/*
* Copyright (c) 2008 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/** @addtogroup fs
* @{
*/
/**
* @file fat_fat.c
* @brief Functions that manipulate the file allocation tables.
*/
#include "fat_fat.h"
#include "fat_dentry.h"
#include "fat.h"
#include "../../vfs/vfs.h"
#include <libfs.h>
#include <errno.h>
#include <byteorder.h>
#include <align.h>
#include <assert.h>
block_t *
_fat_block_get(dev_handle_t dev_handle, fat_cluster_t firstc, off_t offset)
{
block_t *bb;
block_t *b;
unsigned bps;
unsigned spc;
unsigned rscnt; /* block address of the first FAT */
unsigned fatcnt;
unsigned rde;
unsigned rds; /* root directory size */
unsigned sf;
unsigned ssa; /* size of the system area */
unsigned clusters;
fat_cluster_t clst = firstc;
unsigned i;
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
spc = FAT_BS(bb)->spc;
rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
fatcnt = FAT_BS(bb)->fatcnt;
rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
block_put(bb);
rds = (sizeof(fat_dentry_t) * rde) / bps;
rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
ssa = rscnt + fatcnt * sf + rds;
if (firstc == FAT_CLST_ROOT) {
/* root directory special case */
b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
return b;
}
clusters = offset / spc;
for (i = 0; i < clusters; i++) {
unsigned fsec; /* sector offset relative to FAT1 */
unsigned fidx; /* FAT1 entry index */
assert(clst
>= FAT_CLST_FIRST
&& clst
< FAT_CLST_BAD
); fsec = (clst * sizeof(fat_cluster_t)) / bps;
fidx = clst % (bps / sizeof(fat_cluster_t));
/* read FAT1 */
b = block_get(dev_handle, rscnt + fsec, bps);
clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
assert(clst
< FAT_CLST_LAST1
); block_put(b);
}
b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
offset % spc, bps);
return b;
}
/** Return number of blocks allocated to a file.
*
* @param dev_handle Device handle of the device with the file.
* @param firstc First cluster of the file.
*
* @return Number of blocks allocated to the file.
*/
uint16_t
_fat_blcks_get(dev_handle_t dev_handle, fat_cluster_t firstc)
{
block_t *bb;
block_t *b;
unsigned bps;
unsigned spc;
unsigned rscnt; /* block address of the first FAT */
unsigned clusters = 0;
fat_cluster_t clst = firstc;
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
spc = FAT_BS(bb)->spc;
rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
block_put(bb);
if (firstc == FAT_CLST_RES0) {
/* No space allocated to the file. */
return 0;
}
while (clst < FAT_CLST_LAST1) {
unsigned fsec; /* sector offset relative to FAT1 */
unsigned fidx; /* FAT1 entry index */
assert(clst
>= FAT_CLST_FIRST
); fsec = (clst * sizeof(fat_cluster_t)) / bps;
fidx = clst % (bps / sizeof(fat_cluster_t));
/* read FAT1 */
b = block_get(dev_handle, rscnt + fsec, bps);
clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
block_put(b);
clusters++;
}
return clusters * spc;
}
uint16_t fat_bps_get(dev_handle_t dev_handle)
{
block_t *bb;
uint16_t bps;
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
block_put(bb);
return bps;
}
/** Fill the gap between EOF and a new file position.
*
* @param nodep FAT node with the gap.
* @param mcl First cluster in an independent cluster chain that will
* be later appended to the end of the node's own cluster
* chain. If pos is still in the last allocated cluster,
* this argument is ignored.
* @param pos Position in the last node block.
*/
void fat_fill_gap(fat_node_t *nodep, fat_cluster_t mcl, off_t pos)
{
uint16_t bps;
unsigned spc;
block_t *bb, *b;
off_t o, boundary;
bb = block_get(nodep->idx->dev_handle, BS_BLOCK, BS_SIZE);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
spc = FAT_BS(bb)->spc;
block_put(bb);
boundary = ROUND_UP(nodep->size, bps * spc);
/* zero out already allocated space */
for (o = nodep->size - 1; o < pos && o < boundary;
o = ALIGN_DOWN(o + bps, bps)) {
b = fat_block_get(nodep, o / bps);
memset(b
->data
+ o
% bps
, 0, bps
- o
% bps
); b->dirty = true; /* need to sync node */
block_put(b);
}
if (o >= pos)
return;
/* zero out the initial part of the new cluster chain */
for (o = boundary; o < pos; o += bps) {
b = _fat_block_get(nodep->idx->dev_handle, mcl,
(o - boundary) / bps);
memset(b
->data
, 0, min
(bps
, pos
- o
)); b->dirty = true; /* need to sync node */
block_put(b);
}
}
void
fat_mark_cluster(dev_handle_t dev_handle, unsigned fatno, fat_cluster_t clst,
fat_cluster_t value)
{
/* TODO */
}
void fat_alloc_shadow_clusters(dev_handle_t dev_handle, fat_cluster_t *lifo,
unsigned nclsts)
{
uint8_t fatcnt;
uint8_t fatno;
unsigned c;
block_t *bb;
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
fatcnt = FAT_BS(bb)->fatcnt;
block_put(bb);
for (fatno = FAT1 + 1; fatno < fatcnt; fatno++) {
for (c = 0; c < nclsts; c++) {
fat_mark_cluster(dev_handle, fatno, lifo[c],
c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);
}
}
}
int
fat_alloc_clusters(dev_handle_t dev_handle, unsigned nclsts, fat_cluster_t *mcl,
fat_cluster_t *lcl)
{
uint16_t bps;
uint16_t rscnt;
uint16_t sf;
block_t *bb, *blk;
fat_cluster_t *lifo; /* stack for storing free cluster numbers */
unsigned found = 0; /* top of the free cluster number stack */
unsigned b, c, cl;
lifo
= (fat_cluster_t
*) malloc(nclsts
* sizeof(fat_cluster_t
)); if (lifo)
return ENOMEM;
bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
bps = uint16_t_le2host(FAT_BS(bb)->bps);
rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
block_put(bb);
/*
* Search FAT1 for unused clusters.
*/
for (b = 0, cl = 0; b < sf; blk++) {
blk = block_get(dev_handle, rscnt + b, bps);
for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
fat_cluster_t *clst = (fat_cluster_t *)blk->data + c;
if (*clst == FAT_CLST_RES0) {
/*
* The cluster is free. Put it into our stack
* of found clusters and mark it as non-free.
*/
lifo[found] = cl;
if (found == 0)
*clst = FAT_CLST_LAST1;
else
*clst = lifo[found - 1];
blk->dirty = true; /* need to sync block */
if (++found == nclsts) {
/* we are almost done */
block_put(blk);
/* update the shadow copies of FAT */
fat_alloc_shadow_clusters(dev_handle,
lifo, nclsts);
*mcl = lifo[found - 1];
*lcl = lifo[0];
return EOK;
}
}
}
block_put(blk);
}
/*
* We could not find enough clusters. Now we need to free the clusters
* we have allocated so far.
*/
while (found--)
fat_mark_cluster(dev_handle, FAT1, lifo[found], FAT_CLST_RES0);
return ENOSPC;
}
void fat_append_clusters(fat_node_t *nodep, fat_cluster_t mcl)
{
}
/**
* @}
*/