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 <string.h>
36 #include <stddef.h>
37
38 #include "stand.h"
39
40 #include "dosfs.h"
41
42 typedef struct dos_mnt {
43 char *dos_dev;
44 DOS_FS *dos_fs;
45 int dos_fd;
46 STAILQ_ENTRY(dos_mnt) dos_link;
47 } dos_mnt_t;
48
49 typedef STAILQ_HEAD(dos_mnt_list, dos_mnt) dos_mnt_list_t;
50 static dos_mnt_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);
51
52 static int dos_open(const char *path, struct open_file *fd);
53 static int dos_close(struct open_file *fd);
54 static int dos_read(struct open_file *fd, void *buf, size_t size, size_t *resid);
55 static off_t dos_seek(struct open_file *fd, off_t offset, int whence);
56 static int dos_stat(struct open_file *fd, struct stat *sb);
57 static int dos_readdir(struct open_file *fd, struct dirent *d);
58 static int dos_mount(const char *dev, const char *path, void **data);
59 static int dos_unmount(const char *dev, void *data);
60
61 struct fs_ops dosfs_fsops = {
62 .fs_name = "dosfs",
63 .fo_open = dos_open,
64 .fo_close = dos_close,
65 .fo_read = dos_read,
66 .fo_write = null_write,
67 .fo_seek = dos_seek,
68 .fo_stat = dos_stat,
69 .fo_readdir = dos_readdir,
70 .fo_mount = dos_mount,
71 .fo_unmount = dos_unmount
72 };
73
74 #define SECSIZ 512 /* sector size */
75 #define SSHIFT 9 /* SECSIZ shift */
76 #define DEPSEC 16 /* directory entries per sector */
77 #define DSHIFT 4 /* DEPSEC shift */
78 #define LOCLUS 2 /* lowest cluster number */
79 #define FATBLKSZ 0x20000 /* size of block in the FAT cache buffer */
80
81 /* DOS "BIOS Parameter Block" */
82 typedef struct {
83 u_char secsiz[2]; /* sector size */
84 u_char spc; /* sectors per cluster */
85 u_char ressec[2]; /* reserved sectors */
86 u_char fats; /* FATs */
87 u_char dirents[2]; /* root directory entries */
88 u_char secs[2]; /* total sectors */
89 u_char media; /* media descriptor */
90 u_char spf[2]; /* sectors per FAT */
91 u_char spt[2]; /* sectors per track */
92 u_char heads[2]; /* drive heads */
93 u_char hidsec[4]; /* hidden sectors */
94 u_char lsecs[4]; /* huge sectors */
95 u_char lspf[4]; /* huge sectors per FAT */
96 u_char xflg[2]; /* flags */
97 u_char vers[2]; /* filesystem version */
98 u_char rdcl[4]; /* root directory start cluster */
99 u_char infs[2]; /* filesystem info sector */
100 u_char bkbs[2]; /* backup boot sector */
101 } DOS_BPB;
102
103 /* Initial portion of DOS boot sector */
104 typedef struct {
105 u_char jmp[3]; /* usually 80x86 'jmp' opcode */
106 u_char oem[8]; /* OEM name and version */
107 DOS_BPB bpb; /* BPB */
108 } DOS_BS;
109
110 /* Supply missing "." and ".." root directory entries */
111 static const char *const dotstr[2] = {".", ".."};
112 static DOS_DE dot[2] = {
113 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
114 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
115 {".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
116 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
117 };
118
119 /* The usual conversion macros to avoid multiplication and division */
120 #define bytsec(n) ((n) >> SSHIFT)
121 #define secbyt(s) ((s) << SSHIFT)
122 #define entsec(e) ((e) >> DSHIFT)
123 #define bytblk(fs, n) ((n) >> (fs)->bshift)
124 #define blkbyt(fs, b) ((b) << (fs)->bshift)
125 #define secblk(fs, s) ((s) >> ((fs)->bshift - SSHIFT))
126 #define blksec(fs, b) ((b) << ((fs)->bshift - SSHIFT))
127
128 /* Convert cluster number to offset within filesystem */
129 #define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
130
131 /* Convert cluster number to logical sector number */
132 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
133
134 /* Convert cluster number to offset within FAT */
135 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
136 (sz) == 16 ? (c) << 1 : \
137 (c) << 2)
138
139 /* Does cluster number reference a valid data cluster? */
140 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
141
142 /* Get start cluster from directory entry */
143 #define stclus(sz, de) ((sz) != 32 ? (u_int)cv2((de)->clus) : \
144 ((u_int)cv2((de)->dex.h_clus) << 16) | \
145 cv2((de)->clus))
146
147 static int parsebs(DOS_FS *, DOS_BS *);
148 static int namede(DOS_FS *, const char *, DOS_DE **);
149 static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
150 static void cp_xdnm(u_char *, DOS_XDE *);
151 static void cp_sfn(u_char *, DOS_DE *);
152 static off_t fsize(DOS_FS *, DOS_DE *);
153 static int fatcnt(DOS_FS *, u_int);
154 static int fatget(DOS_FS *, u_int *);
155 static int fatend(u_int, u_int);
156 static int ioread(DOS_FS *, uint64_t, void *, size_t);
157 static int ioget(struct open_file *, daddr_t, void *, size_t);
158
159 static int
dos_read_fatblk(DOS_FS * fs,struct open_file * fd,u_int blknum)160 dos_read_fatblk(DOS_FS *fs, struct open_file *fd, u_int blknum)
161 {
162 int err;
163 size_t io_size;
164 daddr_t offset_in_fat, max_offset_in_fat;
165
166 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
167 max_offset_in_fat = secbyt(fs->spf);
168 io_size = FATBLKSZ;
169 if (offset_in_fat > max_offset_in_fat)
170 offset_in_fat = max_offset_in_fat;
171 if (offset_in_fat + io_size > max_offset_in_fat)
172 io_size = ((size_t)(max_offset_in_fat - offset_in_fat));
173
174 if (io_size != 0) {
175 err = ioget(fd, fs->lsnfat + bytsec(offset_in_fat),
176 fs->fatbuf, io_size);
177 if (err != 0) {
178 fs->fatbuf_blknum = ((u_int)(-1));
179 return (err);
180 }
181 }
182 if (io_size < FATBLKSZ)
183 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
184
185 fs->fatbuf_blknum = blknum;
186 return (0);
187 }
188
189 /*
190 * Mount DOS filesystem
191 */
192 static int
dos_mount_impl(DOS_FS * fs,struct open_file * fd)193 dos_mount_impl(DOS_FS *fs, struct open_file *fd)
194 {
195 int err;
196 u_char *buf;
197
198 fs->fd = fd;
199
200 if ((buf = malloc(secbyt(1))) == NULL)
201 return (errno);
202 if ((err = ioget(fs->fd, 0, buf, secbyt(1))) ||
203 (err = parsebs(fs, (DOS_BS *)buf))) {
204 free(buf);
205 return (err);
206 }
207 free(buf);
208
209 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL)
210 return (errno);
211 err = dos_read_fatblk(fs, fd, 0);
212 if (err != 0) {
213 free(fs->fatbuf);
214 return (err);
215 }
216
217 fs->root = dot[0];
218 fs->root.name[0] = ' ';
219 if (fs->fatsz == 32) {
220 fs->root.clus[0] = fs->rdcl & 0xff;
221 fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
222 fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
223 fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
224 }
225 return (0);
226 }
227
228 static int
dos_mount(const char * dev,const char * path,void ** data)229 dos_mount(const char *dev, const char *path, void **data)
230 {
231 char *fs;
232 dos_mnt_t *mnt;
233 struct open_file *f;
234 DOS_FILE *df;
235
236 errno = 0;
237 mnt = calloc(1, sizeof(*mnt));
238 if (mnt == NULL)
239 return (errno);
240 mnt->dos_fd = -1;
241 mnt->dos_dev = strdup(dev);
242 if (mnt->dos_dev == NULL)
243 goto done;
244
245 if (asprintf(&fs, "%s%s", dev, path) < 0)
246 goto done;
247
248 mnt->dos_fd = open(fs, O_RDONLY);
249 free(fs);
250 if (mnt->dos_fd == -1)
251 goto done;
252
253 f = fd2open_file(mnt->dos_fd);
254 if (strcmp(f->f_ops->fs_name, "dosfs") == 0) {
255 df = f->f_fsdata;
256 mnt->dos_fs = df->fs;
257 STAILQ_INSERT_TAIL(&mnt_list, mnt, dos_link);
258 } else {
259 errno = ENXIO;
260 }
261
262 done:
263 if (errno != 0) {
264 free(mnt->dos_dev);
265 if (mnt->dos_fd >= 0)
266 close(mnt->dos_fd);
267 free(mnt);
268 } else {
269 *data = mnt;
270 }
271
272 return (errno);
273 }
274
275 static int
dos_unmount(const char * dev __unused,void * data)276 dos_unmount(const char *dev __unused, void *data)
277 {
278 dos_mnt_t *mnt = data;
279
280 STAILQ_REMOVE(&mnt_list, mnt, dos_mnt, dos_link);
281 free(mnt->dos_dev);
282 close(mnt->dos_fd);
283 free(mnt);
284 return (0);
285 }
286
287 /*
288 * Unmount mounted filesystem
289 */
290 static int
dos_unmount_impl(DOS_FS * fs)291 dos_unmount_impl(DOS_FS *fs)
292 {
293 if (fs->links)
294 return (EBUSY);
295 free(fs->fatbuf);
296 free(fs);
297 return (0);
298 }
299
300 /*
301 * Open DOS file
302 */
303 static int
dos_open(const char * path,struct open_file * fd)304 dos_open(const char *path, struct open_file *fd)
305 {
306 DOS_DE *de;
307 DOS_FILE *f;
308 DOS_FS *fs;
309 dos_mnt_t *mnt;
310 const char *dev;
311 u_int size, clus;
312 int err;
313
314 dev = devformat((struct devdesc *)fd->f_devdata);
315 STAILQ_FOREACH(mnt, &mnt_list, dos_link) {
316 if (strcmp(dev, mnt->dos_dev) == 0)
317 break;
318 }
319
320 if (mnt == NULL) {
321 /* Allocate mount structure, associate with open */
322 if ((fs = calloc(1, sizeof(DOS_FS))) == NULL)
323 return (errno);
324 if ((err = dos_mount_impl(fs, fd))) {
325 free(fs);
326 return (err);
327 }
328 } else {
329 fs = mnt->dos_fs;
330 }
331
332 if ((err = namede(fs, path, &de))) {
333 if (mnt == NULL)
334 dos_unmount_impl(fs);
335 return (err);
336 }
337
338 clus = stclus(fs->fatsz, de);
339 size = cv4(de->size);
340
341 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
342 ((de->attr & FA_DIR) && size) ||
343 (clus && !okclus(fs, clus))) {
344 if (mnt == NULL)
345 dos_unmount_impl(fs);
346 return (EINVAL);
347 }
348 if ((f = calloc(1, sizeof(DOS_FILE))) == NULL) {
349 err = errno;
350 if (mnt == NULL)
351 dos_unmount_impl(fs);
352 return (err);
353 }
354 f->fs = fs;
355 fs->links++;
356 f->de = *de;
357 fd->f_fsdata = f;
358 return (0);
359 }
360
361 /*
362 * Read from file
363 */
364 static int
dos_read(struct open_file * fd,void * buf,size_t nbyte,size_t * resid)365 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
366 {
367 off_t size;
368 uint64_t off;
369 size_t nb;
370 u_int clus, c, cnt, n;
371 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
372 int err = 0;
373
374 /*
375 * as ioget() can be called *a lot*, use twiddle here.
376 * also 4 seems to be good value not to slow loading down too much:
377 * with 270MB file (~540k ioget() calls, twiddle can easily waste
378 * 4-5 sec.
379 */
380 twiddle(4);
381 nb = nbyte;
382 if ((size = fsize(f->fs, &f->de)) == -1)
383 return (EINVAL);
384 if (nb > (n = size - f->offset))
385 nb = n;
386 off = f->offset;
387 if ((clus = stclus(f->fs->fatsz, &f->de)))
388 off &= f->fs->bsize - 1;
389 c = f->c;
390 cnt = nb;
391 while (cnt) {
392 n = 0;
393 if (!c) {
394 if ((c = clus))
395 n = bytblk(f->fs, f->offset);
396 } else if (!off)
397 n++;
398 while (n--) {
399 if ((err = fatget(f->fs, &c)))
400 goto out;
401 if (!okclus(f->fs, c)) {
402 err = EINVAL;
403 goto out;
404 }
405 }
406 if (!clus || (n = f->fs->bsize - off) > cnt)
407 n = cnt;
408 if (c != 0)
409 off += blkoff(f->fs, (uint64_t)c);
410 else
411 off += secbyt(f->fs->lsndir);
412 err = ioread(f->fs, off, buf, n);
413 if (err != 0)
414 goto out;
415 f->offset += n;
416 f->c = c;
417 off = 0;
418 buf = (char *)buf + n;
419 cnt -= n;
420 }
421 out:
422 if (resid)
423 *resid = nbyte - nb + cnt;
424 return (err);
425 }
426
427 /*
428 * Reposition within file
429 */
430 static off_t
dos_seek(struct open_file * fd,off_t offset,int whence)431 dos_seek(struct open_file *fd, off_t offset, int whence)
432 {
433 off_t off;
434 u_int size;
435 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
436
437 size = cv4(f->de.size);
438 switch (whence) {
439 case SEEK_SET:
440 off = 0;
441 break;
442 case SEEK_CUR:
443 off = f->offset;
444 break;
445 case SEEK_END:
446 off = size;
447 break;
448 default:
449 errno = EINVAL;
450 return (-1);
451 }
452 off += offset;
453 if (off < 0 || off > size) {
454 errno = EINVAL;
455 return (-1);
456 }
457 f->offset = (u_int)off;
458 f->c = 0;
459 return (off);
460 }
461
462 /*
463 * Close open file
464 */
465 static int
dos_close(struct open_file * fd)466 dos_close(struct open_file *fd)
467 {
468 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
469 DOS_FS *fs = f->fs;
470
471 f->fs->links--;
472 free(f);
473 dos_unmount_impl(fs);
474 return (0);
475 }
476
477 /*
478 * Return some stat information on a file.
479 */
480 static int
dos_stat(struct open_file * fd,struct stat * sb)481 dos_stat(struct open_file *fd, struct stat *sb)
482 {
483 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
484
485 /* only important stuff */
486 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
487 sb->st_nlink = 1;
488 sb->st_uid = 0;
489 sb->st_gid = 0;
490 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
491 return (EINVAL);
492 return (0);
493 }
494
495 static int
dos_checksum(unsigned char * name,unsigned char * ext)496 dos_checksum(unsigned char *name, unsigned char *ext)
497 {
498 int x, i;
499 char buf[11];
500
501 bcopy(name, buf, 8);
502 bcopy(ext, buf+8, 3);
503 x = 0;
504 for (i = 0; i < 11; i++) {
505 x = ((x & 1) << 7) | (x >> 1);
506 x += buf[i];
507 x &= 0xff;
508 }
509 return (x);
510 }
511
512 static int
dos_readdir(struct open_file * fd,struct dirent * d)513 dos_readdir(struct open_file *fd, struct dirent *d)
514 {
515 /* DOS_FILE *f = (DOS_FILE *)fd->f_fsdata; */
516 u_char fn[261];
517 DOS_DIR dd;
518 size_t res;
519 u_int chk, x, xdn;
520 int err;
521
522 x = chk = 0;
523 for (;;) {
524 xdn = x;
525 x = 0;
526 err = dos_read(fd, &dd, sizeof(dd), &res);
527 if (err)
528 return (err);
529 if (res == sizeof(dd))
530 return (ENOENT);
531 if (dd.de.name[0] == 0)
532 return (ENOENT);
533
534 /* Skip deleted entries */
535 if (dd.de.name[0] == 0xe5)
536 continue;
537
538 /* Check if directory entry is volume label */
539 if (dd.de.attr & FA_LABEL) {
540 /*
541 * If volume label set, check if the current entry is
542 * extended entry (FA_XDE) for long file names.
543 */
544 if ((dd.de.attr & FA_MASK) == FA_XDE) {
545 /*
546 * Read through all following extended entries
547 * to get the long file name. 0x40 marks the
548 * last entry containing part of long file name.
549 */
550 if (dd.xde.seq & 0x40)
551 chk = dd.xde.chk;
552 else if (dd.xde.seq != xdn - 1 ||
553 dd.xde.chk != chk)
554 continue;
555 x = dd.xde.seq & ~0x40;
556 if (x < 1 || x > 20) {
557 x = 0;
558 continue;
559 }
560 cp_xdnm(fn, &dd.xde);
561 } else {
562 /* skip only volume label entries */
563 continue;
564 }
565 } else {
566 if (xdn == 1) {
567 x = dos_checksum(dd.de.name, dd.de.ext);
568 if (x == chk)
569 break;
570 } else {
571 cp_sfn(fn, &dd.de);
572 break;
573 }
574 x = 0;
575 }
576 }
577
578 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
579 d->d_reclen = sizeof(*d);
580 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
581 memcpy(d->d_name, fn, sizeof(d->d_name));
582 return (0);
583 }
584
585 /*
586 * Parse DOS boot sector
587 */
588 static int
parsebs(DOS_FS * fs,DOS_BS * bs)589 parsebs(DOS_FS *fs, DOS_BS *bs)
590 {
591 u_int sc;
592
593 if ((bs->jmp[0] != 0x69 &&
594 bs->jmp[0] != 0xe9 &&
595 (bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
596 bs->bpb.media < 0xf0)
597 return (EINVAL);
598 if (cv2(bs->bpb.secsiz) != SECSIZ)
599 return (EINVAL);
600 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
601 return (EINVAL);
602 fs->bsize = secbyt(fs->spc);
603 fs->bshift = ffs(fs->bsize) - 1;
604 if ((fs->spf = cv2(bs->bpb.spf))) {
605 if (bs->bpb.fats != 2)
606 return (EINVAL);
607 if (!(fs->dirents = cv2(bs->bpb.dirents)))
608 return (EINVAL);
609 } else {
610 if (!(fs->spf = cv4(bs->bpb.lspf)))
611 return (EINVAL);
612 if (!bs->bpb.fats || bs->bpb.fats > 16)
613 return (EINVAL);
614 if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
615 return (EINVAL);
616 }
617 if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
618 return (EINVAL);
619 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
620 fs->lsndta = fs->lsndir + entsec(fs->dirents);
621 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
622 return (EINVAL);
623 if (fs->lsndta > sc)
624 return (EINVAL);
625 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
626 return (EINVAL);
627 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
628 sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
629 if (fs->xclus > sc)
630 fs->xclus = sc;
631 return (0);
632 }
633
634 /*
635 * Return directory entry from path
636 */
637 static int
namede(DOS_FS * fs,const char * path,DOS_DE ** dep)638 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
639 {
640 char name[256];
641 DOS_DE *de;
642 char *s;
643 size_t n;
644 int err;
645
646 err = 0;
647 de = &fs->root;
648 while (*path) {
649 while (*path == '/')
650 path++;
651 if (*path == '\0')
652 break;
653 if (!(s = strchr(path, '/')))
654 s = strchr(path, 0);
655 if ((n = s - path) > 255)
656 return (ENAMETOOLONG);
657 memcpy(name, path, n);
658 name[n] = 0;
659 path = s;
660 if (!(de->attr & FA_DIR))
661 return (ENOTDIR);
662 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
663 return (err);
664 }
665 *dep = de;
666 return (0);
667 }
668
669 /*
670 * Lookup path segment
671 */
672 static int
lookup(DOS_FS * fs,u_int clus,const char * name,DOS_DE ** dep)673 lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
674 {
675 static DOS_DIR dir[DEPSEC];
676 u_char lfn[261];
677 u_char sfn[13];
678 u_int nsec, lsec, xdn, chk, sec, ent, x;
679 int err, ok;
680
681 if (!clus)
682 for (ent = 0; ent < 2; ent++)
683 if (!strcasecmp(name, dotstr[ent])) {
684 *dep = dot + ent;
685 return (0);
686 }
687 if (!clus && fs->fatsz == 32)
688 clus = fs->rdcl;
689 nsec = !clus ? entsec(fs->dirents) : fs->spc;
690 lsec = 0;
691 xdn = chk = 0;
692 for (;;) {
693 if (!clus && !lsec)
694 lsec = fs->lsndir;
695 else if (okclus(fs, clus))
696 lsec = blklsn(fs, clus);
697 else
698 return (EINVAL);
699 for (sec = 0; sec < nsec; sec++) {
700 if ((err = ioget(fs->fd, lsec + sec, dir, secbyt(1))))
701 return (err);
702 for (ent = 0; ent < DEPSEC; ent++) {
703 if (!*dir[ent].de.name)
704 return (ENOENT);
705 if (*dir[ent].de.name != 0xe5) {
706 if ((dir[ent].de.attr & FA_MASK) ==
707 FA_XDE) {
708 x = dir[ent].xde.seq;
709 if (x & 0x40 || (x + 1 == xdn &&
710 dir[ent].xde.chk == chk)) {
711 if (x & 0x40) {
712 chk = dir[ent].xde.chk;
713 x &= ~0x40;
714 }
715 if (x >= 1 && x <= 20) {
716 cp_xdnm(lfn, &dir[ent].xde);
717 xdn = x;
718 continue;
719 }
720 }
721 } else if (!(dir[ent].de.attr &
722 FA_LABEL)) {
723 if ((ok = xdn == 1)) {
724 x = dos_checksum(
725 dir[ent].de.name,
726 dir[ent].de.ext);
727 ok = chk == x &&
728 !strcasecmp(name,
729 (const char *)lfn);
730 }
731 if (!ok) {
732 cp_sfn(sfn,
733 &dir[ent].de);
734 ok = !strcasecmp(name,
735 (const char *)sfn);
736 }
737 if (ok) {
738 *dep = &dir[ent].de;
739 return (0);
740 }
741 }
742 }
743 xdn = 0;
744 }
745 }
746 if (!clus)
747 break;
748 if ((err = fatget(fs, &clus)))
749 return (err);
750 if (fatend(fs->fatsz, clus))
751 break;
752 }
753 return (ENOENT);
754 }
755
756 /*
757 * Copy name from extended directory entry
758 */
759 static void
cp_xdnm(u_char * lfn,DOS_XDE * xde)760 cp_xdnm(u_char *lfn, DOS_XDE *xde)
761 {
762 static struct {
763 u_int off;
764 u_int dim;
765 } ix[3] = {
766 {offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
767 {offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
768 {offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
769 };
770 u_char *p;
771 u_int n, x, c;
772
773 lfn += 13 * ((xde->seq & ~0x40) - 1);
774 for (n = 0; n < 3; n++)
775 for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
776 p += 2, x--) {
777 if ((c = cv2(p)) && (c < 32 || c > 127))
778 c = '?';
779 if (!(*lfn++ = c))
780 return;
781 }
782 if (xde->seq & 0x40)
783 *lfn = 0;
784 }
785
786 /*
787 * Copy short filename
788 */
789 static void
cp_sfn(u_char * sfn,DOS_DE * de)790 cp_sfn(u_char *sfn, DOS_DE *de)
791 {
792 u_char *p;
793 int j, i;
794
795 p = sfn;
796 if (*de->name != ' ') {
797 for (j = 7; de->name[j] == ' '; j--)
798 ;
799 for (i = 0; i <= j; i++)
800 *p++ = de->name[i];
801 if (*de->ext != ' ') {
802 *p++ = '.';
803 for (j = 2; de->ext[j] == ' '; j--)
804 ;
805 for (i = 0; i <= j; i++)
806 *p++ = de->ext[i];
807 }
808 }
809 *p = 0;
810 if (*sfn == 5)
811 *sfn = 0xe5;
812 }
813
814 /*
815 * Return size of file in bytes
816 */
817 static off_t
fsize(DOS_FS * fs,DOS_DE * de)818 fsize(DOS_FS *fs, DOS_DE *de)
819 {
820 u_long size;
821 u_int c;
822 int n;
823
824 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
825 if (!(c = stclus(fs->fatsz, de))) {
826 size = fs->dirents * sizeof(DOS_DE);
827 } else {
828 if ((n = fatcnt(fs, c)) == -1)
829 return (n);
830 size = blkbyt(fs, n);
831 }
832 }
833 return (size);
834 }
835
836 /*
837 * Count number of clusters in chain
838 */
839 static int
fatcnt(DOS_FS * fs,u_int c)840 fatcnt(DOS_FS *fs, u_int c)
841 {
842 int n;
843
844 for (n = 0; okclus(fs, c); n++)
845 if (fatget(fs, &c))
846 return (-1);
847 return (fatend(fs->fatsz, c) ? n : -1);
848 }
849
850 /*
851 * Get next cluster in cluster chain. Use in core fat cache unless
852 * the number of current 128K block in FAT has changed.
853 */
854 static int
fatget(DOS_FS * fs,u_int * c)855 fatget(DOS_FS *fs, u_int *c)
856 {
857 u_int val_in, val_out, offset, blknum, nbyte;
858 const u_char *p_entry;
859 int err;
860
861 /* check input value to prevent overflow in fatoff() */
862 val_in = *c;
863 if (val_in & 0xf0000000)
864 return (EINVAL);
865
866 /* ensure that current 128K FAT block is cached */
867 offset = fatoff(fs->fatsz, val_in);
868 nbyte = fs->fatsz != 32 ? 2 : 4;
869 if (offset + nbyte > secbyt(fs->spf))
870 return (EINVAL);
871 blknum = offset / FATBLKSZ;
872 offset %= FATBLKSZ;
873 if (offset + nbyte > FATBLKSZ)
874 return (EINVAL);
875 if (blknum != fs->fatbuf_blknum) {
876 err = dos_read_fatblk(fs, fs->fd, blknum);
877 if (err != 0)
878 return (err);
879 }
880 p_entry = fs->fatbuf + offset;
881
882 /* extract cluster number from FAT entry */
883 switch (fs->fatsz) {
884 case 32:
885 val_out = cv4(p_entry);
886 val_out &= 0x0fffffff;
887 break;
888 case 16:
889 val_out = cv2(p_entry);
890 break;
891 case 12:
892 val_out = cv2(p_entry);
893 if (val_in & 1)
894 val_out >>= 4;
895 else
896 val_out &= 0xfff;
897 break;
898 default:
899 return (EINVAL);
900 }
901 *c = val_out;
902 return (0);
903 }
904
905 /*
906 * Is cluster an end-of-chain marker?
907 */
908 static int
fatend(u_int sz,u_int c)909 fatend(u_int sz, u_int c)
910 {
911 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
912 }
913
914 /*
915 * Offset-based I/O primitive
916 */
917 static int
ioread(DOS_FS * fs,uint64_t offset,void * buf,size_t nbyte)918 ioread(DOS_FS *fs, uint64_t offset, void *buf, size_t nbyte)
919 {
920 char *s;
921 size_t n;
922 int err;
923 uint64_t off;
924 u_char local_buf[SECSIZ];
925
926 s = buf;
927 if ((off = offset & (SECSIZ - 1))) {
928 offset -= off;
929 if ((n = SECSIZ - off) > nbyte)
930 n = nbyte;
931 err = ioget(fs->fd, bytsec(offset), local_buf,
932 sizeof(local_buf));
933 if (err != 0)
934 return (err);
935 memcpy(s, local_buf + off, n);
936 offset += SECSIZ;
937 s += n;
938 nbyte -= n;
939 }
940 n = nbyte & (SECSIZ - 1);
941 if (nbyte -= n) {
942 if ((err = ioget(fs->fd, bytsec(offset), s, nbyte)))
943 return (err);
944 offset += nbyte;
945 s += nbyte;
946 }
947 if (n != 0) {
948 err = ioget(fs->fd, bytsec(offset), local_buf,
949 sizeof(local_buf));
950 if (err != 0)
951 return (err);
952 memcpy(s, local_buf, n);
953 }
954 return (0);
955 }
956
957 /*
958 * Sector-based I/O primitive
959 */
960 static int
ioget(struct open_file * fd,daddr_t lsec,void * buf,size_t size)961 ioget(struct open_file *fd, daddr_t lsec, void *buf, size_t size)
962 {
963 size_t rsize;
964 int rv;
965
966 /* Make sure we get full read or error. */
967 rsize = 0;
968 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
969 size, buf, &rsize);
970 if ((rv == 0) && (size != rsize))
971 rv = EIO;
972 return (rv);
973 }
974