tar_no_std/

lib.rs

/*
MIT License

Copyright (c) 2025 Philipp Schuster

Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in all
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*/
//! # `tar-no-std` - Parse Tar Archives (Tarballs)
//!
//! _Due to historical reasons, there are several formats of Tar archives. All of
//! them are based on the same principles, but have some subtle differences that
//! often make them incompatible with each other._ [(reference)](https://www.gnu.org/software/tar/manual/html_section/Formats.html)
//!
//! Library to read Tar archives in `no_std` environments with zero allocations. If
//! you have a standard environment and need full feature support, I recommend the
//! use of <https://crates.io/crates/tar> instead.
//!
//! ## TL;DR
//!
//! Most ordinary Tar archives containing regular files will work.
//!
//! ## Limitations
//!
//! Archives created by a typical GNU tar or macOS `tar` invocation work when their
//! regular-file names and sizes fit in the regular Tar headers. This includes
//! basic Tar and ustar [archives](https://www.gnu.org/software/tar/manual/html_section/Formats.html),
//! as well as PAX archives that use extended records only for optional metadata
//! such as high-precision timestamps. PAX headers and their metadata are skipped;
//! the following regular-file headers provide the filenames and sizes.
//!
//! Archives that rely on unsupported extensions do not work correctly. This
//! includes GNU long names, sparse files, incremental archives, and PAX-only paths
//! or file sizes. The maximum supported filename length is 256 characters
//! excluding the NULL-byte, and the maximum supported file size is 8GiB.
//! Directories, links, and other special entries are skipped; iteration yields only
//! regular files, preserving directory paths encoded in their names.
//!
//! ## Use Case
//!
//! This library is useful, if you write a kernel or a similar low-level
//! application, which needs "a bunch of files" from an archive (like an
//! "init ramdisk"). The Tar file could for example come as a Multiboot2 boot module
//! provided by the bootloader.
//!
//! ## Example
//!
//! ```rust
//! use tar_no_std::TarArchiveRef;
//!
//! // also works in no_std environment (except the println!, of course)
//! let archive = include_bytes!("../tests/gnu_tar_default.tar");
//! let archive = TarArchiveRef::new(archive).unwrap();
//! // Vec needs an allocator of course, but the library itself doesn't need one
//! let entries = archive.entries().collect::<Vec<_>>();
//! println!("{:#?}", entries);
//! ```
//!
//! ## Cargo Features
//!
//! This crate allows the usage of the additional Cargo build time feature `alloc`.
//! When this is active, the crate also provides the type `TarArchive`, which owns
//! the data on the heap.
//!
//! ## Compression (`tar.gz`)
//!
//! If your Tar file is compressed, e.g. by `.tar.gz`/`gzip`, you need to uncompress
//! the bytes first (e.g. by a *gzip* library). Afterwards, this crate can read the
//! Tar archive format from the uncompressed bytes.
//!
//! ## MSRV
//!
//! The MSRV is 1.85.0 stable.

#![cfg_attr(not(test), no_std)]
#![deny(
    clippy::all,
    clippy::cargo,
    clippy::nursery,
    clippy::must_use_candidate,
    clippy::undocumented_unsafe_blocks
)]
#![deny(missing_debug_implementations)]
#![deny(rustdoc::all)]

#[cfg_attr(test, macro_use)]
#[cfg(test)]
extern crate std;

#[cfg(feature = "alloc")]
extern crate alloc;

/// Each Archive Entry (either Header or Data Block) is a block of 512 bytes.
const BLOCKSIZE: usize = 512;
/// Maximum filename length of the base Tar format including the terminating NULL-byte.
const NAME_LEN: usize = 100;
/// Maximum long filename length of the base Tar format including the prefix
const POSIX_1003_MAX_FILENAME_LEN: usize = 256;
/// Maximum length of the prefix in Posix tar format
const PREFIX_LEN: usize = 155;

mod archive;
mod header;
mod tar_format_types;

pub use archive::*;
pub use header::*;
pub use tar_format_types::*;