fs: Initial VFS port

fs/internal.h

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: ISC
+
+#pragma once
+
+#include <zinnia/vfs.h>
+
+// Sets the global root of the VFS. Takes a new reference to `root`.
+void vfs_set_root(struct vfs_path root);
+
+// Returns true if both paths reference the same entry on the same mount.
+static inline bool vfs_path_equal(struct vfs_path a, struct vfs_path b) {
+    return a.mount == b.mount && a.entry == b.entry;
+}
+
+void pipe_destroy(struct pipe* pipe);
+errno_t vfs_fifo_open(struct vfs_node* node, struct vfs_file* file);