3 exFAT file system implementation library.
5 Free exFAT implementation.
6 Copyright (C) 2010-2023 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 #include <sys/types.h>
31 static uint64_t rootdir_size(const struct exfat* ef)
33 uint32_t clusters = 0;
34 uint32_t clusters_max = le32_to_cpu(ef->sb->cluster_count);
35 cluster_t rootdir_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
37 /* Iterate all clusters of the root directory to calculate its size.
38 It can't be contiguous because there is no flag to indicate this. */
41 if (clusters == clusters_max) /* infinite loop detected */
43 exfat_error("root directory cannot occupy all %d clusters",
47 if (CLUSTER_INVALID(*ef->sb, rootdir_cluster))
49 exfat_error("bad cluster %#x while reading root directory",
53 rootdir_cluster = exfat_next_cluster(ef, ef->root, rootdir_cluster);
56 while (rootdir_cluster != EXFAT_CLUSTER_END);
58 return (uint64_t) clusters * CLUSTER_SIZE(*ef->sb);
61 static const char* get_option(const char* options, const char* option_name)
64 size_t length = strlen(option_name);
66 for (p = strstr(options, option_name); p; p = strstr(p + 1, option_name))
67 if ((p == options || p[-1] == ',') && p[length] == '=')
68 return p + length + 1;
72 static int get_int_option(const char* options, const char* option_name,
73 int base, int default_value)
75 const char* p = get_option(options, option_name);
79 return strtol(p, NULL, base);
82 static void parse_options(struct exfat* ef, const char* options)
86 opt_umask = get_int_option(options, "umask", 8, 0);
87 ef->dmask = get_int_option(options, "dmask", 8, opt_umask);
88 ef->fmask = get_int_option(options, "fmask", 8, opt_umask);
90 ef->uid = get_int_option(options, "uid", 10, geteuid());
91 ef->gid = get_int_option(options, "gid", 10, getegid());
93 ef->noatime = exfat_match_option(options, "noatime");
95 switch (get_int_option(options, "repair", 10, 0))
98 ef->repair = EXFAT_REPAIR_ASK;
101 ef->repair = EXFAT_REPAIR_YES;
104 ef->repair = EXFAT_REPAIR_NO;
109 static bool verify_vbr_checksum(const struct exfat* ef, void* sector)
111 off_t sector_size = SECTOR_SIZE(*ef->sb);
112 uint32_t vbr_checksum;
115 if (exfat_pread(ef->dev, sector, sector_size, 0) < 0)
117 exfat_error("failed to read boot sector");
120 vbr_checksum = exfat_vbr_start_checksum(sector, sector_size);
121 for (i = 1; i < 11; i++)
123 if (exfat_pread(ef->dev, sector, sector_size, i * sector_size) < 0)
125 exfat_error("failed to read VBR sector");
128 vbr_checksum = exfat_vbr_add_checksum(sector, sector_size,
131 if (exfat_pread(ef->dev, sector, sector_size, i * sector_size) < 0)
133 exfat_error("failed to read VBR checksum sector");
136 for (i = 0; i < sector_size / sizeof(vbr_checksum); i++)
137 if (le32_to_cpu(((const le32_t*) sector)[i]) != vbr_checksum)
139 exfat_error("invalid VBR checksum 0x%x (expected 0x%x)",
140 le32_to_cpu(((const le32_t*) sector)[i]), vbr_checksum);
141 if (!EXFAT_REPAIR(invalid_vbr_checksum, ef, sector, vbr_checksum))
147 static int commit_super_block(const struct exfat* ef)
149 if (exfat_pwrite(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
151 exfat_error("failed to write super block");
154 return exfat_fsync(ef->dev);
157 int exfat_soil_super_block(const struct exfat* ef)
162 ef->sb->volume_state = cpu_to_le16(
163 le16_to_cpu(ef->sb->volume_state) | EXFAT_STATE_MOUNTED);
164 return commit_super_block(ef);
167 static void exfat_free(struct exfat* ef)
169 exfat_close(ef->dev); /* first of all, close the descriptor */
170 ef->dev = NULL; /* struct exfat_dev is freed by exfat_close() */
173 free(ef->zero_cluster);
174 ef->zero_cluster = NULL;
175 free(ef->cmap.chunk);
176 ef->cmap.chunk = NULL;
183 int exfat_mount(struct exfat* ef, const char* spec, const char* options)
186 enum exfat_mode mode;
189 memset(ef, 0, sizeof(struct exfat));
191 parse_options(ef, options);
193 if (exfat_match_option(options, "ro"))
194 mode = EXFAT_MODE_RO;
195 else if (exfat_match_option(options, "ro_fallback"))
196 mode = EXFAT_MODE_ANY;
198 mode = EXFAT_MODE_RW;
199 ef->dev = exfat_open(spec, mode);
202 if (exfat_get_mode(ef->dev) == EXFAT_MODE_RO)
204 if (mode == EXFAT_MODE_ANY)
210 ef->sb = malloc(sizeof(struct exfat_super_block));
213 exfat_error("failed to allocate memory for the super block");
217 memset(ef->sb, 0, sizeof(struct exfat_super_block));
219 if (exfat_pread(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
221 exfat_error("failed to read boot sector");
225 if (memcmp(ef->sb->oem_name, "EXFAT ", 8) != 0)
227 exfat_error("exFAT file system is not found");
231 /* sector cannot be smaller than 512 bytes */
232 if (ef->sb->sector_bits < 9)
234 exfat_error("too small sector size: 2^%hhd", ef->sb->sector_bits);
238 /* officially exFAT supports cluster size up to 32 MB */
239 if ((int) ef->sb->sector_bits + (int) ef->sb->spc_bits > 25)
241 exfat_error("too big cluster size: 2^(%hhd+%hhd)",
242 ef->sb->sector_bits, ef->sb->spc_bits);
246 ef->zero_cluster = malloc(CLUSTER_SIZE(*ef->sb));
247 if (ef->zero_cluster == NULL)
249 exfat_error("failed to allocate zero sector");
253 /* use zero_cluster as a temporary buffer for VBR checksum verification */
254 if (!verify_vbr_checksum(ef, ef->zero_cluster))
259 memset(ef->zero_cluster, 0, CLUSTER_SIZE(*ef->sb));
260 if (ef->sb->version.major != 1 || ef->sb->version.minor != 0)
262 exfat_error("unsupported exFAT version: %hhu.%hhu",
263 ef->sb->version.major, ef->sb->version.minor);
267 if (ef->sb->fat_count != 1)
269 exfat_error("unsupported FAT count: %hhu", ef->sb->fat_count);
273 if (le64_to_cpu(ef->sb->sector_count) * SECTOR_SIZE(*ef->sb) >
274 (uint64_t) exfat_get_size(ef->dev))
276 /* this can cause I/O errors later but we don't fail mounting to let
278 exfat_warn("file system in sectors is larger than device: "
279 "%"PRIu64" * %d > %"PRIu64,
280 le64_to_cpu(ef->sb->sector_count), SECTOR_SIZE(*ef->sb),
281 exfat_get_size(ef->dev));
283 if ((off_t) le32_to_cpu(ef->sb->cluster_count) * CLUSTER_SIZE(*ef->sb) >
284 exfat_get_size(ef->dev))
286 exfat_error("file system in clusters is larger than device: "
288 le32_to_cpu(ef->sb->cluster_count), CLUSTER_SIZE(*ef->sb),
289 exfat_get_size(ef->dev));
293 if (le16_to_cpu(ef->sb->volume_state) & EXFAT_STATE_MOUNTED)
294 exfat_warn("volume was not unmounted cleanly");
296 ef->root = malloc(sizeof(struct exfat_node));
297 if (ef->root == NULL)
299 exfat_error("failed to allocate root node");
303 memset(ef->root, 0, sizeof(struct exfat_node));
304 ef->root->attrib = EXFAT_ATTRIB_DIR;
305 ef->root->start_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
306 ef->root->fptr_cluster = ef->root->start_cluster;
307 ef->root->name[0] = cpu_to_le16('\0');
308 ef->root->valid_size = ef->root->size = rootdir_size(ef);
309 if (ef->root->size == 0)
314 /* exFAT does not have time attributes for the root directory */
317 /* always keep at least 1 reference to the root node */
318 exfat_get_node(ef->root);
320 rc = exfat_cache_directory(ef, ef->root);
323 if (ef->upcase == NULL)
325 exfat_error("upcase table is not found");
328 if (ef->cmap.chunk == NULL)
330 exfat_error("clusters bitmap is not found");
337 exfat_put_node(ef, ef->root);
338 exfat_reset_cache(ef);
343 static void finalize_super_block(struct exfat* ef)
348 ef->sb->volume_state = cpu_to_le16(
349 le16_to_cpu(ef->sb->volume_state) & ~EXFAT_STATE_MOUNTED);
351 /* Some implementations set the percentage of allocated space to 0xff
352 on FS creation and never update it. In this case leave it as is. */
353 if (ef->sb->allocated_percent != 0xff)
355 uint32_t free, total;
357 free = exfat_count_free_clusters(ef);
358 total = le32_to_cpu(ef->sb->cluster_count);
359 ef->sb->allocated_percent = ((total - free) * 100 + total / 2) / total;
362 commit_super_block(ef); /* ignore return code */
365 void exfat_unmount(struct exfat* ef)
367 exfat_flush_nodes(ef); /* ignore return code */
368 exfat_flush(ef); /* ignore return code */
369 exfat_put_node(ef, ef->root);
370 exfat_reset_cache(ef);
371 finalize_super_block(ef);
372 exfat_free(ef); /* will close the descriptor */