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+/** @file
+ * IPRT - Polling I/O Handles.
+ */
+
+/*
+ * Copyright (C) 2010-2022 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
+ */
+
+#ifndef IPRT_INCLUDED_poll_h
+#define IPRT_INCLUDED_poll_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cdefs.h>
+#include <iprt/types.h>
+
+RT_C_DECLS_BEGIN
+
+/** @defgroup grp_rt_poll RTPoll - Polling I/O Handles
+ * @ingroup grp_rt
+ * @{
+ */
+
+/** @name Poll events
+ * @{ */
+/** Readable without blocking. */
+#define RTPOLL_EVT_READ RT_BIT_32(0)
+/** Writable without blocking. */
+#define RTPOLL_EVT_WRITE RT_BIT_32(1)
+/** Error condition, hangup, exception or similar. */
+#define RTPOLL_EVT_ERROR RT_BIT_32(2)
+/** Mask of the valid bits. */
+#define RTPOLL_EVT_VALID_MASK UINT32_C(0x00000007)
+/** @} */
+
+/**
+ * Polls on the specified poll set until an event occurs on one of the handles
+ * or the timeout expires.
+ *
+ * @returns IPRT status code.
+ * @retval VINF_SUCCESS if an event occurred on a handle. Note that these
+ * @retval VERR_INVALID_HANDLE if @a hPollSet is invalid.
+ * @retval VERR_CONCURRENT_ACCESS if another thread is already accessing the set. The
+ * user is responsible for ensuring single threaded access.
+ * @retval VERR_TIMEOUT if @a cMillies ellapsed without any events.
+ * @retval VERR_DEADLOCK if @a cMillies is set to RT_INDEFINITE_WAIT and there
+ * are no valid handles in the set.
+ *
+ * @param hPollSet The set to poll on.
+ * @param cMillies Number of milliseconds to wait. Use
+ * RT_INDEFINITE_WAIT to wait for ever.
+ * @param pfEvents Where to return details about the events that
+ * occurred. Optional.
+ * @param pid Where to return the ID associated with the
+ * handle when calling RTPollSetAdd. Optional.
+ *
+ * @sa RTPollNoResume
+ *
+ * @remarks The caller is responsible for ensuring
+ */
+RTDECL(int) RTPoll(RTPOLLSET hPollSet, RTMSINTERVAL cMillies, uint32_t *pfEvents, uint32_t *pid);
+
+/**
+ * Same as RTPoll except that it will return when interrupted.
+ *
+ * @returns IPRT status code.
+ * @retval VINF_SUCCESS if an event occurred on a handle. Note that these
+ * @retval VERR_INVALID_HANDLE if @a hPollSet is invalid.
+ * @retval VERR_CONCURRENT_ACCESS if another thread is already accessing the set. The
+ * user is responsible for ensuring single threaded access.
+ * @retval VERR_TIMEOUT if @a cMillies ellapsed without any events.
+ * @retval VERR_DEADLOCK if @a cMillies is set to RT_INDEFINITE_WAIT and there
+ * are no valid handles in the set.
+ * @retval VERR_INTERRUPTED if a signal or other asynchronous event interrupted
+ * the polling.
+ *
+ * @param hPollSet The set to poll on.
+ * @param cMillies Number of milliseconds to wait. Use
+ * RT_INDEFINITE_WAIT to wait for ever.
+ * @param pfEvents Where to return details about the events that
+ * occurred. Optional.
+ * @param pid Where to return the ID associated with the
+ * handle when calling RTPollSetAdd. Optional.
+ */
+RTDECL(int) RTPollNoResume(RTPOLLSET hPollSet, RTMSINTERVAL cMillies, uint32_t *pfEvents, uint32_t *pid);
+
+/**
+ * Creates a poll set with no members.
+ *
+ * @returns IPRT status code.
+ * @param phPollSet Where to return the poll set handle.
+ */
+RTDECL(int) RTPollSetCreate(PRTPOLLSET phPollSet);
+
+/**
+ * Destroys a poll set.
+ *
+ * @returns IPRT status code.
+ * @param hPollSet The poll set to destroy. NIL_POLLSET is quietly
+ * ignored (VINF_SUCCESS).
+ */
+RTDECL(int) RTPollSetDestroy(RTPOLLSET hPollSet);
+
+/**
+ * Adds a generic handle to the poll set.
+ *
+ * If a handle is entered more than once, it is recommended to add the one with
+ * RTPOLL_EVT_ERROR first to ensure that you get the right ID back when an error
+ * actually occurs. On some hosts it is possible that polling for
+ * RTPOLL_EVT_READ on a socket may cause it to return error conditions because
+ * the two cannot so easily be distinguished.
+ *
+ * Also note that RTPOLL_EVT_ERROR may be returned by RTPoll even if not asked
+ * for.
+ *
+ * @returns IPRT status code
+ * @retval VERR_CONCURRENT_ACCESS if another thread is already accessing the set. The
+ * user is responsible for ensuring single threaded access.
+ * @retval VERR_POLL_HANDLE_NOT_POLLABLE if the specified handle is not
+ * pollable.
+ * @retval VERR_POLL_HANDLE_ID_EXISTS if the handle ID is already in use in the
+ * set.
+ *
+ * @param hPollSet The poll set to modify.
+ * @param pHandle The handle to add. NIL handles are quietly
+ * ignored.
+ * @param fEvents Which events to poll for.
+ * @param id The handle ID.
+ */
+RTDECL(int) RTPollSetAdd(RTPOLLSET hPollSet, PCRTHANDLE pHandle, uint32_t fEvents, uint32_t id);
+
+/**
+ * Removes a generic handle from the poll set.
+ *
+ * @returns IPRT status code
+ * @retval VERR_INVALID_HANDLE if @a hPollSet not valid.
+ * @retval VERR_CONCURRENT_ACCESS if another thread is already accessing the set. The
+ * user is responsible for ensuring single threaded access.
+ * @retval VERR_POLL_HANDLE_ID_NOT_FOUND if @a id doesn't resolve to a valid
+ * handle.
+ *
+ * @param hPollSet The poll set to modify.
+ * @param id The handle ID of the handle that should be
+ * removed.
+ */
+RTDECL(int) RTPollSetRemove(RTPOLLSET hPollSet, uint32_t id);
+
+
+/**
+ * Query a handle in the poll set by it's ID.
+ *
+ * @returns IPRT status code
+ * @retval VINF_SUCCESS if the handle was found. @a *pHandle is set.
+ * @retval VERR_INVALID_HANDLE if @a hPollSet is invalid.
+ * @retval VERR_CONCURRENT_ACCESS if another thread is already accessing the set. The
+ * user is responsible for ensuring single threaded access.
+ * @retval VERR_POLL_HANDLE_ID_NOT_FOUND if there is no handle with that ID.
+ *
+ * @param hPollSet The poll set to query.
+ * @param id The ID of the handle.
+ * @param pHandle Where to return the handle details. Optional.
+ */
+RTDECL(int) RTPollSetQueryHandle(RTPOLLSET hPollSet, uint32_t id, PRTHANDLE pHandle);
+
+/**
+ * Gets the number of handles in the set.
+ *
+ * @retval The handle count.
+ * @retval UINT32_MAX if @a hPollSet is invalid or there is concurrent access.
+ *
+ * @param hPollSet The poll set.
+ */
+RTDECL(uint32_t) RTPollSetGetCount(RTPOLLSET hPollSet);
+
+/**
+ * Modifies the events to poll for for the given id.
+ *
+ * @returns IPRT status code.
+ * @retval VERR_INVALID_HANDLE if @a hPollSet not valid.
+ * @retval VERR_CONCURRENT_ACCESS if another thread is already accessing the set. The
+ * user is responsible for ensuring single threaded access.
+ * @retval VERR_POLL_HANDLE_ID_NOT_FOUND if @a id doesn't resolve to a valid
+ * handle.
+ *
+ * @param hPollSet The poll set to modify.
+ * @param id The handle ID to change the events for.
+ * @param fEvents Which events to poll for.
+ */
+RTDECL(int) RTPollSetEventsChange(RTPOLLSET hPollSet, uint32_t id, uint32_t fEvents);
+
+/**
+ * Adds a pipe handle to the set.
+ *
+ * @returns See RTPollSetAdd.
+ *
+ * @param hPollSet The poll set.
+ * @param hPipe The pipe handle.
+ * @param fEvents Which events to poll for.
+ * @param id The handle ID.
+ *
+ * @todo Maybe we could figure out what to poll for depending on the kind of
+ * pipe we're dealing with.
+ */
+DECLINLINE(int) RTPollSetAddPipe(RTPOLLSET hPollSet, RTPIPE hPipe, uint32_t fEvents, uint32_t id)
+{
+ RTHANDLE Handle;
+ Handle.enmType = RTHANDLETYPE_PIPE;
+ Handle.u.uInt = 0;
+ Handle.u.hPipe = hPipe;
+ return RTPollSetAdd(hPollSet, &Handle, fEvents, id);
+}
+
+/**
+ * Adds a socket handle to the set.
+ *
+ * @returns See RTPollSetAdd.
+ *
+ * @param hPollSet The poll set.
+ * @param hSocket The socket handle.
+ * @param fEvents Which events to poll for.
+ * @param id The handle ID.
+ */
+DECLINLINE(int) RTPollSetAddSocket(RTPOLLSET hPollSet, RTSOCKET hSocket, uint32_t fEvents, uint32_t id)
+{
+ RTHANDLE Handle;
+ Handle.enmType = RTHANDLETYPE_SOCKET;
+ Handle.u.uInt = 0;
+ Handle.u.hSocket = hSocket;
+ return RTPollSetAdd(hPollSet, &Handle, fEvents, id);
+}
+
+/** @} */
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_poll_h */
+