3 * exFAT file system implementation library.
5 * Created by Andrew Nayenko on 03.09.09.
6 * This software is distributed under the GNU General Public License
7 * version 3 or any later.
14 #define BMAP_GET(bitmap, index) ((bitmap)[(index) / 8] & (1u << ((index) % 8)))
15 #define BMAP_SET(bitmap, index) (bitmap)[(index) / 8] |= (1u << ((index) % 8))
16 #define BMAP_CLR(bitmap, index) (bitmap)[(index) / 8] &= ~(1u << ((index) % 8))
21 static uint32_t c2b(const struct exfat* ef, cluster_t cluster)
23 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
24 exfat_bug("invalid cluster number %u", cluster);
25 return le32_to_cpu(ef->sb->cluster_block_start) +
26 ((cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->bpc_bits);
30 * Cluster to absolute offset.
32 off_t exfat_c2o(const struct exfat* ef, cluster_t cluster)
34 return (off_t) c2b(ef, cluster) << ef->sb->block_bits;
38 * Block to absolute offset.
40 static off_t b2o(const struct exfat* ef, uint32_t block)
42 return (off_t) block << ef->sb->block_bits;
46 * Size in bytes to size in clusters (rounded upwards).
48 static uint32_t bytes2clusters(const struct exfat* ef, uint64_t bytes)
50 uint64_t cluster_size = CLUSTER_SIZE(*ef->sb);
51 return (bytes + cluster_size - 1) / cluster_size;
54 cluster_t exfat_next_cluster(const struct exfat* ef,
55 const struct exfat_node* node, cluster_t cluster)
60 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
61 exfat_bug("bad cluster 0x%x", cluster);
63 if (IS_CONTIGUOUS(*node))
65 fat_offset = b2o(ef, le32_to_cpu(ef->sb->fat_block_start))
66 + cluster * sizeof(cluster_t);
67 exfat_read_raw(&next, sizeof(next), fat_offset, ef->fd);
71 cluster_t exfat_advance_cluster(const struct exfat* ef,
72 struct exfat_node* node, uint32_t count)
76 if (node->fptr_index > count)
79 node->fptr_cluster = node->start_cluster;
82 for (i = node->fptr_index; i < count; i++)
84 node->fptr_cluster = exfat_next_cluster(ef, node, node->fptr_cluster);
85 if (CLUSTER_INVALID(node->fptr_cluster))
88 node->fptr_index = count;
89 return node->fptr_cluster;
92 static cluster_t find_bit_and_set(uint8_t* bitmap, cluster_t start,
95 const cluster_t mid_start = (start + 7) / 8 * 8;
96 const cluster_t mid_end = end / 8 * 8;
100 for (c = start; c < mid_start; c++)
101 if (BMAP_GET(bitmap, c) == 0)
104 return c + EXFAT_FIRST_DATA_CLUSTER;
107 for (byte = mid_start / 8; byte < mid_end / 8; byte++)
108 if (bitmap[byte] != 0xff)
112 for (bit = 0; bit < 8; bit++)
113 if (!(bitmap[byte] & (1u << bit)))
115 bitmap[byte] |= (1u << bit);
116 return byte * 8 + bit + EXFAT_FIRST_DATA_CLUSTER;
120 for (c = mid_end; c < 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_write_raw(ef->cmap.chunk, (ef->cmap.chunk_size + 7) / 8,
133 exfat_c2o(ef, ef->cmap.start_cluster), ef->fd);
137 static void set_next_cluster(const struct exfat* ef, int contiguous,
138 cluster_t current, cluster_t next)
144 fat_offset = b2o(ef, le32_to_cpu(ef->sb->fat_block_start))
145 + current * sizeof(cluster_t);
146 exfat_write_raw(&next, sizeof(next), fat_offset, ef->fd);
149 static void erase_cluster(struct exfat* ef, cluster_t cluster)
151 const int block_size = BLOCK_SIZE(*ef->sb);
152 const int blocks_in_cluster = CLUSTER_SIZE(*ef->sb) / block_size;
155 for (i = 0; i < blocks_in_cluster; i++)
156 exfat_write_raw(ef->zero_block, block_size,
157 exfat_c2o(ef, cluster) + i * block_size, ef->fd);
160 static cluster_t allocate_cluster(struct exfat* ef, cluster_t hint)
164 hint -= EXFAT_FIRST_DATA_CLUSTER;
165 if (hint >= ef->cmap.chunk_size)
168 cluster = find_bit_and_set(ef->cmap.chunk, hint, ef->cmap.chunk_size);
169 if (cluster == EXFAT_CLUSTER_END)
170 cluster = find_bit_and_set(ef->cmap.chunk, 0, hint);
171 if (cluster == EXFAT_CLUSTER_END)
173 exfat_error("no free space left");
174 return EXFAT_CLUSTER_END;
177 erase_cluster(ef, cluster);
179 /* FIXME update percentage of used space */
183 static void free_cluster(struct exfat* ef, cluster_t cluster)
185 if (CLUSTER_INVALID(cluster))
186 exfat_bug("attempting to free invalid cluster");
188 if (cluster < EXFAT_FIRST_DATA_CLUSTER)
189 exfat_bug("bad cluster 0x%x", cluster);
190 BMAP_CLR(ef->cmap.chunk, cluster - EXFAT_FIRST_DATA_CLUSTER);
192 /* FIXME update percentage of used space */
195 static void make_noncontiguous(const struct exfat* ef, cluster_t first,
200 for (c = first; c < last; c++)
201 set_next_cluster(ef, 0, c, c + 1);
204 static int grow_file(struct exfat* ef, struct exfat_node* node,
211 exfat_bug("zero clusters count passed");
213 if (node->start_cluster != EXFAT_CLUSTER_FREE)
215 /* get the last cluster of the file */
216 previous = exfat_advance_cluster(ef, node,
217 bytes2clusters(ef, node->size) - 1);
218 if (CLUSTER_INVALID(previous))
220 exfat_error("invalid cluster in file");
226 if (node->fptr_index != 0)
227 exfat_bug("non-zero pointer index (%u)", node->fptr_index);
228 /* file does not have clusters (i.e. is empty), allocate
229 the first one for it */
230 previous = allocate_cluster(ef, 0);
231 if (CLUSTER_INVALID(previous))
233 node->fptr_cluster = node->start_cluster = previous;
235 /* file consists of only one cluster, so it's contiguous */
236 node->flags |= EXFAT_ATTRIB_CONTIGUOUS;
241 next = allocate_cluster(ef, previous + 1);
242 if (CLUSTER_INVALID(next))
244 if (next != previous - 1 && IS_CONTIGUOUS(*node))
246 /* it's a pity, but we are not able to keep the file contiguous
248 make_noncontiguous(ef, node->start_cluster, previous);
249 node->flags &= ~EXFAT_ATTRIB_CONTIGUOUS;
251 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, next);
255 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous, EXFAT_CLUSTER_END);
259 static int shrink_file(struct exfat* ef, struct exfat_node* node,
262 uint32_t current = bytes2clusters(ef, node->size);
267 exfat_bug("zero difference passed");
268 if (node->start_cluster == EXFAT_CLUSTER_FREE)
269 exfat_bug("unable to shrink empty file (%u clusters)", current);
270 if (current < difference)
271 exfat_bug("file underflow (%u < %u)", current, difference);
274 if (current > difference)
276 cluster_t last = exfat_advance_cluster(ef, node,
277 current - difference - 1);
278 if (CLUSTER_INVALID(last))
280 exfat_error("invalid cluster in file");
283 previous = exfat_next_cluster(ef, node, last);
284 set_next_cluster(ef, IS_CONTIGUOUS(*node), last, EXFAT_CLUSTER_END);
288 previous = node->start_cluster;
289 node->start_cluster = EXFAT_CLUSTER_FREE;
291 node->fptr_index = 0;
292 node->fptr_cluster = node->start_cluster;
294 /* free remaining clusters */
297 if (CLUSTER_INVALID(previous))
299 exfat_error("invalid cluster in file");
302 next = exfat_next_cluster(ef, node, previous);
303 set_next_cluster(ef, IS_CONTIGUOUS(*node), previous,
305 free_cluster(ef, previous);
311 int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size)
313 uint32_t c1 = bytes2clusters(ef, node->size);
314 uint32_t c2 = bytes2clusters(ef, size);
318 rc = grow_file(ef, node, c2 - c1);
320 rc = shrink_file(ef, node, c1 - c2);
325 if (node->size != size)
328 node->flags |= EXFAT_ATTRIB_DIRTY;