1 /*
2 * Copyright (c) 1996, 1998 Robert Nordier
3 * All rights reserved.
4 * Copyright 2024 MNX Cloud, Inc.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
14 * distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
17 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
22 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
24 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
25 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
26 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /*
30 * Readonly filesystem for Microsoft FAT12/FAT16/FAT32 filesystems,
31 * also supports VFAT.
32 */
33
34 #include <sys/types.h>
35 #include <sys/disk.h>
36 #include <string.h>
37 #include <stddef.h>
38
39 #include "stand.h"
40
41 #include "dosfs.h"
42
43 typedef struct dos_mnt {
44 char *dos_dev;
45 DOS_FS *dos_fs;
46 int dos_fd;
47 STAILQ_ENTRY(dos_mnt) dos_link;
48 } dos_mnt_t;
49
50 typedef STAILQ_HEAD(dos_mnt_list, dos_mnt) dos_mnt_list_t;
51 static dos_mnt_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);
52
53 static int dos_open(const char *path, struct open_file *fd);
54 static int dos_close(struct open_file *fd);
55 static int dos_read(struct open_file *fd, void *buf, size_t size, size_t *resid);
56 static off_t dos_seek(struct open_file *fd, off_t offset, int whence);
57 static int dos_stat(struct open_file *fd, struct stat *sb);
58 static int dos_readdir(struct open_file *fd, struct dirent *d);
59 static int dos_mount(const char *dev, const char *path, void **data);
60 static int dos_unmount(const char *dev, void *data);
61
62 struct fs_ops dosfs_fsops = {
63 .fs_name = "dosfs",
64 .fo_open = dos_open,
65 .fo_close = dos_close,
66 .fo_read = dos_read,
67 .fo_write = null_write,
68 .fo_seek = dos_seek,
69 .fo_stat = dos_stat,
70 .fo_readdir = dos_readdir,
71 .fo_mount = dos_mount,
72 .fo_unmount = dos_unmount
73 };
74
75 #define LOCLUS 2 /* lowest cluster number */
76 #define FATBLKSZ 0x20000 /* size of block in the FAT cache buffer */
77
78 /* DOS "BIOS Parameter Block" */
79 typedef struct {
80 u_char secsiz[2]; /* sector size */
81 u_char spc; /* sectors per cluster */
82 u_char ressec[2]; /* reserved sectors */
83 u_char fats; /* FATs */
84 u_char dirents[2]; /* root directory entries */
85 u_char secs[2]; /* total sectors */
86 u_char media; /* media descriptor */
87 u_char spf[2]; /* sectors per FAT */
88 u_char spt[2]; /* sectors per track */
89 u_char heads[2]; /* drive heads */
90 u_char hidsec[4]; /* hidden sectors */
91 u_char lsecs[4]; /* huge sectors */
92 union {
93 struct {
94 u_char drvnum; /* Int 13 drive number */
95 u_char rsvd1; /* Reserved */
96 u_char bootsig; /* Boot signature (0x29) */
97 u_char volid[4]; /* Volume serial number */
98 u_char vollab[11]; /* Volume label */
99 u_char fstype[8]; /* Informational */
100 } f12_f16;
101 struct {
102 u_char lspf[4]; /* huge sectors per FAT */
103 u_char xflg[2]; /* flags */
104 u_char vers[2]; /* filesystem version */
105 u_char rdcl[4]; /* root directory cluster */
106 u_char infs[2]; /* filesystem info sector */
107 u_char bkbs[2]; /* backup boot sector */
108 u_char reserved[12]; /* Reserved */
109 u_char drvnum; /* Int 13 drive number */
110 u_char rsvd1; /* Reserved */
111 u_char bootsig; /* Boot signature (0x29) */
112 u_char volid[4]; /* Volume serial number */
113 u_char vollab[11]; /* Volume label */
114 u_char fstype[8]; /* Informational */
115 } f32;
116 } fstype;
117 } DOS_BPB;
118
119 typedef struct {
120 u_char fsi_leadsig[4]; /* Value 0x41615252 */
121 u_char fsi_reserved1[480];
122 u_char fsi_structsig[4]; /* Value 0x61417272 */
123 u_char fsi_free_count[4]; /* Last known free cluster count */
124 u_char fsi_next_free[4]; /* First free cluster */
125 u_char fsi_reserved2[12];
126 u_char fsi_trailsig[4]; /* Value 0xAA550000 */
127 } DOS_FSINFO;
128
129 /* Initial portion of DOS boot sector */
130 typedef struct {
131 u_char jmp[3]; /* usually 80x86 'jmp' opcode */
132 u_char oem[8]; /* OEM name and version */
133 DOS_BPB bpb; /* BPB */
134 } DOS_BS;
135
136 /* Supply missing "." and ".." root directory entries */
137 static const char *const dotstr[2] = {".", ".."};
138 static DOS_DE dot[2] = {
139 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
140 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
141 {".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
142 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
143 };
144
145 /* The usual conversion macros to avoid multiplication and division */
146 #define bytsec(fs, n) ((n) >> (fs)->sshift)
147 #define secbyt(fs, s) ((s) << (fs)->sshift)
148 #define depsec(fs) (1 << (fs)->dshift)
149 #define entsec(fs, e) ((e) >> (fs)->dshift)
150 #define bytblk(fs, n) ((n) >> (fs)->bshift)
151 #define blkbyt(fs, b) ((b) << (fs)->bshift)
152 #define secblk(fs, s) ((s) >> ((fs)->bshift - (fs)->sshift))
153 #define blksec(fs, b) ((b) << ((fs)->bshift - (fs)->sshift))
154
155 /* Convert cluster number to offset within filesystem */
156 #define blkoff(fs, b) (secbyt(fs, (fs)->lsndta) + \
157 blkbyt(fs, (b) - LOCLUS))
158
159 /* Convert cluster number to logical sector number */
160 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
161
162 /* Convert cluster number to offset within FAT */
163 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
164 (sz) == 16 ? (c) << 1 : \
165 (c) << 2)
166
167 /* Does cluster number reference a valid data cluster? */
168 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
169
170 /* Get start cluster from directory entry */
171 #define stclus(sz, de) ((sz) != 32 ? (u_int)cv2((de)->clus) : \
172 ((u_int)cv2((de)->dex.h_clus) << 16) | \
173 cv2((de)->clus))
174
175 static int parsebs(DOS_FS *, DOS_BS *);
176 static int namede(DOS_FS *, const char *, DOS_DE **);
177 static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
178 static void cp_xdnm(u_char *, DOS_XDE *);
179 static void cp_sfn(u_char *, DOS_DE *);
180 static off_t fsize(DOS_FS *, DOS_DE *);
181 static int fatcnt(DOS_FS *, u_int);
182 static int fatget(DOS_FS *, u_int *);
183 static int fatend(u_int, u_int);
184 static int ioread(DOS_FS *, uint64_t, void *, size_t);
185 static int ioget(DOS_FS *, daddr_t, void *, size_t);
186
187 static int
dos_read_fatblk(DOS_FS * fs,u_int blknum)188 dos_read_fatblk(DOS_FS *fs, u_int blknum)
189 {
190 int err;
191 size_t io_size;
192 daddr_t offset_in_fat, max_offset_in_fat;
193
194 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
195 max_offset_in_fat = secbyt(fs, (daddr_t)fs->spf);
196 io_size = FATBLKSZ;
197 if (offset_in_fat > max_offset_in_fat)
198 offset_in_fat = max_offset_in_fat;
199 if (offset_in_fat + io_size > max_offset_in_fat)
200 io_size = ((size_t)(max_offset_in_fat - offset_in_fat));
201
202 if (io_size != 0) {
203 err = ioget(fs, fs->lsnfat + bytsec(fs, offset_in_fat),
204 fs->fatbuf, io_size);
205 if (err != 0) {
206 fs->fatbuf_blknum = ((u_int)(-1));
207 return (err);
208 }
209 }
210 if (io_size < FATBLKSZ)
211 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
212
213 fs->fatbuf_blknum = blknum;
214 return (0);
215 }
216
217 /*
218 * Mount DOS filesystem
219 */
220 static int
dos_mount_impl(DOS_FS * fs,struct open_file * fd)221 dos_mount_impl(DOS_FS *fs, struct open_file *fd)
222 {
223 int err;
224 unsigned secsz;
225 u_char *buf;
226
227 fs->fd = fd;
228
229 err = ioctl(fd->f_id, DIOCGSECTORSIZE, &secsz);
230 if (err != 0) {
231 return (err);
232 }
233
234 buf = malloc(secsz);
235 if (buf == NULL)
236 return (errno);
237
238 if ((err = ioget(fs, 0, buf, secsz)) ||
239 (err = parsebs(fs, (DOS_BS *)buf))) {
240 free(buf);
241 return (err);
242 }
243 fs->secbuf = buf;
244
245 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL) {
246 free(buf);
247 return (errno);
248 }
249 err = dos_read_fatblk(fs, 0);
250 if (err != 0) {
251 free(buf);
252 free(fs->fatbuf);
253 return (err);
254 }
255
256 fs->root = dot[0];
257 fs->root.name[0] = ' ';
258 if (fs->fatsz == 32) {
259 fs->root.clus[0] = fs->rdcl & 0xff;
260 fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
261 fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
262 fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
263 }
264 return (0);
265 }
266
267 static int
dos_mount(const char * dev,const char * path,void ** data)268 dos_mount(const char *dev, const char *path, void **data)
269 {
270 char *fs;
271 dos_mnt_t *mnt;
272 struct open_file *f;
273 DOS_FILE *df;
274
275 errno = 0;
276 mnt = calloc(1, sizeof(*mnt));
277 if (mnt == NULL)
278 return (errno);
279 mnt->dos_fd = -1;
280 mnt->dos_dev = strdup(dev);
281 if (mnt->dos_dev == NULL)
282 goto done;
283
284 if (asprintf(&fs, "%s%s", dev, path) < 0)
285 goto done;
286
287 mnt->dos_fd = open(fs, O_RDONLY);
288 free(fs);
289 if (mnt->dos_fd == -1)
290 goto done;
291
292 f = fd2open_file(mnt->dos_fd);
293 if (strcmp(f->f_ops->fs_name, "dosfs") == 0) {
294 df = f->f_fsdata;
295 mnt->dos_fs = df->fs;
296 STAILQ_INSERT_TAIL(&mnt_list, mnt, dos_link);
297 } else {
298 errno = ENXIO;
299 }
300
301 done:
302 if (errno != 0) {
303 free(mnt->dos_dev);
304 if (mnt->dos_fd >= 0)
305 close(mnt->dos_fd);
306 free(mnt);
307 } else {
308 *data = mnt;
309 }
310
311 return (errno);
312 }
313
314 static int
dos_unmount(const char * dev __unused,void * data)315 dos_unmount(const char *dev __unused, void *data)
316 {
317 dos_mnt_t *mnt = data;
318
319 STAILQ_REMOVE(&mnt_list, mnt, dos_mnt, dos_link);
320 free(mnt->dos_dev);
321 close(mnt->dos_fd);
322 free(mnt);
323 return (0);
324 }
325
326 /*
327 * Unmount mounted filesystem
328 */
329 static int
dos_unmount_impl(DOS_FS * fs)330 dos_unmount_impl(DOS_FS *fs)
331 {
332 if (fs->links)
333 return (EBUSY);
334 free(fs->secbuf);
335 free(fs->fatbuf);
336 free(fs);
337 return (0);
338 }
339
340 /*
341 * Open DOS file
342 */
343 static int
dos_open(const char * path,struct open_file * fd)344 dos_open(const char *path, struct open_file *fd)
345 {
346 DOS_DE *de;
347 DOS_FILE *f;
348 DOS_FS *fs = NULL;
349 dos_mnt_t *mnt;
350 const char *dev;
351 u_int size, clus;
352 int err;
353
354 dev = devformat((struct devdesc *)fd->f_devdata);
355 STAILQ_FOREACH(mnt, &mnt_list, dos_link) {
356 if (strcmp(dev, mnt->dos_dev) == 0)
357 break;
358 }
359
360 if (mnt == NULL) {
361 /* Allocate mount structure, associate with open */
362 if ((fs = calloc(1, sizeof(DOS_FS))) == NULL)
363 return (errno);
364 if ((err = dos_mount_impl(fs, fd))) {
365 free(fs);
366 return (err);
367 }
368 } else {
369 fs = mnt->dos_fs;
370 }
371
372 if ((err = namede(fs, path, &de))) {
373 if (mnt == NULL)
374 dos_unmount_impl(fs);
375 return (err);
376 }
377
378 clus = stclus(fs->fatsz, de);
379 size = cv4(de->size);
380
381 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
382 ((de->attr & FA_DIR) && size) ||
383 (clus && !okclus(fs, clus))) {
384 if (mnt == NULL)
385 dos_unmount_impl(fs);
386 return (EINVAL);
387 }
388 if ((f = calloc(1, sizeof(DOS_FILE))) == NULL) {
389 err = errno;
390 if (mnt == NULL)
391 dos_unmount_impl(fs);
392 return (err);
393 }
394 f->fs = fs;
395 fs->links++;
396 f->de = *de;
397 fd->f_fsdata = f;
398 return (0);
399 }
400
401 /*
402 * Read from file
403 */
404 static int
dos_read(struct open_file * fd,void * buf,size_t nbyte,size_t * resid)405 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
406 {
407 off_t size;
408 uint64_t off;
409 size_t nb;
410 u_int clus, c, cnt, n;
411 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
412 int err = 0;
413
414 /*
415 * as ioget() can be called *a lot*, use twiddle here.
416 * also 4 seems to be good value not to slow loading down too much:
417 * with 270MB file (~540k ioget() calls, twiddle can easily waste
418 * 4-5 sec.
419 */
420 twiddle(4);
421 nb = nbyte;
422 if ((size = fsize(f->fs, &f->de)) == -1)
423 return (EINVAL);
424 if (nb > (n = size - f->offset))
425 nb = n;
426 off = f->offset;
427 if ((clus = stclus(f->fs->fatsz, &f->de)))
428 off &= f->fs->bsize - 1;
429 c = f->c;
430 cnt = nb;
431 while (cnt) {
432 n = 0;
433 if (!c) {
434 if ((c = clus))
435 n = bytblk(f->fs, f->offset);
436 } else if (!off)
437 n++;
438 while (n--) {
439 if ((err = fatget(f->fs, &c)))
440 goto out;
441 if (!okclus(f->fs, c)) {
442 err = EINVAL;
443 goto out;
444 }
445 }
446 if (!clus || (n = f->fs->bsize - off) > cnt)
447 n = cnt;
448 if (c != 0)
449 off += blkoff(f->fs, (uint64_t)c);
450 else
451 off += secbyt(f->fs, f->fs->lsndir);
452 err = ioread(f->fs, off, buf, n);
453 if (err != 0)
454 goto out;
455 f->offset += n;
456 f->c = c;
457 off = 0;
458 buf = (char *)buf + n;
459 cnt -= n;
460 }
461 out:
462 if (resid)
463 *resid = nbyte - nb + cnt;
464 return (err);
465 }
466
467 /*
468 * Reposition within file
469 */
470 static off_t
dos_seek(struct open_file * fd,off_t offset,int whence)471 dos_seek(struct open_file *fd, off_t offset, int whence)
472 {
473 off_t off;
474 u_int size;
475 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
476
477 size = cv4(f->de.size);
478 switch (whence) {
479 case SEEK_SET:
480 off = 0;
481 break;
482 case SEEK_CUR:
483 off = f->offset;
484 break;
485 case SEEK_END:
486 off = size;
487 break;
488 default:
489 errno = EINVAL;
490 return (-1);
491 }
492 off += offset;
493 if (off < 0 || off > size) {
494 errno = EINVAL;
495 return (-1);
496 }
497 f->offset = (u_int)off;
498 f->c = 0;
499 return (off);
500 }
501
502 /*
503 * Close open file
504 */
505 static int
dos_close(struct open_file * fd)506 dos_close(struct open_file *fd)
507 {
508 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
509 DOS_FS *fs = f->fs;
510
511 f->fs->links--;
512 free(f);
513 dos_unmount_impl(fs);
514 return (0);
515 }
516
517 /*
518 * Return some stat information on a file.
519 */
520 static int
dos_stat(struct open_file * fd,struct stat * sb)521 dos_stat(struct open_file *fd, struct stat *sb)
522 {
523 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
524
525 /* only important stuff */
526 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
527 sb->st_nlink = 1;
528 sb->st_uid = 0;
529 sb->st_gid = 0;
530 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
531 return (EINVAL);
532 return (0);
533 }
534
535 static int
dos_checksum(unsigned char * name,unsigned char * ext)536 dos_checksum(unsigned char *name, unsigned char *ext)
537 {
538 int x, i;
539 char buf[11];
540
541 bcopy(name, buf, 8);
542 bcopy(ext, buf+8, 3);
543 x = 0;
544 for (i = 0; i < 11; i++) {
545 x = ((x & 1) << 7) | (x >> 1);
546 x += buf[i];
547 x &= 0xff;
548 }
549 return (x);
550 }
551
552 static int
dos_readdir(struct open_file * fd,struct dirent * d)553 dos_readdir(struct open_file *fd, struct dirent *d)
554 {
555 /* DOS_FILE *f = (DOS_FILE *)fd->f_fsdata; */
556 u_char fn[261];
557 DOS_DIR dd;
558 size_t res;
559 u_int chk, x, xdn;
560 int err;
561
562 x = chk = 0;
563 for (;;) {
564 xdn = x;
565 x = 0;
566 err = dos_read(fd, &dd, sizeof(dd), &res);
567 if (err)
568 return (err);
569 if (res == sizeof(dd))
570 return (ENOENT);
571 if (dd.de.name[0] == 0)
572 return (ENOENT);
573
574 /* Skip deleted entries */
575 if (dd.de.name[0] == 0xe5)
576 continue;
577
578 /* Check if directory entry is volume label */
579 if (dd.de.attr & FA_LABEL) {
580 /*
581 * If volume label set, check if the current entry is
582 * extended entry (FA_XDE) for long file names.
583 */
584 if ((dd.de.attr & FA_MASK) == FA_XDE) {
585 /*
586 * Read through all following extended entries
587 * to get the long file name. 0x40 marks the
588 * last entry containing part of long file name.
589 */
590 if (dd.xde.seq & 0x40)
591 chk = dd.xde.chk;
592 else if (dd.xde.seq != xdn - 1 ||
593 dd.xde.chk != chk)
594 continue;
595 x = dd.xde.seq & ~0x40;
596 if (x < 1 || x > 20) {
597 x = 0;
598 continue;
599 }
600 cp_xdnm(fn, &dd.xde);
601 } else {
602 /* skip only volume label entries */
603 continue;
604 }
605 } else {
606 if (xdn == 1) {
607 x = dos_checksum(dd.de.name, dd.de.ext);
608 if (x == chk)
609 break;
610 } else {
611 cp_sfn(fn, &dd.de);
612 break;
613 }
614 x = 0;
615 }
616 }
617
618 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
619 d->d_reclen = sizeof(*d);
620 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
621 memcpy(d->d_name, fn, sizeof(d->d_name));
622 return (0);
623 }
624
625 /*
626 * Parse DOS boot sector
627 */
628 static int
parsebs(DOS_FS * fs,DOS_BS * bs)629 parsebs(DOS_FS *fs, DOS_BS *bs)
630 {
631 u_int sc, RootDirSectors;
632
633 if (bs->bpb.media < 0xf0)
634 return (EINVAL);
635
636 /* Check supported sector sizes */
637 switch (cv2(bs->bpb.secsiz)) {
638 case 512:
639 case 1024:
640 case 2048:
641 case 4096:
642 fs->sshift = ffs(cv2(bs->bpb.secsiz)) - 1;
643 break;
644
645 default:
646 return (EINVAL);
647 }
648
649 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
650 return (EINVAL);
651 fs->bsize = secbyt(fs, fs->spc);
652 fs->bshift = ffs(fs->bsize) - 1;
653 fs->dshift = ffs(secbyt(fs, 1) / sizeof (DOS_DE)) - 1;
654 fs->dirents = cv2(bs->bpb.dirents);
655 fs->spf = cv2(bs->bpb.spf);
656 fs->lsnfat = cv2(bs->bpb.ressec);
657
658 if (fs->spf != 0) {
659 if (bs->bpb.fats != 2)
660 return (EINVAL);
661 if (fs->dirents == 0)
662 return (EINVAL);
663 } else {
664 fs->spf = cv4(bs->bpb.fstype.f32.lspf);
665 if (fs->spf == 0)
666 return (EINVAL);
667 if (bs->bpb.fats == 0 || bs->bpb.fats > 16)
668 return (EINVAL);
669 fs->rdcl = cv4(bs->bpb.fstype.f32.rdcl);
670 if (fs->rdcl < LOCLUS)
671 return (EINVAL);
672 }
673
674 RootDirSectors = ((fs->dirents * sizeof (DOS_DE)) +
675 (secbyt(fs, 1) - 1)) / secbyt(fs, 1);
676
677 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
678 fs->lsndta = fs->lsndir + RootDirSectors;
679 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
680 return (EINVAL);
681 if (fs->lsndta > sc)
682 return (EINVAL);
683 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
684 return (EINVAL);
685 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
686 sc = (secbyt(fs, fs->spf) << 1) / (fs->fatsz >> 2) - 1;
687 if (fs->xclus > sc)
688 fs->xclus = sc;
689 return (0);
690 }
691
692 /*
693 * Return directory entry from path
694 */
695 static int
namede(DOS_FS * fs,const char * path,DOS_DE ** dep)696 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
697 {
698 char name[256];
699 DOS_DE *de;
700 char *s;
701 size_t n;
702 int err;
703
704 err = 0;
705 de = &fs->root;
706 while (*path) {
707 while (*path == '/')
708 path++;
709 if (*path == '\0')
710 break;
711 if (!(s = strchr(path, '/')))
712 s = strchr(path, 0);
713 if ((n = s - path) > 255)
714 return (ENAMETOOLONG);
715 memcpy(name, path, n);
716 name[n] = 0;
717 path = s;
718 if (!(de->attr & FA_DIR))
719 return (ENOTDIR);
720 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
721 return (err);
722 }
723 *dep = de;
724 return (0);
725 }
726
727 /*
728 * Lookup path segment
729 */
730 static int
lookup(DOS_FS * fs,u_int clus,const char * name,DOS_DE ** dep)731 lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
732 {
733 DOS_DIR *dir;
734 u_char lfn[261];
735 u_char sfn[13];
736 u_int nsec, lsec, xdn, chk, sec, ent, x;
737 int err, ok;
738
739 if (!clus)
740 for (ent = 0; ent < 2; ent++)
741 if (!strcasecmp(name, dotstr[ent])) {
742 *dep = dot + ent;
743 return (0);
744 }
745 if (!clus && fs->fatsz == 32)
746 clus = fs->rdcl;
747 nsec = !clus ? entsec(fs, fs->dirents) : fs->spc;
748 lsec = 0;
749 xdn = chk = 0;
750 dir = (DOS_DIR *)fs->secbuf;
751 for (;;) {
752 if (!clus && !lsec)
753 lsec = fs->lsndir;
754 else if (okclus(fs, clus))
755 lsec = blklsn(fs, clus);
756 else
757 return (EINVAL);
758 for (sec = 0; sec < nsec; sec++) {
759 if ((err = ioget(fs, lsec + sec, dir,
760 secbyt(fs, 1))))
761 return (err);
762 for (ent = 0; ent < depsec(fs); ent++) {
763 if (!*dir[ent].de.name)
764 return (ENOENT);
765 if (*dir[ent].de.name != 0xe5) {
766 if ((dir[ent].de.attr & FA_MASK) ==
767 FA_XDE) {
768 x = dir[ent].xde.seq;
769 if (x & 0x40 || (x + 1 == xdn &&
770 dir[ent].xde.chk == chk)) {
771 if (x & 0x40) {
772 chk = dir[ent].xde.chk;
773 x &= ~0x40;
774 }
775 if (x >= 1 && x <= 20) {
776 cp_xdnm(lfn, &dir[ent].xde);
777 xdn = x;
778 continue;
779 }
780 }
781 } else if (!(dir[ent].de.attr &
782 FA_LABEL)) {
783 if ((ok = xdn == 1)) {
784 x = dos_checksum(
785 dir[ent].de.name,
786 dir[ent].de.ext);
787 ok = chk == x &&
788 !strcasecmp(name,
789 (const char *)lfn);
790 }
791 if (!ok) {
792 cp_sfn(sfn,
793 &dir[ent].de);
794 ok = !strcasecmp(name,
795 (const char *)sfn);
796 }
797 if (ok) {
798 *dep = &dir[ent].de;
799 return (0);
800 }
801 }
802 }
803 xdn = 0;
804 }
805 }
806 if (!clus)
807 break;
808 if ((err = fatget(fs, &clus)))
809 return (err);
810 if (fatend(fs->fatsz, clus))
811 break;
812 }
813 return (ENOENT);
814 }
815
816 /*
817 * Copy name from extended directory entry
818 */
819 static void
cp_xdnm(u_char * lfn,DOS_XDE * xde)820 cp_xdnm(u_char *lfn, DOS_XDE *xde)
821 {
822 static struct {
823 u_int off;
824 u_int dim;
825 } ix[3] = {
826 {offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
827 {offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
828 {offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
829 };
830 u_char *p;
831 u_int n, x, c;
832
833 lfn += 13 * ((xde->seq & ~0x40) - 1);
834 for (n = 0; n < 3; n++)
835 for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
836 p += 2, x--) {
837 if ((c = cv2(p)) && (c < 32 || c > 127))
838 c = '?';
839 if (!(*lfn++ = c))
840 return;
841 }
842 if (xde->seq & 0x40)
843 *lfn = 0;
844 }
845
846 /*
847 * Copy short filename
848 */
849 static void
cp_sfn(u_char * sfn,DOS_DE * de)850 cp_sfn(u_char *sfn, DOS_DE *de)
851 {
852 u_char *p;
853 int j, i;
854
855 p = sfn;
856 if (*de->name != ' ') {
857 for (j = 7; de->name[j] == ' '; j--)
858 ;
859 for (i = 0; i <= j; i++)
860 *p++ = de->name[i];
861 if (*de->ext != ' ') {
862 *p++ = '.';
863 for (j = 2; de->ext[j] == ' '; j--)
864 ;
865 for (i = 0; i <= j; i++)
866 *p++ = de->ext[i];
867 }
868 }
869 *p = 0;
870 if (*sfn == 5)
871 *sfn = 0xe5;
872 }
873
874 /*
875 * Return size of file in bytes
876 */
877 static off_t
fsize(DOS_FS * fs,DOS_DE * de)878 fsize(DOS_FS *fs, DOS_DE *de)
879 {
880 u_long size;
881 u_int c;
882 int n;
883
884 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
885 if (!(c = stclus(fs->fatsz, de))) {
886 size = fs->dirents * sizeof(DOS_DE);
887 } else {
888 if ((n = fatcnt(fs, c)) == -1)
889 return (n);
890 size = blkbyt(fs, n);
891 }
892 }
893 return (size);
894 }
895
896 /*
897 * Count number of clusters in chain
898 */
899 static int
fatcnt(DOS_FS * fs,u_int c)900 fatcnt(DOS_FS *fs, u_int c)
901 {
902 int n;
903
904 for (n = 0; okclus(fs, c); n++)
905 if (fatget(fs, &c))
906 return (-1);
907 return (fatend(fs->fatsz, c) ? n : -1);
908 }
909
910 /*
911 * Get next cluster in cluster chain. Use in core fat cache unless
912 * the number of current 128K block in FAT has changed.
913 */
914 static int
fatget(DOS_FS * fs,u_int * c)915 fatget(DOS_FS *fs, u_int *c)
916 {
917 u_int val_in, val_out, offset, blknum, nbyte;
918 const u_char *p_entry;
919 int err;
920
921 /* check input value to prevent overflow in fatoff() */
922 val_in = *c;
923 if (val_in & 0xf0000000)
924 return (EINVAL);
925
926 /* ensure that current 128K FAT block is cached */
927 offset = fatoff(fs->fatsz, val_in);
928 nbyte = fs->fatsz != 32 ? 2 : 4;
929 if (offset + nbyte > secbyt(fs, fs->spf))
930 return (EINVAL);
931 blknum = offset / FATBLKSZ;
932 offset %= FATBLKSZ;
933 if (offset + nbyte > FATBLKSZ)
934 return (EINVAL);
935 if (blknum != fs->fatbuf_blknum) {
936 err = dos_read_fatblk(fs, blknum);
937 if (err != 0)
938 return (err);
939 }
940 p_entry = fs->fatbuf + offset;
941
942 /* extract cluster number from FAT entry */
943 switch (fs->fatsz) {
944 case 32:
945 val_out = cv4(p_entry);
946 val_out &= 0x0fffffff;
947 break;
948 case 16:
949 val_out = cv2(p_entry);
950 break;
951 case 12:
952 val_out = cv2(p_entry);
953 if (val_in & 1)
954 val_out >>= 4;
955 else
956 val_out &= 0xfff;
957 break;
958 default:
959 return (EINVAL);
960 }
961 *c = val_out;
962 return (0);
963 }
964
965 /*
966 * Is cluster an end-of-chain marker?
967 */
968 static int
fatend(u_int sz,u_int c)969 fatend(u_int sz, u_int c)
970 {
971 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
972 }
973
974 /*
975 * Offset-based I/O primitive
976 */
977 static int
ioread(DOS_FS * fs,uint64_t offset,void * buf,size_t nbyte)978 ioread(DOS_FS *fs, uint64_t offset, void *buf, size_t nbyte)
979 {
980 char *s;
981 size_t n, secsiz;
982 int err;
983 uint64_t off;
984
985 secsiz = secbyt(fs, 1);
986 s = buf;
987 if ((off = offset & (secsiz - 1))) {
988 offset -= off;
989 if ((n = secsiz - off) > nbyte)
990 n = nbyte;
991 err = ioget(fs, bytsec(fs, offset), fs->secbuf, secsiz);
992 if (err != 0)
993 return (err);
994 memcpy(s, fs->secbuf + off, n);
995 offset += secsiz;
996 s += n;
997 nbyte -= n;
998 }
999 n = nbyte & (secsiz - 1);
1000 if (nbyte -= n) {
1001 if ((err = ioget(fs, bytsec(fs, offset), s, nbyte)))
1002 return (err);
1003 offset += nbyte;
1004 s += nbyte;
1005 }
1006 if (n != 0) {
1007 err = ioget(fs, bytsec(fs, offset), fs->secbuf, secsiz);
1008 if (err != 0)
1009 return (err);
1010 memcpy(s, fs->secbuf, n);
1011 }
1012 return (0);
1013 }
1014
1015 /*
1016 * Sector-based I/O primitive. Note, since strategy functions are operating
1017 * in terms of 512B sectors, we need to do necessary conversion here.
1018 */
1019 static int
ioget(DOS_FS * fs,daddr_t lsec,void * buf,size_t size)1020 ioget(DOS_FS *fs, daddr_t lsec, void *buf, size_t size)
1021 {
1022 size_t rsize;
1023 int rv;
1024 struct open_file *fd = fs->fd;
1025
1026 /* Make sure we get full read or error. */
1027 rsize = 0;
1028 /* convert native sector number to 512B sector number. */
1029 lsec = secbyt(fs, lsec) >> 9;
1030 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
1031 size, buf, &rsize);
1032 if ((rv == 0) && (size != rsize))
1033 rv = EIO;
1034 return (rv);
1035 }
1036