Add mes and mescc-tools-extra

mescc-tools-extra contains two important tools:
- cp
- chmod

mes first builds itself from a mes 0.21 seed as used by guix, and then
builds a mes 0.22 and then mes 0.22 using that created mes 0.22.

It does /not/ use bootstrap.sh as we don't have a proper shell at this
point, it has been manually adapted for kaem.

sysa/mes-0.22/lib/gnu/io-write.c

@@ -0,0 +1,50 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <gnu/syscall.h>
+
+struct mach_msg_pointer_loff
+{
+  mach_msg_header_t header;
+  mach_msg_type_long_t type_one; char *one;
+  mach_msg_type_t type_two; loff_t two;
+};
+
+kern_return_t
+__io_write (io_t io, data_t data, mach_msg_type_number_t size, loff_t offset, vm_size_t *wrote)
+{
+  struct mach_msg_pointer_loff message = {0};
+  message.header.msgh_size = sizeof (struct mach_msg_pointer_loff);
+  message.type_one = mach_msg_type_pointer;
+  message.one = data;
+  message.type_two = mach_msg_type_int64;
+  message.two = offset;
+
+  message.type_one.msgtl_number = size;
+  message.type_one.msgtl_header.msgt_inline = 0;
+  message.header.msgh_bits = MACH_MSGH_BITS_COMPLEX;
+
+  kern_return_t result = __syscall_put (io, SYS__io_write,
+                                        &message.header,
+                                        sizeof (struct mach_msg_2));
+  if (result == KERN_SUCCESS)
+    *wrote = message.two;
+  return result;
+}