1. Cargo.toml

​x
[package]
name = "test_ffi"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
libc = "0.2.149"

2. src/main.rs

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use libc::{c_char, c_int, c_void};
use std::ffi::CString;

fn main() {
    unsafe {
        // 加载 C 库
        let path = CString::new("libc.so.6").unwrap();
        let lib = libc::dlopen(path.as_ptr(), libc::RTLD_LAZY);
        if lib.is_null() {
            panic!("Failed to open libc");
        }

        // 获取 C 库中的函数指针
        let puts = CString::new("puts").unwrap();
        let puts_fn: *mut c_void = libc::dlsym(lib, puts.as_ptr());
        if puts_fn.is_null() {
            let msg = libc::dlerror();
            if !msg.is_null() {
                let msg = std::ffi::CStr::from_ptr(msg).to_string_lossy().to_string();
                println!("Failed to find puts function: {}", msg);
            }
        }

        // 将函数指针转换为函数类型
        let puts: extern "C" fn(*const c_char) -> c_int = std::mem::transmute(puts_fn);

        // 调用 puts 函数
        let str = CString::new("Hello, World!\n").unwrap();
        puts(str.as_ptr());

        // 关闭 C 库
        libc::dlclose(lib);
    }
}