mkfs -a understands how to quote filenames with %q but
mkext doesn't know how to unpack them.

My fix doesn't allow any of the fields in the header to be
zero length, however looking at mkfs it uses %q for the filename
and uid and gid so I don't beleive this is a problem.

Perhaps there some old mkfs archives which have missing uid or gid
that this change might break?

-Steve

Reference: /n/sources/patch/applied/mkext-quoted-filenames
Date: Sun Aug  8 05:41:23 CES 2004

--- /sys/src/cmd/disk/mkext.c	Sun Aug  8 05:41:23 2004
+++ /sys/src/cmd/disk/mkext.c	Sun Aug  8 05:41:22 2004
@@ -72,11 +72,13 @@
 			fprint(2, "done\n");
 			exits(0);
 		}
-		if(getfields(p, fields, NFLDS, 0, " \t") != NFLDS){
+		if (gettokens(p, fields, NFLDS, " \t") != NFLDS){
 			warn("too few fields in file header");
 			continue;
 		}
-		strcpy(namep, fields[0]);
+		p = unquotestrdup(fields[0])
+		strcpy(namep, p);
+		free(p);
 		mode = strtoul(fields[1], 0, 8);
 		uid = fields[2];
 		gid = fields[3];