Crate tar_no_std

source ·
Expand description

§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)

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

Look at the TarArchiveRef type.

§Limitations

This crate is simple and focuses on reading files and their content from a Tar archive. Historic basic Tar and ustar formats are supported. Other formats may work, but likely without all supported features. GNU Extensions such as sparse files, incremental archives, and long filename extension are not supported.

The maximum supported file name length is 256 characters excluding the NULL-byte (using the Tar name/prefix longname implementation of ustar). The maximum supported file size is 8GiB. Directories are supported, but only regular fields are yielded in iteration. The path is reflected in their file name.

§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

use tar_no_std::TarArchiveRef;

// init a logger (optional)
std::env::set_var("RUST_LOG", "trace");
env_logger::init();

// 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 Feature

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. The unstable feature provides additional convenience only available on the nightly channel.

§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 1.76.0 stable.

Structs§

Enums§

  • ModeError
    Errors that may happen when parsing the ModeFlags.
  • TypeFlag
    Describes the kind of payload, that follows after a PosixHeader. The properties of this payload are described inside the header.

Constants§

  • MIN_BLOCK_COUNT
    Minimum amount of blocks that an archive must have to be considered sane.