/** @file * IPRT - Named shared memory. */ /* * Copyright (C) 2018-2020 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the * VirtualBox OSE distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. */ #ifndef IPRT_INCLUDED_shmem_h #define IPRT_INCLUDED_shmem_h #ifndef RT_WITHOUT_PRAGMA_ONCE # pragma once #endif #include RT_C_DECLS_BEGIN /** @defgroup grp_rt_shmem RTShMem - Shared memory. * @ingroup grp_rt * @{ */ /** @name Open flags for RTShMemOpen(). * @{ */ /** Creates a new shared memory object or opens an already existing one. */ #define RTSHMEM_O_F_CREATE RT_BIT_32(0) /** Creates a new shared memory object failing if one with the same name exists already. */ #define RTSHMEM_O_F_CREATE_EXCL (RTSHMEM_O_F_CREATE | RT_BIT_32(1)) /** Opens the shared memory object for read access. */ #define RTSHMEM_O_F_READ RT_BIT_32(2) /** Opens the shared memory object for write access. */ #define RTSHMEM_O_F_WRITE RT_BIT_32(3) /** Opens the shared memory object for read and write access. */ #define RTSHMEM_O_F_READWRITE (RTSHMEM_O_F_READ | RTSHMEM_O_F_WRITE) /** Truncates the shared memory object to 0 bytes on open. */ #define RTSHMEM_O_F_TRUNCATE RT_BIT_32(4) /** Mappings may be created with executable access right (required to be known on Windows beforehand). */ #define RTSHMEM_O_F_MAYBE_EXEC RT_BIT_32(5) /** Mask of all valid flags. */ #define RTSHMEM_O_F_VALID_MASK UINT32_C(0x0000003f) /** @} */ /** * Creates or opens a new shared memory object with the given name. * * @returns IPRT status code. * @retval VERR_OUT_OF_RANGE if the mapping hint count is too big. * @param phShMem Where to store the handle to the shared memory object on success. * @param pszName Name of the shared memory object to open or create. * @param fFlags Combination of RTSHMEM_O_F_* flags. * @param cbMax Maximum number of bytes to reserve for the shared memory object. * On some platforms this can be 0 and set to another value using RTShMemSetSize() afterwards. * Giving 0 on Windows results in an error as shared memory objects there do not support * changing the size afterwards. * @param cMappingsHint Hint about the possible number of mappings created later on, set to 0 for a default value. */ RTDECL(int) RTShMemOpen(PRTSHMEM phShMem, const char *pszName, uint32_t fFlags, size_t cbMax, uint32_t cMappingsHint); /** * Closes the given shared memory object. * * @returns IPRT status code. * @retval VERR_INVALID_STATE if there is still a mapping active for the given shared memory object. * @param hShMem The shared memory object handle. * * @note The shared memory object will be deleted if the creator closes it. */ RTDECL(int) RTShMemClose(RTSHMEM hShMem); /** * Tries to delete a shared memory object with the given name. * * @returns IPRT status code. * @retval VERR_NOT_SUPPORTED if the platform does not support deleting the shared memory object by name. * @param pszName Name of the shared memory object to delete. */ RTDECL(int) RTShMemDelete(const char *pszName); /** * Returns the number of references (i.e. mappings) held for the given shared memory object. * * @returns Reference count or 0 on invalid handle. * @param hShMem The shared memory object handle. */ RTDECL(uint32_t) RTShMemRefCount(RTSHMEM hShMem); /** * Sets the size of the given shared memory object. * * @returns IPRT status code. * @retval VERR_INVALID_STATE if there are mappings active for the given shared memory object. * @retval VERR_NOT_SUPPORTED on some hosts which do not support changing the size after creation. * @param hShMem The shared memory object handle. * @param cbMem Size of the memory object handle in bytes. */ RTDECL(int) RTShMemSetSize(RTSHMEM hShMem, size_t cbMem); /** * Queries the current size of the shared memory object. * * @returns IPRT status code. * @param hShMem The shared memory object handle. * @param pcbMem Where to store the size of the shared memory object on success. */ RTDECL(int) RTShMemQuerySize(RTSHMEM hShMem, size_t *pcbMem); /** @name Region mapping flags for RTShMemMapRegion(). * @{ */ /** Read access. */ #define RTSHMEM_MAP_F_READ RT_BIT_32(0) /** Write access. */ #define RTSHMEM_MAP_F_WRITE RT_BIT_32(1) /** Execute access. */ #define RTSHMEM_MAP_F_EXEC RT_BIT_32(2) /** Copy on write, any write creates a new page private to the callers address space and changes * in that area are not shared with other processes using the hsared memory object. */ #define RTSHMEM_MAP_F_COW RT_BIT_32(3) /** Mask of all valid flags. */ #define RTSHMEM_MAP_F_VALID_MASK UINT32_C(0x0000000f) /** @} */ /** * Maps a region of the given shared memory object into the callers address space. * * @returns IPRT status code. * @retval VERR_SHMEM_MAXIMUM_MAPPINGS_REACHED if the maximum number of mappings was reached (host dependent). * @retval VERR_ACCESS_DENIED if the requested memory access rights do not line up with the flags given when opening * the memory object (requesting write access for a readonly shared memory object for example). * @param hShMem The shared memory object handle. * @param offRegion Offset into the shared memory object to start mapping at. * @param cbRegion Size of the region to map. * @param fFlags Desired properties of the mapped region, combination of RTSHMEM_MAP_F_* defines. * @param ppv Where to store the start address of the mapped region on success. */ RTDECL(int) RTShMemMapRegion(RTSHMEM hShMem, size_t offRegion, size_t cbRegion, uint32_t fFlags, void **ppv); /** * Unmaps the given region of the shared memory object. * * @returns IPRT status code. * @param hShMem The shared memory object handle. * @param pv Pointer to the mapped region obtained with RTShMemMapRegion() earlier on. */ RTDECL(int) RTShMemUnmapRegion(RTSHMEM hShMem, void *pv); /** @} */ RT_C_DECLS_END #endif /* !IPRT_INCLUDED_shmem_h */