// vi:set ft=cpp: -*- Mode: C++ -*-
/**
 * \file
 * \brief Abstract capability-allocator interface
 */
/*
 * (c) 2009 Adam Lackorzynski <adam@os.inf.tu-dresden.de>,
 *          Alexander Warg <warg@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU General Public License 2.
 * Please see the COPYING-GPL-2 file for details.
 *
 * As a special exception, you may use this file as part of a free software
 * library without restriction.  Specifically, if other files instantiate
 * templates or use macros or inline functions from this file, or you compile
 * this file and link it with other files to produce an executable, this
 * file does not by itself cause the resulting executable to be covered by
 * the GNU General Public License.  This exception does not however
 * invalidate any other reasons why the executable file might be covered by
 * the GNU General Public License.
 */

#pragma once

#include <l4/sys/task>
#include <l4/sys/smart_capability>
#include <l4/re/consts>
#include <l4/cxx/type_traits>

namespace L4Re {

/**
 * \addtogroup l4re_cap_api
 */
/*@{*/
/**
 * \brief Capability allocator interface.
 */
class Cap_alloc
{
private:
  void operator = (Cap_alloc const &);

protected:
  Cap_alloc(Cap_alloc const &) {}
  Cap_alloc() {}

public:

  /**
   * \brief Allocate a capability
   * \return Capability of type void
   */
  virtual L4::Cap<void> alloc() noexcept = 0;
  virtual void take(L4::Cap<void> cap) noexcept = 0;

  /**
   * \brief Allocate a capability
   * \return Capability of type T
   */
  template< typename T >
  L4::Cap<T> alloc() noexcept
  { return L4::cap_cast<T>(alloc()); }

  /**
   * \brief Free a capability
   * \param cap          Capability to free.
   * \param task         If set, task to unmap the capability from.
   * \param unmap_flags  Flags for unmap, see l4_unmap_flags_t.
   */
  virtual void free(L4::Cap<void> cap, l4_cap_idx_t task = L4_INVALID_CAP,
                       unsigned unmap_flags = L4_FP_ALL_SPACES) noexcept = 0;
  virtual bool release(L4::Cap<void> cap, l4_cap_idx_t task = L4_INVALID_CAP,
                       unsigned unmap_flags = L4_FP_ALL_SPACES) noexcept = 0;

  /**
   * \brief Destructor.
   */
  virtual ~Cap_alloc() = 0;

  /**
   * \brief Construct an instance of a capability allocator.
   * \param ca  Capability allocator
   * \return Instance of a capability allocator.
   */
  template< typename CAP_ALLOC >
  static inline L4Re::Cap_alloc *
  get_cap_alloc(CAP_ALLOC &ca)
  {
    struct CA : public L4Re::Cap_alloc
    {
      CAP_ALLOC &_ca;
      L4::Cap<void> alloc() noexcept override { return _ca.alloc(); }
      void take(L4::Cap<void> cap) noexcept override { _ca.take(cap); }

      void free(L4::Cap<void> cap, l4_cap_idx_t task = L4_INVALID_CAP,
            unsigned unmap_flags = L4_FP_ALL_SPACES) noexcept override
      { _ca.free(cap, task, unmap_flags); }

      bool release(L4::Cap<void> cap, l4_cap_idx_t task,
                   unsigned unmap_flags) noexcept override
      { return _ca.release(cap, task, unmap_flags); }

      void operator delete(void *) {}

      CA(CAP_ALLOC &ca) : _ca(ca) {}
    };

    static CA _ca(ca);
    return &_ca;
  }
};

template<typename ALLOC>
struct Cap_alloc_t : ALLOC, L4Re::Cap_alloc
{
  template<typename ...ARGS>
  Cap_alloc_t(ARGS &&...args) : ALLOC(cxx::forward<ARGS>(args)...) {}

  L4::Cap<void> alloc() noexcept override { return ALLOC::alloc(); }
  void take(L4::Cap<void> cap) noexcept override { ALLOC::take(cap); }

  void free(L4::Cap<void> cap, l4_cap_idx_t task = L4_INVALID_CAP,
            unsigned unmap_flags = L4_FP_ALL_SPACES) noexcept override
  { ALLOC::free(cap, task, unmap_flags); }

  bool release(L4::Cap<void> cap, l4_cap_idx_t task,
               unsigned unmap_flags) noexcept override
  { return ALLOC::release(cap, task, unmap_flags); }

  void operator delete(void *) {}
};

inline
Cap_alloc::~Cap_alloc()
{}

extern Cap_alloc *virt_cap_alloc;

/**
 * \brief Helper for Unique_cap and Unique_del_cap
 * \ingroup api_l4re_util
 */
template< unsigned long Unmap_flags = L4_FP_ALL_SPACES >
class Smart_cap_auto
{
private:
  Cap_alloc *_ca;

public:
  Smart_cap_auto() : _ca(0) {}
  Smart_cap_auto(Cap_alloc *ca) : _ca(ca) {}

  void free(L4::Cap_base &c)
  {
    if (c.is_valid() && _ca)
      _ca->free(L4::Cap<void>(c.cap()), This_task, Unmap_flags);

    invalidate(c);
  }

  static void invalidate(L4::Cap_base &c)
  {
    if (c.is_valid())
      c.invalidate();
  }

  static L4::Cap_base copy(L4::Cap_base const &src)
  {
    L4::Cap_base r = src;
    invalidate(const_cast<L4::Cap_base &>(src));
    return r;
  }
};

/**
 * Helper for Ref_cap and Ref_del_cap.
 */
template< unsigned long Unmap_flags = L4_FP_ALL_SPACES >
class Smart_count_cap
{
private:
  Cap_alloc *_ca;

public:
  Smart_count_cap() : _ca(nullptr) {}
  Smart_count_cap(Cap_alloc *ca) : _ca(ca) {}
  /**
   * Free operation for L4::Smart_cap
   * (decrement ref count and delete if 0).
   */
  void free(L4::Cap_base &c) noexcept
  {
    if (c.is_valid())
      {
        if (_ca && _ca->release(L4::Cap<void>(c.cap()), This_task, Unmap_flags))
          c.invalidate();
      }
  }

  /**
   * Invalidate operation for L4::Smart_cap.
   */
  static void invalidate(L4::Cap_base &c) noexcept
  {
    if (c.is_valid())
      c.invalidate();
  }

  /**
   * Copy operation for L4::Smart_cap (increment ref count).
   */
  L4::Cap_base copy(L4::Cap_base const &src)
  {
    if (src.is_valid())
      _ca->take(L4::Cap<void>(src.cap()));
    return src;
  }
};
/*@}*/

}