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/****************************************************************************
* fs/nxffs/nxffs_read.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* References: Linux/Documentation/filesystems/romfs.txt
*
* 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 <string.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/fs.h>
#include <nuttx/mtd.h>
#include "nxffs.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_rdseek
*
* Description:
* Seek to the file position before read or write access. Note that the
* simplier nxffs_ioseek() cannot be used for this purpose. File offsets
* are not easily mapped to FLASH offsets due to intervening block and
* data headers.
*
* Input Parameters:
* volume - Describes the current volume
* entry - Describes the open inode
* fpos - The desired file position
*
****************************************************************************/
static ssize_t nxffs_rdseek(FAR struct nxffs_volume_s *volume,
FAR struct nxffs_entry_s *entry,
off_t fpos)
{
#warning "Missing Logic"
return 0;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_read
*
* Description:
* This is an implementation of the NuttX standard file system read
* method.
*
****************************************************************************/
ssize_t nxffs_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
{
FAR struct nxffs_volume_s *volume;
FAR struct nxffs_ofile_s *ofile;
ssize_t ret;
fvdbg("Read %d bytes from offset %d\n", buflen, filep->f_pos);
/* Sanity checks */
DEBUGASSERT(filep->f_priv != NULL && filep->f_inode != NULL);
/* Recover the open file state from the struct file instance */
ofile = (FAR struct nxffs_ofile_s *)filep->f_priv;
/* Recover the volume state from the open file */
volume = (FAR struct nxffs_volume_s *)filep->f_inode->i_private;
DEBUGASSERT(volume != NULL);
/* Get exclusive access to the volume. Note that the volume exclsem
* protects the open file list.
*/
ret = sem_wait(&volume->exclsem);
if (ret != OK)
{
ret = -errno;
fdbg("sem_wait failed: %d\n", ret);
goto errout;
}
/* Check if the file was opened with read access */
if ((ofile->mode & O_RDOK) == 0)
{
fdbg("File not open for read access\n");
ret = -EACCES;
goto errout_with_semaphore;
}
/* Seek to the current file offset */
ret = nxffs_rdseek(volume, &ofile->entry, filep->f_pos);
if (ret < 0)
{
fdbg("nxffs_fwseek failed: %d\n", -ret);
ret = -EACCES;
goto errout_with_semaphore;
}
/* Read data from that file offset */
ret = nxffs_rddata(volume, (FAR uint8_t *)buffer, buflen);
if (ret > 0)
{
/* Update the file offset */
filep->f_pos += ret;
}
errout_with_semaphore:
sem_post(&volume->exclsem);
errout:
return ret;
}
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