redhook is a helper crate for writing interposition libraries
(LD_PRELOAD, DYLD_INSERT_LIBRARIES, etc.) in Rust.
To use redhook, add the lines
```rust
extern crate redhook; ```
to your library, then use the hook! macro to declare the function you
want to hook, and the name you want to give to your hook function:
rust
hook! {
fn existing_function(x: i32) -> i32 => my_function {
42
}
}
To access the underlying function, use real!(existing_function).
Compile your library as a dylib, which can be done via
rustc --crate-type=dylib, or by adding
[lib]
name = "mylib"
crate_type = ["dylib"]
to your Cargo.toml. Then find the resulting .so file (./mylib.so
for rustc, or inside target for Cargo) and set the LD_PRELOAD
environment variable to that.
There are a few examples included, as separate crates:
geofft@cactuar:~/src/rust/redhook/examples/readlinkspy$ cargo build
Compiling redhook v0.0.1 (file:///home/geofft/src/rust/redhook/examples/readlinkspy)
Compiling redhook_ex_readlinkspy v0.0.1 (file:///home/geofft/src/rust/redhook/examples/readlinkspy)
geofft@cactuar:~/src/rust/redhook/examples/readlinkspy$ LD_PRELOAD=target/debug/libreadlinkspy-7cb7c673fbb62878.so ls -l /bin/sh
readlink("/bin/sh")
lrwxrwxrwx 1 root root 4 Feb 19 2014 /bin/sh -> dash
geofft@cactuar:~/src/rust/redhook/examples/fakeroot$ cargo build
geofft@cactuar:~/src/rust/redhook/examples/fakeroot$ LD_PRELOAD=target/debug/libfakeroot-1be6565b67838e2e.so id
uid=0(root) gid=1001(geofft) euid=1001(geofft) groups=1001(geofft),27(sudo),111(sbuild)
At the moment, redhook only supports LD_PRELOAD on glibc, but support
for other platforms is planned.
redhook is named after the Red Hook
neighborhood in Brooklyn, New York. Portions of the implementation
borrow heavily from concepts in @Kimundi's
lazy_static! macro.
redhook is free software, available under the terms of the 2-clause BSD license.