1 /*
2 * Copyright (c) 1996, 1998 Robert Nordier
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
21 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
23 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
25 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29
30 /*
31 * Readonly filesystem for Microsoft FAT12/FAT16/FAT32 filesystems,
32 * also supports VFAT.
33 */
34
35 #include <sys/types.h>
36 #include <string.h>
37 #include <stddef.h>
38
39 #include "stand.h"
40
41 #include "dosfs.h"
42
43
44 static int dos_open(const char *, struct open_file *);
45 static int dos_close(struct open_file *);
46 static int dos_read(struct open_file *, void *, size_t, size_t *);
47 static off_t dos_seek(struct open_file *, off_t offset, int);
48 static int dos_stat(struct open_file *, struct stat *);
49 static int dos_readdir(struct open_file *, struct dirent *);
50
51 struct fs_ops dosfs_fsops = {
52 .fs_name = "dosfs",
53 .fo_open = dos_open,
54 .fo_close = dos_close,
55 .fo_read = dos_read,
56 .fo_write = null_write,
57 .fo_seek = dos_seek,
58 .fo_stat = dos_stat,
59 .fo_readdir = dos_readdir
60 };
61
62 #define SECSIZ 512 /* sector size */
63 #define SSHIFT 9 /* SECSIZ shift */
64 #define DEPSEC 16 /* directory entries per sector */
65 #define DSHIFT 4 /* DEPSEC shift */
66 #define LOCLUS 2 /* lowest cluster number */
67 #define FATBLKSZ 0x20000 /* size of block in the FAT cache buffer */
68
69 /* DOS "BIOS Parameter Block" */
70 typedef struct {
71 uchar_t secsiz[2]; /* sector size */
72 uchar_t spc; /* sectors per cluster */
73 uchar_t ressec[2]; /* reserved sectors */
74 uchar_t fats; /* FATs */
75 uchar_t dirents[2]; /* root directory entries */
76 uchar_t secs[2]; /* total sectors */
77 uchar_t media; /* media descriptor */
78 uchar_t spf[2]; /* sectors per FAT */
79 uchar_t spt[2]; /* sectors per track */
80 uchar_t heads[2]; /* drive heads */
81 uchar_t hidsec[4]; /* hidden sectors */
82 uchar_t lsecs[4]; /* huge sectors */
83 uchar_t lspf[4]; /* huge sectors per FAT */
84 uchar_t xflg[2]; /* flags */
85 uchar_t vers[2]; /* filesystem version */
86 uchar_t rdcl[4]; /* root directory start cluster */
87 uchar_t infs[2]; /* filesystem info sector */
88 uchar_t bkbs[2]; /* backup boot sector */
89 } DOS_BPB;
90
91 /* Initial portion of DOS boot sector */
92 typedef struct {
93 uchar_t jmp[3]; /* usually 80x86 'jmp' opcode */
94 uchar_t oem[8]; /* OEM name and version */
95 DOS_BPB bpb; /* BPB */
96 } DOS_BS;
97
98 /* Supply missing "." and ".." root directory entries */
99 static const char *const dotstr[2] = {".", ".."};
100 static DOS_DE dot[2] = {
101 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
102 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
103 {".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
104 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
105 };
106
107 /* The usual conversion macros to avoid multiplication and division */
108 #define bytsec(n) ((n) >> SSHIFT)
109 #define secbyt(s) ((s) << SSHIFT)
110 #define entsec(e) ((e) >> DSHIFT)
111 #define bytblk(fs, n) ((n) >> (fs)->bshift)
112 #define blkbyt(fs, b) ((b) << (fs)->bshift)
113 #define secblk(fs, s) ((s) >> ((fs)->bshift - SSHIFT))
114 #define blksec(fs, b) ((b) << ((fs)->bshift - SSHIFT))
115
116 /* Convert cluster number to offset within filesystem */
117 #define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
118
119 /* Convert cluster number to logical sector number */
120 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
121
122 /* Convert cluster number to offset within FAT */
123 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
124 (sz) == 16 ? (c) << 1 : \
125 (c) << 2)
126
127 /* Does cluster number reference a valid data cluster? */
128 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
129
130 /* Get start cluster from directory entry */
131 #define stclus(sz, de) ((sz) != 32 ? cv2((de)->clus) : \
132 ((uint_t)cv2((de)->dex.h_clus) << 16) | \
133 cv2((de)->clus))
134
135 static int parsebs(DOS_FS *, DOS_BS *);
136 static int namede(DOS_FS *, const char *, DOS_DE **);
137 static int lookup(DOS_FS *, uint_t, const char *, DOS_DE **);
138 static void cp_xdnm(uchar_t *, DOS_XDE *);
139 static void cp_sfn(uchar_t *, DOS_DE *);
140 static off_t fsize(DOS_FS *, DOS_DE *);
141 static int fatcnt(DOS_FS *, uint_t);
142 static int fatget(DOS_FS *, uint_t *);
143 static int fatend(uint_t, uint_t);
144 static int ioread(DOS_FS *, uint_t, void *, size_t);
145 static int ioget(struct open_file *, daddr_t, void *, size_t);
146
147 static int
dos_read_fatblk(DOS_FS * fs,struct open_file * fd,uint_t blknum)148 dos_read_fatblk(DOS_FS *fs, struct open_file *fd, uint_t blknum)
149 {
150 int err;
151 size_t io_size;
152 daddr_t offset_in_fat, max_offset_in_fat;
153
154 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
155 max_offset_in_fat = secbyt((daddr_t)fs->spf);
156 io_size = FATBLKSZ;
157 if (offset_in_fat > max_offset_in_fat)
158 offset_in_fat = max_offset_in_fat;
159 if (offset_in_fat + io_size > max_offset_in_fat)
160 io_size = ((size_t)(max_offset_in_fat - offset_in_fat));
161
162 if (io_size != 0) {
163 err = ioget(fd, fs->lsnfat + bytsec(offset_in_fat),
164 fs->fatbuf, io_size);
165 if (err != 0) {
166 fs->fatbuf_blknum = ((uint_t)(-1));
167 return (err);
168 }
169 }
170
171 if (io_size < FATBLKSZ)
172 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
173
174 fs->fatbuf_blknum = blknum;
175 return (0);
176 }
177
178 /*
179 * Mount DOS filesystem
180 */
181 static int
dos_mount(DOS_FS * fs,struct open_file * fd)182 dos_mount(DOS_FS *fs, struct open_file *fd)
183 {
184 int err;
185 uchar_t *buf;
186
187 bzero(fs, sizeof (DOS_FS));
188 fs->fd = fd;
189
190 if ((buf = malloc(secbyt(1))) == NULL)
191 return (errno);
192 if ((err = ioget(fs->fd, 0, buf, secbyt(1))) ||
193 (err = parsebs(fs, (DOS_BS *)buf))) {
194 free(buf);
195 return (err);
196 }
197 free(buf);
198
199 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL)
200 return (errno);
201 err = dos_read_fatblk(fs, fd, 0);
202 if (err != 0) {
203 free(fs->fatbuf);
204 return (err);
205 }
206
207 fs->root = dot[0];
208 fs->root.name[0] = ' ';
209 if (fs->fatsz == 32) {
210 fs->root.clus[0] = fs->rdcl & 0xff;
211 fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
212 fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
213 fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
214 }
215 return (0);
216 }
217
218 /*
219 * Unmount mounted filesystem
220 */
221 static int
dos_unmount(DOS_FS * fs)222 dos_unmount(DOS_FS *fs)
223 {
224 if (fs->links)
225 return (EBUSY);
226 free(fs->fatbuf);
227 free(fs);
228 return (0);
229 }
230
231 /*
232 * Open DOS file
233 */
234 static int
dos_open(const char * path,struct open_file * fd)235 dos_open(const char *path, struct open_file *fd)
236 {
237 DOS_DE *de;
238 DOS_FILE *f;
239 DOS_FS *fs;
240 uint_t size, clus;
241 int err;
242
243 /* Allocate mount structure, associate with open */
244 if ((fs = malloc(sizeof (DOS_FS))) == NULL)
245 return (errno);
246 if ((err = dos_mount(fs, fd))) {
247 free(fs);
248 return (err);
249 }
250
251 if ((err = namede(fs, path, &de))) {
252 dos_unmount(fs);
253 return (err);
254 }
255
256 clus = stclus(fs->fatsz, de);
257 size = cv4(de->size);
258
259 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
260 ((de->attr & FA_DIR) && size) ||
261 (clus && !okclus(fs, clus))) {
262 dos_unmount(fs);
263 return (EINVAL);
264 }
265 if ((f = malloc(sizeof (DOS_FILE))) == NULL) {
266 err = errno;
267 dos_unmount(fs);
268 return (err);
269 }
270 bzero(f, sizeof (DOS_FILE));
271 f->fs = fs;
272 fs->links++;
273 f->de = *de;
274 fd->f_fsdata = f;
275 return (0);
276 }
277
278 /*
279 * Read from file
280 */
281 static int
dos_read(struct open_file * fd,void * buf,size_t nbyte,size_t * resid)282 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
283 {
284 off_t size;
285 uint_t nb, off, clus, c, cnt, n;
286 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
287 int err = 0;
288
289 /*
290 * as ioget() can be called *a lot*, use twiddle here.
291 * also 4 seems to be good value not to slow loading down too much:
292 * with 270MB file (~540k ioget() calls, twiddle can easily waste
293 * 4-5 sec.
294 */
295 twiddle(4);
296 nb = (uint_t)nbyte;
297 if ((size = fsize(f->fs, &f->de)) == -1)
298 return (EINVAL);
299 if (nb > (n = size - f->offset))
300 nb = n;
301 off = f->offset;
302 if ((clus = stclus(f->fs->fatsz, &f->de)))
303 off &= f->fs->bsize - 1;
304 c = f->c;
305 cnt = nb;
306 while (cnt) {
307 n = 0;
308 if (!c) {
309 if ((c = clus))
310 n = bytblk(f->fs, f->offset);
311 } else if (!off)
312 n++;
313 while (n--) {
314 if ((err = fatget(f->fs, &c)))
315 goto out;
316 if (!okclus(f->fs, c)) {
317 err = EINVAL;
318 goto out;
319 }
320 }
321 if (!clus || (n = f->fs->bsize - off) > cnt)
322 n = cnt;
323 if ((err = ioread(f->fs, (c ? blkoff(f->fs, c) :
324 secbyt(f->fs->lsndir)) + off, buf, n)))
325 goto out;
326 f->offset += n;
327 f->c = c;
328 off = 0;
329 buf = (char *)buf + n;
330 cnt -= n;
331 }
332 out:
333 if (resid)
334 *resid = nbyte - nb + cnt;
335 return (err);
336 }
337
338 /*
339 * Reposition within file
340 */
341 static off_t
dos_seek(struct open_file * fd,off_t offset,int whence)342 dos_seek(struct open_file *fd, off_t offset, int whence)
343 {
344 off_t off;
345 uint_t size;
346 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
347
348 size = cv4(f->de.size);
349 switch (whence) {
350 case SEEK_SET:
351 off = 0;
352 break;
353 case SEEK_CUR:
354 off = f->offset;
355 break;
356 case SEEK_END:
357 off = size;
358 break;
359 default:
360 errno = EINVAL;
361 return (-1);
362 }
363 off += offset;
364 if (off < 0 || off > size) {
365 errno = EINVAL;
366 return (-1);
367 }
368 f->offset = (uint_t)off;
369 f->c = 0;
370 return (off);
371 }
372
373 /*
374 * Close open file
375 */
376 static int
dos_close(struct open_file * fd)377 dos_close(struct open_file *fd)
378 {
379 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
380 DOS_FS *fs = f->fs;
381
382 f->fs->links--;
383 free(f);
384 dos_unmount(fs);
385 return (0);
386 }
387
388 /*
389 * Return some stat information on a file.
390 */
391 static int
dos_stat(struct open_file * fd,struct stat * sb)392 dos_stat(struct open_file *fd, struct stat *sb)
393 {
394 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
395
396 /* only important stuff */
397 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
398 sb->st_nlink = 1;
399 sb->st_uid = 0;
400 sb->st_gid = 0;
401 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
402 return (EINVAL);
403 return (0);
404 }
405
406 static int
dos_checksum(unsigned char * name,unsigned char * ext)407 dos_checksum(unsigned char *name, unsigned char *ext)
408 {
409 int x, i;
410 char buf[11];
411
412 bcopy(name, buf, 8);
413 bcopy(ext, buf+8, 3);
414 x = 0;
415 for (i = 0; i < 11; i++) {
416 x = ((x & 1) << 7) | (x >> 1);
417 x += buf[i];
418 x &= 0xff;
419 }
420 return (x);
421 }
422
423 static int
dos_readdir(struct open_file * fd,struct dirent * d)424 dos_readdir(struct open_file *fd, struct dirent *d)
425 {
426 uchar_t fn[261];
427 DOS_DIR dd;
428 size_t res;
429 uint_t chk, x, xdn;
430 int err;
431
432 x = chk = 0;
433 while (1) {
434 xdn = x;
435 x = 0;
436 err = dos_read(fd, &dd, sizeof (dd), &res);
437 if (err)
438 return (err);
439 if (res == sizeof (dd))
440 return (ENOENT);
441 if (dd.de.name[0] == 0)
442 return (ENOENT);
443
444 /* Skip deleted entries */
445 if (dd.de.name[0] == 0xe5)
446 continue;
447
448 /* Check if directory entry is volume label */
449 if (dd.de.attr & FA_LABEL) {
450 /*
451 * If volume label set, check if the current entry is
452 * extended entry (FA_XDE) for long file names.
453 */
454 if ((dd.de.attr & FA_MASK) == FA_XDE) {
455 /*
456 * Read through all following extended entries
457 * to get the long file name. 0x40 marks the
458 * last entry containing part of long file name.
459 */
460 if (dd.xde.seq & 0x40)
461 chk = dd.xde.chk;
462 else if (dd.xde.seq != xdn - 1 ||
463 dd.xde.chk != chk)
464 continue;
465 x = dd.xde.seq & ~0x40;
466 if (x < 1 || x > 20) {
467 x = 0;
468 continue;
469 }
470 cp_xdnm(fn, &dd.xde);
471 } else {
472 /* skip only volume label entries */
473 continue;
474 }
475 } else {
476 if (xdn == 1) {
477 x = dos_checksum(dd.de.name, dd.de.ext);
478 if (x == chk)
479 break;
480 } else {
481 cp_sfn(fn, &dd.de);
482 break;
483 }
484 x = 0;
485 }
486 }
487
488 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
489 d->d_reclen = sizeof (*d);
490 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
491 memcpy(d->d_name, fn, sizeof (d->d_name));
492 return (0);
493 }
494
495 /*
496 * Parse DOS boot sector
497 */
498 static int
parsebs(DOS_FS * fs,DOS_BS * bs)499 parsebs(DOS_FS *fs, DOS_BS *bs)
500 {
501 uint_t sc;
502
503 if ((bs->jmp[0] != 0x69 &&
504 bs->jmp[0] != 0xe9 &&
505 (bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
506 bs->bpb.media < 0xf0)
507 return (EINVAL);
508 if (cv2(bs->bpb.secsiz) != SECSIZ)
509 return (EINVAL);
510 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
511 return (EINVAL);
512 fs->bsize = secbyt(fs->spc);
513 fs->bshift = ffs(fs->bsize) - 1;
514 if ((fs->spf = cv2(bs->bpb.spf))) {
515 if (bs->bpb.fats != 2)
516 return (EINVAL);
517 if (!(fs->dirents = cv2(bs->bpb.dirents)))
518 return (EINVAL);
519 } else {
520 if (!(fs->spf = cv4(bs->bpb.lspf)))
521 return (EINVAL);
522 if (!bs->bpb.fats || bs->bpb.fats > 16)
523 return (EINVAL);
524 if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
525 return (EINVAL);
526 }
527 if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
528 return (EINVAL);
529 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
530 fs->lsndta = fs->lsndir + entsec(fs->dirents);
531 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
532 return (EINVAL);
533 if (fs->lsndta > sc)
534 return (EINVAL);
535 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
536 return (EINVAL);
537 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
538 sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
539 if (fs->xclus > sc)
540 fs->xclus = sc;
541 return (0);
542 }
543
544 /*
545 * Return directory entry from path
546 */
547 static int
namede(DOS_FS * fs,const char * path,DOS_DE ** dep)548 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
549 {
550 char name[256];
551 DOS_DE *de;
552 char *s;
553 size_t n;
554 int err;
555
556 err = 0;
557 de = &fs->root;
558 while (*path) {
559 while (*path == '/')
560 path++;
561 if (*path == '\0')
562 break;
563 if (!(s = strchr(path, '/')))
564 s = strchr(path, 0);
565 if ((n = s - path) > 255)
566 return (ENAMETOOLONG);
567 memcpy(name, path, n);
568 name[n] = 0;
569 path = s;
570 if (!(de->attr & FA_DIR))
571 return (ENOTDIR);
572 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
573 return (err);
574 }
575 *dep = de;
576 return (0);
577 }
578
579 /*
580 * Lookup path segment
581 */
582 static int
lookup(DOS_FS * fs,uint_t clus,const char * name,DOS_DE ** dep)583 lookup(DOS_FS *fs, uint_t clus, const char *name, DOS_DE **dep)
584 {
585 static DOS_DIR dir[DEPSEC];
586 uchar_t lfn[261];
587 uchar_t sfn[13];
588 uint_t nsec, lsec, xdn, chk, sec, ent, x;
589 int err, ok;
590
591 if (!clus)
592 for (ent = 0; ent < 2; ent++)
593 if (!strcasecmp(name, dotstr[ent])) {
594 *dep = dot + ent;
595 return (0);
596 }
597 if (!clus && fs->fatsz == 32)
598 clus = fs->rdcl;
599 nsec = !clus ? entsec(fs->dirents) : fs->spc;
600 lsec = 0;
601 xdn = chk = 0;
602 for (;;) {
603 if (!clus && !lsec)
604 lsec = fs->lsndir;
605 else if (okclus(fs, clus))
606 lsec = blklsn(fs, clus);
607 else
608 return (EINVAL);
609
610 for (sec = 0; sec < nsec; sec++) {
611 if ((err = ioget(fs->fd, lsec + sec, dir, secbyt(1))))
612 return (err);
613 for (ent = 0; ent < DEPSEC; ent++) {
614 if (dir[ent].de.name[0] == 0)
615 return (ENOENT);
616 if (dir[ent].de.name[0] == 0xe5) {
617 xdn = 0;
618 continue;
619 }
620 if ((dir[ent].de.attr & FA_MASK) == FA_XDE) {
621 x = dir[ent].xde.seq;
622 if (x & 0x40 ||
623 (x + 1 == xdn &&
624 dir[ent].xde.chk == chk)) {
625 if (x & 0x40) {
626 chk = dir[ent].xde.chk;
627 x &= ~0x40;
628 }
629 if (x >= 1 && x <= 20) {
630 cp_xdnm(lfn,
631 &dir[ent].xde);
632 xdn = x;
633 continue;
634 }
635 }
636 } else if (!(dir[ent].de.attr & FA_LABEL)) {
637 if ((ok = xdn == 1)) {
638 x = dos_checksum(
639 dir[ent].de.name,
640 dir[ent].de.ext);
641 ok = chk == x &&
642 !strcasecmp(name,
643 (const char *)lfn);
644 }
645 if (!ok) {
646 cp_sfn(sfn, &dir[ent].de);
647 ok = !strcasecmp(name,
648 (const char *)sfn);
649 }
650 if (ok) {
651 *dep = &dir[ent].de;
652 return (0);
653 }
654 }
655 xdn = 0;
656 }
657 }
658 if (!clus)
659 break;
660 if ((err = fatget(fs, &clus)))
661 return (err);
662 if (fatend(fs->fatsz, clus))
663 break;
664 }
665 return (ENOENT);
666 }
667
668 /*
669 * Copy name from extended directory entry
670 */
671 static void
cp_xdnm(uchar_t * lfn,DOS_XDE * xde)672 cp_xdnm(uchar_t *lfn, DOS_XDE *xde)
673 {
674 static struct {
675 uint_t off;
676 uint_t dim;
677 } ix[3] = {
678 { offsetof(DOS_XDE, name1), sizeof (xde->name1) / 2},
679 { offsetof(DOS_XDE, name2), sizeof (xde->name2) / 2},
680 { offsetof(DOS_XDE, name3), sizeof (xde->name3) / 2}
681 };
682 uchar_t *p;
683 uint_t n, x, c;
684
685 lfn += 13 * ((xde->seq & ~0x40) - 1);
686 for (n = 0; n < 3; n++)
687 for (p = (uchar_t *)xde + ix[n].off, x = ix[n].dim; x;
688 p += 2, x--) {
689 if ((c = cv2(p)) && (c < 32 || c > 127))
690 c = '?';
691 if (!(*lfn++ = c))
692 return;
693 }
694 if (xde->seq & 0x40)
695 *lfn = 0;
696 }
697
698 /*
699 * Copy short filename
700 */
701 static void
cp_sfn(uchar_t * sfn,DOS_DE * de)702 cp_sfn(uchar_t *sfn, DOS_DE *de)
703 {
704 uchar_t *p;
705 int j, i;
706
707 p = sfn;
708 if (*de->name != ' ') {
709 for (j = 7; de->name[j] == ' '; j--)
710 ;
711 for (i = 0; i <= j; i++)
712 *p++ = de->name[i];
713 if (*de->ext != ' ') {
714 *p++ = '.';
715 for (j = 2; de->ext[j] == ' '; j--)
716 ;
717 for (i = 0; i <= j; i++)
718 *p++ = de->ext[i];
719 }
720 }
721 *p = '\0';
722 if (*sfn == 5)
723 *sfn = 0xe5;
724 }
725
726 /*
727 * Return size of file in bytes
728 */
729 static off_t
fsize(DOS_FS * fs,DOS_DE * de)730 fsize(DOS_FS *fs, DOS_DE *de)
731 {
732 ulong_t size;
733 uint_t c;
734 int n;
735
736 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
737 if (!(c = cv2(de->clus)))
738 size = fs->dirents * sizeof (DOS_DE);
739 else {
740 if ((n = fatcnt(fs, c)) == -1)
741 return (n);
742 size = blkbyt(fs, n);
743 }
744 }
745 return (size);
746 }
747
748 /*
749 * Count number of clusters in chain
750 */
751 static int
fatcnt(DOS_FS * fs,uint_t c)752 fatcnt(DOS_FS *fs, uint_t c)
753 {
754 int n;
755
756 for (n = 0; okclus(fs, c); n++)
757 if (fatget(fs, &c))
758 return (-1);
759 return (fatend(fs->fatsz, c) ? n : -1);
760 }
761
762 /*
763 * Get next cluster in cluster chain. Use in core fat cache unless
764 * the number of current 128K block in FAT has changed.
765 */
766 static int
fatget(DOS_FS * fs,uint_t * c)767 fatget(DOS_FS *fs, uint_t *c)
768 {
769 uint_t val_in, val_out, offset, blknum, nbyte;
770 const uchar_t *p_entry;
771 int err;
772
773 /* check input value to prevent overflow in fatoff() */
774 val_in = *c;
775 if (val_in & 0xf0000000)
776 return (EINVAL);
777
778 /* ensure that current 128K FAT block is cached */
779 offset = fatoff(fs->fatsz, val_in);
780 nbyte = fs->fatsz != 32 ? 2 : 4;
781 if (offset + nbyte > secbyt(fs->spf))
782 return (EINVAL);
783 blknum = offset / FATBLKSZ;
784 offset %= FATBLKSZ;
785 if (offset + nbyte > FATBLKSZ)
786 return (EINVAL);
787 if (blknum != fs->fatbuf_blknum) {
788 err = dos_read_fatblk(fs, fs->fd, blknum);
789 if (err != 0)
790 return (err);
791 }
792 p_entry = fs->fatbuf + offset;
793
794 /* extract cluster number from FAT entry */
795 switch (fs->fatsz) {
796 case 32:
797 val_out = cv4(p_entry);
798 val_out &= 0x0fffffff;
799 break;
800 case 16:
801 val_out = cv2(p_entry);
802 break;
803 case 12:
804 val_out = cv2(p_entry);
805 if (val_in & 1)
806 val_out >>= 4;
807 else
808 val_out &= 0xfff;
809 break;
810 default:
811 return (EINVAL);
812 }
813 *c = val_out;
814 return (0);
815 }
816
817 /*
818 * Is cluster an end-of-chain marker?
819 */
820 static int
fatend(uint_t sz,uint_t c)821 fatend(uint_t sz, uint_t c)
822 {
823 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
824 }
825
826 /*
827 * Offset-based I/O primitive
828 */
829 static int
ioread(DOS_FS * fs,uint_t offset,void * buf,size_t nbyte)830 ioread(DOS_FS *fs, uint_t offset, void *buf, size_t nbyte)
831 {
832 char *s;
833 uint_t off, n;
834 int err;
835 uchar_t local_buf[SECSIZ];
836
837 s = buf;
838 if ((off = offset & (SECSIZ - 1))) {
839 offset -= off;
840 if ((n = SECSIZ - off) > nbyte)
841 n = nbyte;
842 err = ioget(fs->fd, bytsec(offset), local_buf,
843 sizeof (local_buf));
844 if (err != 0)
845 return (err);
846 memcpy(s, local_buf + off, n);
847 offset += SECSIZ;
848 s += n;
849 nbyte -= n;
850 }
851 n = nbyte & (SECSIZ - 1);
852 if (nbyte -= n) {
853 if ((err = ioget(fs->fd, bytsec(offset), s, nbyte)))
854 return (err);
855 offset += nbyte;
856 s += nbyte;
857 }
858 if (n != 0) {
859 err = ioget(fs->fd, bytsec(offset), local_buf,
860 sizeof (local_buf));
861 if (err != 0)
862 return (err);
863 memcpy(s, local_buf, n);
864 }
865 return (0);
866 }
867
868 /*
869 * Sector-based I/O primitive
870 */
871 static int
ioget(struct open_file * fd,daddr_t lsec,void * buf,size_t size)872 ioget(struct open_file *fd, daddr_t lsec, void *buf, size_t size)
873 {
874 size_t rsize;
875 int rv;
876
877 /* Make sure we get full read or error. */
878 rsize = 0;
879 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
880 size, buf, &rsize);
881 if ((rv == 0) && (size != rsize))
882 rv = EIO;
883 return (rv);
884 }
885