2 * Copyright (c) 2017 Conrad Meyer <cem@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
30 #include <sys/param.h>
31 #include <sys/endian.h>
46 * https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specification
53 uint64_t ev_part_offset;
54 uint64_t ev_vol_length;
55 uint32_t ev_fat_offset;
56 uint32_t ev_fat_length;
57 uint32_t ev_cluster_offset;
58 uint32_t ev_cluster_count;
59 uint32_t ev_rootdir_cluster;
60 uint32_t ev_vol_serial;
61 uint16_t ev_fs_revision;
62 uint16_t ev_vol_flags;
63 uint8_t ev_log_bytes_per_sect;
64 uint8_t ev_log_sect_per_clust;
67 uint8_t ev_percent_used;
72 #define XDE_TYPE_INUSE_MASK 0x80 /* 1=in use */
73 #define XDE_TYPE_INUSE_SHIFT 7
74 #define XDE_TYPE_CATEGORY_MASK 0x40 /* 0=primary */
75 #define XDE_TYPE_CATEGORY_SHIFT 6
76 #define XDE_TYPE_IMPORTNC_MASK 0x20 /* 0=critical */
77 #define XDE_TYPE_IMPORTNC_SHIFT 5
78 #define XDE_TYPE_CODE_MASK 0x1f
79 /* InUse=0, ..., TypeCode=0: EOD. */
80 #define XDE_TYPE_EOD 0x00
81 #define XDE_TYPE_ALLOC_BITMAP (XDE_TYPE_INUSE_MASK | 0x01)
82 #define XDE_TYPE_UPCASE_TABLE (XDE_TYPE_INUSE_MASK | 0x02)
83 #define XDE_TYPE_VOL_LABEL (XDE_TYPE_INUSE_MASK | 0x03)
84 #define XDE_TYPE_FILE (XDE_TYPE_INUSE_MASK | 0x05)
85 #define XDE_TYPE_VOL_GUID (XDE_TYPE_INUSE_MASK | XDE_TYPE_IMPORTNC_MASK)
86 #define XDE_TYPE_STREAM_EXT (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK)
87 #define XDE_TYPE_FILE_NAME (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK | 0x01)
88 #define XDE_TYPE_VENDOR (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK | XDE_TYPE_IMPORTNC_MASK)
89 #define XDE_TYPE_VENDOR_ALLOC (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK | XDE_TYPE_IMPORTNC_MASK | 0x01)
91 uint8_t xde_generic_[19];
94 * Count of "secondary" dirents following this one.
96 * A single logical entity may be composed of a
97 * sequence of several dirents, starting with a primary
98 * one; the rest are secondary dirents.
100 uint8_t xde_secondary_count_;
101 uint16_t xde_set_chksum_;
102 uint16_t xde_prim_flags_;
103 uint8_t xde_prim_generic_[14];
104 } __packed xde_primary_;
105 struct exde_secondary {
106 uint8_t xde_sec_flags_;
107 uint8_t xde_sec_generic_[18];
108 } __packed xde_secondary_;
110 uint32_t xde_first_cluster;
111 uint64_t xde_data_len;
113 #define xde_generic u.xde_generic_
114 #define xde_secondary_count u.xde_primary_.xde_secondary_count
115 #define xde_set_chksum u.xde_primary_.xde_set_chksum_
116 #define xde_prim_flags u.xde_primary_.xde_prim_flags_
117 #define xde_sec_flags u.xde_secondary_.xde_sec_flags_
118 _Static_assert(sizeof(struct exfat_dirent) == 32, "spec");
120 struct exfat_de_label {
121 uint8_t xdel_type; /* XDE_TYPE_VOL_LABEL */
122 uint8_t xdel_char_cnt; /* Length of UCS-2 label */
123 uint16_t xdel_vol_lbl[11];
124 uint8_t xdel_reserved[8];
126 _Static_assert(sizeof(struct exfat_de_label) == 32, "spec");
128 #define MAIN_BOOT_REGION_SECT 0
129 #define BACKUP_BOOT_REGION_SECT 12
131 #define SUBREGION_CHKSUM_SECT 11
133 #define FIRST_CLUSTER 2
134 #define BAD_BLOCK_SENTINEL 0xfffffff7u
135 #define END_CLUSTER_SENTINEL 0xffffffffu
138 read_sectn(FILE *fp, off_t sect, unsigned count, unsigned bytespersec)
140 return (read_buf(fp, sect * bytespersec, bytespersec * count));
144 read_sect(FILE *fp, off_t sect, unsigned bytespersec)
146 return (read_sectn(fp, sect, 1, bytespersec));
150 * Compute the byte-by-byte multi-sector checksum of the given boot region
151 * (MAIN or BACKUP), for a given bytespersec (typically 512 or 4096).
153 * Endian-safe; result is host endian.
156 exfat_compute_boot_chksum(FILE *fp, unsigned region, unsigned bytespersec,
159 unsigned char *sector;
164 for (sect = 0; sect < 11; sect++) {
165 sector = read_sect(fp, region + sect, bytespersec);
168 for (n = 0; n < bytespersec; n++) {
177 checksum = ((checksum & 1) ? 0x80000000u : 0u) +
178 (checksum >> 1) + (uint32_t)sector[n];
188 convert_label(const uint16_t *ucs2label /* LE */, unsigned ucs2len, char
189 *label_out, size_t label_sz)
192 char *label_out_orig;
196 /* Currently hardcoded in fstyp.c as 256 or so. */
197 assert(label_sz > 1);
201 * Kind of seems bogus, but the spec allows an empty label
202 * entry with the same meaning as no label.
208 warnx("exfat: Bogus volume label length: %u", ucs2len);
212 /* dstname="" means convert to the current locale. */
213 cd = iconv_open("", EXFAT_ENC);
214 if (cd == (iconv_t)-1) {
215 warn("exfat: Could not open iconv");
219 label_out_orig = label_out;
221 /* Dummy up the byte pointer and byte length iconv's API wants. */
222 label = (const void *)ucs2label;
223 srcleft = ucs2len * sizeof(*ucs2label);
225 rc = iconv(cd, __DECONST(char **, &label), &srcleft, &label_out,
227 if (rc == (size_t)-1) {
228 warn("exfat: iconv()");
229 *label_out_orig = '\0';
231 /* NUL-terminate result (iconv advances label_out). */
241 * Using the FAT table, look up the next cluster in this chain.
244 exfat_fat_next(FILE *fp, const struct exfat_vbr *ev, unsigned BPS,
247 uint32_t fat_offset_sect, clsect, clsectoff;
248 uint32_t *fatsect, nextclust;
250 fat_offset_sect = le32toh(ev->ev_fat_offset);
251 clsect = fat_offset_sect + (cluster / (BPS / sizeof(cluster)));
252 clsectoff = (cluster % (BPS / sizeof(cluster)));
254 /* XXX This is pretty wasteful without a block cache for the FAT. */
255 fatsect = read_sect(fp, clsect, BPS);
256 nextclust = le32toh(fatsect[clsectoff]);
263 exfat_find_label(FILE *fp, const struct exfat_vbr *ev, unsigned BPS,
264 char *label_out, size_t label_sz)
266 uint32_t rootdir_cluster, sects_per_clust, cluster_offset_sect;
268 struct exfat_dirent *declust, *it;
270 cluster_offset_sect = le32toh(ev->ev_cluster_offset);
271 rootdir_cluster = le32toh(ev->ev_rootdir_cluster);
272 sects_per_clust = (1u << ev->ev_log_sect_per_clust);
274 if (rootdir_cluster < FIRST_CLUSTER) {
275 warnx("%s: invalid rootdir cluster %u < %d", __func__,
276 rootdir_cluster, FIRST_CLUSTER);
281 for (; rootdir_cluster != END_CLUSTER_SENTINEL;
282 rootdir_cluster = exfat_fat_next(fp, ev, BPS, rootdir_cluster)) {
283 if (rootdir_cluster == BAD_BLOCK_SENTINEL) {
284 warnx("%s: Bogus bad block in root directory chain",
289 rootdir_sect = (rootdir_cluster - FIRST_CLUSTER) *
290 sects_per_clust + cluster_offset_sect;
291 declust = read_sectn(fp, rootdir_sect, sects_per_clust, BPS);
293 it < declust + (sects_per_clust * BPS / sizeof(*it)); it++) {
297 * Simplistic directory traversal; doesn't do any
298 * validation of "MUST" requirements in spec.
300 switch (it->xde_type) {
304 case XDE_TYPE_VOL_LABEL: {
305 struct exfat_de_label *lde = (void*)it;
306 convert_label(lde->xdel_vol_lbl,
307 lde->xdel_char_cnt, label_out, label_sz);
321 fstyp_exfat(FILE *fp, char *label, size_t size)
323 struct exfat_vbr *ev;
325 unsigned bytespersec;
330 ev = (struct exfat_vbr *)read_buf(fp, 0, 512);
331 if (ev == NULL || strncmp(ev->ev_fsname, "EXFAT ", 8) != 0)
334 if (ev->ev_log_bytes_per_sect < 9 || ev->ev_log_bytes_per_sect > 12) {
335 warnx("exfat: Invalid BytesPerSectorShift");
339 bytespersec = (1u << ev->ev_log_bytes_per_sect);
341 error = exfat_compute_boot_chksum(fp, MAIN_BOOT_REGION_SECT,
342 bytespersec, &chksum);
346 cksect = read_sect(fp, MAIN_BOOT_REGION_SECT + SUBREGION_CHKSUM_SECT,
350 * Technically the entire sector should be full of repeating 4-byte
351 * checksum pattern, but we only verify the first.
353 if (chksum != le32toh(cksect[0])) {
354 warnx("exfat: Found checksum 0x%08x != computed 0x%08x",
355 le32toh(cksect[0]), chksum);
360 exfat_find_label(fp, ev, bytespersec, label, size);