459 lines
13 KiB
C
459 lines
13 KiB
C
/****************************************************************************
|
|
* fs/nxffs/nxffs_read.c
|
|
*
|
|
* Copyright (C) 2011, 2013, 2017-2018 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <gnutt@nuttx.org>
|
|
*
|
|
* 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 <crc32.h>
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <debug.h>
|
|
|
|
#include <nuttx/fs/fs.h>
|
|
#include <nuttx/mtd/mtd.h>
|
|
|
|
#include "nxffs.h"
|
|
|
|
/****************************************************************************
|
|
* Private Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: nxffs_rdseek
|
|
*
|
|
* Description:
|
|
* Seek to the file position before read or write access. Note that the
|
|
* simpler 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
|
|
* blkentry - Describes the block entry that we are positioned in
|
|
*
|
|
****************************************************************************/
|
|
|
|
static ssize_t nxffs_rdseek(FAR struct nxffs_volume_s *volume,
|
|
FAR struct nxffs_entry_s *entry,
|
|
off_t fpos,
|
|
FAR struct nxffs_blkentry_s *blkentry)
|
|
{
|
|
size_t datstart;
|
|
size_t datend;
|
|
off_t offset;
|
|
int ret;
|
|
|
|
/* The initial FLASH offset will be the offset to first data block of
|
|
* the inode
|
|
*/
|
|
|
|
offset = entry->doffset;
|
|
if (offset == 0)
|
|
{
|
|
/* Zero length files will have no data blocks */
|
|
|
|
return -ENOSPC;
|
|
}
|
|
|
|
/* Loop until we read the data block containing the desired position */
|
|
|
|
datend = 0;
|
|
do
|
|
{
|
|
/* Check if the next data block contains the sought after file position */
|
|
|
|
ret = nxffs_nextblock(volume, offset, blkentry);
|
|
if (ret < 0)
|
|
{
|
|
ferr("ERROR: nxffs_nextblock failed: %d\n", -ret);
|
|
return ret;
|
|
}
|
|
|
|
/* Get the range of data offsets for this data block */
|
|
|
|
datstart = datend;
|
|
datend += blkentry->datlen;
|
|
|
|
/* Offset to search for the next data block */
|
|
|
|
offset = blkentry->hoffset + SIZEOF_NXFFS_DATA_HDR + blkentry->datlen;
|
|
}
|
|
while (datend <= fpos);
|
|
|
|
/* Return the offset to the data within the current data block */
|
|
|
|
blkentry->foffset = fpos - datstart;
|
|
nxffs_ioseek(volume, blkentry->hoffset + SIZEOF_NXFFS_DATA_HDR + blkentry->foffset);
|
|
return OK;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* 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;
|
|
struct nxffs_blkentry_s blkentry;
|
|
ssize_t total;
|
|
size_t available;
|
|
size_t readsize;
|
|
int ret;
|
|
|
|
finfo("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 = nxsem_wait(&volume->exclsem);
|
|
if (ret < 0)
|
|
{
|
|
ferr("ERROR: nxsem_wait failed: %d\n", ret);
|
|
goto errout;
|
|
}
|
|
|
|
/* Check if the file was opened with read access */
|
|
|
|
if ((ofile->oflags & O_RDOK) == 0)
|
|
{
|
|
ferr("ERROR: File not open for read access\n");
|
|
ret = -EACCES;
|
|
goto errout_with_semaphore;
|
|
}
|
|
|
|
/* Loop until all bytes have been read */
|
|
|
|
for (total = 0; total < buflen; )
|
|
{
|
|
/* Don't seek past the end of the file */
|
|
|
|
if (filep->f_pos >= ofile->entry.datlen)
|
|
{
|
|
/* Return the partial read */
|
|
|
|
filep->f_pos = ofile->entry.datlen;
|
|
break;
|
|
}
|
|
|
|
/* Seek to the current file offset */
|
|
|
|
ret = nxffs_rdseek(volume, &ofile->entry, filep->f_pos, &blkentry);
|
|
if (ret < 0)
|
|
{
|
|
ferr("ERROR: nxffs_rdseek failed: %d\n", -ret);
|
|
ret = -EACCES;
|
|
goto errout_with_semaphore;
|
|
}
|
|
|
|
/* How many bytes are available at this offset */
|
|
|
|
available = blkentry.datlen - blkentry.foffset;
|
|
|
|
/* Don't read more than we need to */
|
|
|
|
readsize = buflen - total;
|
|
if (readsize > available)
|
|
{
|
|
readsize = available;
|
|
}
|
|
|
|
/* Read data from that file offset */
|
|
|
|
memcpy(&buffer[total], &volume->cache[volume->iooffset], readsize);
|
|
|
|
/* Update the file offset */
|
|
|
|
filep->f_pos += readsize;
|
|
total += readsize;
|
|
}
|
|
|
|
nxsem_post(&volume->exclsem);
|
|
return total;
|
|
|
|
errout_with_semaphore:
|
|
nxsem_post(&volume->exclsem);
|
|
errout:
|
|
return (ssize_t)ret;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Name: nxffs_nextblock
|
|
*
|
|
* Description:
|
|
* Search for the next valid data block starting at the provided
|
|
* FLASH offset.
|
|
*
|
|
* Input Parameters:
|
|
* volume - Describes the NXFFS volume.
|
|
* datlen - A memory location to return the data block length.
|
|
*
|
|
* Returned Value:
|
|
* Zero is returned on success. Otherwise, a negated errno is returned
|
|
* that indicates the nature of the failure.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int nxffs_nextblock(FAR struct nxffs_volume_s *volume, off_t offset,
|
|
FAR struct nxffs_blkentry_s *blkentry)
|
|
{
|
|
int nmagic;
|
|
int ch;
|
|
int nerased;
|
|
int ret;
|
|
|
|
/* Seek to the first FLASH offset provided by the caller. */
|
|
|
|
nxffs_ioseek(volume, offset);
|
|
|
|
/* Skip the block header */
|
|
|
|
if (volume->iooffset < SIZEOF_NXFFS_BLOCK_HDR)
|
|
{
|
|
volume->iooffset = SIZEOF_NXFFS_BLOCK_HDR;
|
|
}
|
|
|
|
/* Then begin searching */
|
|
|
|
nerased = 0;
|
|
nmagic = 0;
|
|
|
|
for (; ; )
|
|
{
|
|
/* Read the next character */
|
|
|
|
ch = nxffs_getc(volume, SIZEOF_NXFFS_DATA_HDR - nmagic);
|
|
if (ch < 0)
|
|
{
|
|
ferr("ERROR: nxffs_getc failed: %d\n", -ch);
|
|
return ch;
|
|
}
|
|
|
|
/* Check for another erased byte */
|
|
|
|
else if (ch == CONFIG_NXFFS_ERASEDSTATE)
|
|
{
|
|
/* If we have encountered NXFFS_NERASED number of consecutive
|
|
* erased bytes, then presume we have reached the end of valid
|
|
* data.
|
|
*/
|
|
|
|
if (++nerased >= NXFFS_NERASED)
|
|
{
|
|
finfo("No entry found\n");
|
|
return -ENOENT;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
nerased = 0;
|
|
|
|
/* Check for the magic sequence indicating the start of an NXFFS
|
|
* data block or start of the next inode. There is the possibility
|
|
* of this magic sequnce occurring in FLASH data. However, the
|
|
* data block CRC should distinguish between real NXFFS data blocks
|
|
* headers and such false alarms.
|
|
*/
|
|
|
|
if (ch != g_datamagic[nmagic])
|
|
{
|
|
/* Ooops... this is the not the right character for the magic
|
|
* Sequence. Check if we need to restart or to cancel the sequence:
|
|
*/
|
|
|
|
if (ch == g_datamagic[0])
|
|
{
|
|
nmagic = 1;
|
|
}
|
|
else
|
|
{
|
|
nmagic = 0;
|
|
}
|
|
}
|
|
else if (nmagic < NXFFS_MAGICSIZE - 1)
|
|
{
|
|
/* We have one more character in the magic sequence */
|
|
|
|
nmagic++;
|
|
}
|
|
|
|
/* We have found the magic sequence in the FLASH data that may
|
|
* indicate the beginning of an NXFFS data block.
|
|
*/
|
|
|
|
else
|
|
{
|
|
/* The offset to the header must be 4 bytes before the current
|
|
* FLASH seek location.
|
|
*/
|
|
|
|
blkentry->hoffset = nxffs_iotell(volume) - NXFFS_MAGICSIZE;
|
|
|
|
/* Read the block header and verify the block at that address */
|
|
|
|
ret = nxffs_rdblkhdr(volume, blkentry->hoffset, &blkentry->datlen);
|
|
if (ret == OK)
|
|
{
|
|
finfo("Found a valid data block, offset: %d datlen: %d\n",
|
|
blkentry->hoffset, blkentry->datlen);
|
|
return OK;
|
|
}
|
|
|
|
/* False alarm.. Restore the volume cache position (that was
|
|
* destroyed by nxfs_rdblkhdr()) and keep looking.
|
|
*/
|
|
|
|
nxffs_ioseek(volume, blkentry->hoffset + NXFFS_MAGICSIZE);
|
|
nmagic = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* We won't get here, but to keep some compilers happy: */
|
|
|
|
return -ENOENT;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Name: nxffs_rdblkhdr
|
|
*
|
|
* Description:
|
|
* Read and verify the data block header at the specified offset.
|
|
*
|
|
* Input Parameters:
|
|
* volume - Describes the current volume.
|
|
* offset - The byte offset from the beginning of FLASH where the data block
|
|
* header is expected.
|
|
* datlen - A memory location to return the data block length.
|
|
*
|
|
* Returned Value:
|
|
* Zero on success. Otherwise, a negated errno value is returned
|
|
* indicating the nature of the failure.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int nxffs_rdblkhdr(FAR struct nxffs_volume_s *volume, off_t offset,
|
|
FAR uint16_t *datlen)
|
|
{
|
|
struct nxffs_data_s blkhdr;
|
|
uint32_t ecrc;
|
|
uint32_t crc;
|
|
uint16_t doffset;
|
|
uint16_t dlen;
|
|
int ret;
|
|
|
|
/* Make sure that the block containing the data block header is in the cache */
|
|
|
|
nxffs_ioseek(volume, offset);
|
|
ret = nxffs_rdcache(volume, volume->ioblock);
|
|
if (ret < 0)
|
|
{
|
|
ferr("ERROR: Failed to read data into cache: %d\n", ret);
|
|
return ret;
|
|
}
|
|
|
|
/* Read the header at the FLASH offset */
|
|
|
|
doffset = volume->iooffset;
|
|
memcpy(&blkhdr, &volume->cache[doffset], SIZEOF_NXFFS_DATA_HDR);
|
|
|
|
/* Extract the data length */
|
|
|
|
dlen = nxffs_rdle16(blkhdr.datlen);
|
|
|
|
/* Get the offset to the beginning of the data */
|
|
|
|
doffset += SIZEOF_NXFFS_DATA_HDR;
|
|
|
|
/* Make sure that all of the data fits within the block */
|
|
|
|
if ((uint32_t)doffset + (uint32_t)dlen > (uint32_t)volume->geo.blocksize)
|
|
{
|
|
ferr("ERROR: Data length=%d is unreasonable at offset=%d\n", dlen, doffset);
|
|
return -EIO;
|
|
}
|
|
|
|
/* Extract the expected CRC and calculate the CRC of the data block */
|
|
|
|
ecrc = nxffs_rdle32(blkhdr.crc);
|
|
|
|
nxffs_wrle32(blkhdr.crc, 0);
|
|
crc = crc32((FAR const uint8_t *)&blkhdr, SIZEOF_NXFFS_DATA_HDR);
|
|
crc = crc32part(&volume->cache[doffset], dlen, crc);
|
|
|
|
if (crc != ecrc)
|
|
{
|
|
ferr("ERROR: CRC failure\n");
|
|
return -EIO;
|
|
}
|
|
|
|
/* Looks good! Return the data length and success */
|
|
|
|
*datlen = dlen;
|
|
return OK;
|
|
}
|