sys/kern: Add VFS support

- Refactor the libio interface

- Move syscalls into an rtemsbsd location

- Provide a root directory mount point

Update #4475

rtemsbsd/fs/rootfs/rootfs.c

@@ -0,0 +1,91 @@
+/**
+ * @file
+ *
+ * @ingroup rtems_bsd_rtems
+ *
+ * @brief TODO.
+ */
+
+/*
+ * Copyright (c) 2020 Chris Johns
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/rtems-bsd-kernel-space.h>
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/mount.h>
+#include <sys/vnode.h>
+
+#include <fs/pseudofs/pseudofs.h>
+
+static struct pfs_node *rootfs_root;
+
+static int
+rootfs_attr(PFS_ATTR_ARGS, int mode)
+{
+	vap->va_mode = 0;
+	return 0;
+}
+
+static int rootfs_attr_all_rwx(PFS_ATTR_ARGS)
+{
+	vap->va_mode = 0777;
+	return 0;
+}
+
+int
+rtems_bsd_rootfs_mkdir(const char *name)
+{
+	struct pfs_node *dir;
+	dir = pfs_create_dir(rootfs_root, name, rootfs_attr_all_rwx, NULL, NULL,
+	    PFS_RDWR | PFS_NOWAIT);
+	if (dir == NULL)
+		return ENOENT;
+	return 0;
+}
+
+int
+rtems_bsd_rootfs_rmdir(const char *name)
+{
+	struct pfs_node *dir;
+	dir = pfs_find_node(rootfs_root, name);
+	if (dir == NULL)
+		return ENOENT;
+	return pfs_destroy(dir);
+}
+
+static int rootfs_init(PFS_INIT_ARGS)
+{
+	rootfs_root = pi->pi_root;
+	return 0;
+}
+
+static int rootfs_uninit(PFS_INIT_ARGS)
+{
+	return 0;
+}
+
+PSEUDOFS(rootfs, 1, VFCF_SYNTHETIC);