59,10 → 59,7 |
* @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 lastc If non-NULL, output argument hodling the last cluster number visited. |
* @param max_clusters Maximum number of clusters to visit. |
* |
* @return Number of clusters seen during the walk. |
69,7 → 66,7 |
*/ |
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) |
fat_cluster_t *lastc, uint16_t max_clusters) |
{ |
block_t *b; |
unsigned bps; |
82,22 → 79,18 |
|
if (firstc == FAT_CLST_RES0) { |
/* No space allocated to the file. */ |
if (ult) |
*ult = firstc; |
if (lastc) |
*lastc = firstc; |
return 0; |
} |
|
/* 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 */ |
bn_t fsec; /* sector offset relative to FAT1 */ |
unsigned fidx; /* FAT1 entry index */ |
|
assert(clst >= FAT_CLST_FIRST); |
if (penult) |
*penult = clst; /* remember the penultimate cluster */ |
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 */ |
108,8 → 101,8 |
clusters++; |
} |
|
if (ult) |
*ult = clst; |
if (lastc && clst < FAT_CLST_LAST1) |
*lastc = clst; |
|
return clusters; |
} |
120,13 → 113,13 |
* @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 bn Block number. |
* |
* @return Block structure holding the requested block. |
*/ |
block_t * |
_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc, |
off_t offset) |
bn_t bn) |
{ |
block_t *b; |
unsigned bps; |
136,7 → 129,7 |
unsigned sf; |
unsigned ssa; /* size of the system area */ |
unsigned clusters, max_clusters; |
fat_cluster_t lastc, clst = firstc; |
fat_cluster_t lastc; |
|
bps = uint16_t_le2host(bs->bps); |
rscnt = uint16_t_le2host(bs->rscnt); |
149,23 → 142,22 |
|
if (firstc == FAT_CLST_ROOT) { |
/* root directory special case */ |
assert(offset < rds); |
b = block_get(dev_handle, rscnt + bs->fatcnt * sf + offset); |
assert(bn < rds); |
b = block_get(dev_handle, rscnt + bs->fatcnt * sf + bn); |
return b; |
} |
|
max_clusters = offset / bs->spc; |
clusters = fat_cluster_walk(bs, dev_handle, firstc, NULL, &lastc, |
max_clusters = bn / bs->spc; |
clusters = fat_cluster_walk(bs, dev_handle, firstc, &lastc, |
max_clusters); |
assert(clusters == max_clusters); |
|
b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc + |
offset % bs->spc); |
bn % bs->spc); |
|
return b; |
} |
|
|
/** Fill the gap between EOF and a new file position. |
* |
* @param bs Buffer holding the boot sector for nodep. |
210,16 → 202,43 |
} |
} |
|
/** 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); |
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; |
256,7 → 275,7 |
|
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]); |
} |
} |
340,7 → 359,7 |
* 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); |
} |
|
348,9 → 367,32 |
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. |
*/ |
360,8 → 402,8 |
fat_cluster_t lcl; |
uint8_t fatno; |
|
if (fat_cluster_walk(bs, nodep->idx->dev_handle, nodep->firstc, &lcl, |
NULL, (uint16_t) -1) == 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 */ |
369,9 → 411,40 |
} |
|
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); |
} |
} |
|
/** |
* @} |
*/ |