fs/vfs: dup() and dup2() were broken some time back. fs_dupfd() was return returing OK on success, not fit the file descriptor of the duplicated fd.

fs/vfs/fs_dupfd.c

@@ -140,7 +140,7 @@ int fs_dupfd(int fd, int minfd)
       goto errout;
     }
 
-  return OK;
+  return ret;
 
 errout:
   set_errno(-ret);