I'm currently developing a plugin loading system that utilizes C++ Boost to load Rust cdylib modules. Everything is functioning correctly, except when I invoke panic!() within a cdylib. The panic originates from a separate thread, leading to the termination of the entire application. I'm actively seeking solutions to prevent the main application from being affected. Does anyone have suggestions on how to accomplish this?
Plugin lib.rs
struct FirstPlugin;
impl Plugin for FirstPlugin {
fn load(&mut self) {
println!("Load");
panic!("Test");
}
fn unload(&mut self) {
println!("Unload")
}
}
impl Default for FirstPlugin {
fn default() -> Self {
Self { }
}
}
#[no_mangle]
#[link_section = ".vtable"]
pub unsafe extern "C" fn __FIRST_PLUGIN_VTABLE() -> ffi::PluginVTable {
ffi::PluginVTable::new::<FirstPlugin>()
}
FFI Vtable
#[repr(C)]
#[derive(Clone, Copy)]
pub struct PluginVTable {
// Construct and destruct
pub construct: extern fn() -> *mut(),
pub destruct: extern fn(*mut()),
// Member methods
pub load: extern fn(*mut ()),
pub unload: extern fn(*mut ())
}
impl PluginVTable {
pub unsafe fn new<T: Plugin>() -> PluginVTable {
PluginVTable {
construct: std::mem::transmute(PluginVTable::construct::<T> as *mut()),
destruct: std::mem::transmute(PluginVTable::destruct::<T> as *mut()),
load: std::mem::transmute(T::load as *mut()),
unload: std::mem::transmute(T::unload as *mut())
}
}
fn construct<T: Plugin>() -> *mut T {
let plugin = Box::new(T::default());
Box::into_raw(plugin)
}
unsafe fn destruct<T: Plugin>(plugin: *mut T) {
let _ = Box::from_raw(plugin);
}
}
Creating thread and call method
pub struct PluginInstance {
instance: Option<std::thread::JoinHandle<PluginData>>
}
impl PluginInstance {
fn new(vtable: PluginVTable) -> Self {
let instance = std::thread::spawn(move||{
PluginInstance::instance_thread(vtable)
});
Self { instance: Some(instance) }
}
fn instance_thread(vtable: PluginVTable) -> PluginData {
let ptr = (vtable.construct)();
(vtable.load)(ptr);
//std::thread::park();
//(vtable.unload)(ptr);
//(vtable.destruct)(ptr);
PluginData
}
}
impl From<PluginVTable> for PluginInstance {
fn from(vtable: PluginVTable) -> Self {
PluginInstance::new(vtable)
}
}
impl Drop for PluginInstance {
fn drop(&mut self) {
println!("Dropping instance")
//if let Some(instance) = self.instance.take() {
// instance.thread().unpark();
// match instance.join() {
// Ok(data) => println!("Plugin ended succesfully {:?}", data),
// Err(e) => println!("Plugin ended with an error {:?}", e),
//}
//}
}
}
Output with backtrace
Finished dev [unoptimized + debuginfo] target(s) in 0.09s
Running `target\debug\plug.exe`
Load
thread '<unnamed>' panicked at 'Test', src\lib.rs:8:9
stack backtrace:
0: 0x7ffe7135871c - std::sys_common::backtrace::_print::impl$0::fmt
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\sys_common\backtrace.rs:44
1: 0x7ffe7136712b - core::fmt::rt::Argument::fmt
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\core\src\fmt\rt.rs:138
2: 0x7ffe7136712b - core::fmt::write
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\core\src\fmt\mod.rs:1094
3: 0x7ffe713569ef - std::io::Write::write_fmt<std::sys::windows::stdio::Stderr>
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\io\mod.rs:1714
4: 0x7ffe713584cb - std::sys_common::backtrace::_print
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\sys_common\backtrace.rs:47
5: 0x7ffe713584cb - std::sys_common::backtrace::print
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\sys_common\backtrace.rs:34
6: 0x7ffe7135a19a - std::panicking::default_hook::closure$1
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\panicking.rs:269
7: 0x7ffe71359def - std::panicking::default_hook
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\panicking.rs:288
8: 0x7ffe7135a84e - std::panicking::rust_panic_with_hook
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\panicking.rs:705
9: 0x7ffe7135a6fa - std::panicking::begin_panic_handler::closure$0
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\panicking.rs:595
10: 0x7ffe71359099 - std::sys_common::backtrace::__rust_end_short_backtrace<std::panicking::begin_panic_handler::closure_env$0,never$>
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\sys_common\backtrace.rs:151
11: 0x7ffe7135a440 - std::panicking::begin_panic_handler
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\panicking.rs:593
12: 0x7ffe7136c1d5 - core::panicking::panic_fmt
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\core\src\panicking.rs:67
13: 0x7ffe71351886 - first::impl$0::load
at C:\Users\Johnny\Desktop\plug-rs\plugins\first\src\lib.rs:8
14: 0x7ff79719425b - plug_loader::PluginInstance::instance_thread
at C:\Users\Johnny\Desktop\plug-rs\loader\src\lib.rs:29
15: 0x7ff797198001 - plug_loader::impl$0::new::closure$0
at C:\Users\Johnny\Desktop\plug-rs\loader\src\lib.rs:19
16: 0x7ff797199339 - std::sys_common::backtrace::__rust_begin_short_backtrace<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData>
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\std\src\sys_common\backtrace.rs:135
17: 0x7ff797199339 - std::sys_common::backtrace::__rust_begin_short_backtrace<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData>
19: 0x7ff797199371 - core::panic::unwind_safe::impl$23::call_once<plug_loader::PluginData,std::thread::impl$0::spawn_unchecked_::closure$1::closure_env$0<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData> >
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\core\src\panic\unwind_safe.rs:271
20: 0x7ff79719651a - std::panicking::try::do_call<core::panic::unwind_safe::AssertUnwindSafe<std::thread::impl$0::spawn_unchecked_::closure$1::closure_env$0<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData> >,plug_loader::PluginData>
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\std\src\panicking.rs:500
21: 0x7ff7971966d3 - std::panicking::try::do_catch<core::panic::unwind_safe::AssertUnwindSafe<std::thread::impl$7::drop::closure_env$0<plug_loader::PluginData> >,tuple$<> >
22: 0x7ff7971963f4 - std::panicking::try<plug_loader::PluginData,core::panic::unwind_safe::AssertUnwindSafe<std::thread::impl$0::spawn_unchecked_::closure$1::closure_env$0<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData> > >
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\std\src\panicking.rs:464
23: 0x7ff797195289 - std::panic::catch_unwind
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\std\src\panic.rs:142
24: 0x7ff797195289 - std::thread::impl$0::spawn_unchecked_::closure$1<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData>
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\std\src\thread\mod.rs:528
25: 0x7ff79719228e - core::ops::function::FnOnce::call_once<std::thread::impl$0::spawn_unchecked_::closure_env$1<plug_loader::impl$0::new::closure_env$0,plug_loader::PluginData>,tuple$<> >
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be\library\core\src\ops\function.rs:250
26: 0x7ff7971a837c - std::sys::windows::thread::impl$0::new::thread_start
at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library\std\src\sys\windows\thread.rs:57
27: 0x7ffeb600257d - BaseThreadInitThunk
28: 0x7ffeb758aa58 - RtlUserThreadStart
fatal runtime error: Rust cannot catch foreign exceptions
error: process didn't exit successfully: `target\debug\plug.exe` (exit code: 0xc0000409, STATUS_STACK_BUFFER_OVERRUN)
I tried using both panic=abort and panic=unwind. Also tried wrapping the (vtable.load)(ptr) with std::panic::catch_unwind.
Solved by wrapping function pointers with catch_unwind before adding them to the vtable.
pub unsafe fn new<T: Plugin>() -> PluginVTable {
PluginVTable {
load: std::mem::transmute(PluginVTable::load::<T> as *mut())
}
}
unsafe fn load<T: Plugin>(ptr: *mut T) -> *mut() {
match catch_unwind(||{ T::load(&mut *ptr) }) {
Ok(_) => std::ptr::null_mut(),
Err(e) => Box::into_raw(e) as *mut(),
}
}
The panic can then be resumed by the caller using resume_unwind.
let result = (vtable.load)(ptr) as *mut (dyn Any + Send);
if !result.is_null() {
std::panic::resume_unwind(Box::from_raw(result))
}