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| -rw-r--r-- | include/iprt/handletable.h | 249 |
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diff --git a/include/iprt/handletable.h b/include/iprt/handletable.h new file mode 100644 index 00000000..1dadc973 --- /dev/null +++ b/include/iprt/handletable.h @@ -0,0 +1,249 @@ +/** @file + * IPRT - Handle Tables. + */ + +/* + * Copyright (C) 2008-2020 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. + */ + +#ifndef IPRT_INCLUDED_handletable_h +#define IPRT_INCLUDED_handletable_h +#ifndef RT_WITHOUT_PRAGMA_ONCE +# pragma once +#endif + +#include <iprt/cdefs.h> +#include <iprt/types.h> + +RT_C_DECLS_BEGIN + +/** @defgroup grp_rt_handletable RTHandleTable - Handle Tables + * @ingroup grp_rt + * @{ + */ + +/** + * Callback for retaining an object during the lookup and free calls. + * + * This callback is executed when a handle is being looked up in one + * way or another from behind the handle table lock. This allows you + * to increase the reference (or some equivalent thing) during the + * handle lookup and thereby eliminate any race with anyone trying + * to free the handle. + * + * Note that there is no counterpart to this callback, so if you make + * use of this you'll have to release the object manually of course. + * + * Another use of this callback is to do some extra access checking. + * Use the return code to indicate whether the lookup should fail + * or not (no object is returned on faliure, naturally). + * + * @returns IPRT status code for the lookup (the caller won't see this). + * + * @param hHandleTable The handle table handle. + * @param pvObj The object which has been looked up. + * @param pvCtx The context argument if the handle table was created with the + * RTHANDLETABLE_FLAGS_CONTEXT set. Otherwise NULL. + * @param pvUser The user context argument specified when creating the table. + */ +typedef DECLCALLBACK(int) FNRTHANDLETABLERETAIN(RTHANDLETABLE hHandleTable, void *pvObj, void *pvCtx, void *pvUser); +/** Pointer to a FNHANDLETABLERETAIN. */ +typedef FNRTHANDLETABLERETAIN *PFNRTHANDLETABLERETAIN; + +/** + * Callback for deleting a left over object during RTHandleTableDestroy. + * + * @param hHandleTable The handle table handle. + * @param h The handle. + * @param pvObj The object. + * @param pvCtx The context argument if the handle table was created with the + * RTHANDLETABLE_FLAGS_CONTEXT set. Otherwise NULL. + * @param pvUser The user context argument specified when creating the table. + * + */ +typedef DECLCALLBACK(void) FNRTHANDLETABLEDELETE(RTHANDLETABLE hHandleTable, uint32_t h, void *pvObj, void *pvCtx, void *pvUser); +/** Pointer to a FNRTHANDLETABLEDELETE. */ +typedef FNRTHANDLETABLEDELETE *PFNRTHANDLETABLEDELETE; + + +/** @name RTHandleTableCreateEx flags + * @{ */ +/** Whether the handle table entries takes a context or not. + * + * This can be useful for associating a handle with for instance a process or + * similar in order to prevent anyone but the owner from using the handle. + * + * Setting this means you will have to use the WithCtx functions to do the + * handle management. */ +#define RTHANDLETABLE_FLAGS_CONTEXT RT_BIT_32(0) +/** Whether the handle table should take care of the serialization (IRQ unsafe). + * If not specified the caller will have to take care of that. */ +#define RTHANDLETABLE_FLAGS_LOCKED RT_BIT_32(1) +/** Like RTHANDLETABLE_FLAGS_LOCKED, except it's IRQ safe. + * A side-effect is that callbacks may be called with IRQs disabled. */ +#define RTHANDLETABLE_FLAGS_LOCKED_IRQ_SAFE RT_BIT_32(2) +/** The mask of valid flags. */ +#define RTHANDLETABLE_FLAGS_MASK UINT32_C(0x00000007) +/** @} */ + + +/** + * Creates a handle table. + * + * The handle table translates a 32-bit handle into an object pointer, + * optionally calling you back so you can retain the object without + * racing RTHandleTableFree. + * + * @returns IPRT status code and on success a handle table handle will be stored at the + * location phHandleTable points at. + * + * @param phHandleTable Where to store the handle table handle on success. + * @param fFlags Flags, see RTHANDLETABLE_FLAGS_*. + * @param uBase The handle base value. This is the value of the + * first handle to be returned. + * @param cMax The max number of handles. When exceeded the RTHandleTableAlloc + * or RTHandleTableAllocWithCtx calls will fail. Note that this + * number will be rounded up to a multiple of the sub-table size, + * or if it's too close to UINT32_MAX it will be rounded down. + * @param pfnRetain Optional retain callback that will be called from behind the + * lock (if any) during lookup. + * @param pvUser The user argument to the retain callback. + */ +RTDECL(int) RTHandleTableCreateEx(PRTHANDLETABLE phHandleTable, uint32_t fFlags, uint32_t uBase, uint32_t cMax, + PFNRTHANDLETABLERETAIN pfnRetain, void *pvUser); + +/** + * A simplified version of the RTHandleTableCreateEx API. + * + * It assumes a max of about 64K handles with 1 being the base. The table + * access will serialized (RTHANDLETABLE_FLAGS_LOCKED). + * + * @returns IPRT status code and *phHandleTable. + * + * @param phHandleTable Where to store the handle table handle on success. + */ +RTDECL(int) RTHandleTableCreate(PRTHANDLETABLE phHandleTable); + +/** + * Destroys a handle table. + * + * If any entries are still in used the pfnDelete callback will be invoked + * on each of them (if specfied) to allow to you clean things up. + * + * @returns IPRT status code + * + * @param hHandleTable The handle to the handle table. + * @param pfnDelete Function to be called back on each handle still in use. Optional. + * @param pvUser The user argument to pfnDelete. + */ +RTDECL(int) RTHandleTableDestroy(RTHANDLETABLE hHandleTable, PFNRTHANDLETABLEDELETE pfnDelete, void *pvUser); + +/** + * Allocates a handle from the handle table. + * + * @returns IPRT status code, almost any. + * @retval VINF_SUCCESS on success. + * @retval VERR_NO_MEMORY if we failed to extend the handle table. + * @retval VERR_NO_MORE_HANDLES if we're out of handles. + * + * @param hHandleTable The handle to the handle table. + * @param pvObj The object to associate with the new handle. + * This must be aligned on a 4 byte boundary. + * @param ph Where to return the handle on success. + * + * @remarks Do not call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation. + */ +RTDECL(int) RTHandleTableAlloc(RTHANDLETABLE hHandleTable, void *pvObj, uint32_t *ph); + +/** + * Looks up a handle. + * + * @returns The object pointer on success. NULL on failure. + * + * @param hHandleTable The handle to the handle table. + * @param h The handle to lookup. + * + * @remarks Do not call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation. + */ +RTDECL(void *) RTHandleTableLookup(RTHANDLETABLE hHandleTable, uint32_t h); + +/** + * Looks up and frees a handle. + * + * @returns The object pointer on success. NULL on failure. + * + * @param hHandleTable The handle to the handle table. + * @param h The handle to lookup. + * + * @remarks Do not call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation. + */ +RTDECL(void *) RTHandleTableFree(RTHANDLETABLE hHandleTable, uint32_t h); + +/** + * Allocates a handle from the handle table. + * + * @returns IPRT status code, almost any. + * @retval VINF_SUCCESS on success. + * @retval VERR_NO_MEMORY if we failed to extend the handle table. + * @retval VERR_NO_MORE_HANDLES if we're out of handles. + * + * @param hHandleTable The handle to the handle table. + * @param pvObj The object to associate with the new handle. + * This must be aligned on a 4 byte boundary. + * @param pvCtx The context to associate with the new handle. + * @param ph Where to return the handle on success. + * + * @remarks Call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation. + */ +RTDECL(int) RTHandleTableAllocWithCtx(RTHANDLETABLE hHandleTable, void *pvObj, void *pvCtx, uint32_t *ph); + +/** + * Looks up a handle. + * + * @returns The object pointer on success. NULL on failure. + * + * @param hHandleTable The handle to the handle table. + * @param h The handle to lookup. + * @param pvCtx The handle context, this must match what was given on allocation. + * + * @remarks Call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation. + */ +RTDECL(void *) RTHandleTableLookupWithCtx(RTHANDLETABLE hHandleTable, uint32_t h, void *pvCtx); + +/** + * Looks up and frees a handle. + * + * @returns The object pointer on success. NULL on failure. + * + * @param hHandleTable The handle to the handle table. + * @param h The handle to lookup. + * @param pvCtx The handle context, this must match what was given on allocation. + * + * @remarks Call this if RTHANDLETABLE_FLAGS_CONTEXT was used during creation. + */ +RTDECL(void *) RTHandleTableFreeWithCtx(RTHANDLETABLE hHandleTable, uint32_t h, void *pvCtx); + +/** @} */ + +RT_C_DECLS_END + + +#endif /* !IPRT_INCLUDED_handletable_h */ + |