = cbuf;
	while((unsigned long)cptr % 4)
		cptr++;

	if ((in = open(argv[1], O_RDONLY)) == -1) {
		perror("opening infile");
		exit(1);
	}

	if ((out = open(argv[2], O_RDWR)) == -1) {
		perror("opening outfile");
		exit(1);
	}

	while((cnt = read(in, cptr, 204800)) != 0) {
		if (cnt == -1) {
			perror("read");
			/*
			 * If the read fails, we want to skip over
			 * this block, but we want to keep the input
			 * and output pointers in sync. So we move
			 * the write pointer ahead just as if things
			 * had worked, and move the read pointer ahead
			 * to match.
			 */
			wpos = lseek(out, (off_t)204800, SEEK_CUR);
			rpos = lseek(in, wpos, SEEK_SET);
		} else {
			write(out, cptr, cnt);
			wpos = lseek(out, (off_t)0, SEEK_CUR);
			rpos = lseek(in, (off_t)0, SEEK_CUR);
		}
	}

	close(in);
	close(out);

	printf("DONE\n");
	printf("Read %llu bytes\n", rpos);
	printf("Wrote %llu bytes\n", wpos);

	exit(0);
}