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nuttx-bb/nuttx/fs/nxffs/nxffs_inode.c

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/****************************************************************************
* fs/nxffs/nxffs_inode.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 <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/mtd.h>
#include "nxffs.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_rdentry
*
* Description:
* Read the inode entry at this offset. Called only from nxffs_nextentry().
*
* Input Parameters:
* volume - Describes the current volume.
* offset - The byte offset from the beginning of FLASH where the inode
* header is expected.
* entry - A memory location to return the expanded inode header
* information.
*
* Returned Value:
* Zero on success. Otherwise, a negater errno value is returned
* indicating the nature of the failure.
*
****************************************************************************/
static int nxffs_rdentry(FAR struct nxffs_volume_s *volume, off_t offset,
FAR struct nxffs_entry_s *entry)
{
struct nxffs_inode_s inode;
uint32_t ecrc;
uint32_t crc;
int namelen;
int ret;
DEBUGASSERT(volume && entry);
memset(entry, 0, sizeof(struct nxffs_entry_s));
/* Read the header at the FLASH offset */
nxffs_ioseek(volume, offset);
ret = nxffs_rddata(volume, (FAR uint8_t *)&inode, SIZEOF_NXFFS_INODE_HDR);
if (ret < 0)
{
fdbg("Failed to read inode, offset %d: %d\n", offset, -ret);
return -EIO;
}
/* Check if the file is marked as deleted. */
if (inode.state != INODE_STATE_FILE)
{
return -ENOENT;
}
/* Copy the packed header into the user-friendly buffer */
entry->hoffset = offset;
entry->doffset = offset + inode.doffset;
entry->utc = nxffs_rdle32(inode.utc);
entry->datlen = nxffs_rdle32(inode.datlen);
/* Modify the packed header and perform the (partial) CRC calculation */
ecrc = nxffs_rdle32(inode.crc);
inode.state = CONFIG_NXFFS_ERASEDSTATE;
memset(inode.crc, 0, 4);
crc = crc32((FAR const uint8_t *)&inode, SIZEOF_NXFFS_INODE_HDR);
/* Allocate memory to hold the variable-length file name */
namelen = (int)inode.doffset - (int)inode.noffset;
if (namelen < 0)
{
fdbg("Bad offsets, name: %d data: %d\n", inode.noffset, inode.doffset);
return -EIO;
}
entry->name = (FAR char *)kmalloc(namelen+1);
if (!entry->name)
{
fdbg("Failed to allocate name, namelen: %d\n", namelen);
return -ENOMEM;
}
/* Read the file name from the expected offset in FLASH */
nxffs_ioseek(volume, offset + inode.noffset);
ret = nxffs_rddata(volume, (FAR uint8_t*)entry->name, namelen);
if (ret < 0)
{
fdbg("Failed to read inode, offset %d: %d\n", offset, -ret);
return -EIO;
}
entry->name[namelen] = '\0';
/* Finish the CRC calculation and verify the entry */
crc = crc32part(entry->name, namelen, crc);
if (crc != ecrc)
{
fdbg("CRC entry: %08x CRC calculated: %08x\n", ecrc, crc);
nxffs_freeentry(entry);
return -EIO;
}
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_freeentry
*
* Description:
* The inode values returned by nxffs_nextentry() include allocated memory
* (specifically, the file name string). This function should be called
* to dispose of that memory when the inode entry is no longer needed.
*
* Note that the nxffs_entry_s containing structure is not freed. The
* caller may call kfree upon return of this function if necessary to
* free the entry container.
*
* Input parameters:
* entry - The entry to be freed.
*
* Returned Value:
* None
*
****************************************************************************/
void nxffs_freeentry(FAR struct nxffs_entry_s *entry)
{
if (entry->name)
{
kfree(entry->name);
entry->name = NULL;
}
}
/****************************************************************************
* Name: nxffs_nextentry
*
* Description:
* Search for the next valid inode starting at the provided FLASH offset.
*
* Input Parameters:
* volume - Describes the NXFFS volume.
* offset - The FLASH memory offset to begin searching.
* entry - A pointer to memory provided by the caller in which to return
* the inode description.
*
* Returned Value:
* Zero is returned on success. Otherwise, a negated errno is returned
* that indicates the nature of the failure.
*
****************************************************************************/
int nxffs_nextentry(FAR struct nxffs_volume_s *volume, off_t offset,
FAR struct nxffs_entry_s *entry)
{
int nmagic;
int ch;
int nerased;
int ret;
/* Seek to the first FLASH offset provided by the caller. */
nxffs_ioseek(volume, offset);
/* Then begin searching */
nerased = 0;
nmagic = 0;
for (;;)
{
/* Read the next character */
ch = nxffs_getc(volume);
if (ch < 0)
{
fvdbg("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)
{
fvdbg("No entry found\n");
return -ENOENT;
}
}
else
{
nerased = 0;
/* Check for the magic sequence indicating the start of an NXFFS
* inode. There is the possibility of this magic sequnce occurring
* in FLASH data. However, the header CRC should distinguish
* between real NXFFS inode headers and such false alarms.
*/
if (ch != g_inodemagic[nmagic])
{
nmagic = 0;
}
else if (nmagic < NXFFS_MAGICSIZE - 1)
{
nmagic++;
}
/* We have found the magic sequence in the FLASH data that may
* indicate the beginning of an NXFFS inode.
*/
else
{
ret = nxffs_rdentry(volume, offset, entry);
if (ret == OK)
{
fdbg("Found a valid fileheader\n");
return OK;
}
/* False alarm.. keep looking */
nmagic = 0;
}
}
}
/* We won't get here, but to keep some compilers happy: */
return -ENOENT;
}
/****************************************************************************
* Name: nxffs_findinode
*
* Description:
* Search for an inode with the provided name starting with the first
* valid inode and proceeding to the end FLASH or until the matching
* inode is found.
*
* Input Parameters:
* volume - Describes the NXFFS volume
* name - The name of the inode to find
* entry - The location to return information about the inode.
*
* Returned Value:
* Zero is returned on success. Otherwise, a negated errno is returned
* that indicates the nature of the failure.
*
****************************************************************************/
int nxffs_findinode(FAR struct nxffs_volume_s *volume, FAR const char *name,
FAR struct nxffs_entry_s *entry)
{
off_t offset;
int ret;
/* Start with the first valid inode that was discovered when the volume
* was created (or modified after the last cleanup).
*/
offset = volume->inoffset;
/* Loop, checking each NXFFS inode until either: (1) we find the NXFFS inode
* with the matching name, or (2) we reach the end of data written on the
* media.
*/
for (;;)
{
/* Get the next, valid NXFFS inode entry */
ret = nxffs_nextentry(volume, offset, entry);
if (ret < 0)
{
fdbg("No inode found: %d\n", -ret);
return ret;
}
/* Is this the NXFFS inode we are looking for? */
else if (strcmp(name, entry->name) == 0)
{
/* Yes, return success with the entry data in 'enty' */
return OK;
}
/* Discard this entry and try the next one. Here we set the
* next offset using the raw data length as the offset
* increment. This is, of course, not accurate because it
* does not account for the data headers that enclose the
* data. But it is guaranteed to be less than or equal to
* the correct offset and, hence, better then searching
* byte-for-byte.
*/
offset = entry->doffset + entry->datlen;
nxffs_freeentry(entry);
}
/* We won't get here, but for some compilers: */
return -ENOENT;
}
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