抓紧恐慌！当Rust从C FFI调用时，没有生成线程 [英] Catching panic! when Rust called from C FFI, without spawning threads

问题描述

我正在研究用于Duktape JavaScript解释器的锈纸包装器。在正常使用情况下，调用堆栈将如下所示：

I'm working on a Rust wrapper for the Duktape JavaScript interpreter. In a normal use case, the call stack will look like this:

1. Rust：任意应用程序代码。


2. Rust：我的库包装。


3. C：Duktape解释器。


4. Rust：我的Rust代码。


5. Rust：任意回调到应用程序代码中。

1. Rust: Arbitrary application code.
2. Rust: My library wrapper.
3. C: The Duktape interpreter.
4. Rust: My Rust code.
5. Rust: Arbitrary callbacks into application code.

如果（5）调用 panic，会发生什么情况！ ？根据IRC上各种Rust开发人员的说法，尝试从非Rust调用框架（如（3））中 panic！可能导致不确定的行为。

What happens if (5) calls panic!? According to various Rust developers on IRC, attempting to panic! from inside non-Rust callframes like (3) may result in undefined behavior.

但是根据Rust文档，捕获恐慌的唯一方法！是使用 std :: task :: try ，这会产生一个额外的线程。还有 rustrt :: unwind :: try ，它不能在单个线程中嵌套两次，还有其他限制。

But according the Rust documentation, the only way to catch a panic! is using std::task::try, which spawns an extra thread. There's also rustrt::unwind::try, which cannot be nested twice within a single thread, among other restrictions.

本杰明·赫尔（Benjamin Herr）提出的一种解决方案是，如果代码无效，则中止该进程在（5）恐慌中。我将他的解决方案打包为 abort_on_panic ，工作，对于工作的值包括使整个程序崩溃，但至少不会巧妙地破坏：

One solution, proposed by Benjamin Herr, is to abort the process if the code in (5) panics. I've packaged his solution as abort_on_panic, and it appears to work, for values of "work" that include "crashing the entire program, but at least not corrupting things subtly":

abort_on_panic!("cannot panic inside this block", {
    panic!("something went wrong!");
});

但这是一种模拟 std :: task :: try 的方法code>没有创建线程/任务的开销？

But is a way to emulate std::task::try without the overhead of thread/task creation?

推荐答案

从Rust 1.9.0开始，您可以使用< a href = https://doc.rust-lang.org/std/panic/fn.catch_unwind.html rel = nofollow noreferrer> panic :: catch_unwind 恢复错误：

As of Rust 1.9.0, you can use panic::catch_unwind to recover the error:

use std::panic;

fn main() {
    let result = panic::catch_unwind(|| {
        panic!("oh no!");
    });
    assert!(result.is_err());
}

通过 panic :: resume_unwind ：

use std::panic;

fn main() {
    let result = panic::catch_unwind(|| {
        panic!("oh no!");
    });

    if let Err(e) = result {
        panic::resume_unwind(e);
    }
}

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