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 <string.h>
38 #include <stddef.h>
39
40 #include "stand.h"
41
42 #include "dosfs.h"
43
44
45 static int dos_open(const char *, struct open_file *);
46 static int dos_close(struct open_file *);
47 static int dos_read(struct open_file *, void *, size_t, size_t *);
48 static off_t dos_seek(struct open_file *, off_t offset, int);
49 static int dos_stat(struct open_file *, struct stat *);
50 static int dos_readdir(struct open_file *, struct dirent *);
51
52 struct fs_ops dosfs_fsops = {
53 .fs_name = "dosfs",
54 .fo_open = dos_open,
55 .fo_close = dos_close,
56 .fo_read = dos_read,
57 .fo_write = null_write,
58 .fo_seek = dos_seek,
59 .fo_stat = dos_stat,
60 .fo_readdir = dos_readdir
61 };
62
63 #define SECSIZ 512 /* sector size */
64 #define SSHIFT 9 /* SECSIZ shift */
65 #define DEPSEC 16 /* directory entries per sector */
66 #define DSHIFT 4 /* DEPSEC shift */
67 #define LOCLUS 2 /* lowest cluster number */
68 #define FATBLKSZ 0x20000 /* size of block in the FAT cache buffer */
69
70 /* DOS "BIOS Parameter Block" */
71 typedef struct {
72 uchar_t secsiz[2]; /* sector size */
73 uchar_t spc; /* sectors per cluster */
74 uchar_t ressec[2]; /* reserved sectors */
75 uchar_t fats; /* FATs */
76 uchar_t dirents[2]; /* root directory entries */
77 uchar_t secs[2]; /* total sectors */
78 uchar_t media; /* media descriptor */
79 uchar_t spf[2]; /* sectors per FAT */
80 uchar_t spt[2]; /* sectors per track */
81 uchar_t heads[2]; /* drive heads */
82 uchar_t hidsec[4]; /* hidden sectors */
83 uchar_t lsecs[4]; /* huge sectors */
84 uchar_t lspf[4]; /* huge sectors per FAT */
85 uchar_t xflg[2]; /* flags */
86 uchar_t vers[2]; /* filesystem version */
87 uchar_t rdcl[4]; /* root directory start cluster */
88 uchar_t infs[2]; /* filesystem info sector */
89 uchar_t bkbs[2]; /* backup boot sector */
90 } DOS_BPB;
91
92 /* Initial portion of DOS boot sector */
93 typedef struct {
94 uchar_t jmp[3]; /* usually 80x86 'jmp' opcode */
95 uchar_t oem[8]; /* OEM name and version */
96 DOS_BPB bpb; /* BPB */
97 } DOS_BS;
98
99 /* Supply missing "." and ".." root directory entries */
100 static const char *const dotstr[2] = {".", ".."};
101 static DOS_DE dot[2] = {
102 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
103 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
104 {".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
105 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
106 };
107
108 /* The usual conversion macros to avoid multiplication and division */
109 #define bytsec(n) ((n) >> SSHIFT)
110 #define secbyt(s) ((s) << SSHIFT)
111 #define entsec(e) ((e) >> DSHIFT)
112 #define bytblk(fs, n) ((n) >> (fs)->bshift)
113 #define blkbyt(fs, b) ((b) << (fs)->bshift)
114 #define secblk(fs, s) ((s) >> ((fs)->bshift - SSHIFT))
115 #define blksec(fs, b) ((b) << ((fs)->bshift - SSHIFT))
116
117 /* Convert cluster number to offset within filesystem */
118 #define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
119
120 /* Convert cluster number to logical sector number */
121 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
122
123 /* Convert cluster number to offset within FAT */
124 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
125 (sz) == 16 ? (c) << 1 : \
126 (c) << 2)
127
128 /* Does cluster number reference a valid data cluster? */
129 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
130
131 /* Get start cluster from directory entry */
132 #define stclus(sz, de) ((sz) != 32 ? (uint_t)cv2((de)->clus) : \
133 ((uint_t)cv2((de)->dex.h_clus) << 16) | \
134 cv2((de)->clus))
135
136 static int parsebs(DOS_FS *, DOS_BS *);
137 static int namede(DOS_FS *, const char *, DOS_DE **);
138 static int lookup(DOS_FS *, uint_t, const char *, DOS_DE **);
139 static void cp_xdnm(uchar_t *, DOS_XDE *);
140 static void cp_sfn(uchar_t *, DOS_DE *);
141 static off_t fsize(DOS_FS *, DOS_DE *);
142 static int fatcnt(DOS_FS *, uint_t);
143 static int fatget(DOS_FS *, uint_t *);
144 static int fatend(uint_t, uint_t);
145 static int ioread(DOS_FS *, uint64_t, void *, size_t);
146 static int ioget(struct open_file *, daddr_t, void *, size_t);
147
148 static int
dos_read_fatblk(DOS_FS * fs,struct open_file * fd,uint_t blknum)149 dos_read_fatblk(DOS_FS *fs, struct open_file *fd, uint_t blknum)
150 {
151 int err;
152 size_t io_size;
153 daddr_t offset_in_fat, max_offset_in_fat;
154
155 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
156 max_offset_in_fat = secbyt((daddr_t)fs->spf);
157 io_size = FATBLKSZ;
158 if (offset_in_fat > max_offset_in_fat)
159 offset_in_fat = max_offset_in_fat;
160 if (offset_in_fat + io_size > max_offset_in_fat)
161 io_size = ((size_t)(max_offset_in_fat - offset_in_fat));
162
163 if (io_size != 0) {
164 err = ioget(fd, fs->lsnfat + bytsec(offset_in_fat),
165 fs->fatbuf, io_size);
166 if (err != 0) {
167 fs->fatbuf_blknum = ((uint_t)(-1));
168 return (err);
169 }
170 }
171
172 if (io_size < FATBLKSZ)
173 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
174
175 fs->fatbuf_blknum = blknum;
176 return (0);
177 }
178
179 /*
180 * Mount DOS filesystem
181 */
182 static int
dos_mount(DOS_FS * fs,struct open_file * fd)183 dos_mount(DOS_FS *fs, struct open_file *fd)
184 {
185 int err;
186 uchar_t *buf;
187
188 bzero(fs, sizeof (DOS_FS));
189 fs->fd = fd;
190
191 if ((buf = malloc(secbyt(1))) == NULL)
192 return (errno);
193 if ((err = ioget(fs->fd, 0, buf, secbyt(1))) ||
194 (err = parsebs(fs, (DOS_BS *)buf))) {
195 free(buf);
196 return (err);
197 }
198 free(buf);
199
200 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL)
201 return (errno);
202 err = dos_read_fatblk(fs, fd, 0);
203 if (err != 0) {
204 free(fs->fatbuf);
205 return (err);
206 }
207
208 fs->root = dot[0];
209 fs->root.name[0] = ' ';
210 if (fs->fatsz == 32) {
211 fs->root.clus[0] = fs->rdcl & 0xff;
212 fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
213 fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
214 fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
215 }
216 return (0);
217 }
218
219 /*
220 * Unmount mounted filesystem
221 */
222 static int
dos_unmount(DOS_FS * fs)223 dos_unmount(DOS_FS *fs)
224 {
225 if (fs->links)
226 return (EBUSY);
227 free(fs->fatbuf);
228 free(fs);
229 return (0);
230 }
231
232 /*
233 * Open DOS file
234 */
235 static int
dos_open(const char * path,struct open_file * fd)236 dos_open(const char *path, struct open_file *fd)
237 {
238 DOS_DE *de;
239 DOS_FILE *f;
240 DOS_FS *fs;
241 uint_t size, clus;
242 int err;
243
244 /* Allocate mount structure, associate with open */
245 if ((fs = malloc(sizeof (DOS_FS))) == NULL)
246 return (errno);
247 if ((err = dos_mount(fs, fd))) {
248 free(fs);
249 return (err);
250 }
251
252 if ((err = namede(fs, path, &de))) {
253 dos_unmount(fs);
254 return (err);
255 }
256
257 clus = stclus(fs->fatsz, de);
258 size = cv4(de->size);
259
260 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
261 ((de->attr & FA_DIR) && size) ||
262 (clus && !okclus(fs, clus))) {
263 dos_unmount(fs);
264 return (EINVAL);
265 }
266 if ((f = malloc(sizeof (DOS_FILE))) == NULL) {
267 err = errno;
268 dos_unmount(fs);
269 return (err);
270 }
271 bzero(f, sizeof (DOS_FILE));
272 f->fs = fs;
273 fs->links++;
274 f->de = *de;
275 fd->f_fsdata = f;
276 return (0);
277 }
278
279 /*
280 * Read from file
281 */
282 static int
dos_read(struct open_file * fd,void * buf,size_t nbyte,size_t * resid)283 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
284 {
285 off_t size;
286 uint64_t off;
287 size_t nb;
288 uint_t clus, c, cnt, n;
289 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
290 int err = 0;
291
292 /*
293 * as ioget() can be called *a lot*, use twiddle here.
294 * also 4 seems to be good value not to slow loading down too much:
295 * with 270MB file (~540k ioget() calls, twiddle can easily waste
296 * 4-5 sec.
297 */
298 twiddle(4);
299 nb = nbyte;
300 if ((size = fsize(f->fs, &f->de)) == -1)
301 return (EINVAL);
302 if (nb > (n = size - f->offset))
303 nb = n;
304 off = f->offset;
305 if ((clus = stclus(f->fs->fatsz, &f->de)))
306 off &= f->fs->bsize - 1;
307 c = f->c;
308 cnt = nb;
309 while (cnt) {
310 n = 0;
311 if (!c) {
312 if ((c = clus))
313 n = bytblk(f->fs, f->offset);
314 } else if (!off)
315 n++;
316 while (n--) {
317 if ((err = fatget(f->fs, &c)))
318 goto out;
319 if (!okclus(f->fs, c)) {
320 err = EINVAL;
321 goto out;
322 }
323 }
324 if (!clus || (n = f->fs->bsize - off) > cnt)
325 n = cnt;
326 if (c != 0)
327 off += blkoff(f->fs, (uint64_t)c);
328 else
329 off += secbyt(f->fs->lsndir);
330 err = ioread(f->fs, off, buf, n);
331 if (err != 0)
332 goto out;
333 f->offset += n;
334 f->c = c;
335 off = 0;
336 buf = (char *)buf + n;
337 cnt -= n;
338 }
339 out:
340 if (resid)
341 *resid = nbyte - nb + cnt;
342 return (err);
343 }
344
345 /*
346 * Reposition within file
347 */
348 static off_t
dos_seek(struct open_file * fd,off_t offset,int whence)349 dos_seek(struct open_file *fd, off_t offset, int whence)
350 {
351 off_t off;
352 uint_t size;
353 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
354
355 size = cv4(f->de.size);
356 switch (whence) {
357 case SEEK_SET:
358 off = 0;
359 break;
360 case SEEK_CUR:
361 off = f->offset;
362 break;
363 case SEEK_END:
364 off = size;
365 break;
366 default:
367 errno = EINVAL;
368 return (-1);
369 }
370 off += offset;
371 if (off < 0 || off > size) {
372 errno = EINVAL;
373 return (-1);
374 }
375 f->offset = (uint_t)off;
376 f->c = 0;
377 return (off);
378 }
379
380 /*
381 * Close open file
382 */
383 static int
dos_close(struct open_file * fd)384 dos_close(struct open_file *fd)
385 {
386 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
387 DOS_FS *fs = f->fs;
388
389 f->fs->links--;
390 free(f);
391 dos_unmount(fs);
392 return (0);
393 }
394
395 /*
396 * Return some stat information on a file.
397 */
398 static int
dos_stat(struct open_file * fd,struct stat * sb)399 dos_stat(struct open_file *fd, struct stat *sb)
400 {
401 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
402
403 /* only important stuff */
404 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
405 sb->st_nlink = 1;
406 sb->st_uid = 0;
407 sb->st_gid = 0;
408 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
409 return (EINVAL);
410 return (0);
411 }
412
413 static int
dos_checksum(unsigned char * name,unsigned char * ext)414 dos_checksum(unsigned char *name, unsigned char *ext)
415 {
416 int x, i;
417 char buf[11];
418
419 bcopy(name, buf, 8);
420 bcopy(ext, buf+8, 3);
421 x = 0;
422 for (i = 0; i < 11; i++) {
423 x = ((x & 1) << 7) | (x >> 1);
424 x += buf[i];
425 x &= 0xff;
426 }
427 return (x);
428 }
429
430 static int
dos_readdir(struct open_file * fd,struct dirent * d)431 dos_readdir(struct open_file *fd, struct dirent *d)
432 {
433 uchar_t fn[261];
434 DOS_DIR dd;
435 size_t res;
436 uint_t chk, x, xdn;
437 int err;
438
439 x = chk = 0;
440 while (1) {
441 xdn = x;
442 x = 0;
443 err = dos_read(fd, &dd, sizeof (dd), &res);
444 if (err)
445 return (err);
446 if (res == sizeof (dd))
447 return (ENOENT);
448 if (dd.de.name[0] == 0)
449 return (ENOENT);
450
451 /* Skip deleted entries */
452 if (dd.de.name[0] == 0xe5)
453 continue;
454
455 /* Check if directory entry is volume label */
456 if (dd.de.attr & FA_LABEL) {
457 /*
458 * If volume label set, check if the current entry is
459 * extended entry (FA_XDE) for long file names.
460 */
461 if ((dd.de.attr & FA_MASK) == FA_XDE) {
462 /*
463 * Read through all following extended entries
464 * to get the long file name. 0x40 marks the
465 * last entry containing part of long file name.
466 */
467 if (dd.xde.seq & 0x40)
468 chk = dd.xde.chk;
469 else if (dd.xde.seq != xdn - 1 ||
470 dd.xde.chk != chk)
471 continue;
472 x = dd.xde.seq & ~0x40;
473 if (x < 1 || x > 20) {
474 x = 0;
475 continue;
476 }
477 cp_xdnm(fn, &dd.xde);
478 } else {
479 /* skip only volume label entries */
480 continue;
481 }
482 } else {
483 if (xdn == 1) {
484 x = dos_checksum(dd.de.name, dd.de.ext);
485 if (x == chk)
486 break;
487 } else {
488 cp_sfn(fn, &dd.de);
489 break;
490 }
491 x = 0;
492 }
493 }
494
495 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
496 d->d_reclen = sizeof (*d);
497 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
498 memcpy(d->d_name, fn, sizeof (d->d_name));
499 return (0);
500 }
501
502 /*
503 * Parse DOS boot sector
504 */
505 static int
parsebs(DOS_FS * fs,DOS_BS * bs)506 parsebs(DOS_FS *fs, DOS_BS *bs)
507 {
508 uint_t sc;
509
510 if ((bs->jmp[0] != 0x69 &&
511 bs->jmp[0] != 0xe9 &&
512 (bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
513 bs->bpb.media < 0xf0)
514 return (EINVAL);
515 if (cv2(bs->bpb.secsiz) != SECSIZ)
516 return (EINVAL);
517 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
518 return (EINVAL);
519 fs->bsize = secbyt(fs->spc);
520 fs->bshift = ffs(fs->bsize) - 1;
521 if ((fs->spf = cv2(bs->bpb.spf))) {
522 if (bs->bpb.fats != 2)
523 return (EINVAL);
524 if (!(fs->dirents = cv2(bs->bpb.dirents)))
525 return (EINVAL);
526 } else {
527 if (!(fs->spf = cv4(bs->bpb.lspf)))
528 return (EINVAL);
529 if (!bs->bpb.fats || bs->bpb.fats > 16)
530 return (EINVAL);
531 if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
532 return (EINVAL);
533 }
534 if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
535 return (EINVAL);
536 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
537 fs->lsndta = fs->lsndir + entsec(fs->dirents);
538 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
539 return (EINVAL);
540 if (fs->lsndta > sc)
541 return (EINVAL);
542 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
543 return (EINVAL);
544 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
545 sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
546 if (fs->xclus > sc)
547 fs->xclus = sc;
548 return (0);
549 }
550
551 /*
552 * Return directory entry from path
553 */
554 static int
namede(DOS_FS * fs,const char * path,DOS_DE ** dep)555 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
556 {
557 char name[256];
558 DOS_DE *de;
559 char *s;
560 size_t n;
561 int err;
562
563 err = 0;
564 de = &fs->root;
565 while (*path) {
566 while (*path == '/')
567 path++;
568 if (*path == '\0')
569 break;
570 if (!(s = strchr(path, '/')))
571 s = strchr(path, 0);
572 if ((n = s - path) > 255)
573 return (ENAMETOOLONG);
574 memcpy(name, path, n);
575 name[n] = 0;
576 path = s;
577 if (!(de->attr & FA_DIR))
578 return (ENOTDIR);
579 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
580 return (err);
581 }
582 *dep = de;
583 return (0);
584 }
585
586 /*
587 * Lookup path segment
588 */
589 static int
lookup(DOS_FS * fs,uint_t clus,const char * name,DOS_DE ** dep)590 lookup(DOS_FS *fs, uint_t clus, const char *name, DOS_DE **dep)
591 {
592 static DOS_DIR dir[DEPSEC];
593 uchar_t lfn[261];
594 uchar_t sfn[13];
595 uint_t nsec, lsec, xdn, chk, sec, ent, x;
596 int err, ok;
597
598 if (!clus)
599 for (ent = 0; ent < 2; ent++)
600 if (!strcasecmp(name, dotstr[ent])) {
601 *dep = dot + ent;
602 return (0);
603 }
604 if (!clus && fs->fatsz == 32)
605 clus = fs->rdcl;
606 nsec = !clus ? entsec(fs->dirents) : fs->spc;
607 lsec = 0;
608 xdn = chk = 0;
609 for (;;) {
610 if (!clus && !lsec)
611 lsec = fs->lsndir;
612 else if (okclus(fs, clus))
613 lsec = blklsn(fs, clus);
614 else
615 return (EINVAL);
616
617 for (sec = 0; sec < nsec; sec++) {
618 if ((err = ioget(fs->fd, lsec + sec, dir, secbyt(1))))
619 return (err);
620 for (ent = 0; ent < DEPSEC; ent++) {
621 if (dir[ent].de.name[0] == 0)
622 return (ENOENT);
623 if (dir[ent].de.name[0] == 0xe5) {
624 xdn = 0;
625 continue;
626 }
627 if ((dir[ent].de.attr & FA_MASK) == FA_XDE) {
628 x = dir[ent].xde.seq;
629 if (x & 0x40 ||
630 (x + 1 == xdn &&
631 dir[ent].xde.chk == chk)) {
632 if (x & 0x40) {
633 chk = dir[ent].xde.chk;
634 x &= ~0x40;
635 }
636 if (x >= 1 && x <= 20) {
637 cp_xdnm(lfn,
638 &dir[ent].xde);
639 xdn = x;
640 continue;
641 }
642 }
643 } else if (!(dir[ent].de.attr & FA_LABEL)) {
644 if ((ok = xdn == 1)) {
645 x = dos_checksum(
646 dir[ent].de.name,
647 dir[ent].de.ext);
648 ok = chk == x &&
649 !strcasecmp(name,
650 (const char *)lfn);
651 }
652 if (!ok) {
653 cp_sfn(sfn, &dir[ent].de);
654 ok = !strcasecmp(name,
655 (const char *)sfn);
656 }
657 if (ok) {
658 *dep = &dir[ent].de;
659 return (0);
660 }
661 }
662 xdn = 0;
663 }
664 }
665 if (!clus)
666 break;
667 if ((err = fatget(fs, &clus)))
668 return (err);
669 if (fatend(fs->fatsz, clus))
670 break;
671 }
672 return (ENOENT);
673 }
674
675 /*
676 * Copy name from extended directory entry
677 */
678 static void
cp_xdnm(uchar_t * lfn,DOS_XDE * xde)679 cp_xdnm(uchar_t *lfn, DOS_XDE *xde)
680 {
681 static struct {
682 uint_t off;
683 uint_t dim;
684 } ix[3] = {
685 { offsetof(DOS_XDE, name1), sizeof (xde->name1) / 2},
686 { offsetof(DOS_XDE, name2), sizeof (xde->name2) / 2},
687 { offsetof(DOS_XDE, name3), sizeof (xde->name3) / 2}
688 };
689 uchar_t *p;
690 uint_t n, x, c;
691
692 lfn += 13 * ((xde->seq & ~0x40) - 1);
693 for (n = 0; n < 3; n++)
694 for (p = (uchar_t *)xde + ix[n].off, x = ix[n].dim; x;
695 p += 2, x--) {
696 if ((c = cv2(p)) && (c < 32 || c > 127))
697 c = '?';
698 if (!(*lfn++ = c))
699 return;
700 }
701 if (xde->seq & 0x40)
702 *lfn = 0;
703 }
704
705 /*
706 * Copy short filename
707 */
708 static void
cp_sfn(uchar_t * sfn,DOS_DE * de)709 cp_sfn(uchar_t *sfn, DOS_DE *de)
710 {
711 uchar_t *p;
712 int j, i;
713
714 p = sfn;
715 if (*de->name != ' ') {
716 for (j = 7; de->name[j] == ' '; j--)
717 ;
718 for (i = 0; i <= j; i++)
719 *p++ = de->name[i];
720 if (*de->ext != ' ') {
721 *p++ = '.';
722 for (j = 2; de->ext[j] == ' '; j--)
723 ;
724 for (i = 0; i <= j; i++)
725 *p++ = de->ext[i];
726 }
727 }
728 *p = '\0';
729 if (*sfn == 5)
730 *sfn = 0xe5;
731 }
732
733 /*
734 * Return size of file in bytes
735 */
736 static off_t
fsize(DOS_FS * fs,DOS_DE * de)737 fsize(DOS_FS *fs, DOS_DE *de)
738 {
739 ulong_t size;
740 uint_t c;
741 int n;
742
743 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
744 if (!(c = stclus(fs->fatsz, de)))
745 size = fs->dirents * sizeof (DOS_DE);
746 else {
747 if ((n = fatcnt(fs, c)) == -1)
748 return (n);
749 size = blkbyt(fs, n);
750 }
751 }
752 return (size);
753 }
754
755 /*
756 * Count number of clusters in chain
757 */
758 static int
fatcnt(DOS_FS * fs,uint_t c)759 fatcnt(DOS_FS *fs, uint_t c)
760 {
761 int n;
762
763 for (n = 0; okclus(fs, c); n++)
764 if (fatget(fs, &c))
765 return (-1);
766 return (fatend(fs->fatsz, c) ? n : -1);
767 }
768
769 /*
770 * Get next cluster in cluster chain. Use in core fat cache unless
771 * the number of current 128K block in FAT has changed.
772 */
773 static int
fatget(DOS_FS * fs,uint_t * c)774 fatget(DOS_FS *fs, uint_t *c)
775 {
776 uint_t val_in, val_out, offset, blknum, nbyte;
777 const uchar_t *p_entry;
778 int err;
779
780 /* check input value to prevent overflow in fatoff() */
781 val_in = *c;
782 if (val_in & 0xf0000000)
783 return (EINVAL);
784
785 /* ensure that current 128K FAT block is cached */
786 offset = fatoff(fs->fatsz, val_in);
787 nbyte = fs->fatsz != 32 ? 2 : 4;
788 if (offset + nbyte > secbyt(fs->spf))
789 return (EINVAL);
790 blknum = offset / FATBLKSZ;
791 offset %= FATBLKSZ;
792 if (offset + nbyte > FATBLKSZ)
793 return (EINVAL);
794 if (blknum != fs->fatbuf_blknum) {
795 err = dos_read_fatblk(fs, fs->fd, blknum);
796 if (err != 0)
797 return (err);
798 }
799 p_entry = fs->fatbuf + offset;
800
801 /* extract cluster number from FAT entry */
802 switch (fs->fatsz) {
803 case 32:
804 val_out = cv4(p_entry);
805 val_out &= 0x0fffffff;
806 break;
807 case 16:
808 val_out = cv2(p_entry);
809 break;
810 case 12:
811 val_out = cv2(p_entry);
812 if (val_in & 1)
813 val_out >>= 4;
814 else
815 val_out &= 0xfff;
816 break;
817 default:
818 return (EINVAL);
819 }
820 *c = val_out;
821 return (0);
822 }
823
824 /*
825 * Is cluster an end-of-chain marker?
826 */
827 static int
fatend(uint_t sz,uint_t c)828 fatend(uint_t sz, uint_t c)
829 {
830 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
831 }
832
833 /*
834 * Offset-based I/O primitive
835 */
836 static int
ioread(DOS_FS * fs,uint64_t offset,void * buf,size_t nbyte)837 ioread(DOS_FS *fs, uint64_t offset, void *buf, size_t nbyte)
838 {
839 char *s;
840 size_t n;
841 int err;
842 uint64_t off;
843 uchar_t local_buf[SECSIZ];
844
845 s = buf;
846 if ((off = offset & (SECSIZ - 1))) {
847 offset -= off;
848 if ((n = SECSIZ - off) > nbyte)
849 n = nbyte;
850 err = ioget(fs->fd, bytsec(offset), local_buf,
851 sizeof (local_buf));
852 if (err != 0)
853 return (err);
854 memcpy(s, local_buf + off, n);
855 offset += SECSIZ;
856 s += n;
857 nbyte -= n;
858 }
859 n = nbyte & (SECSIZ - 1);
860 if (nbyte -= n) {
861 if ((err = ioget(fs->fd, bytsec(offset), s, nbyte)))
862 return (err);
863 offset += nbyte;
864 s += nbyte;
865 }
866 if (n != 0) {
867 err = ioget(fs->fd, bytsec(offset), local_buf,
868 sizeof (local_buf));
869 if (err != 0)
870 return (err);
871 memcpy(s, local_buf, n);
872 }
873 return (0);
874 }
875
876 /*
877 * Sector-based I/O primitive
878 */
879 static int
ioget(struct open_file * fd,daddr_t lsec,void * buf,size_t size)880 ioget(struct open_file *fd, daddr_t lsec, void *buf, size_t size)
881 {
882 size_t rsize;
883 int rv;
884
885 /* Make sure we get full read or error. */
886 rsize = 0;
887 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
888 size, buf, &rsize);
889 if ((rv == 0) && (size != rsize))
890 rv = EIO;
891 return (rv);
892 }
893