rust-elf

The elf crate provides a pure-rust interface for reading ELF object files.

Documentation

Capabilities

Contains no unsafe code: Many of the other rust ELF parsers out there contain bits of unsafe code deep down or in dependencies to reinterpret/transmute byte contents as structures in order to drive zero-copy parsing. They're slick, and that also introduces unsafe code blocks (albeit small ones). This crate strives to serve as an alternate implementation with zero unsafe code blocks.

Endian-aware: This crate properly handles translating between file and host endianness when parsing the ELF contents.

Lazy parsing: This crate strives for lazy evaluation and parsing when possible. For example, the SymbolTable simply acts as an interpretation layer on top of a &[u8]. Parsing of Symbols takes place only when symbols are requested.

Tiny compiled library size: At the time of writing this, the release crate was only ~30kB!

Future plans

Add no_std option: Currently, the main impediment to a no_std option is the use of allocating datastructures, such as the parsed section contents' Vec<u8>.

Lazily loading section contents: Currently, all of the section data is read from the input stream into allocated Vec<u8> when the stream is opened. This can be unnecessarily expensive for use-cases that don't need to inspect all the section contents.

A potential future vision for both of these issues is to rework the parsing code's reader trait implementations to provide two options:

• A wrapper around a &[u8] which already contains the full ELF contents. This could be used for a no_std option where we want to simply parse out the ELF structures from the existing data without needing to heap-allocate buffers in which to store the reads.
• An allocating CachedReader type which wraps a stream which can allocate and remember Vec<u8> buffers in which to land the data from file reads.

The former no_std option is useful when you need no_std, however it forces the user to invoke the performance penalty of reading the entire file contents up front.

The latter option is useful for use-cases that only want to interpret parts of an ELF object, where allocating buffers to store the reads is a much smaller cost than reading in the whole large object contents.

Example:

extern crate elf;

fn main() {
    let path: std::path::PathBuf = From::from("some_file");
    let mut io = match std::fs::File::open(path) {
        Ok(f) => f,
        Err(e) => panic!("Error: {:?}", e),
    };

    let elf_file = match elf::File::open_stream(&mut io) {
        Ok(f) => f,
        Err(e) => panic!("Error: {:?}", e),
    };

    println!("ELF: {}", elf_file.ehdr);

    let text_scn = match elf_file.sections.get_by_name(".text") {
        Some(s) => s,
        None => panic!("Failed to find .text section"),
    };

    println!("{:?}", text_scn.data);
}