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source: vbox/trunk/include/iprt/shmem.h@ 103224

Last change on this file since 103224 was 98103, checked in by vboxsync, 21 months ago

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1/** @file
2 * IPRT - Named shared memory.
3 */
4
5/*
6 * Copyright (C) 2018-2023 Oracle and/or its affiliates.
7 *
8 * This file is part of VirtualBox base platform packages, as
9 * available from https://www.virtualbox.org.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation, in version 3 of the
14 * License.
15 *
16 * This program is distributed in the hope that it will be useful, but
17 * WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, see <https://www.gnu.org/licenses>.
23 *
24 * The contents of this file may alternatively be used under the terms
25 * of the Common Development and Distribution License Version 1.0
26 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
27 * in the VirtualBox distribution, in which case the provisions of the
28 * CDDL are applicable instead of those of the GPL.
29 *
30 * You may elect to license modified versions of this file under the
31 * terms and conditions of either the GPL or the CDDL or both.
32 *
33 * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
34 */
35
36#ifndef IPRT_INCLUDED_shmem_h
37#define IPRT_INCLUDED_shmem_h
38#ifndef RT_WITHOUT_PRAGMA_ONCE
39# pragma once
40#endif
41
42#include <iprt/types.h>
43
44RT_C_DECLS_BEGIN
45
46/** @defgroup grp_rt_shmem RTShMem - Shared memory.
47 * @ingroup grp_rt
48 * @{
49 */
50
51/** @name Open flags for RTShMemOpen().
52 * @{
53 */
54/** Creates a new shared memory object or opens an already existing one. */
55#define RTSHMEM_O_F_CREATE RT_BIT_32(0)
56/** Creates a new shared memory object failing if one with the same name exists already. */
57#define RTSHMEM_O_F_CREATE_EXCL (RTSHMEM_O_F_CREATE | RT_BIT_32(1))
58/** Opens the shared memory object for read access. */
59#define RTSHMEM_O_F_READ RT_BIT_32(2)
60/** Opens the shared memory object for write access. */
61#define RTSHMEM_O_F_WRITE RT_BIT_32(3)
62/** Opens the shared memory object for read and write access. */
63#define RTSHMEM_O_F_READWRITE (RTSHMEM_O_F_READ | RTSHMEM_O_F_WRITE)
64/** Truncates the shared memory object to 0 bytes on open. */
65#define RTSHMEM_O_F_TRUNCATE RT_BIT_32(4)
66/** Mappings may be created with executable access right (required to be known on Windows beforehand). */
67#define RTSHMEM_O_F_MAYBE_EXEC RT_BIT_32(5)
68/** Mask of all valid flags. */
69#define RTSHMEM_O_F_VALID_MASK UINT32_C(0x0000003f)
70/** @} */
71
72/**
73 * Creates or opens a new shared memory object with the given name.
74 *
75 * @returns IPRT status code.
76 * @retval VERR_OUT_OF_RANGE if the mapping hint count is too big.
77 * @param phShMem Where to store the handle to the shared memory object on success.
78 * @param pszName Name of the shared memory object to open or create.
79 * @param fFlags Combination of RTSHMEM_O_F_* flags.
80 * @param cbMax Maximum number of bytes to reserve for the shared memory object.
81 * On some platforms this can be 0 and set to another value using RTShMemSetSize() afterwards.
82 * Giving 0 on Windows results in an error as shared memory objects there do not support
83 * changing the size afterwards.
84 * @param cMappingsHint Hint about the possible number of mappings created later on, set to 0 for a default value.
85 */
86RTDECL(int) RTShMemOpen(PRTSHMEM phShMem, const char *pszName, uint32_t fFlags, size_t cbMax, uint32_t cMappingsHint);
87
88/**
89 * Closes the given shared memory object.
90 *
91 * @returns IPRT status code.
92 * @retval VERR_INVALID_STATE if there is still a mapping active for the given shared memory object.
93 * @param hShMem The shared memory object handle.
94 *
95 * @note The shared memory object will be deleted if the creator closes it.
96 */
97RTDECL(int) RTShMemClose(RTSHMEM hShMem);
98
99/**
100 * Tries to delete a shared memory object with the given name.
101 *
102 * @returns IPRT status code.
103 * @retval VERR_NOT_SUPPORTED if the platform does not support deleting the shared memory object by name.
104 * @param pszName Name of the shared memory object to delete.
105 */
106RTDECL(int) RTShMemDelete(const char *pszName);
107
108/**
109 * Returns the number of references (i.e. mappings) held for the given shared memory object.
110 *
111 * @returns Reference count or 0 on invalid handle.
112 * @param hShMem The shared memory object handle.
113 */
114RTDECL(uint32_t) RTShMemRefCount(RTSHMEM hShMem);
115
116/**
117 * Sets the size of the given shared memory object.
118 *
119 * @returns IPRT status code.
120 * @retval VERR_INVALID_STATE if there are mappings active for the given shared memory object.
121 * @retval VERR_NOT_SUPPORTED on some hosts which do not support changing the size after creation.
122 * @param hShMem The shared memory object handle.
123 * @param cbMem Size of the memory object handle in bytes.
124 */
125RTDECL(int) RTShMemSetSize(RTSHMEM hShMem, size_t cbMem);
126
127/**
128 * Queries the current size of the shared memory object.
129 *
130 * @returns IPRT status code.
131 * @param hShMem The shared memory object handle.
132 * @param pcbMem Where to store the size of the shared memory object on success.
133 */
134RTDECL(int) RTShMemQuerySize(RTSHMEM hShMem, size_t *pcbMem);
135
136/** @name Region mapping flags for RTShMemMapRegion().
137 * @{
138 */
139/** Read access. */
140#define RTSHMEM_MAP_F_READ RT_BIT_32(0)
141/** Write access. */
142#define RTSHMEM_MAP_F_WRITE RT_BIT_32(1)
143/** Execute access. */
144#define RTSHMEM_MAP_F_EXEC RT_BIT_32(2)
145/** Copy on write, any write creates a new page private to the callers address space and changes
146 * in that area are not shared with other processes using the hsared memory object. */
147#define RTSHMEM_MAP_F_COW RT_BIT_32(3)
148/** Mask of all valid flags. */
149#define RTSHMEM_MAP_F_VALID_MASK UINT32_C(0x0000000f)
150/** @} */
151
152/**
153 * Maps a region of the given shared memory object into the callers address space.
154 *
155 * @returns IPRT status code.
156 * @retval VERR_SHMEM_MAXIMUM_MAPPINGS_REACHED if the maximum number of mappings was reached (host dependent).
157 * @retval VERR_ACCESS_DENIED if the requested memory access rights do not line up with the flags given when opening
158 * the memory object (requesting write access for a readonly shared memory object for example).
159 * @param hShMem The shared memory object handle.
160 * @param offRegion Offset into the shared memory object to start mapping at.
161 * @param cbRegion Size of the region to map.
162 * @param fFlags Desired properties of the mapped region, combination of RTSHMEM_MAP_F_* defines.
163 * @param ppv Where to store the start address of the mapped region on success.
164 */
165RTDECL(int) RTShMemMapRegion(RTSHMEM hShMem, size_t offRegion, size_t cbRegion, uint32_t fFlags, void **ppv);
166
167/**
168 * Unmaps the given region of the shared memory object.
169 *
170 * @returns IPRT status code.
171 * @param hShMem The shared memory object handle.
172 * @param pv Pointer to the mapped region obtained with RTShMemMapRegion() earlier on.
173 */
174RTDECL(int) RTShMemUnmapRegion(RTSHMEM hShMem, void *pv);
175
176/** @} */
177RT_C_DECLS_END
178
179#endif /* !IPRT_INCLUDED_shmem_h */
180
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