Crate embala_pkg 

macOS flat-package (.pkg) builder — product archives on any OS.

build writes the same shape productbuild emits: a xar archive holding a Distribution script plus a <name>.pkg/ component directory with PackageInfo, Bom, a gzipped odc-cpio Payload, and (with PkgSpec::scripts) a Scripts archive in the same format. Every layer was pinned against Apple tooling on macOS 26.5 (pkgbuild/productbuild output dissected byte-by-byte; results verified with pkgutil --expand-full, lsbom, and installer).

Lower-level pieces are public for reuse and testing: write_xar (xar archives with nested directories) and write_bom (Bill of Materials over a staged tree).

Spike outcomes the implementation rests on:

• xar: apple-xar 0.20 has no turn-key writer, but its primitives compose: TableOfContents/File/FileData are public with to_xml(), ChecksumType::digest_data provides digests, and XarHeader derives scroll IOwrite. The only wrinkle is that TableOfContents’s inner field is private with no constructor, so we bootstrap one by parsing a minimal template TOC via from_reader and mutating it through its DerefMut<Target = XarToC> impl. No hand-rolled writer needed.
• BOM: apple-bom 0.3’s shipped BomBuilder is unusable — its build_bom() panics unconditionally, and beneath that lie a dozen more writer bugs (wrong checksum algorithm, wrong B-tree order, missing free list, …; see bom_builder.rs for the catalog). Bounded fallback taken: bom_builder ports the assembly on top of apple-bom’s public format types with those fixes; the output matches both mkbom and pkgbuild’s embedded Bom under lsbom -p fmugsc (paths, modes, uid, gid, size, cksum). Per-file modes must include the file-type bits (e.g. 0o100755).
• cpio: the Payload is odc/ASCII cpio (magic 070707), hand-rolled here because the format is a 76-byte octal header and pkgbuild’s conventions (sequential inodes, dir nlink = 2 + children, zero pad to a 512-byte boundary) need exact control no crate offered.

Structs

DirSpec

A payload directory declared explicitly, to give it a mode or to ship it with nothing under it. Directories only implied by file dests are 0o755.

FileSpec

A payload file: src on disk (already resolved to a real path), dest the /-separated path relative to the install location.

PkgSpec

Everything needed to author one product archive. Deliberately independent of the embala config types so the crate is usable on its own.

XarEntry

An entry to store in a xar archive.

Enums

Error

XarEntryKind

Functions

build

Build the product-archive .pkg described by spec at out (parent dirs are created). Output is deterministic: fixed timestamps everywhere (xar TOC, cpio, gzip) and sorted payload entries.

validate

Check spec without touching the filesystem: dests are relative and unique, no file sits where a directory must be, and modes are permission bits only. build runs this first; it is public so callers can reject a bad layout before building anything.

write_bom

Build a BOM over the file tree rooted at root, recording uid:gid as the owner of every entry (pkgbuild’s convention is 0:0, root:wheel).

write_xar

Write a xar archive holding entries (files and directories).

Type Aliases

Result