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