#include "ao_fat.h"
#include "ao_bufio.h"
+/*
+ * Basic file system types
+ */
+
+typedef ao_fat_offset_t offset_t;
+typedef ao_fat_sector_t sector_t;
+typedef ao_fat_cluster_t cluster_t;
+typedef ao_fat_dirent_t dirent_t;
+typedef ao_fat_cluster_offset_t cluster_offset_t;
+
/* Partition information, sector numbers */
-static uint8_t partition_type;
-static uint32_t partition_start, partition_end;
+static uint8_t partition_type;
+static sector_t partition_start, partition_end;
+
+#define AO_FAT_BAD_CLUSTER 0xffffff7
+#define AO_FAT_LAST_CLUSTER 0xfffffff
+#define AO_FAT_IS_LAST_CLUSTER(c) (((c) & 0xffffff8) == 0xffffff8)
+#define AO_FAT_IS_LAST_CLUSTER16(c) (((c) & 0xfff8) == 0xfff8)
+
#define SECTOR_SIZE 512
#define SECTOR_MASK (SECTOR_SIZE - 1)
#define DIRENT_SIZE 32
/* File system parameters */
-static uint8_t sectors_per_cluster;
-static uint32_t bytes_per_cluster;
-static uint16_t reserved_sector_count;
-static uint8_t number_fat;
-static uint16_t root_entries;
-static uint16_t sectors_per_fat;
-static uint16_t number_cluster;
-static uint32_t fat_start;
-static uint32_t root_start;
-static uint32_t data_start;
-static uint16_t first_free_cluster;
+static uint8_t sectors_per_cluster;
+static uint32_t bytes_per_cluster;
+static sector_t reserved_sector_count;
+static uint8_t number_fat;
+static dirent_t root_entries;
+static sector_t sectors_per_fat;
+static cluster_t number_cluster;
+static sector_t fat_start;
+static sector_t root_start;
+static sector_t data_start;
+static cluster_t next_free;
+static uint8_t filesystem_full;
+
+/* FAT32 extra data */
+static uint8_t fat32;
+static uint8_t fsinfo_dirty;
+static cluster_t root_cluster;
+static sector_t fsinfo_sector;
+static cluster_t free_count;
/*
* Deal with LSB FAT data structures
}
static uint8_t
-ao_fat_cluster_valid(uint16_t cluster)
+ao_fat_cluster_valid(cluster_t cluster)
{
return (2 <= cluster && cluster < number_cluster);
}
/* Start using a sector */
static uint8_t *
-ao_fat_sector_get(uint32_t sector)
+ao_fat_sector_get(sector_t sector)
{
sector += partition_start;
if (sector >= partition_end)
/* Finish using a sector, 'w' is 1 if modified */
#define ao_fat_sector_put(b,w) ao_bufio_put(b,w)
-/* Start using a root directory entry */
-static uint8_t *
-ao_fat_root_get(uint16_t e)
-{
- uint32_t byte = e * DIRENT_SIZE;
- uint32_t sector = byte >> SECTOR_SHIFT;
- uint16_t offset = byte & SECTOR_MASK;
- uint8_t *buf;
-
- buf = ao_fat_sector_get(root_start + sector);
- if (!buf)
- return NULL;
- return buf + offset;
-}
-
-/* Finish using a root directory entry, 'w' is 1 if modified */
-static void
-ao_fat_root_put(uint8_t *root, uint16_t e, uint8_t write)
-{
- uint16_t offset = ((e * DIRENT_SIZE) & SECTOR_MASK);
- uint8_t *buf = root - offset;
-
- ao_fat_sector_put(buf, write);
-}
-
/* Get the next cluster entry in the chain */
-static uint16_t
-ao_fat_entry_read(uint16_t cluster)
+static cluster_t
+ao_fat_entry_read(cluster_t cluster)
{
- uint32_t sector;
- uint16_t offset;
+ sector_t sector;
+ cluster_t offset;
uint8_t *buf;
- uint16_t ret;
+ cluster_t ret;
if (!ao_fat_cluster_valid(cluster))
- return 0xfff7;
-
- sector = cluster >> (SECTOR_SHIFT - 1);
- offset = (cluster << 1) & SECTOR_MASK;
+ return 0xfffffff7;
+
+ if (fat32)
+ cluster <<= 2;
+ else
+ cluster <<= 1;
+ sector = cluster >> (SECTOR_SHIFT);
+ offset = cluster & SECTOR_MASK;
buf = ao_fat_sector_get(fat_start + sector);
if (!buf)
return 0;
- ret = get_u16(buf + offset);
+
+ if (fat32) {
+ ret = get_u32(buf + offset);
+ ret &= 0xfffffff;
+ } else {
+ ret = get_u16(buf + offset);
+ if (AO_FAT_IS_LAST_CLUSTER16(ret))
+ ret |= 0xfff0000;
+ }
ao_fat_sector_put(buf, 0);
return ret;
}
/* Replace the referenced cluster entry in the chain with
* 'new_value'. Return the previous value.
*/
-static uint16_t
-ao_fat_entry_replace(uint16_t cluster, uint16_t new_value)
+static cluster_t
+ao_fat_entry_replace(cluster_t cluster, cluster_t new_value)
{
- uint32_t sector;
- uint16_t offset;
- uint8_t *buf;
- uint16_t ret;
- uint8_t other_fats;
+ sector_t sector;
+ cluster_offset_t offset;
+ uint8_t *buf;
+ cluster_t ret;
+ cluster_t old_value;
+ uint8_t fat;
if (!ao_fat_cluster_valid(cluster))
- return 0;
-
- sector = cluster >> (SECTOR_SHIFT - 1);
- offset = (cluster << 1) & SECTOR_MASK;
- buf = ao_fat_sector_get(fat_start + sector);
- if (!buf)
- return 0;
- ret = get_u16(buf + offset);
- put_u16(buf + offset, new_value);
- ao_fat_sector_put(buf, 1);
-
- /*
- * Keep the other FATs in sync
- */
- for (other_fats = 1; other_fats < number_fat; other_fats++) {
- buf = ao_fat_sector_get(fat_start + other_fats * sectors_per_fat + sector);
- if (buf) {
+ return 0xfffffff7;
+
+ /* Convert from cluster index to byte index */
+ if (fat32)
+ cluster <<= 2;
+ else
+ cluster <<= 1;
+ sector = cluster >> SECTOR_SHIFT;
+ offset = cluster & SECTOR_MASK;
+
+ new_value &= 0xfffffff;
+ for (fat = 0; fat < number_fat; fat++) {
+ buf = ao_fat_sector_get(fat_start + fat * sectors_per_fat + sector);
+ if (!buf)
+ return 0;
+ if (fat32) {
+ old_value = get_u32(buf + offset);
+ put_u32(buf + offset, new_value | (old_value & 0xf0000000));
+ if (fat == 0) {
+ ret = old_value & 0xfffffff;
+
+ /* Track the free count if it wasn't marked
+ * invalid when we mounted the file system
+ */
+ if (free_count != 0xffffffff) {
+ if (new_value && !ret) {
+ --free_count;
+ fsinfo_dirty = 1;
+ } else if (!new_value && ret) {
+ ++free_count;
+ fsinfo_dirty = 1;
+ }
+ }
+ }
+ } else {
+ if (fat == 0) {
+ ret = get_u16(buf + offset);
+ if (AO_FAT_IS_LAST_CLUSTER16(ret))
+ ret |= 0xfff0000;
+ }
put_u16(buf + offset, new_value);
- ao_fat_sector_put(buf, 1);
}
+ ao_fat_sector_put(buf, 1);
}
return ret;
* all of them as free
*/
static void
-ao_fat_free_cluster_chain(uint16_t cluster)
+ao_fat_free_cluster_chain(cluster_t cluster)
{
while (ao_fat_cluster_valid(cluster)) {
- if (cluster < first_free_cluster)
- first_free_cluster = cluster;
- cluster = ao_fat_entry_replace(cluster, 0x0000);
+ if (cluster < next_free) {
+ next_free = cluster;
+ fsinfo_dirty = 1;
+ }
+ cluster = ao_fat_entry_replace(cluster, 0x00000000);
}
}
* 0xffff if we walk off the end of the file or the cluster chain
* is damaged somehow
*/
-static uint16_t
-ao_fat_cluster_seek(uint16_t cluster, uint16_t distance)
+static cluster_t
+ao_fat_cluster_seek(cluster_t cluster, cluster_t distance)
{
while (distance) {
cluster = ao_fat_entry_read(cluster);
return cluster;
}
+/*
+ * ao_fat_cluster_set_size
+ *
+ * Set the number of clusters in the specified chain,
+ * freeing extra ones or alocating new ones as needed
+ *
+ * Returns AO_FAT_BAD_CLUSTER on allocation failure
+ */
+
+static cluster_t
+ao_fat_cluster_set_size(cluster_t first_cluster, cluster_t size)
+{
+ cluster_t clear_cluster = 0;
+
+ if (size == 0) {
+ clear_cluster = first_cluster;
+ first_cluster = 0;
+ } else {
+ cluster_t have;
+ cluster_t last_cluster = 0;
+ cluster_t next_cluster;
+
+ /* Walk the cluster chain to the
+ * spot where it needs to change. That
+ * will either be the end of the chain (in case it needs to grow),
+ * or after the desired number of clusters, in which case it needs to shrink
+ */
+ next_cluster = first_cluster;
+ for (have = 0; have < size; have++) {
+ last_cluster = next_cluster;
+ next_cluster = ao_fat_entry_read(last_cluster);
+ if (!ao_fat_cluster_valid(next_cluster))
+ break;
+ }
+
+ if (have == size) {
+ /* The file is large enough, truncate as needed */
+ if (ao_fat_cluster_valid(next_cluster)) {
+ /* Rewrite that cluster entry with 0xffff to mark the end of the chain */
+ clear_cluster = ao_fat_entry_replace(last_cluster, AO_FAT_LAST_CLUSTER);
+ filesystem_full = 0;
+ } else {
+ /* The chain is already the right length, don't mess with it */
+ ;
+ }
+ } else {
+ cluster_t need;
+ cluster_t free;
+
+ if (filesystem_full)
+ return AO_FAT_BAD_CLUSTER;
+
+ if (next_free < 2 || number_cluster <= next_free) {
+ next_free = 2;
+ fsinfo_dirty = 1;
+ }
+
+ /* See if there are enough free clusters in the file system */
+ need = size - have;
+
+#define loop_cluster for (free = next_free; need > 0;)
+#define next_cluster \
+ if (++free == number_cluster) \
+ free = 2; \
+ if (free == next_free) \
+ break; \
+
+ loop_cluster {
+ if (!ao_fat_entry_read(free))
+ need--;
+ next_cluster;
+ }
+ /* Still need some, tell the user that we've failed */
+ if (need) {
+ filesystem_full = 1;
+ return AO_FAT_BAD_CLUSTER;
+ }
+
+ /* Now go allocate those clusters and
+ * thread them onto the chain
+ */
+ need = size - have;
+ loop_cluster {
+ if (!ao_fat_entry_read(free)) {
+ next_free = free + 1;
+ if (next_free >= number_cluster)
+ next_free = 2;
+ fsinfo_dirty = 1;
+ if (last_cluster)
+ ao_fat_entry_replace(last_cluster, free);
+ else
+ first_cluster = free;
+ last_cluster = free;
+ need--;
+ }
+ next_cluster;
+ }
+#undef loop_cluster
+#undef next_cluster
+ /* Mark the new end of the chain */
+ ao_fat_entry_replace(last_cluster, AO_FAT_LAST_CLUSTER);
+ }
+ }
+
+ /* Deallocate clusters off the end of the file */
+ if (ao_fat_cluster_valid(clear_cluster))
+ ao_fat_free_cluster_chain(clear_cluster);
+ return first_cluster;
+}
+
+/* Start using a root directory entry */
+static uint8_t *
+ao_fat_root_get(dirent_t e)
+{
+ offset_t byte = e * DIRENT_SIZE;
+ sector_t sector = byte >> SECTOR_SHIFT;
+ cluster_offset_t offset = byte & SECTOR_MASK;
+ uint8_t *buf;
+
+ if (fat32) {
+ cluster_t cluster_distance = sector / sectors_per_cluster;
+ sector_t sector_index = sector % sectors_per_cluster;
+ cluster_t cluster = ao_fat_cluster_seek(root_cluster, cluster_distance);
+
+ if (ao_fat_cluster_valid(cluster))
+ sector = data_start + (cluster-2) * sectors_per_cluster + sector_index;
+ else
+ return NULL;
+ } else {
+ if (e >= root_entries)
+ return NULL;
+ sector = root_start + sector;
+ }
+
+ buf = ao_fat_sector_get(sector);
+ if (!buf)
+ return NULL;
+ return buf + offset;
+}
+
+/* Finish using a root directory entry, 'w' is 1 if modified */
+static void
+ao_fat_root_put(uint8_t *root, dirent_t e, uint8_t write)
+{
+ cluster_offset_t offset = ((e * DIRENT_SIZE) & SECTOR_MASK);
+ uint8_t *buf = root - offset;
+
+ ao_fat_sector_put(buf, write);
+}
+
+/*
+ * ao_fat_root_extend
+ *
+ * On FAT32, make the
+ */
+static int8_t
+ao_fat_root_extend(dirent_t ents)
+{
+ offset_t byte_size;
+ cluster_t cluster_size;
+ if (!fat32)
+ return 0;
+
+ byte_size = ents * 0x20;
+ cluster_size = byte_size / bytes_per_cluster;
+ if (ao_fat_cluster_set_size(root_cluster, cluster_size) != AO_FAT_BAD_CLUSTER)
+ return 1;
+ return 0;
+}
+
/*
* ao_fat_setup_partition
*
number_fat = boot[0x10];
root_entries = get_u16(boot + 0x11);
sectors_per_fat = get_u16(boot+0x16);
+ fat32 = 0;
+ if (sectors_per_fat == 0) {
+ fat32 = 1;
+ sectors_per_fat = get_u32(boot+0x24);
+ root_cluster = get_u32(boot+0x2c);
+ fsinfo_sector = get_u16(boot + 0x30);
+ }
+ ao_fat_sector_put(boot, 0);
+
+ free_count = 0xffffffff;
+ next_free = 0;
+ if (fat32 && fsinfo_sector) {
+ uint8_t *fsinfo = ao_fat_sector_get(fsinfo_sector);
+
+ if (fsinfo) {
+ free_count = get_u32(fsinfo + 0x1e8);
+ next_free = get_u32(fsinfo + 0x1ec);
+ ao_fat_sector_put(fsinfo, 0);
+ }
+ }
fat_start = reserved_sector_count;;
root_start = fat_start + number_fat * sectors_per_fat;
number_cluster = data_sectors / sectors_per_cluster;
+ printf ("fat32: %d\n", fat32);
printf ("sectors per cluster %d\n", sectors_per_cluster);
printf ("reserved sectors %d\n", reserved_sector_count);
printf ("number of FATs %d\n", number_fat);
printf ("root start %d\n", root_start);
printf ("data start %d\n", data_start);
- ao_fat_sector_put(boot, 0);
-
return 1;
}
+/*
+ * State for the current opened file
+ */
+static struct ao_fat_dirent ao_file_dirent;
+static uint32_t ao_file_offset;
+static uint32_t ao_file_cluster_offset;
+static cluster_t ao_file_cluster;
+static uint8_t ao_file_opened;
+
static uint8_t
ao_fat_setup(void)
{
+ ao_bufio_setup();
+
+ partition_type = partition_start = partition_end = 0;
+ sectors_per_cluster = bytes_per_cluster = reserved_sector_count = 0;
+ number_fat = root_entries = sectors_per_fat = 0;
+ number_cluster = fat_start = root_start = data_start = 0;
+ next_free = filesystem_full = 0;
+ fat32 = fsinfo_dirty = root_cluster = fsinfo_sector = free_count = 0;
+ memset(&ao_file_dirent, '\0', sizeof (ao_file_dirent));
+ ao_file_offset = ao_file_cluster_offset = ao_file_cluster = ao_file_opened = 0;
if (!ao_fat_setup_partition())
return 0;
- check_bufio("partition setup");
if (!ao_fat_setup_fs())
return 0;
- check_bufio("fs setup");
return 1;
}
* Basic file operations
*/
-static struct ao_fat_dirent ao_file_dirent;
-static uint32_t ao_file_offset;
-static uint32_t ao_file_cluster_offset;
-static uint16_t ao_file_cluster;
-static uint8_t ao_file_opened;
-
static uint32_t
ao_fat_current_sector(void)
{
- uint16_t cluster_offset;
+ cluster_t cluster_offset;
uint32_t sector_offset;
uint16_t sector_index;
- uint16_t cluster;
+ cluster_t cluster;
if (ao_file_offset > ao_file_dirent.size)
return 0xffffffff;
}
if (ao_file_cluster_offset + bytes_per_cluster <= ao_file_offset) {
- uint16_t cluster_distance;
+ cluster_t cluster_distance;
cluster_offset = sector_offset / sectors_per_cluster;
static int8_t
ao_fat_set_size(uint32_t size)
{
- uint16_t clear_cluster = 0;
uint8_t *dent;
- uint16_t first_cluster;
+ cluster_t first_cluster;
+ cluster_t have_clusters, need_clusters;
- first_cluster = ao_file_dirent.cluster;
if (size == ao_file_dirent.size)
return AO_FAT_SUCCESS;
- if (size == 0) {
- clear_cluster = ao_file_dirent.cluster;
- first_cluster = 0;
- } else {
- uint16_t new_num;
- uint16_t old_num;
-
- new_num = (size + bytes_per_cluster - 1) / bytes_per_cluster;
- old_num = (ao_file_dirent.size + bytes_per_cluster - 1) / bytes_per_cluster;
- if (new_num < old_num) {
- uint16_t last_cluster;
-
- /* Go find the last cluster we want to preserve in the file */
- last_cluster = ao_fat_cluster_seek(ao_file_dirent.cluster, new_num - 1);
-
- /* Rewrite that cluster entry with 0xffff to mark the end of the chain */
- clear_cluster = ao_fat_entry_replace(last_cluster, 0xffff);
- } else if (new_num > old_num) {
- uint16_t need;
- uint16_t free;
- uint16_t last_cluster;
- uint16_t highest_allocated = 0;
-
- if (old_num)
- last_cluster = ao_fat_cluster_seek(ao_file_dirent.cluster, old_num - 1);
- else
- last_cluster = 0;
- if (first_free_cluster < 2 || number_cluster <= first_free_cluster)
- first_free_cluster = 2;
+ first_cluster = ao_file_dirent.cluster;
+ have_clusters = (ao_file_dirent.size + bytes_per_cluster - 1) / bytes_per_cluster;
+ need_clusters = (size + bytes_per_cluster - 1) / bytes_per_cluster;
- /* See if there are enough free clusters in the file system */
- need = new_num - old_num;
+ if (have_clusters != need_clusters) {
+ if (ao_file_cluster && size >= ao_file_cluster_offset) {
+ cluster_t offset_clusters = (ao_file_cluster_offset + bytes_per_cluster) / bytes_per_cluster;
+ cluster_t extra_clusters = need_clusters - offset_clusters;
+ cluster_t next_cluster;
-#define loop_cluster for (free = first_free_cluster; need > 0;)
-#define next_cluster \
- if (++free == number_cluster) \
- free = 2; \
- if (free == first_free_cluster) \
- break; \
-
- loop_cluster {
- if (!ao_fat_entry_read(free))
- need--;
- next_cluster;
- }
- /* Still need some, tell the user that we've failed */
- if (need)
+ next_cluster = ao_fat_cluster_set_size(ao_file_cluster, extra_clusters);
+ if (next_cluster == AO_FAT_BAD_CLUSTER)
return -AO_FAT_ENOSPC;
+ } else {
+ first_cluster = ao_fat_cluster_set_size(first_cluster, need_clusters);
- /* Now go allocate those clusters */
- need = new_num - old_num;
- loop_cluster {
- if (!ao_fat_entry_read(free)) {
- if (free > highest_allocated)
- highest_allocated = free;
- if (last_cluster)
- ao_fat_entry_replace(last_cluster, free);
- else
- first_cluster = free;
- last_cluster = free;
- need--;
- }
- next_cluster;
- }
- first_free_cluster = highest_allocated + 1;
- if (first_free_cluster >= number_cluster)
- first_free_cluster = 2;
-
- /* Mark the new end of the chain */
- ao_fat_entry_replace(last_cluster, 0xffff);
+ if (first_cluster == AO_FAT_BAD_CLUSTER)
+ return -AO_FAT_ENOSPC;
}
}
- /* Deallocate clusters off the end of the file */
- if (ao_fat_cluster_valid(clear_cluster))
- ao_fat_free_cluster_chain(clear_cluster);
-
/* Update the directory entry */
dent = ao_fat_root_get(ao_file_dirent.entry);
if (!dent)
return -AO_FAT_EIO;
put_u32(dent + 0x1c, size);
put_u16(dent + 0x1a, first_cluster);
+ if (fat32)
+ put_u16(dent + 0x14, first_cluster >> 16);
ao_fat_root_put(dent, ao_file_dirent.entry, 1);
+
ao_file_dirent.size = size;
ao_file_dirent.cluster = first_cluster;
return AO_FAT_SUCCESS;
dirent->attr = dent[0x0b];
dirent->size = get_u32(dent+0x1c);
dirent->cluster = get_u16(dent+0x1a);
+ if (fat32)
+ dirent->cluster |= (cluster_t) get_u16(dent + 0x14) << 16;
dirent->entry = entry;
}
+/*
+ * ao_fat_flush_fsinfo
+ *
+ * Write out any fsinfo changes to disk
+ */
+
+void
+ao_fat_flush_fsinfo(void)
+{
+ uint8_t *fsinfo;
+
+ if (!fat32)
+ return;
+
+ if (!fsinfo_dirty)
+ return;
+ fsinfo_dirty = 0;
+ if (!fsinfo_sector)
+ return;
+
+ fsinfo = ao_fat_sector_get(fsinfo_sector);
+ if (fsinfo) {
+ put_u32(fsinfo + 0x1e8, free_count);
+ put_u32(fsinfo + 0x1ec, next_free);
+ ao_fat_sector_put(fsinfo, 1);
+ }
+}
+
/*
* Public API
*/
{
uint16_t entry;
int8_t status;
+ uint8_t *dent;
if (ao_file_opened)
return -AO_FAT_EMFILE;
status = ao_fat_set_size(0);
break;
case -AO_FAT_ENOENT:
- for (entry = 0; entry < root_entries; entry++) {
- uint8_t *dent = ao_fat_root_get(entry);
-
+ entry = 0;
+ for (;;) {
+ dent = ao_fat_root_get(entry);
if (!dent) {
- status = -AO_FAT_EIO;
- ao_fat_root_put(dent, entry, 0);
+
+ if (ao_fat_root_extend(entry))
+ continue;
+ status = -AO_FAT_ENOSPC;
break;
}
} else {
ao_fat_root_put(dent, entry, 0);
}
+ entry++;
}
- if (entry == root_entries)
- status = -AO_FAT_ENOSPC;
}
return status;
}
ao_file_offset = 0;
ao_file_cluster = 0;
ao_file_opened = 0;
+
+ ao_fat_flush_fsinfo();
ao_bufio_flush();
return AO_FAT_SUCCESS;
}
{
uint8_t *dent;
- if (*entry >= root_entries)
- return 0;
for (;;) {
dent = ao_fat_root_get(*entry);
+ if (!dent)
+ return 0;
if (dent[0] == AO_FAT_DENT_END) {
ao_fat_root_put(dent, *entry, 0);
projects / fw / altos / blobdiff