我正在尝试从 C++ 调用一些用 Rust 编写的函数。到目前为止,我已经相当成功,但我仍然有一个小问题CString
运行时相关的恐慌。
功能hello
应该接受一个输入字符串,将其与其他字符串连接起来并返回结果。
这是我的fun.rs
:
use std::ffi::CString;
#[no_mangle]
pub extern "C" fn add(a: i32, b: i32) -> i32 {
a + b
}
#[no_mangle]
pub extern "C" fn hello(cs: CString) -> CString {
let slice = cs.to_str().unwrap();
let mut s = "Hello, ".to_string();
s = s + slice;
CString::new(&s[..]).unwrap() // runtime error
// CString::new(cs).unwrap() // empty string if no borrow
// cs // works if no borrow, but this is not what I meant
}
Here's main.cpp
:
#include <iostream>
using namespace std;
extern "C" {
int add(int a, int b);
const char* hello(const char*x);
}
int main()
{
int a, b;
cin >> a >> b;
cout << add(a,b) << ";" << hello("Pawel") << std::endl;
return 0;
}
And makefile
:
rust:
rustc --crate-type=staticlib -C panic=abort fun.rs
cpp:
g++ -c main.cpp
link:
g++ main.o -L . libfun.a -o main -lpthread -ldl -lgcc_s -lc -lm -lrt -lutil
运行可执行文件的命令:
$ make rust
$ make cpp
$ make link
$ ./main
1 2
可执行输出:
1 2
thread '<unnamed>' panicked at 'index 18446744073709551615 out of range for slice of length 0', ../src/libcore/slice.rs:549
note: Run with `RUST_BACKTRACE=1` for a backtrace..
回溯:
stack backtrace:
1: 0x435d4f - std::sys::backtrace::tracing::imp::write::h46e546df6e4e4fe6
2: 0x44405b - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::h077deeda8b799591
3: 0x443c8f - std::panicking::default_hook::heb8b6fd640571a4f
4: 0x4099fe - std::panicking::rust_panic_with_hook::hd7b83626099d3416
5: 0x4442a1 - std::panicking::begin_panic::h941ea76fc945d925
6: 0x40b74a - std::panicking::begin_panic_fmt::h30280d4dd3f149f5
7: 0x44423e - rust_begin_unwind
8: 0x451d8f - core::panicking::panic_fmt::h2d3cc8234dde51b4
9: 0x452073 - core::slice::slice_index_len_fail::ha4faf37254d75f20
10: 0x40e903 - std::ffi::c_str::CStr::to_str::ha9642252376bab15
11: 0x4048e0 - hello
12: 0x40476f - main
13: 0x7f78ff688f44 - __libc_start_main
14: 0x404678 - <unknown>
15: 0x0 - <unknown>
有什么想法让 Rust 如此恐慌吗?