bindgen automatically generates Rust FFI bindings to C and C++ libraries.

For example, given the C header cool.h:

typedef struct CoolStruct {
    int x;
    int y;
} CoolStruct;

void cool_function(int i, char c, CoolStruct* cs);

bindgen produces Rust FFI code allowing you to call into the cool library's functions and use its types:

# #![allow(unused_variables)]
#fn main() {
/* automatically generated by rust-bindgen */

#[repr(C)]
pub struct CoolStruct {
    pub x: ::std::os::raw::c_int,
    pub y: ::std::os::raw::c_int,
}

extern "C" {
    pub fn cool_function(i: ::std::os::raw::c_int,
                         c: ::std::os::raw::c_char,
                         cs: *mut CoolStruct);
}
#}