257 lines
9.1 KiB
C
257 lines
9.1 KiB
C
/****************************************************************************
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* fs/aio/aio_read.c
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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 <unistd.h>
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#include <sched.h>
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#include <aio.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/net/net.h>
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#include "aio/aio.h"
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#ifdef CONFIG_FS_AIO
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: aio_read_worker
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*
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* Description:
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* This function executes on the worker thread and performs the
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* asynchronous I/O operation.
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*
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* Input Parameters:
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* arg - Worker argument. In this case, a pointer to an instance of
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* struct aiocb cast to void *.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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static void aio_read_worker(FAR void *arg)
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{
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FAR struct aio_container_s *aioc = (FAR struct aio_container_s *)arg;
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FAR struct aiocb *aiocbp;
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pid_t pid;
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#ifdef CONFIG_PRIORITY_INHERITANCE
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uint8_t prio;
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#endif
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ssize_t nread = 0;
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/* Get the information from the container, decant the AIO control block,
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* and free the container before starting any I/O. That will minimize
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* the delays by any other threads waiting for a pre-allocated container.
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*/
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DEBUGASSERT(aioc && aioc->aioc_aiocbp);
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pid = aioc->aioc_pid;
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#ifdef CONFIG_PRIORITY_INHERITANCE
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prio = aioc->aioc_prio;
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#endif
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aiocbp = aioc_decant(aioc);
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/* Perform the file read using:
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*
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* aioc_filep - File structure pointer
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* aio_buf - Location of buffer
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* aio_nbytes - Length of transfer
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* aio_offset - File offset
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*/
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nread = file_pread(aioc->aioc_filep, (FAR void *)aiocbp->aio_buf,
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aiocbp->aio_nbytes, aiocbp->aio_offset);
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/* Set the result of the read operation. */
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#ifdef CONFIG_DEBUG_FS_ERROR
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if (nread < 0)
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{
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ferr("ERROR: read failed: %d\n", (int)nread);
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}
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#endif
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aiocbp->aio_result = nread;
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/* Signal the client */
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aio_signal(pid, aiocbp);
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#ifdef CONFIG_PRIORITY_INHERITANCE
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/* Restore the low priority worker thread default priority */
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lpwork_restorepriority(prio);
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#endif
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: aio_read
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*
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* Description:
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* The aio_read() function reads aiocbp->aio_nbytes from the file
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* associated with aiocbp->aio_fildes into the buffer pointed to by
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* aiocbp->aio_buf. The function call will return when the read request
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* has been initiated or queued to the file or device (even when the data
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* cannot be delivered immediately).
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*
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* If prioritized I/O is supported for this file, then the asynchronous
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* operation will be submitted at a priority equal to a base scheduling
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* priority minus aiocbp->aio_reqprio. If Thread Execution Scheduling is
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* not supported, then the base scheduling priority is that of the calling
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* thread (the latter is implemented at present).
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*
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* The aiocbp value may be used as an argument to aio_error() and
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* aio_return() in order to determine the error status and return status,
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* respectively, of the asynchronous operation while it is proceeding. If
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* an error condition is encountered during queuing, the function call
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* will return without having initiated or queued the request. The
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* requested operation takes place at the absolute position in the file as
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* given by aio_offset, as if lseek() were called immediately prior to the
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* operation with an offset equal to aio_offset and a whence equal to
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* SEEK_SET. After a successful call to enqueue an asynchronous I/O
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* operation, the value of the file offset for the file is unspecified.
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*
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* The aiocbp->aio_lio_opcode field will be ignored by aio_read().
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*
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* The aiocbp argument points to an aiocb structure. If the buffer pointed
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* to by aiocbp->aio_buf or the control block pointed to by aiocbp becomes
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* an illegal address prior to asynchronous I/O completion, then the
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* behavior is undefined.
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*
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* Simultaneous asynchronous operations using the same aiocbp produce
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* undefined results.
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*
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* For any system action that changes the process memory space while an
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* synchronous I/O is outstanding to the address range being changed, the
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* result of that action is undefined.
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*
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* Input Parameters:
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* aiocbp - A pointer to an instance of struct aiocb
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*
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* Returned Value:
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*
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* The aio_read() function will return the value zero if the I/O operation
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* is successfully queued; otherwise, the function will return the value
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* -1 and set errno to indicate the error. The aio_read() function will
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* ail if:
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*
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* EAGAIN - The requested asynchronous I/O operation was not queued due to
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* system resource limitations.
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*
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* Each of the following conditions may be detected synchronously at the
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* time of the call to aio_read(), or asynchronously. If any of the
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* conditions below are detected synchronously, the aio_read() function
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* will return -1 and set errno to the corresponding value. If any of the
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* conditions below are detected asynchronously, the return status of the
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* asynchronous operation is set to -1, and the error status of the
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* asynchronous operation is set to the corresponding value.
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*
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* EBADF - The aiocbp->aio_fildes argument is not a valid file descriptor
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* open for reading.
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* EINVAL - The file offset value implied by aiocbp->aio_offset would be
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* invalid, aiocbp->aio_reqprio is not a valid value, or
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* aiocbp->aio_nbytes is an invalid value.
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*
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* In the case that the aio_read() successfully queues the I/O operation
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* but the operation is subsequently canceled or encounters an error, the
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* return status of the asynchronous operation is one of the values
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* normally returned by the read() function call. In addition, the error
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* status of the asynchronous operation is set to one of the error
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* statuses normally set by the read() function call, or one of the
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* following values:
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*
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* EBADF - The aiocbp->aio_fildes argument is not a valid file descriptor
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* open for reading.
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* ECANCELED - The requested I/O was canceled before the I/O completed
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* due to an explicit aio_cancel() request.
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* EINVAL - The file offset value implied by aiocbp->aio_offset would be
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* invalid.
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*
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* The following condition may be detected synchronously or asynchronously:
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*
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* EOVERFLOW - The file is a regular file, aiobcp->aio_nbytes is greater
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* than 0, and the starting offset in aiobcp->aio_offset is before the
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* end-of-file and is at or beyond the offset maximum in the open file
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* description associated with aiocbp->aio_fildes.
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*
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* POSIX Compliance:
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* - Most errors required in the standard are not detected at this point.
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* There are no pre-queuing checks for the validity of the operation.
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*
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****************************************************************************/
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int aio_read(FAR struct aiocb *aiocbp)
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{
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FAR struct aio_container_s *aioc;
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int ret;
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DEBUGASSERT(aiocbp);
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/* The result -EINPROGRESS means that the transfer has not yet completed */
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sigwork_init(&aiocbp->aio_sigwork);
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aiocbp->aio_result = -EINPROGRESS;
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aiocbp->aio_priv = NULL;
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/* Create a container for the AIO control block. This may cause us to
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* block if there are insufficient resources to satisfy the request.
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*/
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aioc = aio_contain(aiocbp);
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if (!aioc)
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{
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/* The errno has already been set (probably EBADF) */
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aiocbp->aio_result = -get_errno();
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return ERROR;
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}
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/* Defer the work to the worker thread */
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ret = aio_queue(aioc, aio_read_worker);
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if (ret < 0)
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{
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/* The result and the errno have already been set */
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aioc_decant(aioc);
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return ERROR;
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}
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return OK;
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}
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#endif /* CONFIG_FS_AIO */
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