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Ignore whitespace Rev 3560 → Rev 3561

/branches/dynload/uspace/srv/fs/fat/fat_fat.c
54,127 → 54,118
*/
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 penult If non-NULL, output argument hodling the
* the penultimate cluster visited.
* @param ult If non-NULL, output argument holding the
* ultimate cluster 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 *penult, fat_cluster_t *ult, 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 (ult)
*ult = firstc;
return 0;
}
 
clusters = offset / spc;
for (i = 0; i < clusters; i++) {
/* At this point, the meaning of penult is not well-defined. */
if (penult)
*penult = FAT_CLST_RES0;
 
while (clst < FAT_CLST_LAST1 && clusters < max_clusters) {
unsigned 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 (penult)
*penult = clst; /* remember the penultimate 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);
b = block_get(dev_handle, rscnt + fsec);
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 (ult)
*ult = 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 offset Offset in blocks.
*
* @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,
off_t offset)
{
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, clst = firstc;
 
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(offset < rds);
b = block_get(dev_handle, rscnt + bs->fatcnt * sf + offset);
return b;
}
 
while (clst < FAT_CLST_LAST1) {
unsigned fsec; /* sector offset relative to FAT1 */
unsigned fidx; /* FAT1 entry index */
max_clusters = offset / bs->spc;
clusters = fat_cluster_walk(bs, dev_handle, firstc, NULL, &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 +
offset % bs->spc);
 
if (lastc)
*lastc = clst;
return clusters * spc;
return b;
}
 
 
/** Fill the gap between EOF and a new file position.
*
* @param bs Buffer holding the boot sector for nodep.
243,7 → 234,7
 
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);
cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));
*cp = host2uint16_t_le(value);
b->dirty = true; /* need to sync block */
313,7 → 304,7
*/
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);
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) {
369,7 → 360,9
fat_cluster_t lcl;
uint8_t fatno;
 
if (_fat_blcks_get(bs, dev_handle, nodep->firstc, &lcl) == 0) {
if (fat_cluster_walk(bs, nodep->idx->dev_handle, nodep->firstc, &lcl,
NULL, (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;