/**************************************************************************** * fs/aio/aio_read.c * * Copyright (C) 2014 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #include #include #include #include "aio/aio.h" #ifdef CONFIG_FS_AIO /**************************************************************************** * 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); #ifdef AIO_HAVE_PSOCK if (aiocbp->aio_fildes < CONFIG_NFILE_DESCRIPTORS) #endif { /* 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); } #ifdef AIO_HAVE_PSOCK else { /* 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 operation. */ #ifdef CONFIG_DEBUG_FS_ERROR if (nread < 0) { ferr("ERROR: read failed: %d\n", (int)nread); } #endif aiocbp->aio_result = nread; /* Signal the client */ 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 canceled 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 canceled 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 */ sigwork_init(&aiocbp->aio_sigwork); 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 */ aioc_decant(aioc); return ERROR; } return OK; } #endif /* CONFIG_FS_AIO */