/*
- * cluster.c
- * exFAT file system implementation library.
- *
- * Created by Andrew Nayenko on 03.09.09.
- * This software is distributed under the GNU General Public License
- * version 3 or any later.
- */
+ cluster.c (03.09.09)
+ exFAT file system implementation library.
+
+ Free exFAT implementation.
+ Copyright (C) 2010-2013 Andrew Nayenko
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
#include "exfat.h"
+#include <errno.h>
+#include <string.h>
+
+/*
+ * Sector to absolute offset.
+ */
+static off_t s2o(const struct exfat* ef, off_t sector)
+{
+ return sector << ef->sb->sector_bits;
+}
/*
- * Cluster to block.
+ * Cluster to sector.
*/
-static uint32_t c2b(const struct exfat* ef, cluster_t cluster)
+static off_t c2s(const struct exfat* ef, cluster_t cluster)
{
if (cluster < EXFAT_FIRST_DATA_CLUSTER)
exfat_bug("invalid cluster number %u", cluster);
- return le32_to_cpu(ef->sb->cluster_block_start) +
- ((cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->bpc_bits);
+ return le32_to_cpu(ef->sb->cluster_sector_start) +
+ ((off_t) (cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->spc_bits);
}
/*
*/
off_t exfat_c2o(const struct exfat* ef, cluster_t cluster)
{
- return (off_t) c2b(ef, cluster) << ef->sb->block_bits;
+ return s2o(ef, c2s(ef, cluster));
+}
+
+/*
+ * Sector to cluster.
+ */
+static cluster_t s2c(const struct exfat* ef, off_t sector)
+{
+ return ((sector - le32_to_cpu(ef->sb->cluster_sector_start)) >>
+ ef->sb->spc_bits) + EXFAT_FIRST_DATA_CLUSTER;
}
/*
- * Block to absolute offset.
+ * Size in bytes to size in clusters (rounded upwards).
*/
-static off_t b2o(const struct exfat* ef, uint32_t block)
+static uint32_t bytes2clusters(const struct exfat* ef, uint64_t bytes)
{
- return (off_t) block << ef->sb->block_bits;
+ uint64_t cluster_size = CLUSTER_SIZE(*ef->sb);
+ return (bytes + cluster_size - 1) / cluster_size;
}
-cluster_t exfat_next_cluster(const struct exfat* ef, cluster_t cluster,
- int contiguous)
+cluster_t exfat_next_cluster(const struct exfat* ef,
+ const struct exfat_node* node, cluster_t cluster)
{
- cluster_t next;
+ le32_t next;
off_t fat_offset;
- if (contiguous)
+ if (cluster < EXFAT_FIRST_DATA_CLUSTER)
+ exfat_bug("bad cluster 0x%x", cluster);
+
+ if (IS_CONTIGUOUS(*node))
return cluster + 1;
- fat_offset = b2o(ef, le32_to_cpu(ef->sb->fat_block_start))
+ fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
+ cluster * sizeof(cluster_t);
- exfat_read_raw(&next, sizeof(next), fat_offset, ef->fd);
- return next;
+ exfat_pread(ef->dev, &next, sizeof(next), fat_offset);
+ return le32_to_cpu(next);
}
-cluster_t exfat_advance_cluster(const struct exfat* ef, cluster_t cluster,
- int contiguous, uint32_t count)
+cluster_t exfat_advance_cluster(const struct exfat* ef,
+ struct exfat_node* node, uint32_t count)
{
uint32_t i;
- for (i = 0; i < count; i++)
+ if (node->fptr_index > count)
+ {
+ node->fptr_index = 0;
+ node->fptr_cluster = node->start_cluster;
+ }
+
+ for (i = node->fptr_index; i < count; i++)
+ {
+ node->fptr_cluster = exfat_next_cluster(ef, node, node->fptr_cluster);
+ if (CLUSTER_INVALID(node->fptr_cluster))
+ break; /* the caller should handle this and print appropriate
+ error message */
+ }
+ node->fptr_index = count;
+ return node->fptr_cluster;
+}
+
+static cluster_t find_bit_and_set(uint8_t* bitmap, size_t start, size_t end)
+{
+ const size_t start_index = start / 8;
+ const size_t end_index = DIV_ROUND_UP(end, 8);
+ size_t i;
+ size_t c;
+
+ for (i = start_index; i < end_index; i++)
+ {
+ if (bitmap[i] == 0xff)
+ continue;
+ for (c = MAX(i * 8, start); c < MIN((i + 1) * 8, end); c++)
+ if (BMAP_GET(bitmap, c) == 0)
+ {
+ BMAP_SET(bitmap, c);
+ return c + EXFAT_FIRST_DATA_CLUSTER;
+ }
+ }
+ return EXFAT_CLUSTER_END;
+}
+
+void exfat_flush_cmap(struct exfat* ef)
+{
+ exfat_pwrite(ef->dev, ef->cmap.chunk, (ef->cmap.chunk_size + 7) / 8,
+ exfat_c2o(ef, ef->cmap.start_cluster));
+ ef->cmap.dirty = false;
+}
+
+static void set_next_cluster(const struct exfat* ef, bool contiguous,
+ cluster_t current, cluster_t next)
+{
+ off_t fat_offset;
+ le32_t next_le32;
+
+ if (contiguous)
+ return;
+ fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
+ + current * sizeof(cluster_t);
+ next_le32 = cpu_to_le32(next);
+ exfat_pwrite(ef->dev, &next_le32, sizeof(next_le32), fat_offset);
+}
+
+static cluster_t allocate_cluster(struct exfat* ef, cluster_t hint)
+{
+ cluster_t cluster;
+
+ hint -= EXFAT_FIRST_DATA_CLUSTER;
+ if (hint >= ef->cmap.chunk_size)
+ hint = 0;
+
+ cluster = find_bit_and_set(ef->cmap.chunk, hint, ef->cmap.chunk_size);
+ if (cluster == EXFAT_CLUSTER_END)
+ cluster = find_bit_and_set(ef->cmap.chunk, 0, hint);
+ if (cluster == EXFAT_CLUSTER_END)
+ {
+ exfat_error("no free space left");
+ return EXFAT_CLUSTER_END;
+ }
+
+ ef->cmap.dirty = true;
+ return cluster;
+}
+
+static void free_cluster(struct exfat* ef, cluster_t cluster)
+{
+ if (CLUSTER_INVALID(cluster))
+ exfat_bug("freeing invalid cluster 0x%x", cluster);
+ if (cluster - EXFAT_FIRST_DATA_CLUSTER >= ef->cmap.size)
+ exfat_bug("freeing non-existing cluster 0x%x (0x%x)", cluster,
+ ef->cmap.size);
+
+ BMAP_CLR(ef->cmap.chunk, cluster - EXFAT_FIRST_DATA_CLUSTER);
+ ef->cmap.dirty = true;
+}
+
+static void make_noncontiguous(const struct exfat* ef, cluster_t first,
+ cluster_t last)
+{
+ cluster_t c;
+
+ for (c = first; c < last; c++)
+ set_next_cluster(ef, false, c, c + 1);
+}
+
+static int shrink_file(struct exfat* ef, struct exfat_node* node,
+ uint32_t current, uint32_t difference);
+
+static int grow_file(struct exfat* ef, struct exfat_node* node,
+ uint32_t current, uint32_t difference)
+{
+ cluster_t previous;
+ cluster_t next;
+ uint32_t allocated = 0;
+
+ if (difference == 0)
+ exfat_bug("zero clusters count passed");
+
+ if (node->start_cluster != EXFAT_CLUSTER_FREE)
+ {
+ /* get the last cluster of the file */
+ previous = exfat_advance_cluster(ef, node, current - 1);
+ if (CLUSTER_INVALID(previous))
+ {
+ exfat_error("invalid cluster 0x%x while growing", previous);
+ return -EIO;
+ }
+ }
+ else
+ {
+ if (node->fptr_index != 0)
+ exfat_bug("non-zero pointer index (%u)", node->fptr_index);
+ /* file does not have clusters (i.e. is empty), allocate
+ the first one for it */
+ previous = allocate_cluster(ef, 0);
+ if (CLUSTER_INVALID(previous))
+ return -ENOSPC;
+ node->fptr_cluster = node->start_cluster = previous;
+ allocated = 1;
+ /* file consists of only one cluster, so it's contiguous */
+ node->flags |= EXFAT_ATTRIB_CONTIGUOUS;
+ }
+
+ while (allocated < difference)
+ {
+ next = allocate_cluster(ef, previous + 1);
+ if (CLUSTER_INVALID(next))
+ {
+ if (allocated != 0)
+ shrink_file(ef, node, current + allocated, allocated);
+ return -ENOSPC;
+ }
+ if (next != previous - 1 && IS_CONTIGUOUS(*node))
+ {
+ /* it's a pity, but we are not able to keep the file contiguous
+ anymore */
+ make_noncontiguous(ef, node->start_cluster, previous);
+ node->flags &= ~EXFAT_ATTRIB_CONTIGUOUS;
+ node->flags |= EXFAT_ATTRIB_DIRTY;
+ }
+ set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, next);
+ previous = next;
+ allocated++;
+ }
+
+ set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, EXFAT_CLUSTER_END);
+ return 0;
+}
+
+static int shrink_file(struct exfat* ef, struct exfat_node* node,
+ uint32_t current, uint32_t difference)
+{
+ cluster_t previous;
+ cluster_t next;
+
+ if (difference == 0)
+ exfat_bug("zero difference passed");
+ if (node->start_cluster == EXFAT_CLUSTER_FREE)
+ exfat_bug("unable to shrink empty file (%u clusters)", current);
+ if (current < difference)
+ exfat_bug("file underflow (%u < %u)", current, difference);
+
+ /* crop the file */
+ if (current > difference)
+ {
+ cluster_t last = exfat_advance_cluster(ef, node,
+ current - difference - 1);
+ if (CLUSTER_INVALID(last))
+ {
+ exfat_error("invalid cluster 0x%x while shrinking", last);
+ return -EIO;
+ }
+ previous = exfat_next_cluster(ef, node, last);
+ set_next_cluster(ef, IS_CONTIGUOUS(*node), last, EXFAT_CLUSTER_END);
+ }
+ else
+ {
+ previous = node->start_cluster;
+ node->start_cluster = EXFAT_CLUSTER_FREE;
+ }
+ node->fptr_index = 0;
+ node->fptr_cluster = node->start_cluster;
+
+ /* free remaining clusters */
+ while (difference--)
+ {
+ if (CLUSTER_INVALID(previous))
+ {
+ exfat_error("invalid cluster 0x%x while freeing after shrink",
+ previous);
+ return -EIO;
+ }
+ next = exfat_next_cluster(ef, node, previous);
+ set_next_cluster(ef, IS_CONTIGUOUS(*node), previous,
+ EXFAT_CLUSTER_FREE);
+ free_cluster(ef, previous);
+ previous = next;
+ }
+ return 0;
+}
+
+static void erase_raw(struct exfat* ef, size_t size, off_t offset)
+{
+ exfat_pwrite(ef->dev, ef->zero_cluster, size, offset);
+}
+
+static int erase_range(struct exfat* ef, struct exfat_node* node,
+ uint64_t begin, uint64_t end)
+{
+ uint64_t cluster_boundary;
+ cluster_t cluster;
+
+ if (begin >= end)
+ return 0;
+
+ cluster_boundary = (begin | (CLUSTER_SIZE(*ef->sb) - 1)) + 1;
+ cluster = exfat_advance_cluster(ef, node,
+ begin / CLUSTER_SIZE(*ef->sb));
+ if (CLUSTER_INVALID(cluster))
+ {
+ exfat_error("invalid cluster 0x%x while erasing", cluster);
+ return -EIO;
+ }
+ /* erase from the beginning to the closest cluster boundary */
+ erase_raw(ef, MIN(cluster_boundary, end) - begin,
+ exfat_c2o(ef, cluster) + begin % CLUSTER_SIZE(*ef->sb));
+ /* erase whole clusters */
+ while (cluster_boundary < end)
{
- cluster = exfat_next_cluster(ef, cluster, contiguous);
+ cluster = exfat_next_cluster(ef, node, cluster);
+ /* the cluster cannot be invalid because we have just allocated it */
if (CLUSTER_INVALID(cluster))
+ exfat_bug("invalid cluster 0x%x after allocation", cluster);
+ erase_raw(ef, CLUSTER_SIZE(*ef->sb), exfat_c2o(ef, cluster));
+ cluster_boundary += CLUSTER_SIZE(*ef->sb);
+ }
+ return 0;
+}
+
+int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
+ bool erase)
+{
+ uint32_t c1 = bytes2clusters(ef, node->size);
+ uint32_t c2 = bytes2clusters(ef, size);
+ int rc = 0;
+
+ if (node->references == 0 && node->parent)
+ exfat_bug("no references, node changes can be lost");
+
+ if (node->size == size)
+ return 0;
+
+ if (c1 < c2)
+ rc = grow_file(ef, node, c1, c2 - c1);
+ else if (c1 > c2)
+ rc = shrink_file(ef, node, c1, c1 - c2);
+
+ if (rc != 0)
+ return rc;
+
+ if (erase)
+ {
+ rc = erase_range(ef, node, node->size, size);
+ if (rc != 0)
+ return rc;
+ }
+
+ exfat_update_mtime(node);
+ node->size = size;
+ node->flags |= EXFAT_ATTRIB_DIRTY;
+ return 0;
+}
+
+uint32_t exfat_count_free_clusters(const struct exfat* ef)
+{
+ uint32_t free_clusters = 0;
+ uint32_t i;
+
+ for (i = 0; i < ef->cmap.size; i++)
+ if (BMAP_GET(ef->cmap.chunk, i) == 0)
+ free_clusters++;
+ return free_clusters;
+}
+
+static int find_used_clusters(const struct exfat* ef,
+ cluster_t* a, cluster_t* b)
+{
+ const cluster_t end = le32_to_cpu(ef->sb->cluster_count);
+
+ /* find first used cluster */
+ for (*a = *b + 1; *a < end; (*a)++)
+ if (BMAP_GET(ef->cmap.chunk, *a - EXFAT_FIRST_DATA_CLUSTER))
+ break;
+ if (*a >= end)
+ return 1;
+
+ /* find last contiguous used cluster */
+ for (*b = *a; *b < end; (*b)++)
+ if (BMAP_GET(ef->cmap.chunk, *b - EXFAT_FIRST_DATA_CLUSTER) == 0)
+ {
+ (*b)--;
break;
+ }
+
+ return 0;
+}
+
+int exfat_find_used_sectors(const struct exfat* ef, off_t* a, off_t* b)
+{
+ cluster_t ca, cb;
+
+ if (*a == 0 && *b == 0)
+ ca = cb = EXFAT_FIRST_DATA_CLUSTER - 1;
+ else
+ {
+ ca = s2c(ef, *a);
+ cb = s2c(ef, *b);
}
- return cluster;
+ if (find_used_clusters(ef, &ca, &cb) != 0)
+ return 1;
+ if (*a != 0 || *b != 0)
+ *a = c2s(ef, ca);
+ *b = c2s(ef, cb) + (CLUSTER_SIZE(*ef->sb) - 1) / SECTOR_SIZE(*ef->sb);
+ return 0;
}
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