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/* EINA - EFL data type library
* Copyright (C) 2015-2016 Carsten Haitzler, Cedric Bail
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library;
* if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef EINA_SAFEPOINTER_H__
#define EINA_SAFEPOINTER_H__
/**
* @addtogroup Eina_Safepointer_Group Safe Pointer
*
* @brief These functions provide a wrapper that protect access to pointers
*
* Eina_Safepointer is an pointer to index converter that allows an increased
* level of safety by forbidding direct access to the pointer. The protection
* works by using a set of indirection tables that are mmapped and mprotected
* against write access. Thus the pointer they store and that map to a specific
* index is always correct. Also once a pointer is unregistered the index
* won't be served back for 2^8 on 32 bits system and 2^28 on 64 bits system
* for that specific slot. Finally we guarantee that the lower 2 bits of the
* returned index are actually never used and completely ignored by our API.
* So you can safely store whatever information you want in it, we will ignore
* it and treat as if it wasn't there.
*
* @note The use of Eina_Safepointer is thread safe.
*/
/**
* @addtogroup Eina_Data_Types_Group Data Types
*
* @{
*/
/**
* @addtogroup Eina_Containers_Group Containers
*
* @{
*/
/**
* @defgroup Eina_Safepointer_Group Safe Pointer
*
* @{
*/
/**
* @typedef Eina_Safepointer
* Type of the protected index.
*/
typedef struct _Eina_Safepointer Eina_Safepointer;
/**
* @brief Register a pointer and get an Eina_Safepointer that maps to it.
*
* @param[in] target The pointer to register.
* @return A valid pointer that is an index to the mapped pointer.
*
* @note It will return @c NULL on error or if @p target is @c NULL.
*
* @note The lower 2 bits of the returned pointer will always be 0.
*
* @note The returned pointer can be used like a pointer, but cannot
* be touched except with Eina_Safepointer functions.
*
* @since 1.18
*/
EAPI const Eina_Safepointer *eina_safepointer_register(const void *target);
/**
* @brief Unregister an Eina_Safepointer and the pointer that maps to it.
*
* @param[in] safe The index to unregister from the mapping.
*
* @note This function will ignore the lower 2 bits of the given pointer.
*
* @since 1.18
*/
EAPI void eina_safepointer_unregister(const Eina_Safepointer *safe);
/**
* @brief Get the associated pointer from an Eina_Safepointer mapping.
*
* @param[in] safe The Eina_Safepointer index to lookup at.
* @return The pointer registered with that index or @c NULL in any other case.
*
* @note It is always safe to ask for a pointer for any value of the mapping.
* If the pointer is invalid or @c NULL, we will return @c NULL and not crash.
*/
static inline void *eina_safepointer_get(const Eina_Safepointer *safe);
/**
* @}
*/
/**
* @}
*/
/**
* @}
*/
# include "eina_inline_safepointer.x"
#endif
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