Try 4, lol.

src/inode.zig

@@ -0,0 +1,85 @@
+const std = @import("std");
+
+const dir = @import("inode/dir.zig");
+const file = @import("inode/file.zig");
+const misc = @import("inode/misc.zig");
+
+pub const Ref = packed struct {
+    offset: u16,
+    block: u32,
+    _: u16,
+};
+
+const Type = enum(u16) {
+    dir = 1,
+    file,
+    symlink,
+    block_dev,
+    char_dev,
+    fifo,
+    socket,
+    ext_dir,
+    ext_file,
+    ext_symlink,
+    ext_block_dev,
+    ext_char_dev,
+    ext_fifo,
+    ext_socket,
+};
+
+const Header = packed struct {
+    type: Type,
+    perm: u16,
+    uid_idx: u16,
+    gid_idx: u16,
+    mod_time: u32,
+    num: u32,
+};
+
+const Data = union(enum) {
+    dir: dir.Dir,
+    file: file.File,
+    symlink: misc.Symlink,
+    block_dev: misc.Dev,
+    char_dev: misc.Dev,
+    fifo: misc.IPC,
+    socket: misc.IPC,
+    ext_dir: dir.ExtDir,
+    ext_file: file.ExtFile,
+    ext_symlink: misc.ExtSymlink,
+    ext_block_dev: misc.ExtDev,
+    ext_char_dev: misc.ExtDev,
+    ext_fifo: misc.ExtIPC,
+    ext_socket: misc.ExtIPC,
+};
+
+const Self = @This();
+
+hdr: Header,
+data: Data,
+
+pub fn init(rdr: anytype, alloc: std.mem.Allocator, block_size: u32) !Self {
+    std.debug.assert(std.meta.hasFn(@TypeOf(rdr), "read"));
+    var hdr: Header = undefined;
+    _ = try rdr.read(std.mem.asBytes(&hdr));
+    const data = switch (hdr.type) {
+        .dir => .{ .dir = .init(rdr) },
+        .file => .{ .file = .init(rdr, alloc, block_size) },
+        .symlink => .{ .symlink = .init(rdr, alloc) },
+        .block_dev => .{ .block_dev = .init(rdr) },
+        .char_dev => .{ .char_dev = .init(rdr) },
+        .fifo => .{ .fifo = .init(rdr) },
+        .socket => .{ .socket = .init(rdr) },
+        .ext_dir => .{ .ext_dir = .init(rdr) },
+        .ext_file => .{ .ext_file = .init(rdr, alloc, block_size) },
+        .ext_symlink => .{ .ext_symlink = .init(rdr, alloc) },
+        .ext_block_dev => .{ .ext_block_dev = .init(rdr) },
+        .ext_char_dev => .{ .ext_char_dev = .init(rdr) },
+        .ext_fifo => .{ .ext_fifo = .init(rdr) },
+        .ext_socket => .{ .ext_socket = .init(rdr) },
+    };
+    return .{
+        .hdr = hdr,
+        .data = data,
+    };
+}