SVR2 tar bug

[Doug Gwyn <gwyn>]

The UNIX System V Release 2.0 "tar" has introduced a new bug as a
side-effect of attempting to handle both old and new styles of
magtape device names.  The bug shows up when creating an ordinary
archive file that does not already exist; "tar" attempts to open the
magtape drive!  The two lines below involving `usefil1' and `NULL'
are my kludge to avoid the problem:


/*	@(#)tar.c	1.7	*/
...
main(argc, argv)
...
		switch(*cp) {
		case 'f':
			usefile = *argv++;
			usefil1 = NULL;	/* DAG -- part of bug fix (added) */
			if (nblock == 1)
				nblock = 0;
			break;
...
	if (rflag) {
...
		if (strcmp(usefile, "-") == 0) {
...
		}
		else
		if ((mt = open(usefile,2)) < 0 &&	/* DAG -- bug fix: */
		    (usefil1 == NULL || (mt = open(usefil1,2)) < 0)) {
			if (cflag == 0 || (mt =  creat(usefile, 0666)) < 0) {
				fprintf(stderr, "tar: cannot open %s\n", usefile);
				done(1);
			}
		}
...