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-- --
-- --
-- G N A T . C P P _ E X C E P T I O N S --
-- --
-- B o d y --
-- --
-- Copyright (C) 2013-2021, AdaCore --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
with System;
with System.Storage_Elements;
with Interfaces.C; use Interfaces.C;
with Ada.Unchecked_Conversion;
with System.Standard_Library; use System.Standard_Library;
package body GNAT.CPP_Exceptions is
-- Note: all functions prefixed by __cxa are part of the c++ ABI for
-- exception handling. As they are provided by the c++ library, there
-- must be no dependencies on it in the compiled code of this unit, but
-- there can be dependencies in instances. This is required to be able
-- to build the shared library without the c++ library.
function To_Exception_Data_Ptr is new
(Exception_Id, Exception_Data_Ptr);
-- Convert an Exception_Id to its non-private type. This is used to get
-- the RTTI of a C++ exception
function Get_Exception_Machine_Occurrence
(X : Exception_Occurrence) return System.Address;
pragma Import (Ada, Get_Exception_Machine_Occurrence,
-- Imported function (from Ada.Exceptions) that returns the machine
-- occurrence from an exception occurrence.
-- Raise_Cpp_Exception --
procedure Raise_Cpp_Exception (Id : Exception_Id; Value : T)
Id_Data : constant Exception_Data_Ptr := To_Exception_Data_Ptr (Id);
-- Get a non-private view on the exception
type T_Acc is access all T;
pragma Convention (C, T_Acc);
-- Access type to the object compatible with C
Occ : T_Acc;
-- The occurrence to propagate
function cxa_allocate_exception (Size : size_t) return T_Acc;
pragma Import (C, cxa_allocate_exception, "__cxa_allocate_exception");
-- The C++ function to allocate an occurrence
procedure cxa_throw (Obj : T_Acc; Tinfo : System.Address;
Dest : System.Address);
pragma Import (C, cxa_throw, "__cxa_throw");
pragma No_Return (cxa_throw);
-- The C++ function to raise an exception
-- Check the exception was imported from C++
if Id_Data.Lang /= 'C' then
raise Constraint_Error;
end if;
-- Allocate the C++ occurrence
Occ := cxa_allocate_exception (T'Size / System.Storage_Unit);
-- Set the object
Occ.all := Value;
-- Throw the exception
cxa_throw (Occ, Id_Data.Foreign_Data, System.Null_Address);
end Raise_Cpp_Exception;
-- Get_Object --
function Get_Object (X : Exception_Occurrence) return T
use System;
use System.Storage_Elements;
Unwind_Exception_Size : Natural;
pragma Import (C, Unwind_Exception_Size, "__gnat_unwind_exception_size");
-- Size in bytes of _Unwind_Exception
Exception_Addr : constant Address :=
Get_Exception_Machine_Occurrence (X);
-- Machine occurrence of X
-- Check the machine occurrence exists
if Exception_Addr = Null_Address then
raise Constraint_Error;
end if;
-- Import the object from the occurrence
Result : T;
pragma Import (Ada, Result);
for Result'Address use
Exception_Addr + Storage_Offset (Unwind_Exception_Size);
-- And return it
return Result;
end Get_Object;
end GNAT.CPP_Exceptions;