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/dirent/readdir.c

@@ -0,0 +1,88 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright (C) 1991,92,93,94,95,96,97,99,2000 Free Software Foundation, Inc.
+ * Copyright © 2018 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/>.
+ */
+
+// Taken from GNU C Library 2.2.5
+
+#include <errno.h>
+#include <limits.h>
+#include <stddef.h>
+#include <string.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <assert.h>
+
+#include <dirstream.h>
+
+int getdents (int filedes, char *buffer, size_t nbytes);
+
+/* Read a directory entry from DIRP.  */
+struct dirent *
+readdir (DIR * dirp)
+{
+  struct dirent *dp;
+  int saved_errno = errno;
+
+  do
+    {
+      size_t reclen;
+
+      if (dirp->offset >= dirp->size)
+        {
+          /* We've emptied out our buffer.  Refill it.  */
+
+          size_t maxread;
+          ssize_t bytes;
+
+          maxread = dirp->allocation;
+
+#if 0
+          off_t base;
+          bytes = __getdirentries (dirp->fd, dirp->data, maxread, &base);
+#else
+          bytes = getdents (dirp->fd, dirp->data, maxread);
+#endif
+          if (bytes <= 0)
+            {
+              /* Don't modifiy errno when reaching EOF.  */
+              if (bytes == 0)
+                errno = saved_errno;
+              dp = 0;
+              break;
+            }
+          dirp->size = (size_t) bytes;
+
+          /* Reset the offset into the buffer.  */
+          dirp->offset = 0;
+        }
+
+      dp = (struct dirent *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+      dirp->offset += reclen;
+      dirp->filepos = dp->d_off;
+
+      /* Skip deleted files.  */
+    }
+  while (dp->d_ino == 0);
+
+  return dp;
+}