67d
/* Creates a tape in SIMH format from a tar archive */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>

int main(int argc, char **argv)
{
	int f1, f2, n, rootlen;
	int err = 0;
	char tarfile[512], tapefile[512];
	char buf[512], *p;

	if (argc < 2) {
		fprintf(stderr, "usage: mktape <tarfile> [<tapefile>]\n");
		exit(0);
	}

	strcpy(tarfile, argv[1]);
	if (argc > 2)
		strcpy(tapefile, argv[2]);
	else {
		p = strchr(tarfile, '.');
		if (! p)
			rootlen = strlen(tarfile);
		else
			rootlen = p - tarfile;
		memset(tapefile, 0, 512);
		strncpy(tapefile, tarfile, rootlen);
		strcat(tapefile, ".tape");
	}

	if ((f1 = open(tarfile, O_RDONLY)) == -1) {
		perror("open");
		exit(1);
	}
	if ((f2 = open(tapefile, O_CREAT | O_WRONLY)) == -1) {
		perror("open");
		exit(1);
	}
	fchmod(f2, 0666);

	while (1) {
		if ((n = read(f1, buf, 512)) == 0)
			break;
		if (n == -1) {
			perror("read");
			err++;
			break;
		}
		if (n != sizeof(buf)) {
			fprintf(stderr, "Error: too few bytes read\n");
			err++;
			break;
		}
		if ((write(f2, &n, sizeof(n))) == -1) {
			perror("write");
			err++;
			break;
		}
		if ((write(f2, buf, sizeof(buf))) == -1) {
			perror("write");
			err++;
			break;
		}
		if ((write(f2, &n, sizeof(n))) == -1) {
			perror("write");
			err++;
			break;
		}
	}

	n = 0;
	if ((write(f2, &n, sizeof(n))) == -1) {
		perror("write");
		err++;
		goto error;
	}
	if ((write(f2, &n, sizeof(n))) == -1) {
		perror("write");
		err++;
	}

error:
	close(f1);
	close(f2);
	if (err) {
		unlink(tapefile);
		exit(1);
	}
	exit(0);
}
.

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