/****************************************************************************
* fs/aio/aio_read.c
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <unistd.h>
#include <sched.h>
#include <aio.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/net/net.h>
#include "aio/aio.h"
#ifdef CONFIG_FS_AIO
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: aio_read_worker
*
* Description:
* This function executes on the worker thread and performs the
* asynchronous I/O operation.
*
* Input Parameters:
* arg - Worker argument. In this case, a pointer to an instance of
* struct aiocb cast to void *.
*
* Returned Value:
* None
*
****************************************************************************/
static void aio_read_worker(FAR void *arg)
{
FAR struct aio_container_s *aioc = (FAR struct aio_container_s *)arg;
FAR struct aiocb *aiocbp;
pid_t pid;
#ifdef CONFIG_PRIORITY_INHERITANCE
uint8_t prio;
#endif
ssize_t nread = 0;
/* Get the information from the container, decant the AIO control block,
* and free the container before starting any I/O. That will minimize
* the delays by any other threads waiting for a pre-allocated container.
*/
DEBUGASSERT(aioc && aioc->aioc_aiocbp);
pid = aioc->aioc_pid;
#ifdef CONFIG_PRIORITY_INHERITANCE
prio = aioc->aioc_prio;
#endif
aiocbp = aioc_decant(aioc);
#if defined(AIO_HAVE_FILEP) && defined(AIO_HAVE_PSOCK)
if (aiocbp->aio_fildes < CONFIG_NFILE_DESCRIPTORS)
#endif
#ifdef AIO_HAVE_FILEP
{
/* Perform the file read using:
*
* u.aioc_filep - File structure pointer
* aio_buf - Location of buffer
* aio_nbytes - Length of transfer
* aio_offset - File offset
*/
nread = file_pread(aioc->u.aioc_filep, (FAR void *)aiocbp->aio_buf,
aiocbp->aio_nbytes, aiocbp->aio_offset);
}
#endif
#if defined(AIO_HAVE_FILEP) && defined(AIO_HAVE_PSOCK)
else
#endif
#ifdef AIO_HAVE_PSOCK
{
/* Perform the socket receive using:
*
* u.aioc_psock - Socket structure pointer
* aio_buf - Location of buffer
* aio_nbytes - Length of transfer
*/
nread = psock_recv(aioc->u.aioc_psock, (FAR void *)aiocbp->aio_buf,
aiocbp->aio_nbytes, 0);
}
#endif
/* Set the result of the read */
if (nread < 0)
{
int errcode = get_errno();
fdbg("ERROR: pread failed: %d\n", errcode);
DEBUGASSERT(errcode > 0);
aiocbp->aio_result = -errcode;
}
else
{
aiocbp->aio_result = nread;
}
/* Signal the client */
(void)aio_signal(pid, aiocbp);
#ifdef CONFIG_PRIORITY_INHERITANCE
/* Restore the low priority worker thread default priority */
lpwork_restorepriority(prio);
#endif
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: aio_read
*
* Description:
* The aio_read() function reads aiocbp->aio_nbytes from the file
* associated with aiocbp->aio_fildes into the buffer pointed to by
* aiocbp->aio_buf. The function call will return when the read request
* has been initiated or queued to the file or device (even when the data
* cannot be delivered immediately).
*
* If prioritized I/O is supported for this file, then the asynchronous
* operation will be submitted at a priority equal to a base scheduling
* priority minus aiocbp->aio_reqprio. If Thread Execution Scheduling is
* not supported, then the base scheduling priority is that of the calling
* thread (the latter is implemented at present).
*
* The aiocbp value may be used as an argument to aio_error() and
* aio_return() in order to determine the error status and return status,
* respectively, of the asynchronous operation while it is proceeding. If
* an error condition is encountered during queuing, the function call
* will return without having initiated or queued the request. The
* requested operation takes place at the absolute position in the file as
* given by aio_offset, as if lseek() were called immediately prior to the
* operation with an offset equal to aio_offset and a whence equal to
* SEEK_SET. After a successful call to enqueue an asynchronous I/O
* operation, the value of the file offset for the file is unspecified.
*
* The aiocbp->aio_lio_opcode field will be ignored by aio_read().
*
* The aiocbp argument points to an aiocb structure. If the buffer pointed
* to by aiocbp->aio_buf or the control block pointed to by aiocbp becomes
* an illegal address prior to asynchronous I/O completion, then the
* behavior is undefined.
*
* Simultaneous asynchronous operations using the same aiocbp produce
* undefined results.
*
* For any system action that changes the process memory space while an
* synchronous I/O is outstanding to the address range being changed, the
* result of that action is undefined.
*
* Input Parameters:
* aiocbp - A pointer to an instance of struct aiocb
*
* Returned Value:
*
* The aio_read() function will return the value zero if the I/O operation
* is successfully queued; otherwise, the function will return the value
* -1 and set errno to indicate the error. The aio_read() function will
* ail if:
*
* EAGAIN - The requested asynchronous I/O operation was not queued due to
* system resource limitations.
*
* Each of the following conditions may be detected synchronously at the
* time of the call to aio_read(), or asynchronously. If any of the
* conditions below are detected synchronously, the aio_read() function
* will return -1 and set errno to the corresponding value. If any of the
* conditions below are detected asynchronously, the return status of the
* asynchronous operation is set to -1, and the error status of the
* asynchronous operation is set to the corresponding value.
*
* EBADF - The aiocbp->aio_fildes argument is not a valid file descriptor
* open for reading.
* EINVAL - The file offset value implied by aiocbp->aio_offset would be
* invalid, aiocbp->aio_reqprio is not a valid value, or
* aiocbp->aio_nbytes is an invalid value.
*
* In the case that the aio_read() successfully queues the I/O operation
* but the operation is subsequently cancelled or encounters an error, the
* return status of the asynchronous operation is one of the values
* normally returned by the read() function call. In addition, the error
* status of the asynchronous operation is set to one of the error
* statuses normally set by the read() function call, or one of the
* following values:
*
* EBADF - The aiocbp->aio_fildes argument is not a valid file descriptor
* open for reading.
* ECANCELED - The requested I/O was cancelled before the I/O completed
* due to an explicit aio_cancel() request.
* EINVAL - The file offset value implied by aiocbp->aio_offset would be
* invalid.
*
* The following condition may be detected synchronously or asynchronously:
*
* EOVERFLOW - The file is a regular file, aiobcp->aio_nbytes is greater
* than 0, and the starting offset in aiobcp->aio_offset is before the
* end-of-file and is at or beyond the offset maximum in the open file
* description associated with aiocbp->aio_fildes.
*
* POSIX Compliance:
* - Most errors required in the standard are not detected at this point.
* There are no pre-queuing checks for the validity of the operation.
*
****************************************************************************/
int aio_read(FAR struct aiocb *aiocbp)
{
FAR struct aio_container_s *aioc;
int ret;
DEBUGASSERT(aiocbp);
/* The result -EINPROGRESS means that the transfer has not yet completed */
aiocbp->aio_result = -EINPROGRESS;
aiocbp->aio_priv = NULL;
/* Create a container for the AIO control block. This may cause us to
* block if there are insufficient resources to satisfy the request.
*/
aioc = aio_contain(aiocbp);
if (!aioc)
{
/* The errno has already been set (probably EBADF) */
aiocbp->aio_result = -get_errno();
return ERROR;
}
/* Defer the work to the worker thread */
ret = aio_queue(aioc, aio_read_worker);
if (ret < 0)
{
/* The result and the errno have already been set */
return ERROR;
}
return OK;
}
#endif /* CONFIG_FS_AIO */