3 exFAT file system implementation library.
5 Copyright (C) 2010-2013 Andrew Nayenko
7 This program is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
26 * Sector to absolute offset.
28 static off_t s2o(const struct exfat* ef, off_t sector)
30 return sector << ef->sb->sector_bits;
36 static off_t c2s(const struct exfat* ef, cluster_t cluster)
38 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
39 exfat_bug("invalid cluster number %u", cluster);
40 return le32_to_cpu(ef->sb->cluster_sector_start) +
41 ((off_t) (cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->spc_bits);
45 * Cluster to absolute offset.
47 off_t exfat_c2o(const struct exfat* ef, cluster_t cluster)
49 return s2o(ef, c2s(ef, cluster));
55 static cluster_t s2c(const struct exfat* ef, off_t sector)
57 return ((sector - le32_to_cpu(ef->sb->cluster_sector_start)) >>
58 ef->sb->spc_bits) + EXFAT_FIRST_DATA_CLUSTER;
62 * Size in bytes to size in clusters (rounded upwards).
64 static uint32_t bytes2clusters(const struct exfat* ef, uint64_t bytes)
66 uint64_t cluster_size = CLUSTER_SIZE(*ef->sb);
67 return (bytes + cluster_size - 1) / cluster_size;
70 cluster_t exfat_next_cluster(const struct exfat* ef,
71 const struct exfat_node* node, cluster_t cluster)
76 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
77 exfat_bug("bad cluster 0x%x", cluster);
79 if (IS_CONTIGUOUS(*node))
81 fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
82 + cluster * sizeof(cluster_t);
83 exfat_pread(ef->dev, &next, sizeof(next), fat_offset);
84 return le32_to_cpu(next);
87 cluster_t exfat_advance_cluster(const struct exfat* ef,
88 struct exfat_node* node, uint32_t count)
92 if (node->fptr_index > count)
95 node->fptr_cluster = node->start_cluster;
98 for (i = node->fptr_index; i < count; i++)
100 node->fptr_cluster = exfat_next_cluster(ef, node, node->fptr_cluster);
101 if (CLUSTER_INVALID(node->fptr_cluster))
102 break; /* the caller should handle this and print appropriate
105 node->fptr_index = count;
106 return node->fptr_cluster;
109 static cluster_t find_bit_and_set(uint8_t* bitmap, size_t start, size_t end)
111 const size_t start_index = start / 8;
112 const size_t end_index = DIV_ROUND_UP(end, 8);
116 for (i = start_index; i < end_index; i++)
118 if (bitmap[i] == 0xff)
120 for (c = MAX(i * 8, start); c < MIN((i + 1) * 8, end); c++)
121 if (BMAP_GET(bitmap, c) == 0)
124 return c + EXFAT_FIRST_DATA_CLUSTER;
127 return EXFAT_CLUSTER_END;
130 void exfat_flush_cmap(struct exfat* ef)
132 exfat_pwrite(ef->dev, ef->cmap.chunk, (ef->cmap.chunk_size + 7) / 8,
133 exfat_c2o(ef, ef->cmap.start_cluster));
134 ef->cmap.dirty = false;
137 static void set_next_cluster(const struct exfat* ef, int contiguous,
138 cluster_t current, cluster_t next)
145 fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
146 + current * sizeof(cluster_t);
147 next_le32 = cpu_to_le32(next);
148 exfat_pwrite(ef->dev, &next_le32, sizeof(next_le32), fat_offset);
151 static cluster_t allocate_cluster(struct exfat* ef, cluster_t hint)
155 hint -= EXFAT_FIRST_DATA_CLUSTER;
156 if (hint >= ef->cmap.chunk_size)
159 cluster = find_bit_and_set(ef->cmap.chunk, hint, ef->cmap.chunk_size);
160 if (cluster == EXFAT_CLUSTER_END)
161 cluster = find_bit_and_set(ef->cmap.chunk, 0, hint);
162 if (cluster == EXFAT_CLUSTER_END)
164 exfat_error("no free space left");
165 return EXFAT_CLUSTER_END;
168 ef->cmap.dirty = true;
172 static void free_cluster(struct exfat* ef, cluster_t cluster)
174 if (CLUSTER_INVALID(cluster))
175 exfat_bug("freeing invalid cluster 0x%x", cluster);
176 if (cluster - EXFAT_FIRST_DATA_CLUSTER >= ef->cmap.size)
177 exfat_bug("freeing non-existing cluster 0x%x (0x%x)", cluster,
180 BMAP_CLR(ef->cmap.chunk, cluster - EXFAT_FIRST_DATA_CLUSTER);
181 ef->cmap.dirty = true;
184 static void make_noncontiguous(const struct exfat* ef, cluster_t first,
189 for (c = first; c < last; c++)
190 set_next_cluster(ef, 0, c, c + 1);
193 static int shrink_file(struct exfat* ef, struct exfat_node* node,
194 uint32_t current, uint32_t difference);
196 static int grow_file(struct exfat* ef, struct exfat_node* node,
197 uint32_t current, uint32_t difference)
201 uint32_t allocated = 0;
204 exfat_bug("zero clusters count passed");
206 if (node->start_cluster != EXFAT_CLUSTER_FREE)
208 /* get the last cluster of the file */
209 previous = exfat_advance_cluster(ef, node, current - 1);
210 if (CLUSTER_INVALID(previous))
212 exfat_error("invalid cluster 0x%x while growing", previous);
218 if (node->fptr_index != 0)
219 exfat_bug("non-zero pointer index (%u)", node->fptr_index);
220 /* file does not have clusters (i.e. is empty), allocate
221 the first one for it */
222 previous = allocate_cluster(ef, 0);
223 if (CLUSTER_INVALID(previous))
225 node->fptr_cluster = node->start_cluster = previous;
227 /* file consists of only one cluster, so it's contiguous */
228 node->flags |= EXFAT_ATTRIB_CONTIGUOUS;
231 while (allocated < difference)
233 next = allocate_cluster(ef, previous + 1);
234 if (CLUSTER_INVALID(next))
237 shrink_file(ef, node, current + allocated, allocated);
240 if (next != previous - 1 && IS_CONTIGUOUS(*node))
242 /* it's a pity, but we are not able to keep the file contiguous
244 make_noncontiguous(ef, node->start_cluster, previous);
245 node->flags &= ~EXFAT_ATTRIB_CONTIGUOUS;
246 node->flags |= EXFAT_ATTRIB_DIRTY;
248 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, next);
253 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, EXFAT_CLUSTER_END);
257 static int shrink_file(struct exfat* ef, struct exfat_node* node,
258 uint32_t current, uint32_t difference)
264 exfat_bug("zero difference passed");
265 if (node->start_cluster == EXFAT_CLUSTER_FREE)
266 exfat_bug("unable to shrink empty file (%u clusters)", current);
267 if (current < difference)
268 exfat_bug("file underflow (%u < %u)", current, difference);
271 if (current > difference)
273 cluster_t last = exfat_advance_cluster(ef, node,
274 current - difference - 1);
275 if (CLUSTER_INVALID(last))
277 exfat_error("invalid cluster 0x%x while shrinking", last);
280 previous = exfat_next_cluster(ef, node, last);
281 set_next_cluster(ef, IS_CONTIGUOUS(*node), last, EXFAT_CLUSTER_END);
285 previous = node->start_cluster;
286 node->start_cluster = EXFAT_CLUSTER_FREE;
288 node->fptr_index = 0;
289 node->fptr_cluster = node->start_cluster;
291 /* free remaining clusters */
294 if (CLUSTER_INVALID(previous))
296 exfat_error("invalid cluster 0x%x while freeing after shrink",
300 next = exfat_next_cluster(ef, node, previous);
301 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous,
303 free_cluster(ef, previous);
309 static void erase_raw(struct exfat* ef, size_t size, off_t offset)
311 exfat_pwrite(ef->dev, ef->zero_cluster, size, offset);
314 static int erase_range(struct exfat* ef, struct exfat_node* node,
315 uint64_t begin, uint64_t end)
317 uint64_t cluster_boundary;
323 cluster_boundary = (begin | (CLUSTER_SIZE(*ef->sb) - 1)) + 1;
324 cluster = exfat_advance_cluster(ef, node,
325 begin / CLUSTER_SIZE(*ef->sb));
326 if (CLUSTER_INVALID(cluster))
328 exfat_error("invalid cluster 0x%x while erasing", cluster);
331 /* erase from the beginning to the closest cluster boundary */
332 erase_raw(ef, MIN(cluster_boundary, end) - begin,
333 exfat_c2o(ef, cluster) + begin % CLUSTER_SIZE(*ef->sb));
334 /* erase whole clusters */
335 while (cluster_boundary < end)
337 cluster = exfat_next_cluster(ef, node, cluster);
338 /* the cluster cannot be invalid because we have just allocated it */
339 if (CLUSTER_INVALID(cluster))
340 exfat_bug("invalid cluster 0x%x after allocation", cluster);
341 erase_raw(ef, CLUSTER_SIZE(*ef->sb), exfat_c2o(ef, cluster));
342 cluster_boundary += CLUSTER_SIZE(*ef->sb);
347 int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size)
349 uint32_t c1 = bytes2clusters(ef, node->size);
350 uint32_t c2 = bytes2clusters(ef, size);
353 if (node->references == 0 && node->parent)
354 exfat_bug("no references, node changes can be lost");
356 if (node->size == size)
360 rc = grow_file(ef, node, c1, c2 - c1);
362 rc = shrink_file(ef, node, c1, c1 - c2);
367 rc = erase_range(ef, node, node->size, size);
371 exfat_update_mtime(node);
373 node->flags |= EXFAT_ATTRIB_DIRTY;
377 uint32_t exfat_count_free_clusters(const struct exfat* ef)
379 uint32_t free_clusters = 0;
382 for (i = 0; i < ef->cmap.size; i++)
383 if (BMAP_GET(ef->cmap.chunk, i) == 0)
385 return free_clusters;
388 static int find_used_clusters(const struct exfat* ef,
389 cluster_t* a, cluster_t* b)
391 const cluster_t end = le32_to_cpu(ef->sb->cluster_count);
393 /* find first used cluster */
394 for (*a = *b + 1; *a < end; (*a)++)
395 if (BMAP_GET(ef->cmap.chunk, *a - EXFAT_FIRST_DATA_CLUSTER))
400 /* find last contiguous used cluster */
401 for (*b = *a; *b < end; (*b)++)
402 if (BMAP_GET(ef->cmap.chunk, *b - EXFAT_FIRST_DATA_CLUSTER) == 0)
411 int exfat_find_used_sectors(const struct exfat* ef, off_t* a, off_t* b)
415 if (*a == 0 && *b == 0)
416 ca = cb = EXFAT_FIRST_DATA_CLUSTER - 1;
422 if (find_used_clusters(ef, &ca, &cb) != 0)
424 if (*a != 0 || *b != 0)
426 *b = c2s(ef, cb) + (CLUSTER_SIZE(*ef->sb) - 1) / SECTOR_SIZE(*ef->sb);