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diff --git a/src/VBox/Runtime/r3/posix/shmem-posix.cpp b/src/VBox/Runtime/r3/posix/shmem-posix.cpp
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+/* $Id: shmem-posix.cpp $ */
+/** @file
+ * IPRT - Named shared memory object, POSIX Implementation.
+ */
+
+/*
+ * Copyright (C) 2018-2022 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+* Header Files *
+*********************************************************************************************************************************/
+#include <iprt/shmem.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/cdefs.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include "internal/magics.h"
+
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <limits.h>
+
+/* Workaround on systems which do not provide this. */
+#ifndef NAME_MAX
+# define NAME_MAX 255
+#endif
+
+
+/*********************************************************************************************************************************
+* Structures and Typedefs *
+*********************************************************************************************************************************/
+
+/**
+ * Shared memory object mapping descriptor.
+ */
+typedef struct RTSHMEMMAPPINGDESC
+{
+ /** Number of references held to this mapping, 0 if the descriptor is free. */
+ volatile uint32_t cMappings;
+ /** Pointer to the region mapping. */
+ void *pvMapping;
+ /** Start offset */
+ size_t offRegion;
+ /** Size of the region. */
+ size_t cbRegion;
+ /** Access flags for this region .*/
+ uint32_t fFlags;
+} RTSHMEMMAPPINGDESC;
+/** Pointer to a shared memory object mapping descriptor. */
+typedef RTSHMEMMAPPINGDESC *PRTSHMEMMAPPINGDESC;
+/** Pointer to a constant shared memory object mapping descriptor. */
+typedef const RTSHMEMMAPPINGDESC *PCRTSHMEMMAPPINGDESC;
+
+
+/**
+ * Internal shared memory object state.
+ */
+typedef struct RTSHMEMINT
+{
+ /** Magic value (RTSHMEM_MAGIC). */
+ uint32_t u32Magic;
+ /** File descriptor for the underlying shared memory object. */
+ int iFdShm;
+ /** Pointer to the shared memory object name. */
+ char *pszName;
+ /** Flag whether this instance created the named shared memory object. */
+ bool fCreate;
+ /** Overall number of mappings active for this shared memory object. */
+ volatile uint32_t cMappings;
+ /** Maximum number of mapping descriptors allocated. */
+ uint32_t cMappingDescsMax;
+ /** Number of mapping descriptors used. */
+ volatile uint32_t cMappingDescsUsed;
+ /** Array of mapping descriptors - variable in size. */
+ RTSHMEMMAPPINGDESC aMappingDescs[1];
+} RTSHMEMINT;
+/** Pointer to the internal shared memory object state. */
+typedef RTSHMEMINT *PRTSHMEMINT;
+
+
+
+/**
+ * Returns a mapping descriptor matching the given region properties or NULL if none was found.
+ *
+ * @returns Pointer to the matching mapping descriptor or NULL if not found.
+ * @param pThis Pointer to the shared memory object instance.
+ * @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.
+ */
+DECLINLINE(PRTSHMEMMAPPINGDESC) rtShMemMappingDescFindByProp(PRTSHMEMINT pThis, size_t offRegion, size_t cbRegion, uint32_t fFlags)
+{
+ for (uint32_t i = 0; i < pThis->cMappingDescsMax; i++)
+ {
+ if ( pThis->aMappingDescs[i].offRegion == offRegion
+ && pThis->aMappingDescs[i].cbRegion == cbRegion
+ && pThis->aMappingDescs[i].fFlags == fFlags)
+ return &pThis->aMappingDescs[i];
+ }
+
+ return NULL;
+}
+
+
+RTDECL(int) RTShMemOpen(PRTSHMEM phShMem, const char *pszName, uint32_t fFlags, size_t cbMax, uint32_t cMappingsHint)
+{
+ AssertPtrReturn(phShMem, VERR_INVALID_PARAMETER);
+ AssertPtrReturn(pszName, VERR_INVALID_PARAMETER);
+ AssertReturn(!(fFlags & ~RTSHMEM_O_F_VALID_MASK), VERR_INVALID_PARAMETER);
+ AssertReturn(cMappingsHint < 64, VERR_OUT_OF_RANGE);
+
+ size_t cchName = strlen(pszName);
+ AssertReturn(cchName, VERR_INVALID_PARAMETER);
+ AssertReturn(cchName < NAME_MAX - 1, VERR_INVALID_PARAMETER); /* account for the / we add later on. */
+ cMappingsHint = cMappingsHint == 0 ? 5 : cMappingsHint;
+ int rc = VINF_SUCCESS;
+ PRTSHMEMINT pThis = (PRTSHMEMINT)RTMemAllocZ(RT_UOFFSETOF_DYN(RTSHMEMINT, aMappingDescs[cMappingsHint]) + cchName + 2); /* '/' + terminator. */
+ if (RT_LIKELY(pThis))
+ {
+ pThis->u32Magic = RTSHMEM_MAGIC;
+ pThis->pszName = (char *)&pThis->aMappingDescs[cMappingsHint];
+ /*pThis->fCreate = false; */
+ /*pThis->cMappings = 0; */
+ pThis->cMappingDescsMax = cMappingsHint;
+ /*pThis->cMappingDescsUsed = 0; */
+ pThis->pszName[0] = '/';
+ memcpy(&pThis->pszName[1], pszName, cchName);
+ int fShmFlags = 0;
+ if (fFlags & RTSHMEM_O_F_CREATE)
+ {
+ fShmFlags |= O_CREAT;
+ pThis->fCreate = true;
+ }
+ if ((fFlags & RTSHMEM_O_F_CREATE_EXCL) == RTSHMEM_O_F_CREATE_EXCL)
+ fShmFlags |= O_EXCL;
+ if ( (fFlags & RTSHMEM_O_F_READWRITE) == RTSHMEM_O_F_READWRITE
+ || (fFlags & RTSHMEM_O_F_WRITE))
+ fShmFlags |= O_RDWR;
+ else
+ fShmFlags |= O_RDONLY;
+ if (fFlags & RTSHMEM_O_F_TRUNCATE)
+ fShmFlags |= O_TRUNC;
+ pThis->iFdShm = shm_open(pThis->pszName, fShmFlags , 0600);
+ if (pThis->iFdShm > 0)
+ {
+ if (cbMax)
+ rc = RTShMemSetSize(pThis, cbMax);
+ if (RT_SUCCESS(rc))
+ {
+ *phShMem = pThis;
+ return VINF_SUCCESS;
+ }
+
+ close(pThis->iFdShm);
+ }
+ else
+ rc = RTErrConvertFromErrno(errno);
+
+ RTMemFree(pThis);
+ }
+ else
+ rc = VERR_NO_MEMORY;
+
+ return rc;
+}
+
+
+RTDECL(int) RTShMemClose(RTSHMEM hShMem)
+{
+ PRTSHMEMINT pThis = hShMem;
+ AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+ AssertReturn(pThis->u32Magic == RTSHMEM_MAGIC, VERR_INVALID_HANDLE);
+ AssertReturn(!pThis->cMappings, VERR_INVALID_STATE);
+
+ int rc = VINF_SUCCESS;
+ if (!close(pThis->iFdShm))
+ {
+ if (pThis->fCreate)
+ shm_unlink(pThis->pszName); /* Ignore any error here. */
+ pThis->u32Magic = RTSHMEM_MAGIC_DEAD;
+ RTMemFree(pThis);
+ }
+ else
+ rc = RTErrConvertFromErrno(errno);
+
+ return rc;
+}
+
+
+RTDECL(int) RTShMemDelete(const char *pszName)
+{
+ AssertPtrReturn(pszName, VERR_INVALID_POINTER);
+
+ size_t cchName = strlen(pszName);
+ AssertReturn(cchName, VERR_INVALID_PARAMETER);
+ AssertReturn(cchName < NAME_MAX - 1, VERR_INVALID_PARAMETER); /* account for the / we add later on. */
+ char *psz = NULL;
+
+ int rc = RTStrAllocEx(&psz, cchName + 2); /* '/' + terminator */
+ if (RT_SUCCESS(rc))
+ {
+ psz[0] = '/';
+ memcpy(&psz[1], pszName, cchName + 1);
+ if (shm_unlink(psz))
+ rc = RTErrConvertFromErrno(errno);
+ RTStrFree(psz);
+ }
+
+ return rc;
+}
+
+
+RTDECL(uint32_t) RTShMemRefCount(RTSHMEM hShMem)
+{
+ PRTSHMEMINT pThis = hShMem;
+ AssertPtrReturn(pThis, 0);
+ AssertReturn(pThis->u32Magic == RTSHMEM_MAGIC, 0);
+
+ return pThis->cMappings;
+}
+
+
+RTDECL(int) RTShMemSetSize(RTSHMEM hShMem, size_t cbMem)
+{
+ PRTSHMEMINT pThis = hShMem;
+ AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+ AssertReturn(pThis->u32Magic == RTSHMEM_MAGIC, VERR_INVALID_HANDLE);
+ AssertReturn(!pThis->cMappings, VERR_INVALID_STATE);
+
+ int rc = VINF_SUCCESS;
+ if (ftruncate(pThis->iFdShm, (off_t)cbMem))
+ rc = RTErrConvertFromErrno(errno);
+
+ return rc;
+}
+
+
+RTDECL(int) RTShMemQuerySize(RTSHMEM hShMem, size_t *pcbMem)
+{
+ PRTSHMEMINT pThis = hShMem;
+ AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+ AssertReturn(pThis->u32Magic == RTSHMEM_MAGIC, VERR_INVALID_HANDLE);
+ AssertPtrReturn(pcbMem, VERR_INVALID_PARAMETER);
+
+ struct stat st;
+ if (!fstat(pThis->iFdShm, &st))
+ {
+ *pcbMem = st.st_size;
+ return VINF_SUCCESS;
+ }
+ return RTErrConvertFromErrno(errno);
+}
+
+
+RTDECL(int) RTShMemMapRegion(RTSHMEM hShMem, size_t offRegion, size_t cbRegion, uint32_t fFlags, void **ppv)
+{
+ PRTSHMEMINT pThis = hShMem;
+ AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+ AssertReturn(pThis->u32Magic == RTSHMEM_MAGIC, VERR_INVALID_HANDLE);
+ AssertPtrReturn(ppv, VERR_INVALID_PARAMETER);
+ AssertReturn(!(fFlags & ~RTSHMEM_MAP_F_VALID_MASK), VERR_INVALID_PARAMETER);
+
+ /* Try to find a mapping with compatible parameters first. */
+ PRTSHMEMMAPPINGDESC pMappingDesc = NULL;
+ for (uint32_t iTry = 0; iTry < 10; iTry++)
+ {
+ pMappingDesc = rtShMemMappingDescFindByProp(pThis, offRegion, cbRegion, fFlags);
+ if (!pMappingDesc)
+ break;
+
+ /* Increase the mapping count and check that the region is still accessible by us. */
+ if ( ASMAtomicIncU32(&pMappingDesc->cMappings) > 1
+ && pMappingDesc->offRegion == offRegion
+ && pMappingDesc->cbRegion == cbRegion
+ && pMappingDesc->fFlags == fFlags)
+ break;
+ /* Mapping was freed inbetween, next round. */
+ }
+
+ int rc = VINF_SUCCESS;
+ if (!pMappingDesc)
+ {
+ /* Find an empty region descriptor and map the region. */
+ for (uint32_t i = 0; i < pThis->cMappingDescsMax && !pMappingDesc; i++)
+ {
+ if (!pThis->aMappingDescs[i].cMappings)
+ {
+ pMappingDesc = &pThis->aMappingDescs[i];
+
+ /* Try to grab this one. */
+ if (ASMAtomicIncU32(&pMappingDesc->cMappings) == 1)
+ break;
+
+ /* Somebody raced us, drop reference and continue. */
+ ASMAtomicDecU32(&pMappingDesc->cMappings);
+ pMappingDesc = NULL;
+ }
+ }
+
+ if (RT_LIKELY(pMappingDesc))
+ {
+ /* Try to map it. */
+ int fMmapFlags = 0;
+ int fProt = 0;
+ if (fFlags & RTSHMEM_MAP_F_READ)
+ fProt |= PROT_READ;
+ if (fFlags & RTSHMEM_MAP_F_WRITE)
+ fProt |= PROT_WRITE;
+ if (fFlags & RTSHMEM_MAP_F_EXEC)
+ fProt |= PROT_EXEC;
+ if (fFlags & RTSHMEM_MAP_F_COW)
+ fMmapFlags |= MAP_PRIVATE;
+ else
+ fMmapFlags |= MAP_SHARED;
+
+ void *pv = mmap(NULL, cbRegion, fProt, fMmapFlags, pThis->iFdShm, (off_t)offRegion);
+ if (pv != MAP_FAILED)
+ {
+ pMappingDesc->pvMapping = pv;
+ pMappingDesc->offRegion = offRegion;
+ pMappingDesc->cbRegion = cbRegion;
+ pMappingDesc->fFlags = fFlags;
+ }
+ else
+ {
+ rc = RTErrConvertFromErrno(errno);
+ ASMAtomicDecU32(&pMappingDesc->cMappings);
+ }
+ }
+ else
+ rc = VERR_SHMEM_MAXIMUM_MAPPINGS_REACHED;
+ }
+
+ if (RT_SUCCESS(rc))
+ {
+ *ppv = pMappingDesc->pvMapping;
+ ASMAtomicIncU32(&pThis->cMappings);
+ }
+
+ return rc;
+}
+
+
+RTDECL(int) RTShMemUnmapRegion(RTSHMEM hShMem, void *pv)
+{
+ PRTSHMEMINT pThis = hShMem;
+ AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+ AssertReturn(pThis->u32Magic == RTSHMEM_MAGIC, VERR_INVALID_HANDLE);
+ AssertPtrReturn(pv, VERR_INVALID_PARAMETER);
+
+ /* Find the mapping descriptor by the given region address. */
+ PRTSHMEMMAPPINGDESC pMappingDesc = NULL;
+ for (uint32_t i = 0; i < pThis->cMappingDescsMax && !pMappingDesc; i++)
+ {
+ if (pThis->aMappingDescs[i].pvMapping == pv)
+ {
+ pMappingDesc = &pThis->aMappingDescs[i];
+ break;
+ }
+ }
+
+ AssertPtrReturn(pMappingDesc, VERR_INVALID_PARAMETER);
+
+ int rc = VINF_SUCCESS;
+ size_t cbRegion = pMappingDesc->cMappings;
+ if (!ASMAtomicDecU32(&pMappingDesc->cMappings))
+ {
+ /* Last mapping of this region was unmapped, so do the real unmapping now. */
+ if (munmap(pv, cbRegion))
+ {
+ ASMAtomicIncU32(&pMappingDesc->cMappings);
+ rc = RTErrConvertFromErrno(errno);
+ }
+ else
+ {
+ ASMAtomicDecU32(&pThis->cMappingDescsUsed);
+ ASMAtomicDecU32(&pThis->cMappings);
+ }
+ }
+
+ return rc;
+}
+