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Diffstat (limited to '')
| -rw-r--r-- | src/VBox/Runtime/r3/posix/shmem-posix.cpp | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/src/VBox/Runtime/r3/posix/shmem-posix.cpp b/src/VBox/Runtime/r3/posix/shmem-posix.cpp new file mode 100644 index 00000000..6000f669 --- /dev/null +++ b/src/VBox/Runtime/r3/posix/shmem-posix.cpp @@ -0,0 +1,409 @@ +/* $Id: shmem-posix.cpp $ */ +/** @file + * IPRT - Named shared memory object, POSIX Implementation. + */ + +/* + * 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. + */ + + +/********************************************************************************************************************************* +* 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; +} + |