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.
29 * Sector to absolute offset.
31 static off_t s2o(const struct exfat* ef, off_t sector)
33 return sector << ef->sb->sector_bits;
39 static off_t c2s(const struct exfat* ef, cluster_t cluster)
41 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
42 exfat_bug("invalid cluster number %u", cluster);
43 return le32_to_cpu(ef->sb->cluster_sector_start) +
44 ((off_t) (cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->spc_bits);
48 * Cluster to absolute offset.
50 off_t exfat_c2o(const struct exfat* ef, cluster_t cluster)
52 return s2o(ef, c2s(ef, cluster));
58 static cluster_t s2c(const struct exfat* ef, off_t sector)
60 return ((sector - le32_to_cpu(ef->sb->cluster_sector_start)) >>
61 ef->sb->spc_bits) + EXFAT_FIRST_DATA_CLUSTER;
65 * Size in bytes to size in clusters (rounded upwards).
67 static uint32_t bytes2clusters(const struct exfat* ef, uint64_t bytes)
69 uint64_t cluster_size = CLUSTER_SIZE(*ef->sb);
70 return (bytes + cluster_size - 1) / cluster_size;
73 cluster_t exfat_next_cluster(const struct exfat* ef,
74 const struct exfat_node* node, cluster_t cluster)
79 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
80 exfat_bug("bad cluster 0x%x", cluster);
82 if (IS_CONTIGUOUS(*node))
84 fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
85 + cluster * sizeof(cluster_t);
86 /* FIXME handle I/O error */
87 if (exfat_pread(ef->dev, &next, sizeof(next), fat_offset) < 0)
88 exfat_bug("failed to read the next cluster after %#x", cluster);
89 return le32_to_cpu(next);
92 cluster_t exfat_advance_cluster(const struct exfat* ef,
93 struct exfat_node* node, uint32_t count)
97 if (node->fptr_index > count)
100 node->fptr_cluster = node->start_cluster;
103 for (i = node->fptr_index; i < count; i++)
105 node->fptr_cluster = exfat_next_cluster(ef, node, node->fptr_cluster);
106 if (CLUSTER_INVALID(node->fptr_cluster))
107 break; /* the caller should handle this and print appropriate
110 node->fptr_index = count;
111 return node->fptr_cluster;
114 static cluster_t find_bit_and_set(bitmap_t* bitmap, size_t start, size_t end)
116 const size_t start_index = start / sizeof(bitmap_t) / 8;
117 const size_t end_index = DIV_ROUND_UP(end, sizeof(bitmap_t) * 8);
119 size_t start_bitindex;
123 for (i = start_index; i < end_index; i++)
125 if (bitmap[i] == ~((bitmap_t) 0))
127 start_bitindex = MAX(i * sizeof(bitmap_t) * 8, start);
128 end_bitindex = MIN((i + 1) * sizeof(bitmap_t) * 8, end);
129 for (c = start_bitindex; c < end_bitindex; c++)
130 if (BMAP_GET(bitmap, c) == 0)
133 return c + EXFAT_FIRST_DATA_CLUSTER;
136 return EXFAT_CLUSTER_END;
139 void exfat_flush(struct exfat* ef)
143 /* FIXME handle I/O error */
144 if (exfat_pwrite(ef->dev, ef->cmap.chunk,
145 BMAP_SIZE(ef->cmap.chunk_size),
146 exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
147 exfat_bug("failed to write clusters bitmap");
148 ef->cmap.dirty = false;
152 static void set_next_cluster(const struct exfat* ef, bool contiguous,
153 cluster_t current, cluster_t next)
160 fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
161 + current * sizeof(cluster_t);
162 next_le32 = cpu_to_le32(next);
163 /* FIXME handle I/O error */
164 if (exfat_pwrite(ef->dev, &next_le32, sizeof(next_le32), fat_offset) < 0)
165 exfat_bug("failed to write the next cluster");
168 static cluster_t allocate_cluster(struct exfat* ef, cluster_t hint)
172 hint -= EXFAT_FIRST_DATA_CLUSTER;
173 if (hint >= ef->cmap.chunk_size)
176 cluster = find_bit_and_set(ef->cmap.chunk, hint, ef->cmap.chunk_size);
177 if (cluster == EXFAT_CLUSTER_END)
178 cluster = find_bit_and_set(ef->cmap.chunk, 0, hint);
179 if (cluster == EXFAT_CLUSTER_END)
181 exfat_error("no free space left");
182 return EXFAT_CLUSTER_END;
185 ef->cmap.dirty = true;
189 static void free_cluster(struct exfat* ef, cluster_t cluster)
191 if (CLUSTER_INVALID(cluster))
192 exfat_bug("freeing invalid cluster 0x%x", cluster);
193 if (cluster - EXFAT_FIRST_DATA_CLUSTER >= ef->cmap.size)
194 exfat_bug("freeing non-existing cluster 0x%x (0x%x)", cluster,
197 BMAP_CLR(ef->cmap.chunk, cluster - EXFAT_FIRST_DATA_CLUSTER);
198 ef->cmap.dirty = true;
201 static void make_noncontiguous(const struct exfat* ef, cluster_t first,
206 for (c = first; c < last; c++)
207 set_next_cluster(ef, false, c, c + 1);
210 static int shrink_file(struct exfat* ef, struct exfat_node* node,
211 uint32_t current, uint32_t difference);
213 static int grow_file(struct exfat* ef, struct exfat_node* node,
214 uint32_t current, uint32_t difference)
218 uint32_t allocated = 0;
221 exfat_bug("zero clusters count passed");
223 if (node->start_cluster != EXFAT_CLUSTER_FREE)
225 /* get the last cluster of the file */
226 previous = exfat_advance_cluster(ef, node, current - 1);
227 if (CLUSTER_INVALID(previous))
229 exfat_error("invalid cluster 0x%x while growing", previous);
235 if (node->fptr_index != 0)
236 exfat_bug("non-zero pointer index (%u)", node->fptr_index);
237 /* file does not have clusters (i.e. is empty), allocate
238 the first one for it */
239 previous = allocate_cluster(ef, 0);
240 if (CLUSTER_INVALID(previous))
242 node->fptr_cluster = node->start_cluster = previous;
244 /* file consists of only one cluster, so it's contiguous */
245 node->flags |= EXFAT_ATTRIB_CONTIGUOUS;
248 while (allocated < difference)
250 next = allocate_cluster(ef, previous + 1);
251 if (CLUSTER_INVALID(next))
254 shrink_file(ef, node, current + allocated, allocated);
257 if (next != previous - 1 && IS_CONTIGUOUS(*node))
259 /* it's a pity, but we are not able to keep the file contiguous
261 make_noncontiguous(ef, node->start_cluster, previous);
262 node->flags &= ~EXFAT_ATTRIB_CONTIGUOUS;
263 node->flags |= EXFAT_ATTRIB_DIRTY;
265 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, next);
270 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, EXFAT_CLUSTER_END);
274 static int shrink_file(struct exfat* ef, struct exfat_node* node,
275 uint32_t current, uint32_t difference)
281 exfat_bug("zero difference passed");
282 if (node->start_cluster == EXFAT_CLUSTER_FREE)
283 exfat_bug("unable to shrink empty file (%u clusters)", current);
284 if (current < difference)
285 exfat_bug("file underflow (%u < %u)", current, difference);
288 if (current > difference)
290 cluster_t last = exfat_advance_cluster(ef, node,
291 current - difference - 1);
292 if (CLUSTER_INVALID(last))
294 exfat_error("invalid cluster 0x%x while shrinking", last);
297 previous = exfat_next_cluster(ef, node, last);
298 set_next_cluster(ef, IS_CONTIGUOUS(*node), last, EXFAT_CLUSTER_END);
302 previous = node->start_cluster;
303 node->start_cluster = EXFAT_CLUSTER_FREE;
305 node->fptr_index = 0;
306 node->fptr_cluster = node->start_cluster;
308 /* free remaining clusters */
311 if (CLUSTER_INVALID(previous))
313 exfat_error("invalid cluster 0x%x while freeing after shrink",
317 next = exfat_next_cluster(ef, node, previous);
318 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous,
320 free_cluster(ef, previous);
326 static bool erase_raw(struct exfat* ef, size_t size, off_t offset)
328 if (exfat_pwrite(ef->dev, ef->zero_cluster, size, offset) < 0)
330 exfat_error("failed to erase %zu bytes at %"PRId64, size, offset);
336 static int erase_range(struct exfat* ef, struct exfat_node* node,
337 uint64_t begin, uint64_t end)
339 uint64_t cluster_boundary;
345 cluster_boundary = (begin | (CLUSTER_SIZE(*ef->sb) - 1)) + 1;
346 cluster = exfat_advance_cluster(ef, node,
347 begin / CLUSTER_SIZE(*ef->sb));
348 if (CLUSTER_INVALID(cluster))
350 exfat_error("invalid cluster 0x%x while erasing", cluster);
353 /* erase from the beginning to the closest cluster boundary */
354 if (!erase_raw(ef, MIN(cluster_boundary, end) - begin,
355 exfat_c2o(ef, cluster) + begin % CLUSTER_SIZE(*ef->sb)))
357 /* erase whole clusters */
358 while (cluster_boundary < end)
360 cluster = exfat_next_cluster(ef, node, cluster);
361 /* the cluster cannot be invalid because we have just allocated it */
362 if (CLUSTER_INVALID(cluster))
363 exfat_bug("invalid cluster 0x%x after allocation", cluster);
364 if (!erase_raw(ef, CLUSTER_SIZE(*ef->sb), exfat_c2o(ef, cluster)))
366 cluster_boundary += CLUSTER_SIZE(*ef->sb);
371 int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
374 uint32_t c1 = bytes2clusters(ef, node->size);
375 uint32_t c2 = bytes2clusters(ef, size);
378 if (node->references == 0 && node->parent)
379 exfat_bug("no references, node changes can be lost");
381 if (node->size == size)
385 rc = grow_file(ef, node, c1, c2 - c1);
387 rc = shrink_file(ef, node, c1, c1 - c2);
394 rc = erase_range(ef, node, node->size, size);
399 exfat_update_mtime(node);
401 node->flags |= EXFAT_ATTRIB_DIRTY;
405 uint32_t exfat_count_free_clusters(const struct exfat* ef)
407 uint32_t free_clusters = 0;
410 for (i = 0; i < ef->cmap.size; i++)
411 if (BMAP_GET(ef->cmap.chunk, i) == 0)
413 return free_clusters;
416 static int find_used_clusters(const struct exfat* ef,
417 cluster_t* a, cluster_t* b)
419 const cluster_t end = le32_to_cpu(ef->sb->cluster_count);
421 /* find first used cluster */
422 for (*a = *b + 1; *a < end; (*a)++)
423 if (BMAP_GET(ef->cmap.chunk, *a - EXFAT_FIRST_DATA_CLUSTER))
428 /* find last contiguous used cluster */
429 for (*b = *a; *b < end; (*b)++)
430 if (BMAP_GET(ef->cmap.chunk, *b - EXFAT_FIRST_DATA_CLUSTER) == 0)
439 int exfat_find_used_sectors(const struct exfat* ef, off_t* a, off_t* b)
443 if (*a == 0 && *b == 0)
444 ca = cb = EXFAT_FIRST_DATA_CLUSTER - 1;
450 if (find_used_clusters(ef, &ca, &cb) != 0)
452 if (*a != 0 || *b != 0)
454 *b = c2s(ef, cb) + (CLUSTER_SIZE(*ef->sb) - 1) / SECTOR_SIZE(*ef->sb);