Build script to link against a .so file

[Shaenfre]

I am generating rust bindings for a c .so library using bindgen inside a build script
My build.rs file

    let curr_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
    println!(
         "cargo:rustc-link-search=native={}",
         curr_dir
     );


    println!("cargo:rustc-link-lib=dylib=my_library");
    
    let bindings = bindgen::Builder::default()
        .header("library_header.h")
        .generate()
        .expect("Unable to generate bindings");

    let out_path = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
    bindings
        .write_to_file(out_path.join("src/bindings.rs"))
        .expect("Couldn't write bindings!");

The bindings are generated correctly but when I am trying to use the library by running cargo test I am getting error

/target/debug/deps/rust-binary: error while loading shared libraries: my_library.so: cannot open shared object file: No such file or directory

I have created an env varible also export LD_LIBRARY_PATH= /path/to/my_library/ as suggested by @jofas
Weirdly when I place my .so file inside /usr/lib I am able to access the library functions. I am new to rust and ffi and I know I am doing something stupid. Can someone please help

[jofas]

You can generate your bindings, because you add

@Shaenfre

println!(
         "cargo:rustc-link-search=native={}",
         curr_dir
     );

to tell Cargo (which then tells rustc) where to look for the library. Because you are using a dynamically linked .so lib, you need to tell Cargo, or more precisely the linker, where to find the library at run time as well. One way is to put the library in a path where the linker can find it, as you already discovered. But you should also be able to use LD_LIBRARY_PATH or pass -L native=path/to/your/lib to rustc via the build.rustflags of your Cargo configuration file.

[Shaenfre]

Thanks for your reply. I tried

[build]
rustflags = ["-L", "native=my_library/"]

And I tried

export LD_LIBRARY_PATH= /path/to/my_library/
cargo test -- --nocapture 

I tried by providing both absolute and relative path above.
I then ran cargo build and then cargo test

But still I am getting the same error

[jonh]

Make sure the file name starts with lib end .so and in-between matches case of what you have written.

[Shaenfre]

thanks for your reply
yes my library name follows what you mentioned.
but still I am facing the problem

[Shaenfre]

Putting this in build.rs worked for me

    println!("cargo:rustc-env=LD_LIBRARY_PATH=absolute/path/to/my_library");