93a94
> nflag : int;			# use /dev/null for absent files
99c100
< Usage : con  "usage: diff [ -efbwr ] file1 ... file2";
---
> Usage : con  "usage: diff [ -efbwrn ] file1 ... file2";
158a160,161
> 		'n' =>
> 			nflag = 1;
691a695,699
> isdir(p: string): int
> {
> 	(ok, d) := sys->stat(p);
> 	return ok == 0 && d.mode&Sys->DMDIR;
> }
692a701,763
> # fd, td are directories; ff, tf are files in those directories.  one file may be nil (its directory will ignored).
> # should we print something about one-way directories too?
> ndiff(fd, ff, td, tf: string, level: int)
> {
> 	fb:=sys->sprint("%s/%s", fd, ff);
> 	tb:=sys->sprint("%s/%s", td, tf);
> 
> 	if (ff != nil && tf != nil) {
> 		dir1 := isdir(fb);
> 		dir2 := isdir(tb);
> 		if (dir1 && dir2) {
> 			diffdir(fb, tb, level);
> 		} else if (dir1 || dir2) {
> 			ndiff(fd, ff, td, nil, level);
> 			ndiff(fd, nil, td, tf, level);
> 		} else
> 			diffreg(fb, tb);
> 		return;
> 	}
> 
> 	if (!nflag) {
> 		if (mode != 0)
> 			return;
> 
> 		if (ff == nil)
> 			out.puts(sys->sprint("Only in %s: %s\n", td, tf));
> 		else
> 			out.puts(sys->sprint("Only in %s: %s\n", fd, ff));
> 	}
> 
> 	# one file doesn't exist.
> 	# if the existing file is a directory, call ndiff for all its elements.
> 	# if it is a file, diff against /dev/null
> 	p: string;
> 	if (ff != nil)
> 		p = sys->sprint("%s/%s", fd, ff);
> 	else
> 		p = sys->sprint("%s/%s", td, tf);
> 
> 	(ok, dir) := sys->stat(p);
> 	if (ok != 0)
> 		error(sys->sprint("cannot stat %q: %r", p));
> 
> 	if (!(dir.mode&Sys->DMDIR)) {
> 		if(ff == nil)
> 			fb = "/dev/null";
> 		else
> 			tb = "/dev/null";
> 		diffreg(fb, tb);
> 		return;
> 	}
> 
> 	elems := scandir(p);
> 	for (i := 0; i < len elems; i++) {
> 		nff := ntf := "";
> 		if (ff != nil)
> 			nff = elems[i];
> 		else
> 			ntf = elems[i];
> 		ndiff(fb, nff, tb, ntf, level);
> 	}
> }
> 
695,696c766,772
< 	df, dt : array of string;
< 	fb, tb : string;
---
> 	df := array[0] of string;
> 	dt := array[0] of string;
> 	if (f != nil)
> 		df = scandir(f);
> 	if (t != nil)
> 		dt = scandir(t);
> 
699,700d774
< 	df = scandir(f);
< 	dt = scandir(t);
703,706c777,784
< 			if (mode == 0)
< 				out.puts(sys->sprint("Only in %s: %s\n", f, df[i]));
< 			i++;
< 			continue;
---
> 			# only f/df[i] exists
> 			ndiff(f, df[i++], t, nil, level+1);
> 		} else if ((i==len df) || (j<len dt && df[i] > dt[j])) {
> 			# only t/dt[j] exists
> 			ndiff(f, nil, t, dt[j++], level+1);
> 		} else {
> 			# both exist
> 			ndiff(f, df[i++], t, dt[j++], level+1);
708,717d785
< 		if ((i==len df) || (j<len dt && df[i] > dt[j])) {
< 			if (mode == 0)
< 				out.puts(sys->sprint("Only in %s: %s\n", t, dt[j]));
< 			j++;
< 			continue;
< 		}
< 		fb=sys->sprint("%s/%s", f, df[i]);
< 		tb=sys->sprint("%s/%s", t, dt[j]);		
< 		diff(fb, tb, level+1);
< 		i++; j++;