dlopen-rs

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A pure-rust library designed for loading ELF dynamic libraries from memory or from files.

This library serves three purposes:

1. Provide a pure Rust alternative to musl/glibc ld.so.
2. Provide loading ELF dynamic libraries support for #![no_std] targets.
3. Easily swap out symbols in shared libraries with your own custom symbols at runtime

Additional, it integrates seamlessly with the system’s dynamic linker in std environments when the ldso feature is enabled. Currently, it supports x86_64, x86, RV64, and AArch64 architectures.

Feature

Examples

Example 1

Fine-grained control over the dynamic library loading process:

use dlopen_rs::ELFLibrary;
use nix::libc::size_t;
use std::{ffi::c_void, path::Path};

extern "C" fn mymalloc(size: size_t) -> *mut c_void {
    println!("malloc:{}bytes", size);
    unsafe { nix::libc::malloc(size) }
}

fn main() {
    let path = Path::new("./target/release/libexample.so");
    let libc = ELFLibrary::sys_load("libc.so.6").unwrap();
    let libgcc = ELFLibrary::sys_load("libgcc_s.so.1").unwrap();
    let libexample = ELFLibrary::from_file(path)
        .unwrap()
        .relocate_with_func(&[libc, libgcc], |name| {
            if name == "malloc" {
                return Some(mymalloc as _);
            } else {
                return None;
            }
        })
        .unwrap();
    let add = unsafe {
        libexample
            .get::<fn(i32, i32) -> i32>("add")
            .unwrap()
    };
    println!("{}", f(1,1));

    let print = unsafe {
        libexample
            .get::<fn(&str)>("print")
            .unwrap()
    };
    f("dlopen-rs: hello world!");
}

Example 2

Set the path to load the dynamic library:

export RUST_LD_LIBRARY_PATH=/lib32

Load dynamic libraries using the dlopen interface:

use dlopen_rs::ELFLibrary;
use std::path::Path;

fn main() {
    let path = Path::new("./target/release/libexample.so");
    let libexample = ELFLibrary::dlopen(path).unwrap();
    let add = unsafe { libexample.get::<fn(i32, i32) -> i32>("add").unwrap() };
    println!("{}", add(1, 1));

    let print = unsafe { libexample.get::<fn(&str)>("print").unwrap() };
    print("dlopen-rs: hello world");
}

NOTE

If you encounter any issues while using it or need any new features, feel free to raise an issue on GitHub.