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); |
} |
} |
|
/** |
* @} |
*/ |