/* $Id: shmem-posix.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */ /** @file * IPRT - Named shared memory object, POSIX Implementation. */ /* * 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. */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #include #include "internal/iprt.h" #include #include #include #include #include #include #include "internal/magics.h" #include #include #include #include #include #include /* 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(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; }