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