3 exFAT file system implementation library.
5 Free exFAT implementation.
6 Copyright (C) 2010-2013 Andrew Nayenko
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation, either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
28 * Sector to absolute offset.
30 static off_t s2o(const struct exfat* ef, off_t sector)
32 return sector << ef->sb->sector_bits;
38 static off_t c2s(const struct exfat* ef, cluster_t cluster)
40 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
41 exfat_bug("invalid cluster number %u", cluster);
42 return le32_to_cpu(ef->sb->cluster_sector_start) +
43 ((off_t) (cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->spc_bits);
47 * Cluster to absolute offset.
49 off_t exfat_c2o(const struct exfat* ef, cluster_t cluster)
51 return s2o(ef, c2s(ef, cluster));
57 static cluster_t s2c(const struct exfat* ef, off_t sector)
59 return ((sector - le32_to_cpu(ef->sb->cluster_sector_start)) >>
60 ef->sb->spc_bits) + EXFAT_FIRST_DATA_CLUSTER;
64 * Size in bytes to size in clusters (rounded upwards).
66 static uint32_t bytes2clusters(const struct exfat* ef, uint64_t bytes)
68 uint64_t cluster_size = CLUSTER_SIZE(*ef->sb);
69 return (bytes + cluster_size - 1) / cluster_size;
72 cluster_t exfat_next_cluster(const struct exfat* ef,
73 const struct exfat_node* node, cluster_t cluster)
78 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
79 exfat_bug("bad cluster 0x%x", cluster);
81 if (IS_CONTIGUOUS(*node))
83 fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
84 + cluster * sizeof(cluster_t);
85 exfat_pread(ef->dev, &next, sizeof(next), fat_offset);
86 return le32_to_cpu(next);
89 cluster_t exfat_advance_cluster(const struct exfat* ef,
90 struct exfat_node* node, uint32_t count)
94 if (node->fptr_index > count)
97 node->fptr_cluster = node->start_cluster;
100 for (i = node->fptr_index; i < count; i++)
102 node->fptr_cluster = exfat_next_cluster(ef, node, node->fptr_cluster);
103 if (CLUSTER_INVALID(node->fptr_cluster))
104 break; /* the caller should handle this and print appropriate
107 node->fptr_index = count;
108 return node->fptr_cluster;
111 static cluster_t find_bit_and_set(uint8_t* bitmap, size_t start, size_t end)
113 const size_t start_index = start / 8;
114 const size_t end_index = DIV_ROUND_UP(end, 8);
118 for (i = start_index; i < end_index; i++)
120 if (bitmap[i] == 0xff)
122 for (c = MAX(i * 8, start); c < MIN((i + 1) * 8, end); c++)
123 if (BMAP_GET(bitmap, c) == 0)
126 return c + EXFAT_FIRST_DATA_CLUSTER;
129 return EXFAT_CLUSTER_END;
132 void exfat_flush(struct exfat* ef)
136 exfat_pwrite(ef->dev, ef->cmap.chunk, (ef->cmap.chunk_size + 7) / 8,
137 exfat_c2o(ef, ef->cmap.start_cluster));
138 ef->cmap.dirty = false;
142 static void set_next_cluster(const struct exfat* ef, bool contiguous,
143 cluster_t current, cluster_t next)
150 fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
151 + current * sizeof(cluster_t);
152 next_le32 = cpu_to_le32(next);
153 exfat_pwrite(ef->dev, &next_le32, sizeof(next_le32), fat_offset);
156 static cluster_t allocate_cluster(struct exfat* ef, cluster_t hint)
160 hint -= EXFAT_FIRST_DATA_CLUSTER;
161 if (hint >= ef->cmap.chunk_size)
164 cluster = find_bit_and_set(ef->cmap.chunk, hint, ef->cmap.chunk_size);
165 if (cluster == EXFAT_CLUSTER_END)
166 cluster = find_bit_and_set(ef->cmap.chunk, 0, hint);
167 if (cluster == EXFAT_CLUSTER_END)
169 exfat_error("no free space left");
170 return EXFAT_CLUSTER_END;
173 ef->cmap.dirty = true;
177 static void free_cluster(struct exfat* ef, cluster_t cluster)
179 if (CLUSTER_INVALID(cluster))
180 exfat_bug("freeing invalid cluster 0x%x", cluster);
181 if (cluster - EXFAT_FIRST_DATA_CLUSTER >= ef->cmap.size)
182 exfat_bug("freeing non-existing cluster 0x%x (0x%x)", cluster,
185 BMAP_CLR(ef->cmap.chunk, cluster - EXFAT_FIRST_DATA_CLUSTER);
186 ef->cmap.dirty = true;
189 static void make_noncontiguous(const struct exfat* ef, cluster_t first,
194 for (c = first; c < last; c++)
195 set_next_cluster(ef, false, c, c + 1);
198 static int shrink_file(struct exfat* ef, struct exfat_node* node,
199 uint32_t current, uint32_t difference);
201 static int grow_file(struct exfat* ef, struct exfat_node* node,
202 uint32_t current, uint32_t difference)
206 uint32_t allocated = 0;
209 exfat_bug("zero clusters count passed");
211 if (node->start_cluster != EXFAT_CLUSTER_FREE)
213 /* get the last cluster of the file */
214 previous = exfat_advance_cluster(ef, node, current - 1);
215 if (CLUSTER_INVALID(previous))
217 exfat_error("invalid cluster 0x%x while growing", previous);
223 if (node->fptr_index != 0)
224 exfat_bug("non-zero pointer index (%u)", node->fptr_index);
225 /* file does not have clusters (i.e. is empty), allocate
226 the first one for it */
227 previous = allocate_cluster(ef, 0);
228 if (CLUSTER_INVALID(previous))
230 node->fptr_cluster = node->start_cluster = previous;
232 /* file consists of only one cluster, so it's contiguous */
233 node->flags |= EXFAT_ATTRIB_CONTIGUOUS;
236 while (allocated < difference)
238 next = allocate_cluster(ef, previous + 1);
239 if (CLUSTER_INVALID(next))
242 shrink_file(ef, node, current + allocated, allocated);
245 if (next != previous - 1 && IS_CONTIGUOUS(*node))
247 /* it's a pity, but we are not able to keep the file contiguous
249 make_noncontiguous(ef, node->start_cluster, previous);
250 node->flags &= ~EXFAT_ATTRIB_CONTIGUOUS;
251 node->flags |= EXFAT_ATTRIB_DIRTY;
253 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, next);
258 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, EXFAT_CLUSTER_END);
262 static int shrink_file(struct exfat* ef, struct exfat_node* node,
263 uint32_t current, uint32_t difference)
269 exfat_bug("zero difference passed");
270 if (node->start_cluster == EXFAT_CLUSTER_FREE)
271 exfat_bug("unable to shrink empty file (%u clusters)", current);
272 if (current < difference)
273 exfat_bug("file underflow (%u < %u)", current, difference);
276 if (current > difference)
278 cluster_t last = exfat_advance_cluster(ef, node,
279 current - difference - 1);
280 if (CLUSTER_INVALID(last))
282 exfat_error("invalid cluster 0x%x while shrinking", last);
285 previous = exfat_next_cluster(ef, node, last);
286 set_next_cluster(ef, IS_CONTIGUOUS(*node), last, EXFAT_CLUSTER_END);
290 previous = node->start_cluster;
291 node->start_cluster = EXFAT_CLUSTER_FREE;
293 node->fptr_index = 0;
294 node->fptr_cluster = node->start_cluster;
296 /* free remaining clusters */
299 if (CLUSTER_INVALID(previous))
301 exfat_error("invalid cluster 0x%x while freeing after shrink",
305 next = exfat_next_cluster(ef, node, previous);
306 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous,
308 free_cluster(ef, previous);
314 static void erase_raw(struct exfat* ef, size_t size, off_t offset)
316 exfat_pwrite(ef->dev, ef->zero_cluster, size, offset);
319 static int erase_range(struct exfat* ef, struct exfat_node* node,
320 uint64_t begin, uint64_t end)
322 uint64_t cluster_boundary;
328 cluster_boundary = (begin | (CLUSTER_SIZE(*ef->sb) - 1)) + 1;
329 cluster = exfat_advance_cluster(ef, node,
330 begin / CLUSTER_SIZE(*ef->sb));
331 if (CLUSTER_INVALID(cluster))
333 exfat_error("invalid cluster 0x%x while erasing", cluster);
336 /* erase from the beginning to the closest cluster boundary */
337 erase_raw(ef, MIN(cluster_boundary, end) - begin,
338 exfat_c2o(ef, cluster) + begin % CLUSTER_SIZE(*ef->sb));
339 /* erase whole clusters */
340 while (cluster_boundary < end)
342 cluster = exfat_next_cluster(ef, node, cluster);
343 /* the cluster cannot be invalid because we have just allocated it */
344 if (CLUSTER_INVALID(cluster))
345 exfat_bug("invalid cluster 0x%x after allocation", cluster);
346 erase_raw(ef, CLUSTER_SIZE(*ef->sb), exfat_c2o(ef, cluster));
347 cluster_boundary += CLUSTER_SIZE(*ef->sb);
352 int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
355 uint32_t c1 = bytes2clusters(ef, node->size);
356 uint32_t c2 = bytes2clusters(ef, size);
359 if (node->references == 0 && node->parent)
360 exfat_bug("no references, node changes can be lost");
362 if (node->size == size)
366 rc = grow_file(ef, node, c1, c2 - c1);
368 rc = shrink_file(ef, node, c1, c1 - c2);
375 rc = erase_range(ef, node, node->size, size);
380 exfat_update_mtime(node);
382 node->flags |= EXFAT_ATTRIB_DIRTY;
386 uint32_t exfat_count_free_clusters(const struct exfat* ef)
388 uint32_t free_clusters = 0;
391 for (i = 0; i < ef->cmap.size; i++)
392 if (BMAP_GET(ef->cmap.chunk, i) == 0)
394 return free_clusters;
397 static int find_used_clusters(const struct exfat* ef,
398 cluster_t* a, cluster_t* b)
400 const cluster_t end = le32_to_cpu(ef->sb->cluster_count);
402 /* find first used cluster */
403 for (*a = *b + 1; *a < end; (*a)++)
404 if (BMAP_GET(ef->cmap.chunk, *a - EXFAT_FIRST_DATA_CLUSTER))
409 /* find last contiguous used cluster */
410 for (*b = *a; *b < end; (*b)++)
411 if (BMAP_GET(ef->cmap.chunk, *b - EXFAT_FIRST_DATA_CLUSTER) == 0)
420 int exfat_find_used_sectors(const struct exfat* ef, off_t* a, off_t* b)
424 if (*a == 0 && *b == 0)
425 ca = cb = EXFAT_FIRST_DATA_CLUSTER - 1;
431 if (find_used_clusters(ef, &ca, &cb) != 0)
433 if (*a != 0 || *b != 0)
435 *b = c2s(ef, cb) + (CLUSTER_SIZE(*ef->sb) - 1) / SECTOR_SIZE(*ef->sb);