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Diffstat (limited to 'include/iprt/shmem.h')
| -rw-r--r-- | include/iprt/shmem.h | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/include/iprt/shmem.h b/include/iprt/shmem.h new file mode 100644 index 00000000..74877903 --- /dev/null +++ b/include/iprt/shmem.h @@ -0,0 +1,160 @@ +/** @file + * IPRT - Named shared memory. + */ + +/* + * Copyright (C) 2018-2019 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 <iprt/types.h> + +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); + +/** + * 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 */ + |