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 .fs_flags = 0,
65 .fo_open = dos_open,
66 .fo_close = dos_close,
67 .fo_read = dos_read,
68 .fo_write = null_write,
69 .fo_seek = dos_seek,
70 .fo_stat = dos_stat,
71 .fo_readdir = dos_readdir,
72 .fo_mount = dos_mount,
73 .fo_unmount = dos_unmount
74 };
75
76 #define LOCLUS 2 /* lowest cluster number */
77 #define FATBLKSZ 0x20000 /* size of block in the FAT cache buffer */
78
79 /* DOS "BIOS Parameter Block" */
80 typedef struct {
81 u_char secsiz[2]; /* sector size */
82 u_char spc; /* sectors per cluster */
83 u_char ressec[2]; /* reserved sectors */
84 u_char fats; /* FATs */
85 u_char dirents[2]; /* root directory entries */
86 u_char secs[2]; /* total sectors */
87 u_char media; /* media descriptor */
88 u_char spf[2]; /* sectors per FAT */
89 u_char spt[2]; /* sectors per track */
90 u_char heads[2]; /* drive heads */
91 u_char hidsec[4]; /* hidden sectors */
92 u_char lsecs[4]; /* huge sectors */
93 union {
94 struct {
95 u_char drvnum; /* Int 13 drive number */
96 u_char rsvd1; /* Reserved */
97 u_char bootsig; /* Boot signature (0x29) */
98 u_char volid[4]; /* Volume serial number */
99 u_char vollab[11]; /* Volume label */
100 u_char fstype[8]; /* Informational */
101 } f12_f16;
102 struct {
103 u_char lspf[4]; /* huge sectors per FAT */
104 u_char xflg[2]; /* flags */
105 u_char vers[2]; /* filesystem version */
106 u_char rdcl[4]; /* root directory cluster */
107 u_char infs[2]; /* filesystem info sector */
108 u_char bkbs[2]; /* backup boot sector */
109 u_char reserved[12]; /* Reserved */
110 u_char drvnum; /* Int 13 drive number */
111 u_char rsvd1; /* Reserved */
112 u_char bootsig; /* Boot signature (0x29) */
113 u_char volid[4]; /* Volume serial number */
114 u_char vollab[11]; /* Volume label */
115 u_char fstype[8]; /* Informational */
116 } f32;
117 } fstype;
118 } DOS_BPB;
119
120 typedef struct {
121 u_char fsi_leadsig[4]; /* Value 0x41615252 */
122 u_char fsi_reserved1[480];
123 u_char fsi_structsig[4]; /* Value 0x61417272 */
124 u_char fsi_free_count[4]; /* Last known free cluster count */
125 u_char fsi_next_free[4]; /* First free cluster */
126 u_char fsi_reserved2[12];
127 u_char fsi_trailsig[4]; /* Value 0xAA550000 */
128 } DOS_FSINFO;
129
130 /* Initial portion of DOS boot sector */
131 typedef struct {
132 u_char jmp[3]; /* usually 80x86 'jmp' opcode */
133 u_char oem[8]; /* OEM name and version */
134 DOS_BPB bpb; /* BPB */
135 } DOS_BS;
136
137 /* Supply missing "." and ".." root directory entries */
138 static const char *const dotstr[2] = {".", ".."};
139 static DOS_DE dot[2] = {
140 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
141 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
142 {".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
143 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
144 };
145
146 /* The usual conversion macros to avoid multiplication and division */
147 #define bytsec(fs, n) ((n) >> (fs)->sshift)
148 #define secbyt(fs, s) ((s) << (fs)->sshift)
149 #define depsec(fs) (1 << (fs)->dshift)
150 #define entsec(fs, e) ((e) >> (fs)->dshift)
151 #define bytblk(fs, n) ((n) >> (fs)->bshift)
152 #define blkbyt(fs, b) ((b) << (fs)->bshift)
153 #define secblk(fs, s) ((s) >> ((fs)->bshift - (fs)->sshift))
154 #define blksec(fs, b) ((b) << ((fs)->bshift - (fs)->sshift))
155
156 /* Convert cluster number to offset within filesystem */
157 #define blkoff(fs, b) (secbyt(fs, (fs)->lsndta) + \
158 blkbyt(fs, (b) - LOCLUS))
159
160 /* Convert cluster number to logical sector number */
161 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
162
163 /* Convert cluster number to offset within FAT */
164 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
165 (sz) == 16 ? (c) << 1 : \
166 (c) << 2)
167
168 /* Does cluster number reference a valid data cluster? */
169 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
170
171 /* Get start cluster from directory entry */
172 #define stclus(sz, de) ((sz) != 32 ? (u_int)cv2((de)->clus) : \
173 ((u_int)cv2((de)->dex.h_clus) << 16) | \
174 cv2((de)->clus))
175
176 static int parsebs(DOS_FS *, DOS_BS *);
177 static int namede(DOS_FS *, const char *, DOS_DE **);
178 static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
179 static void cp_xdnm(u_char *, DOS_XDE *);
180 static void cp_sfn(u_char *, DOS_DE *);
181 static off_t fsize(DOS_FS *, DOS_DE *);
182 static int fatcnt(DOS_FS *, u_int);
183 static int fatget(DOS_FS *, u_int *);
184 static int fatend(u_int, u_int);
185 static int ioread(DOS_FS *, uint64_t, void *, size_t);
186 static int ioget(DOS_FS *, daddr_t, void *, size_t);
187
188 static int
dos_read_fatblk(DOS_FS * fs,u_int blknum)189 dos_read_fatblk(DOS_FS *fs, u_int blknum)
190 {
191 int err;
192 size_t io_size;
193 daddr_t offset_in_fat, max_offset_in_fat;
194
195 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
196 max_offset_in_fat = secbyt(fs, (daddr_t)fs->spf);
197 io_size = FATBLKSZ;
198 if (offset_in_fat > max_offset_in_fat)
199 offset_in_fat = max_offset_in_fat;
200 if (offset_in_fat + io_size > max_offset_in_fat)
201 io_size = ((size_t)(max_offset_in_fat - offset_in_fat));
202
203 if (io_size != 0) {
204 err = ioget(fs, fs->lsnfat + bytsec(fs, offset_in_fat),
205 fs->fatbuf, io_size);
206 if (err != 0) {
207 fs->fatbuf_blknum = ((u_int)(-1));
208 return (err);
209 }
210 }
211 if (io_size < FATBLKSZ)
212 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
213
214 fs->fatbuf_blknum = blknum;
215 return (0);
216 }
217
218 /*
219 * Mount DOS filesystem
220 */
221 static int
dos_mount_impl(DOS_FS * fs,struct open_file * fd)222 dos_mount_impl(DOS_FS *fs, struct open_file *fd)
223 {
224 int err;
225 unsigned secsz;
226 u_char *buf;
227
228 fs->fd = fd;
229
230 err = ioctl(fd->f_id, DIOCGSECTORSIZE, &secsz);
231 if (err != 0) {
232 return (err);
233 }
234
235 buf = malloc(secsz);
236 if (buf == NULL)
237 return (errno);
238
239 if ((err = ioget(fs, 0, buf, secsz)) ||
240 (err = parsebs(fs, (DOS_BS *)buf))) {
241 free(buf);
242 return (err);
243 }
244 fs->secbuf = buf;
245
246 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL) {
247 free(buf);
248 return (errno);
249 }
250 err = dos_read_fatblk(fs, 0);
251 if (err != 0) {
252 free(buf);
253 free(fs->fatbuf);
254 return (err);
255 }
256
257 fs->root = dot[0];
258 fs->root.name[0] = ' ';
259 if (fs->fatsz == 32) {
260 fs->root.clus[0] = fs->rdcl & 0xff;
261 fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
262 fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
263 fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
264 }
265 return (0);
266 }
267
268 static int
dos_mount(const char * dev,const char * path,void ** data)269 dos_mount(const char *dev, const char *path, void **data)
270 {
271 char *fs;
272 dos_mnt_t *mnt;
273 struct open_file *f;
274 DOS_FILE *df;
275
276 errno = 0;
277 mnt = calloc(1, sizeof(*mnt));
278 if (mnt == NULL)
279 return (errno);
280 mnt->dos_fd = -1;
281 mnt->dos_dev = strdup(dev);
282 if (mnt->dos_dev == NULL)
283 goto done;
284
285 if (asprintf(&fs, "%s%s", dev, path) < 0)
286 goto done;
287
288 mnt->dos_fd = open(fs, O_RDONLY);
289 free(fs);
290 if (mnt->dos_fd == -1)
291 goto done;
292
293 f = fd2open_file(mnt->dos_fd);
294 if (strcmp(f->f_ops->fs_name, "dosfs") == 0) {
295 df = f->f_fsdata;
296 mnt->dos_fs = df->fs;
297 STAILQ_INSERT_TAIL(&mnt_list, mnt, dos_link);
298 } else {
299 errno = ENXIO;
300 }
301
302 done:
303 if (errno != 0) {
304 free(mnt->dos_dev);
305 if (mnt->dos_fd >= 0)
306 close(mnt->dos_fd);
307 free(mnt);
308 } else {
309 *data = mnt;
310 }
311
312 return (errno);
313 }
314
315 static int
dos_unmount(const char * dev __unused,void * data)316 dos_unmount(const char *dev __unused, void *data)
317 {
318 dos_mnt_t *mnt = data;
319
320 STAILQ_REMOVE(&mnt_list, mnt, dos_mnt, dos_link);
321 free(mnt->dos_dev);
322 close(mnt->dos_fd);
323 free(mnt);
324 return (0);
325 }
326
327 /*
328 * Unmount mounted filesystem
329 */
330 static int
dos_unmount_impl(DOS_FS * fs)331 dos_unmount_impl(DOS_FS *fs)
332 {
333 if (fs->links)
334 return (EBUSY);
335 free(fs->secbuf);
336 free(fs->fatbuf);
337 free(fs);
338 return (0);
339 }
340
341 /*
342 * Open DOS file
343 */
344 static int
dos_open(const char * path,struct open_file * fd)345 dos_open(const char *path, struct open_file *fd)
346 {
347 DOS_DE *de;
348 DOS_FILE *f;
349 DOS_FS *fs = NULL;
350 dos_mnt_t *mnt;
351 const char *dev;
352 u_int size, clus;
353 int err;
354
355 dev = devformat((struct devdesc *)fd->f_devdata);
356 STAILQ_FOREACH(mnt, &mnt_list, dos_link) {
357 if (strcmp(dev, mnt->dos_dev) == 0)
358 break;
359 }
360
361 if (mnt == NULL) {
362 /* Allocate mount structure, associate with open */
363 if ((fs = calloc(1, sizeof(DOS_FS))) == NULL)
364 return (errno);
365 if ((err = dos_mount_impl(fs, fd))) {
366 free(fs);
367 return (err);
368 }
369 } else {
370 fs = mnt->dos_fs;
371 }
372
373 if ((err = namede(fs, path, &de))) {
374 if (mnt == NULL)
375 dos_unmount_impl(fs);
376 return (err);
377 }
378
379 clus = stclus(fs->fatsz, de);
380 size = cv4(de->size);
381
382 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
383 ((de->attr & FA_DIR) && size) ||
384 (clus && !okclus(fs, clus))) {
385 if (mnt == NULL)
386 dos_unmount_impl(fs);
387 return (EINVAL);
388 }
389 if ((f = calloc(1, sizeof(DOS_FILE))) == NULL) {
390 err = errno;
391 if (mnt == NULL)
392 dos_unmount_impl(fs);
393 return (err);
394 }
395 f->fs = fs;
396 fs->links++;
397 f->de = *de;
398 fd->f_fsdata = f;
399 return (0);
400 }
401
402 /*
403 * Read from file
404 */
405 static int
dos_read(struct open_file * fd,void * buf,size_t nbyte,size_t * resid)406 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
407 {
408 off_t size;
409 uint64_t off;
410 size_t nb;
411 u_int clus, c, cnt, n;
412 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
413 int err = 0;
414
415 /*
416 * as ioget() can be called *a lot*, use twiddle here.
417 * also 4 seems to be good value not to slow loading down too much:
418 * with 270MB file (~540k ioget() calls, twiddle can easily waste
419 * 4-5 sec.
420 */
421 twiddle(4);
422 nb = nbyte;
423 if ((size = fsize(f->fs, &f->de)) == -1)
424 return (EINVAL);
425 if (nb > (n = size - f->offset))
426 nb = n;
427 off = f->offset;
428 if ((clus = stclus(f->fs->fatsz, &f->de)))
429 off &= f->fs->bsize - 1;
430 c = f->c;
431 cnt = nb;
432 while (cnt) {
433 n = 0;
434 if (!c) {
435 if ((c = clus))
436 n = bytblk(f->fs, f->offset);
437 } else if (!off)
438 n++;
439 while (n--) {
440 if ((err = fatget(f->fs, &c)))
441 goto out;
442 if (!okclus(f->fs, c)) {
443 err = EINVAL;
444 goto out;
445 }
446 }
447 if (!clus || (n = f->fs->bsize - off) > cnt)
448 n = cnt;
449 if (c != 0)
450 off += blkoff(f->fs, (uint64_t)c);
451 else
452 off += secbyt(f->fs, f->fs->lsndir);
453 err = ioread(f->fs, off, buf, n);
454 if (err != 0)
455 goto out;
456 f->offset += n;
457 f->c = c;
458 off = 0;
459 buf = (char *)buf + n;
460 cnt -= n;
461 }
462 out:
463 if (resid)
464 *resid = nbyte - nb + cnt;
465 return (err);
466 }
467
468 /*
469 * Reposition within file
470 */
471 static off_t
dos_seek(struct open_file * fd,off_t offset,int whence)472 dos_seek(struct open_file *fd, off_t offset, int whence)
473 {
474 off_t off;
475 u_int size;
476 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
477
478 size = cv4(f->de.size);
479 switch (whence) {
480 case SEEK_SET:
481 off = 0;
482 break;
483 case SEEK_CUR:
484 off = f->offset;
485 break;
486 case SEEK_END:
487 off = size;
488 break;
489 default:
490 errno = EINVAL;
491 return (-1);
492 }
493 off += offset;
494 if (off < 0 || off > size) {
495 errno = EINVAL;
496 return (-1);
497 }
498 f->offset = (u_int)off;
499 f->c = 0;
500 return (off);
501 }
502
503 /*
504 * Close open file
505 */
506 static int
dos_close(struct open_file * fd)507 dos_close(struct open_file *fd)
508 {
509 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
510 DOS_FS *fs = f->fs;
511
512 f->fs->links--;
513 free(f);
514 dos_unmount_impl(fs);
515 return (0);
516 }
517
518 /*
519 * Return some stat information on a file.
520 */
521 static int
dos_stat(struct open_file * fd,struct stat * sb)522 dos_stat(struct open_file *fd, struct stat *sb)
523 {
524 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
525
526 /* only important stuff */
527 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
528 sb->st_nlink = 1;
529 sb->st_uid = 0;
530 sb->st_gid = 0;
531 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
532 return (EINVAL);
533 return (0);
534 }
535
536 static int
dos_checksum(unsigned char * name,unsigned char * ext)537 dos_checksum(unsigned char *name, unsigned char *ext)
538 {
539 int x, i;
540 char buf[11];
541
542 bcopy(name, buf, 8);
543 bcopy(ext, buf+8, 3);
544 x = 0;
545 for (i = 0; i < 11; i++) {
546 x = ((x & 1) << 7) | (x >> 1);
547 x += buf[i];
548 x &= 0xff;
549 }
550 return (x);
551 }
552
553 static int
dos_readdir(struct open_file * fd,struct dirent * d)554 dos_readdir(struct open_file *fd, struct dirent *d)
555 {
556 /* DOS_FILE *f = (DOS_FILE *)fd->f_fsdata; */
557 u_char fn[261];
558 DOS_DIR dd;
559 size_t res;
560 u_int chk, x, xdn;
561 int err;
562
563 x = chk = 0;
564 for (;;) {
565 xdn = x;
566 x = 0;
567 err = dos_read(fd, &dd, sizeof(dd), &res);
568 if (err)
569 return (err);
570 if (res == sizeof(dd))
571 return (ENOENT);
572 if (dd.de.name[0] == 0)
573 return (ENOENT);
574
575 /* Skip deleted entries */
576 if (dd.de.name[0] == 0xe5)
577 continue;
578
579 /* Check if directory entry is volume label */
580 if (dd.de.attr & FA_LABEL) {
581 /*
582 * If volume label set, check if the current entry is
583 * extended entry (FA_XDE) for long file names.
584 */
585 if ((dd.de.attr & FA_MASK) == FA_XDE) {
586 /*
587 * Read through all following extended entries
588 * to get the long file name. 0x40 marks the
589 * last entry containing part of long file name.
590 */
591 if (dd.xde.seq & 0x40)
592 chk = dd.xde.chk;
593 else if (dd.xde.seq != xdn - 1 ||
594 dd.xde.chk != chk)
595 continue;
596 x = dd.xde.seq & ~0x40;
597 if (x < 1 || x > 20) {
598 x = 0;
599 continue;
600 }
601 cp_xdnm(fn, &dd.xde);
602 } else {
603 /* skip only volume label entries */
604 continue;
605 }
606 } else {
607 if (xdn == 1) {
608 x = dos_checksum(dd.de.name, dd.de.ext);
609 if (x == chk)
610 break;
611 } else {
612 cp_sfn(fn, &dd.de);
613 break;
614 }
615 x = 0;
616 }
617 }
618
619 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
620 d->d_reclen = sizeof(*d);
621 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
622 memcpy(d->d_name, fn, sizeof(d->d_name));
623 return (0);
624 }
625
626 /*
627 * Parse DOS boot sector
628 */
629 static int
parsebs(DOS_FS * fs,DOS_BS * bs)630 parsebs(DOS_FS *fs, DOS_BS *bs)
631 {
632 u_int sc, RootDirSectors;
633
634 if (bs->bpb.media < 0xf0)
635 return (EINVAL);
636
637 /* Check supported sector sizes */
638 switch (cv2(bs->bpb.secsiz)) {
639 case 512:
640 case 1024:
641 case 2048:
642 case 4096:
643 fs->sshift = ffs(cv2(bs->bpb.secsiz)) - 1;
644 break;
645
646 default:
647 return (EINVAL);
648 }
649
650 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
651 return (EINVAL);
652 fs->bsize = secbyt(fs, fs->spc);
653 fs->bshift = ffs(fs->bsize) - 1;
654 fs->dshift = ffs(secbyt(fs, 1) / sizeof (DOS_DE)) - 1;
655 fs->dirents = cv2(bs->bpb.dirents);
656 fs->spf = cv2(bs->bpb.spf);
657 fs->lsnfat = cv2(bs->bpb.ressec);
658
659 if (fs->spf != 0) {
660 if (bs->bpb.fats != 2)
661 return (EINVAL);
662 if (fs->dirents == 0)
663 return (EINVAL);
664 } else {
665 fs->spf = cv4(bs->bpb.fstype.f32.lspf);
666 if (fs->spf == 0)
667 return (EINVAL);
668 if (bs->bpb.fats == 0 || bs->bpb.fats > 16)
669 return (EINVAL);
670 fs->rdcl = cv4(bs->bpb.fstype.f32.rdcl);
671 if (fs->rdcl < LOCLUS)
672 return (EINVAL);
673 }
674
675 RootDirSectors = ((fs->dirents * sizeof (DOS_DE)) +
676 (secbyt(fs, 1) - 1)) / secbyt(fs, 1);
677
678 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
679 fs->lsndta = fs->lsndir + RootDirSectors;
680 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
681 return (EINVAL);
682 if (fs->lsndta > sc)
683 return (EINVAL);
684 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
685 return (EINVAL);
686 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
687 sc = (secbyt(fs, fs->spf) << 1) / (fs->fatsz >> 2) - 1;
688 if (fs->xclus > sc)
689 fs->xclus = sc;
690 return (0);
691 }
692
693 /*
694 * Return directory entry from path
695 */
696 static int
namede(DOS_FS * fs,const char * path,DOS_DE ** dep)697 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
698 {
699 char name[256];
700 DOS_DE *de;
701 char *s;
702 size_t n;
703 int err;
704
705 err = 0;
706 de = &fs->root;
707 while (*path) {
708 while (*path == '/')
709 path++;
710 if (*path == '\0')
711 break;
712 if (!(s = strchr(path, '/')))
713 s = strchr(path, 0);
714 if ((n = s - path) > 255)
715 return (ENAMETOOLONG);
716 memcpy(name, path, n);
717 name[n] = 0;
718 path = s;
719 if (!(de->attr & FA_DIR))
720 return (ENOTDIR);
721 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
722 return (err);
723 }
724 *dep = de;
725 return (0);
726 }
727
728 /*
729 * Lookup path segment
730 */
731 static int
lookup(DOS_FS * fs,u_int clus,const char * name,DOS_DE ** dep)732 lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
733 {
734 DOS_DIR *dir;
735 u_char lfn[261];
736 u_char sfn[13];
737 u_int nsec, lsec, xdn, chk, sec, ent, x;
738 int err, ok;
739
740 if (!clus)
741 for (ent = 0; ent < 2; ent++)
742 if (!strcasecmp(name, dotstr[ent])) {
743 *dep = dot + ent;
744 return (0);
745 }
746 if (!clus && fs->fatsz == 32)
747 clus = fs->rdcl;
748 nsec = !clus ? entsec(fs, fs->dirents) : fs->spc;
749 lsec = 0;
750 xdn = chk = 0;
751 dir = (DOS_DIR *)fs->secbuf;
752 for (;;) {
753 if (!clus && !lsec)
754 lsec = fs->lsndir;
755 else if (okclus(fs, clus))
756 lsec = blklsn(fs, clus);
757 else
758 return (EINVAL);
759 for (sec = 0; sec < nsec; sec++) {
760 if ((err = ioget(fs, lsec + sec, dir,
761 secbyt(fs, 1))))
762 return (err);
763 for (ent = 0; ent < depsec(fs); ent++) {
764 if (!*dir[ent].de.name)
765 return (ENOENT);
766 if (*dir[ent].de.name != 0xe5) {
767 if ((dir[ent].de.attr & FA_MASK) ==
768 FA_XDE) {
769 x = dir[ent].xde.seq;
770 if (x & 0x40 || (x + 1 == xdn &&
771 dir[ent].xde.chk == chk)) {
772 if (x & 0x40) {
773 chk = dir[ent].xde.chk;
774 x &= ~0x40;
775 }
776 if (x >= 1 && x <= 20) {
777 cp_xdnm(lfn, &dir[ent].xde);
778 xdn = x;
779 continue;
780 }
781 }
782 } else if (!(dir[ent].de.attr &
783 FA_LABEL)) {
784 if ((ok = xdn == 1)) {
785 x = dos_checksum(
786 dir[ent].de.name,
787 dir[ent].de.ext);
788 ok = chk == x &&
789 !strcasecmp(name,
790 (const char *)lfn);
791 }
792 if (!ok) {
793 cp_sfn(sfn,
794 &dir[ent].de);
795 ok = !strcasecmp(name,
796 (const char *)sfn);
797 }
798 if (ok) {
799 *dep = &dir[ent].de;
800 return (0);
801 }
802 }
803 }
804 xdn = 0;
805 }
806 }
807 if (!clus)
808 break;
809 if ((err = fatget(fs, &clus)))
810 return (err);
811 if (fatend(fs->fatsz, clus))
812 break;
813 }
814 return (ENOENT);
815 }
816
817 /*
818 * Copy name from extended directory entry
819 */
820 static void
cp_xdnm(u_char * lfn,DOS_XDE * xde)821 cp_xdnm(u_char *lfn, DOS_XDE *xde)
822 {
823 static struct {
824 u_int off;
825 u_int dim;
826 } ix[3] = {
827 {offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
828 {offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
829 {offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
830 };
831 u_char *p;
832 u_int n, x, c;
833
834 lfn += 13 * ((xde->seq & ~0x40) - 1);
835 for (n = 0; n < 3; n++)
836 for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
837 p += 2, x--) {
838 if ((c = cv2(p)) && (c < 32 || c > 127))
839 c = '?';
840 if (!(*lfn++ = c))
841 return;
842 }
843 if (xde->seq & 0x40)
844 *lfn = 0;
845 }
846
847 /*
848 * Copy short filename
849 */
850 static void
cp_sfn(u_char * sfn,DOS_DE * de)851 cp_sfn(u_char *sfn, DOS_DE *de)
852 {
853 u_char *p;
854 int j, i;
855
856 p = sfn;
857 if (*de->name != ' ') {
858 for (j = 7; de->name[j] == ' '; j--)
859 ;
860 for (i = 0; i <= j; i++)
861 *p++ = de->name[i];
862 if (*de->ext != ' ') {
863 *p++ = '.';
864 for (j = 2; de->ext[j] == ' '; j--)
865 ;
866 for (i = 0; i <= j; i++)
867 *p++ = de->ext[i];
868 }
869 }
870 *p = 0;
871 if (*sfn == 5)
872 *sfn = 0xe5;
873 }
874
875 /*
876 * Return size of file in bytes
877 */
878 static off_t
fsize(DOS_FS * fs,DOS_DE * de)879 fsize(DOS_FS *fs, DOS_DE *de)
880 {
881 u_long size;
882 u_int c;
883 int n;
884
885 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
886 if (!(c = stclus(fs->fatsz, de))) {
887 size = fs->dirents * sizeof(DOS_DE);
888 } else {
889 if ((n = fatcnt(fs, c)) == -1)
890 return (n);
891 size = blkbyt(fs, n);
892 }
893 }
894 return (size);
895 }
896
897 /*
898 * Count number of clusters in chain
899 */
900 static int
fatcnt(DOS_FS * fs,u_int c)901 fatcnt(DOS_FS *fs, u_int c)
902 {
903 int n;
904
905 for (n = 0; okclus(fs, c); n++)
906 if (fatget(fs, &c))
907 return (-1);
908 return (fatend(fs->fatsz, c) ? n : -1);
909 }
910
911 /*
912 * Get next cluster in cluster chain. Use in core fat cache unless
913 * the number of current 128K block in FAT has changed.
914 */
915 static int
fatget(DOS_FS * fs,u_int * c)916 fatget(DOS_FS *fs, u_int *c)
917 {
918 u_int val_in, val_out, offset, blknum, nbyte;
919 const u_char *p_entry;
920 int err;
921
922 /* check input value to prevent overflow in fatoff() */
923 val_in = *c;
924 if (val_in & 0xf0000000)
925 return (EINVAL);
926
927 /* ensure that current 128K FAT block is cached */
928 offset = fatoff(fs->fatsz, val_in);
929 nbyte = fs->fatsz != 32 ? 2 : 4;
930 if (offset + nbyte > secbyt(fs, fs->spf))
931 return (EINVAL);
932 blknum = offset / FATBLKSZ;
933 offset %= FATBLKSZ;
934 if (offset + nbyte > FATBLKSZ)
935 return (EINVAL);
936 if (blknum != fs->fatbuf_blknum) {
937 err = dos_read_fatblk(fs, blknum);
938 if (err != 0)
939 return (err);
940 }
941 p_entry = fs->fatbuf + offset;
942
943 /* extract cluster number from FAT entry */
944 switch (fs->fatsz) {
945 case 32:
946 val_out = cv4(p_entry);
947 val_out &= 0x0fffffff;
948 break;
949 case 16:
950 val_out = cv2(p_entry);
951 break;
952 case 12:
953 val_out = cv2(p_entry);
954 if (val_in & 1)
955 val_out >>= 4;
956 else
957 val_out &= 0xfff;
958 break;
959 default:
960 return (EINVAL);
961 }
962 *c = val_out;
963 return (0);
964 }
965
966 /*
967 * Is cluster an end-of-chain marker?
968 */
969 static int
fatend(u_int sz,u_int c)970 fatend(u_int sz, u_int c)
971 {
972 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
973 }
974
975 /*
976 * Offset-based I/O primitive
977 */
978 static int
ioread(DOS_FS * fs,uint64_t offset,void * buf,size_t nbyte)979 ioread(DOS_FS *fs, uint64_t offset, void *buf, size_t nbyte)
980 {
981 char *s;
982 size_t n, secsiz;
983 int err;
984 uint64_t off;
985
986 secsiz = secbyt(fs, 1);
987 s = buf;
988 if ((off = offset & (secsiz - 1))) {
989 offset -= off;
990 if ((n = secsiz - off) > nbyte)
991 n = nbyte;
992 err = ioget(fs, bytsec(fs, offset), fs->secbuf, secsiz);
993 if (err != 0)
994 return (err);
995 memcpy(s, fs->secbuf + off, n);
996 offset += secsiz;
997 s += n;
998 nbyte -= n;
999 }
1000 n = nbyte & (secsiz - 1);
1001 if (nbyte -= n) {
1002 if ((err = ioget(fs, bytsec(fs, offset), s, nbyte)))
1003 return (err);
1004 offset += nbyte;
1005 s += nbyte;
1006 }
1007 if (n != 0) {
1008 err = ioget(fs, bytsec(fs, offset), fs->secbuf, secsiz);
1009 if (err != 0)
1010 return (err);
1011 memcpy(s, fs->secbuf, n);
1012 }
1013 return (0);
1014 }
1015
1016 /*
1017 * Sector-based I/O primitive. Note, since strategy functions are operating
1018 * in terms of 512B sectors, we need to do necessary conversion here.
1019 */
1020 static int
ioget(DOS_FS * fs,daddr_t lsec,void * buf,size_t size)1021 ioget(DOS_FS *fs, daddr_t lsec, void *buf, size_t size)
1022 {
1023 size_t rsize;
1024 int rv;
1025 struct open_file *fd = fs->fd;
1026
1027 /* Make sure we get full read or error. */
1028 rsize = 0;
1029 /* convert native sector number to 512B sector number. */
1030 lsec = secbyt(fs, lsec) >> 9;
1031 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
1032 size, buf, &rsize);
1033 if ((rv == 0) && (size != rsize))
1034 rv = EIO;
1035 return (rv);
1036 }
1037