228 lines
7.3 KiB
C
228 lines
7.3 KiB
C
/****************************************************************************
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* sched/mqueue/mq_receive.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <errno.h>
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#include <mqueue.h>
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#include <debug.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/mqueue.h>
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#include <nuttx/cancelpt.h>
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#include "mqueue/mqueue.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: file_mq_receive
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*
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* Description:
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* This function receives the oldest of the highest priority messages
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* from the message queue specified by "mq." This is an internal OS
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* interface. It is functionally equivalent to mq_receive except that:
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*
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* - It is not a cancellation point, and
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* - It does not modify the errno value.
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*
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* See comments with mq_receive() for a more complete description of the
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* behavior of this function
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*
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* Input Parameters:
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* mq - Message Queue Descriptor
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* msg - Buffer to receive the message
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* msglen - Size of the buffer in bytes
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* prio - If not NULL, the location to store message priority.
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*
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* Returned Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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* (see mq_receive() for the list list valid return values).
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*
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****************************************************************************/
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ssize_t file_mq_receive(FAR struct file *mq, FAR char *msg, size_t msglen,
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FAR unsigned int *prio)
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{
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FAR struct mqueue_inode_s *msgq;
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FAR struct mqueue_msg_s *mqmsg;
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irqstate_t flags;
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ssize_t ret;
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DEBUGASSERT(up_interrupt_context() == false);
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/* Verify the input parameters and, in case of an error, set
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* errno appropriately.
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*/
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ret = nxmq_verify_receive(mq, msg, msglen);
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if (ret < 0)
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{
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return ret;
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}
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msgq = mq->f_inode->i_private;
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/* Furthermore, nxmq_wait_receive() expects to have interrupts disabled
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* because messages can be sent from interrupt level.
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*/
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flags = enter_critical_section();
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/* Get the message from the message queue */
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ret = nxmq_wait_receive(msgq, mq->f_oflags, &mqmsg);
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/* Check if we got a message from the message queue. We might
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* not have a message if:
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*
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* - The message queue is empty and O_NONBLOCK is set in the mq
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* - The wait was interrupted by a signal
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*/
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if (ret == OK)
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{
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ret = nxmq_do_receive(msgq, mqmsg, msg, prio);
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}
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leave_critical_section(flags);
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return ret;
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}
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/****************************************************************************
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* Name: nxmq_receive
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*
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* Description:
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* This function receives the oldest of the highest priority messages
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* from the message queue specified by "mqdes." This is an internal OS
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* interface. It is functionally equivalent to mq_receive except that:
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*
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* - It is not a cancellation point, and
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* - It does not modify the errno value.
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*
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* See comments with mq_receive() for a more complete description of the
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* behavior of this function
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*
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* Input Parameters:
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* mqdes - Message Queue Descriptor
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* msg - Buffer to receive the message
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* msglen - Size of the buffer in bytes
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* prio - If not NULL, the location to store message priority.
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*
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* Returned Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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* (see mq_receive() for the list list valid return values).
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*
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****************************************************************************/
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ssize_t nxmq_receive(mqd_t mqdes, FAR char *msg, size_t msglen,
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FAR unsigned int *prio)
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{
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FAR struct file *filep;
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ssize_t ret;
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ret = fs_getfilep(mqdes, &filep);
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if (ret < 0)
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{
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return ret;
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}
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ret = file_mq_receive(filep, msg, msglen, prio);
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fs_putfilep(filep);
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return ret;
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}
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/****************************************************************************
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* Name: mq_receive
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*
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* Description:
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* This function receives the oldest of the highest priority messages
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* from the message queue specified by "mqdes." If the size of the
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* buffer in bytes (msglen) is less than the "mq_msgsize" attribute of
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* the message queue, mq_receive will return an error. Otherwise, the
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* selected message is removed from the queue and copied to "msg."
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*
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* If the message queue is empty and O_NONBLOCK was not set,
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* mq_receive() will block until a message is added to the message
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* queue. If more than one task is waiting to receive a message, only
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* the task with the highest priority that has waited the longest will
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* be unblocked.
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*
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* If the queue is empty and O_NONBLOCK is set, ERROR will be returned.
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*
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* Input Parameters:
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* mqdes - Message Queue Descriptor
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* msg - Buffer to receive the message
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* msglen - Size of the buffer in bytes
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* prio - If not NULL, the location to store message priority.
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*
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* Returned Value:
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* On success, the length of the selected message in bytes is returned.
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* On failure, -1 (ERROR) is returned and the errno is set appropriately:
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*
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* EAGAIN The queue was empty, and the O_NONBLOCK flag was set
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* for the message queue description referred to by 'mqdes'.
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* EBADF Message queue opened not opened for reading.
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* EMSGSIZE 'msglen' was less than the maxmsgsize attribute of the
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* message queue.
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* EINTR The call was interrupted by a signal handler.
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* EINVAL Invalid 'msg' or 'mqdes'
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*
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****************************************************************************/
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ssize_t mq_receive(mqd_t mqdes, FAR char *msg, size_t msglen,
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FAR unsigned int *prio)
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{
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int ret;
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/* mq_receive() is a cancellation point */
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enter_cancellation_point();
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/* Let nxmq_receive do all of the work */
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ret = nxmq_receive(mqdes, msg, msglen, prio);
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if (ret < 0)
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{
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set_errno(-ret);
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ret = ERROR;
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}
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leave_cancellation_point();
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return ret;
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}
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