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Ignore whitespace Rev 3596 → Rev 3597

/branches/tracing/uspace/srv/fs/fat/fat_fat.c
54,125 → 54,109
*/
static futex_t fat_alloc_lock = FUTEX_INITIALIZER;
 
/** Read block from file located on a FAT file system.
/** Walk the cluster chain.
*
* @param bs Buffer holding the boot sector of the file system.
* @param dev_handle Device handle of the file system.
* @param firstc First cluster used by the file. Can be zero if the file
* is empty.
* @param offset Offset in blocks.
* @param bs Buffer holding the boot sector for the file.
* @param dev_handle Device handle of the device with the file.
* @param firstc First cluster to start the walk with.
* @param lastc If non-NULL, output argument hodling the last cluster number visited.
* @param max_clusters Maximum number of clusters to visit.
*
* @return Block structure holding the requested block.
* @return Number of clusters seen during the walk.
*/
block_t *
_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
off_t offset)
uint16_t
fat_cluster_walk(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
fat_cluster_t *lastc, uint16_t max_clusters)
{
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;
uint16_t clusters = 0;
fat_cluster_t clst = firstc;
unsigned i;
 
bps = uint16_t_le2host(bs->bps);
spc = bs->spc;
rscnt = uint16_t_le2host(bs->rscnt);
fatcnt = bs->fatcnt;
rde = uint16_t_le2host(bs->root_ent_max);
sf = uint16_t_le2host(bs->sec_per_fat);
 
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 */
assert(offset < rds);
b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
return b;
if (firstc == FAT_CLST_RES0) {
/* No space allocated to the file. */
if (lastc)
*lastc = firstc;
return 0;
}
 
clusters = offset / spc;
for (i = 0; i < clusters; i++) {
unsigned fsec; /* sector offset relative to FAT1 */
while (clst < FAT_CLST_LAST1 && clusters < max_clusters) {
bn_t fsec; /* sector offset relative to FAT1 */
unsigned fidx; /* FAT1 entry index */
 
assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);
assert(clst >= FAT_CLST_FIRST);
if (lastc)
*lastc = clst; /* remember the last cluster number */
fsec = (clst * sizeof(fat_cluster_t)) / bps;
fidx = clst % (bps / sizeof(fat_cluster_t));
/* read FAT1 */
b = block_get(dev_handle, rscnt + fsec, bps);
b = block_get(dev_handle, rscnt + fsec, BLOCK_FLAGS_NONE);
clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
assert(clst != FAT_CLST_BAD);
assert(clst < FAT_CLST_LAST1);
block_put(b);
clusters++;
}
 
b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
offset % spc, bps);
if (lastc && clst < FAT_CLST_LAST1)
*lastc = clst;
 
return b;
return clusters;
}
 
/** Return number of blocks allocated to a file.
/** Read block from file located on a FAT file system.
*
* @param bs Buffer holding the boot sector for the file.
* @param dev_handle Device handle of the device with the file.
* @param firstc First cluster of the file.
* @param lastc If non-NULL, output argument holding the
* last cluster.
* @param bs Buffer holding the boot sector of the file system.
* @param dev_handle Device handle of the file system.
* @param firstc First cluster used by the file. Can be zero if the file
* is empty.
* @param bn Block number.
* @param flags Flags passed to libblock.
*
* @return Number of blocks allocated to the file.
* @return Block structure holding the requested block.
*/
uint16_t
_fat_blcks_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
fat_cluster_t *lastc)
block_t *
_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
bn_t bn, int flags)
{
block_t *b;
unsigned bps;
unsigned spc;
unsigned rscnt; /* block address of the first FAT */
unsigned clusters = 0;
fat_cluster_t clst = firstc;
unsigned rde;
unsigned rds; /* root directory size */
unsigned sf;
unsigned ssa; /* size of the system area */
unsigned clusters, max_clusters;
fat_cluster_t lastc;
 
bps = uint16_t_le2host(bs->bps);
spc = bs->spc;
rscnt = uint16_t_le2host(bs->rscnt);
rde = uint16_t_le2host(bs->root_ent_max);
sf = uint16_t_le2host(bs->sec_per_fat);
 
if (firstc == FAT_CLST_RES0) {
/* No space allocated to the file. */
if (lastc)
*lastc = firstc;
return 0;
rds = (sizeof(fat_dentry_t) * rde) / bps;
rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
ssa = rscnt + bs->fatcnt * sf + rds;
 
if (firstc == FAT_CLST_ROOT) {
/* root directory special case */
assert(bn < rds);
b = block_get(dev_handle, rscnt + bs->fatcnt * sf + bn, flags);
return b;
}
 
while (clst < FAT_CLST_LAST1) {
unsigned fsec; /* sector offset relative to FAT1 */
unsigned fidx; /* FAT1 entry index */
max_clusters = bn / bs->spc;
clusters = fat_cluster_walk(bs, dev_handle, firstc, &lastc,
max_clusters);
assert(clusters == max_clusters);
 
assert(clst >= FAT_CLST_FIRST);
if (lastc)
*lastc = clst; /* remember the last cluster */
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_BAD);
block_put(b);
clusters++;
}
b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc +
bn % bs->spc, flags);
 
if (lastc)
*lastc = clst;
return clusters * spc;
return b;
}
 
/** Fill the gap between EOF and a new file position.
200,7 → 184,9
/* zero out already allocated space */
for (o = nodep->size - 1; o < pos && o < boundary;
o = ALIGN_DOWN(o + bps, bps)) {
b = fat_block_get(bs, nodep, o / bps);
int flags = (o % bps == 0) ?
BLOCK_FLAGS_NOREAD : BLOCK_FLAGS_NONE;
b = fat_block_get(bs, nodep, o / bps, flags);
memset(b->data + o % bps, 0, bps - o % bps);
b->dirty = true; /* need to sync node */
block_put(b);
212,7 → 198,7
/* zero out the initial part of the new cluster chain */
for (o = boundary; o < pos; o += bps) {
b = _fat_block_get(bs, nodep->idx->dev_handle, mcl,
(o - boundary) / bps);
(o - boundary) / bps, BLOCK_FLAGS_NOREAD);
memset(b->data, 0, min(bps, pos - o));
b->dirty = true; /* need to sync node */
block_put(b);
219,16 → 205,44
}
}
 
/** Mark cluster in one instance of FAT.
/** Get cluster from the first FAT.
*
* @param bs Buffer holding the boot sector for the file system.
* @param dev_handle Device handle for the file system.
* @param clst Cluster which to get.
*
* @return Value found in the cluster.
*/
fat_cluster_t
fat_get_cluster(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t clst)
{
block_t *b;
uint16_t bps;
uint16_t rscnt;
fat_cluster_t *cp, value;
 
bps = uint16_t_le2host(bs->bps);
rscnt = uint16_t_le2host(bs->rscnt);
 
b = block_get(dev_handle, rscnt + (clst * sizeof(fat_cluster_t)) / bps,
BLOCK_FLAGS_NONE);
cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));
value = uint16_t_le2host(*cp);
block_put(b);
return value;
}
 
/** Set cluster in one instance of FAT.
*
* @param bs Buffer holding the boot sector for the file system.
* @param dev_handle Device handle for the file system.
* @param fatno Number of the FAT instance where to make the change.
* @param clst Cluster which is to be marked.
* @param value Value mark the cluster with.
* @param clst Cluster which is to be set.
* @param value Value to set the cluster with.
*/
void
fat_mark_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,
fat_set_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,
fat_cluster_t clst, fat_cluster_t value)
{
block_t *b;
243,7 → 257,7
 
assert(fatno < bs->fatcnt);
b = block_get(dev_handle, rscnt + sf * fatno +
(clst * sizeof(fat_cluster_t)) / bps, bps);
(clst * sizeof(fat_cluster_t)) / bps, BLOCK_FLAGS_NONE);
cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));
*cp = host2uint16_t_le(value);
b->dirty = true; /* need to sync block */
265,7 → 279,7
 
for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) {
for (c = 0; c < nclsts; c++) {
fat_mark_cluster(bs, dev_handle, fatno, lifo[c],
fat_set_cluster(bs, dev_handle, fatno, lifo[c],
c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);
}
}
313,7 → 327,7
*/
futex_down(&fat_alloc_lock);
for (b = 0, cl = 0; b < sf; blk++) {
blk = block_get(dev_handle, rscnt + b, bps);
blk = block_get(dev_handle, rscnt + b, BLOCK_FLAGS_NOREAD);
for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
fat_cluster_t *clst = (fat_cluster_t *)blk->data + c;
if (uint16_t_le2host(*clst) == FAT_CLST_RES0) {
349,7 → 363,7
* we have allocated so far.
*/
while (found--) {
fat_mark_cluster(bs, dev_handle, FAT1, lifo[found],
fat_set_cluster(bs, dev_handle, FAT1, lifo[found],
FAT_CLST_RES0);
}
357,9 → 371,32
return ENOSPC;
}
 
/** Free clusters forming a cluster chain in all copies of FAT.
*
* @param bs Buffer hodling the boot sector of the file system.
* @param dev_handle Device handle of the file system.
* @param firstc First cluster in the chain which is to be freed.
*/
void
fat_free_clusters(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc)
{
unsigned fatno;
fat_cluster_t nextc;
 
/* Mark all clusters in the chain as free in all copies of FAT. */
while (firstc < FAT_CLST_LAST1) {
nextc = fat_get_cluster(bs, dev_handle, firstc);
assert(nextc >= FAT_CLST_FIRST && nextc < FAT_CLST_BAD);
for (fatno = FAT1; fatno < bs->fatcnt; fatno++)
fat_set_cluster(bs, dev_handle, fatno, firstc,
FAT_CLST_RES0);
firstc = nextc;
}
}
 
/** Append a cluster chain to the last file cluster in all FATs.
*
* @param bs Buffer holding boot sector of the file system.
* @param bs Buffer holding the boot sector of the file system.
* @param nodep Node representing the file.
* @param mcl First cluster of the cluster chain to append.
*/
369,7 → 406,9
fat_cluster_t lcl;
uint8_t fatno;
 
if (_fat_blcks_get(bs, dev_handle, nodep->firstc, &lcl) == 0) {
if (fat_cluster_walk(bs, dev_handle, nodep->firstc, &lcl,
(uint16_t) -1) == 0) {
/* No clusters allocated to the node yet. */
nodep->firstc = host2uint16_t_le(mcl);
nodep->dirty = true; /* need to sync node */
return;
376,9 → 415,40
}
 
for (fatno = FAT1; fatno < bs->fatcnt; fatno++)
fat_mark_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);
fat_set_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);
}
 
/** Chop off node clusters in all copies of FAT.
*
* @param bs Buffer holding the boot sector of the file system.
* @param nodep FAT node where the chopping will take place.
* @param lastc Last cluster which will remain in the node. If this
* argument is FAT_CLST_RES0, then all clusters will
* be chopped off.
*/
void fat_chop_clusters(fat_bs_t *bs, fat_node_t *nodep, fat_cluster_t lastc)
{
dev_handle_t dev_handle = nodep->idx->dev_handle;
if (lastc == FAT_CLST_RES0) {
/* The node will have zero size and no clusters allocated. */
fat_free_clusters(bs, dev_handle, nodep->firstc);
nodep->firstc = FAT_CLST_RES0;
nodep->dirty = true; /* need to sync node */
} else {
fat_cluster_t nextc;
unsigned fatno;
 
nextc = fat_get_cluster(bs, dev_handle, lastc);
 
/* Terminate the cluster chain in all copies of FAT. */
for (fatno = FAT1; fatno < bs->fatcnt; fatno++)
fat_set_cluster(bs, dev_handle, fatno, lastc, FAT_CLST_LAST1);
 
/* Free all following clusters. */
fat_free_clusters(bs, dev_handle, nextc);
}
}
 
/**
* @}
*/