Shared seek+read seam and flat-memory backing for the unarchivers. More...

#include <stddef.h>
#include <stdint.h>

Include dependency graph for unarch_io.h:

This graph shows which files directly or indirectly include this file:

Data Structures
struct	unarch_mem_t
	Bounded flat-memory backing for unarch_read_fn. More...

Typedefs
typedef size_t(*	unarch_read_fn) (void ctx, uint64_t offset, void buf, size_t len)
	Seek+read backing over an archive's bytes.

Functions
size_t	unarch_mem_read (void ctx, uint64_t offset, void buf, size_t len)
	unarch_read_fn over a flat unarch_mem_t view.

Detailed Description

Shared seek+read seam and flat-memory backing for the unarchivers.

Tag: [Ring 4 / Domain] {World: NS}

Every decoder in unarch (tar walker, gzip member, XZ stream) consumes its untrusted input through the same seek+read function shape the streaming EPUB / CBZ / CBR readers already use, so one ra8_fs file or ra8_vmem page-cache backing drives every container format identically. This header owns that typedef plus the one trivial backing everybody needs: a bounded flat-memory view (unarch_mem_t + unarch_mem_read) used to re-open the decompressed bytes of a wrapped archive (.tar.gz, .tar.xz) without copying them again.

Note: Thread-safety follows the backing: the flat-memory reader is a pure read and safe anywhere; file-backed readers are single-threaded.

See also: unarch_tar.h The tar walker driven through this seam.; unarch_gzip.h The gzip member decoder driven through this seam.; unarch_xz.h The XZ stream decoder driven through this seam.

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Since: Version 0.1.0

Definition in file unarch_io.h.

Typedef Documentation

◆ unarch_read_fn

typedef size_t(* unarch_read_fn) (void *ctx, uint64_t offset, void *buf, size_t len)

Seek+read backing over an archive's bytes.

Identical in shape to comic_read_fn / ra8_rar_read_fn: an absolute offset plus a byte count in, bytes-actually-read out. A return shorter than len signals end-of-file (or a backing error); the decoders treat any short read fail-closed.

Parameters

[in]	ctx	Opaque backing context.
[in]	offset	Absolute byte offset within the archive.
[out]	buf	Destination buffer (`len` writable bytes).
[in]	len	Bytes requested.

Returns: Bytes actually read (0 at/after EOF or on error).

Note: Thread-safety follows the backing implementation.

Since: Version 0.1.0

Definition at line 55 of file unarch_io.h.

Function Documentation

◆ unarch_mem_read()

size_t unarch_mem_read	(	void *	ctx,
		uint64_t	offset,
		void *	buf,
		size_t	len )

nodiscard

unarch_read_fn over a flat unarch_mem_t view.

Serves [offset, offset + len) clamped to the view's bounds by plain copy. Reads at or past the end return 0 (EOF); a NULL context or view base also returns 0, which every decoder treats as a failed read (fail-closed).

Parameters

[in]	ctx	The unarch_mem_t view (may be NULL: reads 0).
[in]	offset	Absolute byte offset within the view.
[out]	buf	Destination buffer (`len` writable bytes, non-NULL).
[in]	len	Bytes requested.