From 614b74c24bb80e17230e58a74ef5a4725972f84a Mon Sep 17 00:00:00 2001 From: Cobrand Date: Wed, 7 Dec 2016 18:43:07 +0100 Subject: [PATCH] Update book/ffi to use catch_unwind r? @GuillaumeGomez The doc mentioned to spawn a new thread instead of using catch_unwind, which has been the recommended way to catch panics for foreign function interfaces for a few releases now. --- src/doc/book/ffi.md | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/src/doc/book/ffi.md b/src/doc/book/ffi.md index 7510cd0b3b5..b53af694428 100644 --- a/src/doc/book/ffi.md +++ b/src/doc/book/ffi.md @@ -662,26 +662,31 @@ attribute turns off Rust's name mangling, so that it is easier to link to. It’s important to be mindful of `panic!`s when working with FFI. A `panic!` across an FFI boundary is undefined behavior. If you’re writing code that may -panic, you should run it in another thread, so that the panic doesn’t bubble up -to C: +panic, you should run it in a closure with [`catch_unwind()`]: ```rust -use std::thread; +use std::panic::catch_unwind; #[no_mangle] pub extern fn oh_no() -> i32 { - let h = thread::spawn(|| { + let result = catch_unwind(|| { panic!("Oops!"); }); - - match h.join() { - Ok(_) => 1, - Err(_) => 0, + match result { + Ok(_) => 0, + Err(_) => 1, } } -# fn main() {} + +fn main() {} ``` +Please note that [`catch_unwind()`] will only catch unwinding panics, not +those who abort the process. See the documentation of [`catch_unwind()`] +for more information. + +[`catch_unwind()`]: https://doc.rust-lang.org/std/panic/fn.catch_unwind.html + # Representing opaque structs Sometimes, a C library wants to provide a pointer to something, but not let you