180 lines
7.3 KiB
C
180 lines
7.3 KiB
C
/** @file
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* IPRT - Named shared memory.
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*/
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/*
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* Copyright (C) 2018-2023 Oracle and/or its affiliates.
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*
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* This file is part of VirtualBox base platform packages, as
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* available from https://www.virtualbox.org.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, in version 3 of the
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* License.
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*
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* This program is distributed in the hope that it will be useful, but
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* 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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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses>.
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*
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* The contents of this file may alternatively be used under the terms
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* of the Common Development and Distribution License Version 1.0
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* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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* in the VirtualBox distribution, in which case the provisions of the
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* CDDL are applicable instead of those of the GPL.
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*
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* You may elect to license modified versions of this file under the
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* terms and conditions of either the GPL or the CDDL or both.
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*
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* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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*/
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#ifndef IPRT_INCLUDED_shmem_h
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#define IPRT_INCLUDED_shmem_h
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#ifndef RT_WITHOUT_PRAGMA_ONCE
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# pragma once
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#endif
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#include <iprt/types.h>
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RT_C_DECLS_BEGIN
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/** @defgroup grp_rt_shmem RTShMem - Shared memory.
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* @ingroup grp_rt
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* @{
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*/
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/** @name Open flags for RTShMemOpen().
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* @{
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*/
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/** Creates a new shared memory object or opens an already existing one. */
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#define RTSHMEM_O_F_CREATE RT_BIT_32(0)
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/** Creates a new shared memory object failing if one with the same name exists already. */
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#define RTSHMEM_O_F_CREATE_EXCL (RTSHMEM_O_F_CREATE | RT_BIT_32(1))
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/** Opens the shared memory object for read access. */
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#define RTSHMEM_O_F_READ RT_BIT_32(2)
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/** Opens the shared memory object for write access. */
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#define RTSHMEM_O_F_WRITE RT_BIT_32(3)
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/** Opens the shared memory object for read and write access. */
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#define RTSHMEM_O_F_READWRITE (RTSHMEM_O_F_READ | RTSHMEM_O_F_WRITE)
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/** Truncates the shared memory object to 0 bytes on open. */
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#define RTSHMEM_O_F_TRUNCATE RT_BIT_32(4)
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/** Mappings may be created with executable access right (required to be known on Windows beforehand). */
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#define RTSHMEM_O_F_MAYBE_EXEC RT_BIT_32(5)
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/** Mask of all valid flags. */
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#define RTSHMEM_O_F_VALID_MASK UINT32_C(0x0000003f)
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/** @} */
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/**
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* Creates or opens a new shared memory object with the given name.
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*
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* @returns IPRT status code.
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* @retval VERR_OUT_OF_RANGE if the mapping hint count is too big.
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* @param phShMem Where to store the handle to the shared memory object on success.
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* @param pszName Name of the shared memory object to open or create.
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* @param fFlags Combination of RTSHMEM_O_F_* flags.
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* @param cbMax Maximum number of bytes to reserve for the shared memory object.
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* On some platforms this can be 0 and set to another value using RTShMemSetSize() afterwards.
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* Giving 0 on Windows results in an error as shared memory objects there do not support
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* changing the size afterwards.
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* @param cMappingsHint Hint about the possible number of mappings created later on, set to 0 for a default value.
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*/
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RTDECL(int) RTShMemOpen(PRTSHMEM phShMem, const char *pszName, uint32_t fFlags, size_t cbMax, uint32_t cMappingsHint);
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/**
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* Closes the given shared memory object.
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*
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* @returns IPRT status code.
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* @retval VERR_INVALID_STATE if there is still a mapping active for the given shared memory object.
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* @param hShMem The shared memory object handle.
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*
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* @note The shared memory object will be deleted if the creator closes it.
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*/
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RTDECL(int) RTShMemClose(RTSHMEM hShMem);
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/**
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* Tries to delete a shared memory object with the given name.
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*
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* @returns IPRT status code.
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* @retval VERR_NOT_SUPPORTED if the platform does not support deleting the shared memory object by name.
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* @param pszName Name of the shared memory object to delete.
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*/
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RTDECL(int) RTShMemDelete(const char *pszName);
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/**
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* Returns the number of references (i.e. mappings) held for the given shared memory object.
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*
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* @returns Reference count or 0 on invalid handle.
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* @param hShMem The shared memory object handle.
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*/
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RTDECL(uint32_t) RTShMemRefCount(RTSHMEM hShMem);
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/**
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* Sets the size of the given shared memory object.
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*
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* @returns IPRT status code.
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* @retval VERR_INVALID_STATE if there are mappings active for the given shared memory object.
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* @retval VERR_NOT_SUPPORTED on some hosts which do not support changing the size after creation.
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* @param hShMem The shared memory object handle.
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* @param cbMem Size of the memory object handle in bytes.
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*/
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RTDECL(int) RTShMemSetSize(RTSHMEM hShMem, size_t cbMem);
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/**
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* Queries the current size of the shared memory object.
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*
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* @returns IPRT status code.
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* @param hShMem The shared memory object handle.
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* @param pcbMem Where to store the size of the shared memory object on success.
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*/
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RTDECL(int) RTShMemQuerySize(RTSHMEM hShMem, size_t *pcbMem);
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/** @name Region mapping flags for RTShMemMapRegion().
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* @{
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*/
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/** Read access. */
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#define RTSHMEM_MAP_F_READ RT_BIT_32(0)
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/** Write access. */
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#define RTSHMEM_MAP_F_WRITE RT_BIT_32(1)
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/** Execute access. */
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#define RTSHMEM_MAP_F_EXEC RT_BIT_32(2)
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/** Copy on write, any write creates a new page private to the callers address space and changes
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* in that area are not shared with other processes using the hsared memory object. */
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#define RTSHMEM_MAP_F_COW RT_BIT_32(3)
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/** Mask of all valid flags. */
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#define RTSHMEM_MAP_F_VALID_MASK UINT32_C(0x0000000f)
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/** @} */
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/**
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* Maps a region of the given shared memory object into the callers address space.
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*
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* @returns IPRT status code.
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* @retval VERR_SHMEM_MAXIMUM_MAPPINGS_REACHED if the maximum number of mappings was reached (host dependent).
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* @retval VERR_ACCESS_DENIED if the requested memory access rights do not line up with the flags given when opening
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* the memory object (requesting write access for a readonly shared memory object for example).
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* @param hShMem The shared memory object handle.
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* @param offRegion Offset into the shared memory object to start mapping at.
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* @param cbRegion Size of the region to map.
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* @param fFlags Desired properties of the mapped region, combination of RTSHMEM_MAP_F_* defines.
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* @param ppv Where to store the start address of the mapped region on success.
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*/
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RTDECL(int) RTShMemMapRegion(RTSHMEM hShMem, size_t offRegion, size_t cbRegion, uint32_t fFlags, void **ppv);
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/**
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* Unmaps the given region of the shared memory object.
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*
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* @returns IPRT status code.
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* @param hShMem The shared memory object handle.
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* @param pv Pointer to the mapped region obtained with RTShMemMapRegion() earlier on.
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*/
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RTDECL(int) RTShMemUnmapRegion(RTSHMEM hShMem, void *pv);
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/** @} */
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RT_C_DECLS_END
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#endif /* !IPRT_INCLUDED_shmem_h */
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