6b289a1423
This patch replaces the former prominent use of pointers by references wherever feasible. This has the following benefits: * The contract between caller and callee becomes more obvious. When passing a reference, the contract says that the argument cannot be a null pointer. The caller is responsible to ensure that. Therefore, the use of reference eliminates the need to add defensive null-pointer checks at the callee site, which sometimes merely exist to be on the safe side. The bottom line is that the code becomes easier to follow. * Reference members must be initialized via an object initializer, which promotes a programming style that avoids intermediate object- construction states. Within core, there are still a few pointers as member variables left though. E.g., caused by the late association of 'Platform_thread' objects with their 'Platform_pd' objects. * If no pointers are present as member variables, we don't need to manually provide declarations of a private copy constructor and an assignment operator to avoid -Weffc++ errors "class ... has pointer data members [-Werror=effc++]". This patch also changes a few system bindings on NOVA and Fiasco.OC, e.g., the return value of the global 'cap_map' accessor has become a reference. Hence, the patch touches a few places outside of core. Fixes #3135
83 lines
1.7 KiB
C++
83 lines
1.7 KiB
C++
/*
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* \brief Kernel object handling in core
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* \author Stefan Kalkowski
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* \date 2015-04-21
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*/
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/*
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* Copyright (C) 2015-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _CORE__OBJECT_H_
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#define _CORE__OBJECT_H_
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/* Genode includes */
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#include <util/construct_at.h>
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/* base-internal includes */
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#include <base/internal/capability_space.h>
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/* base-hw includes */
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#include <kernel/interface.h>
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#include <kernel/object.h>
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namespace Genode {
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/**
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* Represents a kernel object in core
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*
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* \param T type of the kernel object
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*/
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template <typename T> class Kernel_object;
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}
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template <typename T>
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class Genode::Kernel_object
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{
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private:
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uint8_t _data[sizeof(Kernel::Core_object<T>)]
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__attribute__((aligned(sizeof(addr_t))));
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protected:
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Untyped_capability _cap { };
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public:
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Kernel_object() {}
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/**
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* Creates a kernel object either via a syscall or directly
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*/
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template <typename... ARGS>
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Kernel_object(bool syscall, ARGS &&... args)
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: _cap(Capability_space::import(syscall ? T::syscall_create(&_data, args...)
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: Kernel::cap_id_invalid()))
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{
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if (!syscall) construct_at<T>(&_data, args...);
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}
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~Kernel_object() { T::syscall_destroy(kernel_object()); }
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T * kernel_object() { return reinterpret_cast<T*>(_data); }
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Untyped_capability cap() { return _cap; }
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/**
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* Create the kernel object explicitely via this function
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*/
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template <typename... ARGS>
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bool create(ARGS &&... args)
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{
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if (_cap.valid()) return false;
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_cap = Capability_space::import(T::syscall_create(&_data, args...));
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return _cap.valid();
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}
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};
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#endif /* _CORE__OBJECT_H_ */
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