gazagnaire.org
Build Linux initramfs cpio archives from OCaml
1(*---------------------------------------------------------------------------
2 Copyright (c) 2025 Thomas Gazagnaire. All rights reserved.
3 SPDX-License-Identifier: ISC
4 ---------------------------------------------------------------------------*)
5
6(** Build initramfs cpio archives.
7
8 High-level API for creating Linux initramfs images (cpio newc format) from
9 directories, files, and recursive directory trees. *)
10
11type entry =
12 | Dir of string (** Empty directory. *)
13 | File of { name : string; path : string }
14 (** File from disk, renamed to [name] in the archive. *)
15 | Content of { name : string; data : string; perm : int }
16 (** Inline content, stored as [name] with [perm] permissions. *)
17 | Tree of string (** Recursive directory tree. *)
18
19val build : entry list -> string
20(** [build entries] builds a cpio newc archive from [entries].
21
22 - [Dir name] creates an empty directory with permissions 0o755.
23 - [File { name; path }] reads a file from [path] and stores it as [name],
24 preserving the original file permissions.
25 - [Content { name; data; perm }] stores inline [data] as [name] with [perm]
26 permissions.
27 - [Tree path] recursively walks [path], adding all files and subdirectories
28 as cpio entries, preserving permissions. *)