initial commit

overlay.hh

@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: Apache-2.0
+ * (c) 2025, Konstantin Demin
+ */
+
+#ifndef INCLUDE_OVERLAY_HH
+#define INCLUDE_OVERLAY_HH 1
+
+#include <cstring>
+
+extern "C" {
+	#include <sys/types.h>
+}
+
+#include "overlay-common.hh"
+
+#include "print.hh"
+#include "sort.hh"
+#include "xxhash.hh"
+
+struct ovl_dirspec_t {
+	dev_t       dev;
+	ino_t       ino;
+	int         fd;
+	ovl_path_t  root;
+};
+typedef std::vector<ovl_dirspec_t>  ovl_dirspec_vec;
+
+enum ovl_rootspec_flags : uint32_t {
+	none = 0,
+
+	// relative path (if possible)
+	relative = (1 << 0),
+};
+
+// forward declaration
+struct ovl_entry_t;
+typedef std::vector<ovl_entry_t>  ovl_entry_vec;
+
+enum struct ovl_entry_kind : uint32_t {
+	unknown = 0,
+
+	// entry may have it's own entries
+	directory,
+
+	// entry may NOT have it's own entries
+	// this applies to:
+	// - regular files
+	// - directories at maximum depth (!)
+	// - block and character devices
+	// - pipes (FIFO)
+	// - sockets
+	file,
+};
+
+struct ovl_entry_t {
+	ovl_entry_kind  type;
+	int32_t         root_id;
+	xxhash_t        name_hash;
+	ovl_entry_vec   children;
+	ovl_name_t      name;
+
+	ovl_entry_t() {
+		root_id = -1;
+		type = ovl_entry_kind::unknown;
+		name_hash = 0;
+		children = ovl_entry_vec();
+		(void) memset(&name, 0, sizeof(name));
+	}
+};
+
+struct ovl_result {
+	ovl_path_vec   roots;
+	ovl_entry_vec  entries;
+
+	ovl_result() {
+		roots = ovl_path_vec();
+		entries = ovl_entry_vec();
+	}
+};
+
+bool arg_to_rootspec(const char * arg, ovl_dirspec_t * path, uint32_t flags = ovl_rootspec_flags::none);
+
+bool is_empty_dir(int dirfd);
+
+ovl_result process_overlay(ovl_dirspec_vec & roots, sort_mode sort = sort_mode::none, unsigned int depth = ovl_depth_max);
+
+void list_overlay(const ovl_result & overlay, print_mode print = print_mode::normal);
+int merge_overlay(const ovl_result & overlay, const ovl_dirspec_t & target);
+
+#endif /* INCLUDE_OVERLAY_HH */