root / prex-0.9.0 / usr / server / fs / fatfs / fatfs_fat.c @ 03e9c04a
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/*
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* Copyright (c) 2005-2008, Kohsuke Ohtani
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/prex.h> |
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#include <sys/buf.h> |
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#include <ctype.h> |
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#include <errno.h> |
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#include <string.h> |
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#include <stdlib.h> |
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#include "fatfs.h" |
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/*
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* Read the FAT entry for specified cluster.
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*/
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static int |
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read_fat_entry(struct fatfsmount *fmp, u_long cl)
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{ |
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u_long sec; |
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char *buf = fmp->fat_buf;
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int error, border = 0; |
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struct buf *bp;
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/* Get the sector number in FAT entry. */
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if (FAT16(fmp))
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sec = (cl * 2) / SEC_SIZE;
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else {
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sec = (cl * 3 / 2) / SEC_SIZE; |
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/*
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* Check if the entry data is placed at the
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* end of sector. If so, we have to read one
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* more sector to get complete FAT12 entry.
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*/
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if ((cl * 3 / 2) % SEC_SIZE == SEC_SIZE - 1) |
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border = 1;
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} |
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sec += fmp->fat_start; |
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/* Read first sector. */
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if ((error = bread(fmp->dev, sec, &bp)) != 0) |
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return error;
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memcpy(buf, bp->b_data, SEC_SIZE); |
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brelse(bp); |
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if (!FAT12(fmp) || border == 0) |
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return 0; |
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/* Read second sector for the border entry of FAT12. */
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if ((error = bread(fmp->dev, sec + 1, &bp)) != 0) |
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return error;
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memcpy(buf + SEC_SIZE, bp->b_data, SEC_SIZE); |
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brelse(bp); |
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return 0; |
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} |
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/*
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* Write fat entry from buffer.
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*/
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static int |
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write_fat_entry(struct fatfsmount *fmp, u_long cl)
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{ |
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u_long sec; |
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char *buf = fmp->fat_buf;
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int error, border = 0; |
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struct buf *bp;
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/* Get the sector number in FAT entry. */
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if (FAT16(fmp))
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sec = (cl * 2) / SEC_SIZE;
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else {
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sec = (cl * 3 / 2) / SEC_SIZE; |
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/* Check if border entry for FAT12 */
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if ((cl * 3 / 2) % SEC_SIZE == SEC_SIZE - 1) |
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border = 1;
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} |
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sec += fmp->fat_start; |
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/* Write first sector. */
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bp = getblk(fmp->dev, sec); |
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memcpy(bp->b_data, buf, SEC_SIZE); |
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if ((error = bwrite(bp)) != 0) |
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return error;
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if (!FAT12(fmp) || border == 0) |
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return 0; |
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/* Write second sector for the border entry of FAT12. */
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bp = getblk(fmp->dev, sec + 1);
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memcpy(bp->b_data, buf + SEC_SIZE, SEC_SIZE); |
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error = bwrite(bp); |
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return error;
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} |
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/*
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* Get next cluster number of FAT chain.
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* @fmp: fat mount data
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* @cl: previous cluster#
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* @next: next cluster# to return
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*/
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int
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fat_next_cluster(struct fatfsmount *fmp, u_long cl, u_long *next)
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{ |
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u_int offset; |
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uint16_t val; |
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int error;
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/* Read FAT entry */
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error = read_fat_entry(fmp, cl); |
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if (error)
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return error;
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/* Get offset in buffer. */
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if (FAT16(fmp))
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offset = (cl * 2) % SEC_SIZE;
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else
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offset = (cl * 3 / 2) % SEC_SIZE; |
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/* Pick up cluster# */
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val = *((uint16_t *)(fmp->fat_buf + offset)); |
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/* Adjust data for FAT12 entry */
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if (FAT12(fmp)) {
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if (cl & 1) |
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val >>= 4;
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else
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val &= 0xfff;
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} |
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*next = (u_long)val; |
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DPRINTF(("fat_next_cluster: %d => %d\n", cl, *next));
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return 0; |
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} |
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/*
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* Set next cluster number in FAT chain.
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* @fmp: fat mount data
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* @cl: previous cluster#
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* @next: cluster# to set (can be eof)
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*/
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int
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fat_set_cluster(struct fatfsmount *fmp, u_long cl, u_long next)
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{ |
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u_int offset; |
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char *buf = fmp->fat_buf;
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int error;
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uint16_t val, tmp; |
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/* Read FAT entry */
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error = read_fat_entry(fmp, cl); |
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if (error)
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return error;
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/* Get offset in buffer. */
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if (FAT16(fmp))
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offset = (cl * 2) % SEC_SIZE;
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else
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offset = (cl * 3 / 2) % SEC_SIZE; |
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/* Modify FAT entry for target cluster. */
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val = (uint16_t)(next & fmp->fat_mask); |
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if (FAT12(fmp)) {
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tmp = *((uint16_t *)(buf + offset)); |
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if (cl & 1) { |
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val <<= 4;
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val |= (tmp & 0xf);
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} else {
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tmp &= 0xf000;
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val |= tmp; |
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} |
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} |
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*((uint16_t *)(buf + offset)) = val; |
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/* Write FAT entry */
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error = write_fat_entry(fmp, cl); |
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return error;
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} |
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/*
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* Allocate free cluster in FAT chain.
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*
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* @fmp: fat mount data
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* @scan_start: cluster# to scan first. If 0, use the previous used value.
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* @free: allocated cluster# to return
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*/
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int
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fat_alloc_cluster(struct fatfsmount *fmp, u_long scan_start, u_long *free)
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{ |
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u_long cl, next; |
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int error;
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if (scan_start == 0) |
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scan_start = fmp->free_scan; |
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DPRINTF(("fat_alloc_cluster: start=%d\n", scan_start));
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cl = scan_start + 1;
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while (cl != scan_start) {
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error = fat_next_cluster(fmp, cl, &next); |
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if (error)
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return error;
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if (next == CL_FREE) { /* free ? */ |
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DPRINTF(("fat_alloc_cluster: free cluster=%d\n", cl));
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*free = cl; |
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return 0; |
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} |
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if (++cl >= fmp->last_cluster)
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cl = CL_FIRST; |
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} |
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return ENOSPC; /* no space */ |
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} |
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/*
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* Deallocate needless cluster.
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* @fmp: fat mount data
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* @start: first cluster# of FAT chain
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*/
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int
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fat_free_clusters(struct fatfsmount *fmp, u_long start)
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{ |
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int error;
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u_long cl, next; |
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cl = start; |
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if (cl < CL_FIRST)
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return EINVAL;
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while (!IS_EOFCL(fmp, cl)) {
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error = fat_next_cluster(fmp, cl, &next); |
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if (error)
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return error;
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error = fat_set_cluster(fmp, cl, CL_FREE); |
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if (error)
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return error;
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cl = next; |
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} |
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/* Clear eof */
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error = fat_set_cluster(fmp, cl, CL_FREE); |
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if (error)
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return error;
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return 0; |
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} |
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/*
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* Get the cluster# for the specific file offset.
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*
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* @fmp: fat mount data
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* @start: start cluster# of file.
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* @offset: file offset
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* @cl: cluster# to return
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*/
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int
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fat_seek_cluster(struct fatfsmount *fmp, u_long start, u_long offset,
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u_long *cl) |
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{ |
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int error, i;
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u_long c, target; |
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if (start > fmp->last_cluster)
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return EIO;
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c = start; |
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target = offset / fmp->cluster_size; |
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for (i = 0; i < target; i++) { |
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error = fat_next_cluster(fmp, c, &c); |
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if (error)
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return error;
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if (IS_EOFCL(fmp, c))
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return EIO;
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} |
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*cl = c; |
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return 0; |
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} |
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/*
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* Expand file size.
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*
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* @fmp: fat mount data
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* @cl: cluster# of target file.
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* @size: new size of file in bytes.
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*/
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int
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fat_expand_file(struct fatfsmount *fmp, u_long cl, int size) |
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{ |
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int i, cl_len, alloc, error;
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u_long next; |
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alloc = 0;
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cl_len = size / fmp->cluster_size + 1;
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for (i = 0; i < cl_len; i++) { |
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error = fat_next_cluster(fmp, cl, &next); |
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if (error)
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return error;
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if (alloc || next >= fmp->fat_eof) {
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error = fat_alloc_cluster(fmp, cl, &next); |
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if (error)
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return error;
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alloc = 1;
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} |
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if (alloc) {
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error = fat_set_cluster(fmp, cl, next); |
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if (error)
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return error;
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} |
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cl = next; |
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} |
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if (alloc)
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fat_set_cluster(fmp, cl, fmp->fat_eof); /* add eof */
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DPRINTF(("fat_expand_file: new size=%d\n", size));
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return 0; |
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} |
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/*
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* Expand directory size.
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*
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* @fmp: fat mount data
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* @cl: cluster# of target directory
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* @new_cl: cluster# for new directory to return
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*
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* Note: The root directory can not be expanded.
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*/
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int
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fat_expand_dir(struct fatfsmount *fmp, u_long cl, u_long *new_cl)
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{ |
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int error;
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u_long next; |
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/* Find last cluster number of FAT chain. */
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while (!IS_EOFCL(fmp, cl)) {
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error = fat_next_cluster(fmp, cl, &next); |
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if (error)
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return error;
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cl = next; |
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} |
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error = fat_alloc_cluster(fmp, cl, &next); |
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if (error)
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return error;
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error = fat_set_cluster(fmp, cl, next); |
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if (error)
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return error;
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error = fat_set_cluster(fmp, next, fmp->fat_eof); |
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if (error)
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return error;
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*new_cl = next; |
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return 0; |
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} |