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[rust.git] / src / libpanic_unwind / emcc.rs

diff --git a/src/libpanic_unwind/emcc.rs b/src/libpanic_unwind/emcc.rs
index 3d0d5a4151eed925b1716bf0e8a9a22b86f559a1..fbadf4ac6a058dd50e1d4a01789c917f3132b600 100644 (file)
--- a/src/libpanic_unwind/emcc.rs
+++ b/src/libpanic_unwind/emcc.rs
@@ -8,10 +8,10 @@
 
 #![allow(private_no_mangle_fns)]
 
+use alloc::boxed::Box;
 use core::any::Any;
-use core::ptr;
 use core::mem;
-use alloc::boxed::Box;
+use core::ptr;
 use libc::{self, c_int};
 use unwind as uw;
 
@@ -52,32 +52,47 @@ pub fn payload() -> *mut u8 {
     ptr::null_mut()
 }
 
+struct Exception {
+    // This needs to be an Option because the object's lifetime follows C++
+    // semantics: when catch_unwind moves the Box out of the exception it must
+    // still leave the exception object in a valid state because its destructor
+    // is still going to be called by __cxa_end_catch..
+    data: Option<Box<dyn Any + Send>>,
+}
+
 pub unsafe fn cleanup(ptr: *mut u8) -> Box<dyn Any + Send> {
     assert!(!ptr.is_null());
-    let adjusted_ptr = __cxa_begin_catch(ptr as *mut libc::c_void);
-    let ex = ptr::read(adjusted_ptr as *mut _);
+    let adjusted_ptr = __cxa_begin_catch(ptr as *mut libc::c_void) as *mut Exception;
+    let ex = (*adjusted_ptr).data.take();
     __cxa_end_catch();
-    ex
+    ex.unwrap()
 }
 
 pub unsafe fn panic(data: Box<dyn Any + Send>) -> u32 {
     let sz = mem::size_of_val(&data);
-    let exception = __cxa_allocate_exception(sz);
-    if exception == ptr::null_mut() {
+    let exception = __cxa_allocate_exception(sz) as *mut Exception;
+    if exception.is_null() {
         return uw::_URC_FATAL_PHASE1_ERROR as u32;
     }
-    ptr::write(exception as *mut _, data);
-    __cxa_throw(exception as *mut _, &EXCEPTION_TYPE_INFO, ptr::null_mut());
+    ptr::write(exception, Exception { data: Some(data) });
+    __cxa_throw(exception as *mut _, &EXCEPTION_TYPE_INFO, exception_cleanup);
+
+    extern "C" fn exception_cleanup(ptr: *mut libc::c_void) {
+        unsafe {
+            ptr::drop_in_place(ptr as *mut Exception);
+        }
+    }
 }
 
 #[lang = "eh_personality"]
 #[no_mangle]
-unsafe extern "C" fn rust_eh_personality(version: c_int,
-                                         actions: uw::_Unwind_Action,
-                                         exception_class: uw::_Unwind_Exception_Class,
-                                         exception_object: *mut uw::_Unwind_Exception,
-                                         context: *mut uw::_Unwind_Context)
-                                         -> uw::_Unwind_Reason_Code {
+unsafe extern "C" fn rust_eh_personality(
+    version: c_int,
+    actions: uw::_Unwind_Action,
+    exception_class: uw::_Unwind_Exception_Class,
+    exception_object: *mut uw::_Unwind_Exception,
+    context: *mut uw::_Unwind_Context,
+) -> uw::_Unwind_Reason_Code {
     __gxx_personality_v0(version, actions, exception_class, exception_object, context)
 }
 
@@ -85,13 +100,16 @@ pub unsafe fn panic(data: Box<dyn Any + Send>) -> u32 {
     fn __cxa_allocate_exception(thrown_size: libc::size_t) -> *mut libc::c_void;
     fn __cxa_begin_catch(thrown_exception: *mut libc::c_void) -> *mut libc::c_void;
     fn __cxa_end_catch();
-    fn __cxa_throw(thrown_exception: *mut libc::c_void,
-                   tinfo: *const TypeInfo,
-                   dest: *mut libc::c_void) -> !;
-    fn __gxx_personality_v0(version: c_int,
-                            actions: uw::_Unwind_Action,
-                            exception_class: uw::_Unwind_Exception_Class,
-                            exception_object: *mut uw::_Unwind_Exception,
-                            context: *mut uw::_Unwind_Context)
-                            -> uw::_Unwind_Reason_Code;
+    fn __cxa_throw(
+        thrown_exception: *mut libc::c_void,
+        tinfo: *const TypeInfo,
+        dest: extern "C" fn(*mut libc::c_void),
+    ) -> !;
+    fn __gxx_personality_v0(
+        version: c_int,
+        actions: uw::_Unwind_Action,
+        exception_class: uw::_Unwind_Exception_Class,
+        exception_object: *mut uw::_Unwind_Exception,
+        context: *mut uw::_Unwind_Context,
+    ) -> uw::_Unwind_Reason_Code;
 }