genode/base/include/base/capability.h
2012-01-03 15:35:05 +01:00

292 lines
8.4 KiB
C++

/*
* \brief Capability
* \author Norman Feske
* \date 2011-05-22
*
* A typed capability is a capability tied to one specifiec RPC interface
*/
/*
* Copyright (C) 2011-2012 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__BASE__CAPABILITY_H_
#define _INCLUDE__BASE__CAPABILITY_H_
#include <util/string.h>
#include <base/rpc.h>
#include <base/native_types.h>
namespace Genode {
/**
* Forward declaration needed for internal interfaces of 'Capability'
*/
class Ipc_client;
/**
* Capability that is not associated with a specific RPC interface
*/
typedef Native_capability Untyped_capability;
/**
* Capability referring to a specific RPC interface
*
* \param RPC_INTERFACE class containing the RPC interface declaration
*/
template <typename RPC_INTERFACE>
class Capability : public Untyped_capability
{
private:
/**
* Insert RPC arguments into the message buffer
*/
template <typename ATL>
void _marshal_args(Ipc_client &ipc_client, ATL &args);
void _marshal_args(Ipc_client &, Meta::Empty &) { }
/**
* Unmarshal single RPC argument from the message buffer
*/
template <typename T>
void _unmarshal_result(Ipc_client &ipc_client, T &arg,
Meta::Overload_selector<Rpc_arg_out>);
template <typename T>
void _unmarshal_result(Ipc_client &ipc_client, T &arg,
Meta::Overload_selector<Rpc_arg_inout>);
template <typename T>
void _unmarshal_result(Ipc_client &, T &arg,
Meta::Overload_selector<Rpc_arg_in>) { }
/**
* Read RPC results from the message buffer
*/
template <typename ATL>
void _unmarshal_results(Ipc_client &ipc_client, ATL &args);
void _unmarshal_results(Ipc_client &, Meta::Empty &) { }
/**
* Check RPC return code for the occurrence of exceptions
*
* A server-side exception is indicated by a non-zero exception
* code. Each exception code corresponds to an entry in the
* exception type list specified in the RPC function declaration.
* The '_check_for_exception' function template throws the
* exception type belonging to the received exception code.
*/
template <typename EXC_TL>
void _check_for_exceptions(Rpc_exception_code const exc_code,
Meta::Overload_selector<EXC_TL>)
{
enum { EXCEPTION_CODE = RPC_EXCEPTION_BASE - Meta::Length<EXC_TL>::Value };
if (exc_code == EXCEPTION_CODE)
throw typename EXC_TL::Head();
_check_for_exceptions(exc_code, Meta::Overload_selector<typename EXC_TL::Tail>());
}
void _check_for_exceptions(Rpc_exception_code const,
Meta::Overload_selector<Meta::Empty>) { }
/**
* Perform RPC call, arguments passed a as nested 'Ref_tuple' object
*/
template <typename IF>
void _call(typename IF::Client_args &args, typename IF::Ret_type &ret);
/**
* Shortcut for querying argument types used in 'call' functions
*/
template <typename IF, unsigned I>
struct Arg
{
typedef typename Meta::Type_at<typename IF::Client_args, I>::Type Type;
};
template <typename FROM_RPC_INTERFACE>
Untyped_capability
_check_compatibility(Capability<FROM_RPC_INTERFACE> const &cap)
{
FROM_RPC_INTERFACE *from = 0;
RPC_INTERFACE *to = from;
(void)to;
return cap;
}
public:
typedef RPC_INTERFACE Rpc_interface;
/**
* Constructor
*
* This implicit constructor checks at compile time for the
* compatibility of the source and target capability types. The
* construction is performed only if the target capability type is
* identical to or a base type of the source capability type.
*/
template <typename FROM_RPC_INTERFACE>
Capability(Capability<FROM_RPC_INTERFACE> const &cap)
: Untyped_capability(_check_compatibility(cap))
{ }
/**
* Default constructor creates invalid capability
*/
Capability() { }
/*
* Suppress warning about uninitialized 'ret' variable in 'call'
* functions on compilers that support the #praga. If this is
* not the case, the pragma can be masked by supplying the
* 'SUPPRESS_GCC_PRAGMA_WUNINITIALIZED' define to the compiler.
*/
#ifndef SUPPRESS_GCC_PRAGMA_WUNINITIALIZED
#pragma GCC diagnostic ignored "-Wuninitialized" call();
#endif
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call()
{
Meta::Empty e;
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(e, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1)
{
Meta::Empty e;
typename IF::Client_args args(v1, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1, typename Arg<IF, 1>::Type v2)
{
Meta::Empty e;
typename IF::Client_args args(v1, v2, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1, typename Arg<IF, 1>::Type v2,
typename Arg<IF, 2>::Type v3)
{
Meta::Empty e;
typename IF::Client_args args(v1, v2, v3, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1, typename Arg<IF, 1>::Type v2,
typename Arg<IF, 2>::Type v3, typename Arg<IF, 3>::Type v4)
{
Meta::Empty e;
typename IF::Client_args args(v1, v2, v3, v4, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1, typename Arg<IF, 1>::Type v2,
typename Arg<IF, 2>::Type v3, typename Arg<IF, 3>::Type v4,
typename Arg<IF, 4>::Type v5)
{
Meta::Empty e;
typename IF::Client_args args(v1, v2, v3, v4, v5, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1, typename Arg<IF, 1>::Type v2,
typename Arg<IF, 2>::Type v3, typename Arg<IF, 3>::Type v4,
typename Arg<IF, 4>::Type v5, typename Arg<IF, 5>::Type v6)
{
Meta::Empty e;
typename IF::Client_args args(v1, v2, v3, v4, v5, v6, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
template <typename IF>
typename Trait::Call_return<typename IF::Ret_type>::Type
call(typename Arg<IF, 0>::Type v1, typename Arg<IF, 1>::Type v2,
typename Arg<IF, 2>::Type v3, typename Arg<IF, 3>::Type v4,
typename Arg<IF, 4>::Type v5, typename Arg<IF, 5>::Type v6,
typename Arg<IF, 6>::Type v7)
{
Meta::Empty e;
typename IF::Client_args args(v1, v2, v3, v4, v5, v6, v7, e);
typename Trait::Call_return<typename IF::Ret_type>::Type ret;
_call<IF>(args, ret);
return ret;
}
};
/**
* Convert an untyped capability to a typed capability
*/
template <typename RPC_INTERFACE>
Capability<RPC_INTERFACE>
reinterpret_cap_cast(Untyped_capability const &untyped_cap)
{
Capability<RPC_INTERFACE> typed_cap;
/*
* The object layout of untyped and typed capabilities is identical.
* Hence we can use memcpy to load the values of the supplied untyped
* capability into a typed capability.
*/
::Genode::memcpy(&typed_cap, &untyped_cap, sizeof(untyped_cap));
return typed_cap;
}
/**
* Convert capability type from an interface base type to an inherited
* interface type
*/
template <typename TO_RPC_INTERFACE, typename FROM_RPC_INTERFACE>
Capability<TO_RPC_INTERFACE>
static_cap_cast(Capability<FROM_RPC_INTERFACE> cap)
{
/* check interface compatibility */
(void)static_cast<TO_RPC_INTERFACE *>((FROM_RPC_INTERFACE *)0);
return reinterpret_cap_cast<TO_RPC_INTERFACE>(cap);
}
}
#endif /* _INCLUDE__BASE__CAPABILITY_H_ */