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 /*
29 * Readonly filesystem for Microsoft FAT12/FAT16/FAT32 filesystems,
30 * also supports VFAT.
31 */
32
33 #include <sys/types.h>
34 #include <string.h>
35 #include <stddef.h>
36
37 #include "stand.h"
38
39 #include "dosfs.h"
40
41 typedef struct dos_mnt {
42 char *dos_dev;
43 DOS_FS *dos_fs;
44 int dos_fd;
45 STAILQ_ENTRY(dos_mnt) dos_link;
46 } dos_mnt_t;
47
48 typedef STAILQ_HEAD(dos_mnt_list, dos_mnt) dos_mnt_list_t;
49 static dos_mnt_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);
50
51 static int dos_open(const char *path, struct open_file *fd);
52 static int dos_close(struct open_file *fd);
53 static int dos_read(struct open_file *fd, void *buf, size_t size, size_t *resid);
54 static off_t dos_seek(struct open_file *fd, off_t offset, int whence);
55 static int dos_stat(struct open_file *fd, struct stat *sb);
56 static int dos_readdir(struct open_file *fd, struct dirent *d);
57 static int dos_mount(const char *dev, const char *path, void **data);
58 static int dos_unmount(const char *dev, void *data);
59
60 struct fs_ops dosfs_fsops = {
61 .fs_name = "dosfs",
62 .fo_open = dos_open,
63 .fo_close = dos_close,
64 .fo_read = dos_read,
65 .fo_write = null_write,
66 .fo_seek = dos_seek,
67 .fo_stat = dos_stat,
68 .fo_readdir = dos_readdir,
69 .fo_mount = dos_mount,
70 .fo_unmount = dos_unmount
71 };
72
73 #define SECSIZ 512 /* sector size */
74 #define SSHIFT 9 /* SECSIZ shift */
75 #define DEPSEC 16 /* directory entries per sector */
76 #define DSHIFT 4 /* DEPSEC shift */
77 #define LOCLUS 2 /* lowest cluster number */
78 #define FATBLKSZ 0x20000 /* size of block in the FAT cache buffer */
79
80 /* DOS "BIOS Parameter Block" */
81 typedef struct {
82 u_char secsiz[2]; /* sector size */
83 u_char spc; /* sectors per cluster */
84 u_char ressec[2]; /* reserved sectors */
85 u_char fats; /* FATs */
86 u_char dirents[2]; /* root directory entries */
87 u_char secs[2]; /* total sectors */
88 u_char media; /* media descriptor */
89 u_char spf[2]; /* sectors per FAT */
90 u_char spt[2]; /* sectors per track */
91 u_char heads[2]; /* drive heads */
92 u_char hidsec[4]; /* hidden sectors */
93 u_char lsecs[4]; /* huge sectors */
94 u_char lspf[4]; /* huge sectors per FAT */
95 u_char xflg[2]; /* flags */
96 u_char vers[2]; /* filesystem version */
97 u_char rdcl[4]; /* root directory start cluster */
98 u_char infs[2]; /* filesystem info sector */
99 u_char bkbs[2]; /* backup boot sector */
100 } DOS_BPB;
101
102 /* Initial portion of DOS boot sector */
103 typedef struct {
104 u_char jmp[3]; /* usually 80x86 'jmp' opcode */
105 u_char oem[8]; /* OEM name and version */
106 DOS_BPB bpb; /* BPB */
107 } DOS_BS;
108
109 /* Supply missing "." and ".." root directory entries */
110 static const char *const dotstr[2] = {".", ".."};
111 static DOS_DE dot[2] = {
112 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
113 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
114 {".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
115 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
116 };
117
118 /* The usual conversion macros to avoid multiplication and division */
119 #define bytsec(n) ((n) >> SSHIFT)
120 #define secbyt(s) ((s) << SSHIFT)
121 #define entsec(e) ((e) >> DSHIFT)
122 #define bytblk(fs, n) ((n) >> (fs)->bshift)
123 #define blkbyt(fs, b) ((b) << (fs)->bshift)
124 #define secblk(fs, s) ((s) >> ((fs)->bshift - SSHIFT))
125 #define blksec(fs, b) ((b) << ((fs)->bshift - SSHIFT))
126
127 /* Convert cluster number to offset within filesystem */
128 #define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
129
130 /* Convert cluster number to logical sector number */
131 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
132
133 /* Convert cluster number to offset within FAT */
134 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
135 (sz) == 16 ? (c) << 1 : \
136 (c) << 2)
137
138 /* Does cluster number reference a valid data cluster? */
139 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
140
141 /* Get start cluster from directory entry */
142 #define stclus(sz, de) ((sz) != 32 ? cv2((de)->clus) : \
143 ((u_int)cv2((de)->dex.h_clus) << 16) | \
144 cv2((de)->clus))
145
146 static int parsebs(DOS_FS *, DOS_BS *);
147 static int namede(DOS_FS *, const char *, DOS_DE **);
148 static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
149 static void cp_xdnm(u_char *, DOS_XDE *);
150 static void cp_sfn(u_char *, DOS_DE *);
151 static off_t fsize(DOS_FS *, DOS_DE *);
152 static int fatcnt(DOS_FS *, u_int);
153 static int fatget(DOS_FS *, u_int *);
154 static int fatend(u_int, u_int);
155 static int ioread(DOS_FS *, u_int, void *, size_t);
156 static int ioget(struct open_file *, daddr_t, void *, size_t);
157
158 static int
dos_read_fatblk(DOS_FS * fs,struct open_file * fd,u_int blknum)159 dos_read_fatblk(DOS_FS *fs, struct open_file *fd, u_int blknum)
160 {
161 int err;
162 size_t io_size;
163 daddr_t offset_in_fat, max_offset_in_fat;
164
165 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
166 max_offset_in_fat = secbyt(fs->spf);
167 io_size = FATBLKSZ;
168 if (offset_in_fat > max_offset_in_fat)
169 offset_in_fat = max_offset_in_fat;
170 if (offset_in_fat + io_size > max_offset_in_fat)
171 io_size = ((size_t)(max_offset_in_fat - offset_in_fat));
172
173 if (io_size != 0) {
174 err = ioget(fd, fs->lsnfat + bytsec(offset_in_fat),
175 fs->fatbuf, io_size);
176 if (err != 0) {
177 fs->fatbuf_blknum = ((u_int)(-1));
178 return (err);
179 }
180 }
181 if (io_size < FATBLKSZ)
182 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
183
184 fs->fatbuf_blknum = blknum;
185 return (0);
186 }
187
188 /*
189 * Mount DOS filesystem
190 */
191 static int
dos_mount_impl(DOS_FS * fs,struct open_file * fd)192 dos_mount_impl(DOS_FS *fs, struct open_file *fd)
193 {
194 int err;
195 u_char *buf;
196
197 fs->fd = fd;
198
199 if ((buf = malloc(secbyt(1))) == NULL)
200 return (errno);
201 if ((err = ioget(fs->fd, 0, buf, secbyt(1))) ||
202 (err = parsebs(fs, (DOS_BS *)buf))) {
203 free(buf);
204 return (err);
205 }
206 free(buf);
207
208 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL)
209 return (errno);
210 err = dos_read_fatblk(fs, fd, 0);
211 if (err != 0) {
212 free(fs->fatbuf);
213 return (err);
214 }
215
216 fs->root = dot[0];
217 fs->root.name[0] = ' ';
218 if (fs->fatsz == 32) {
219 fs->root.clus[0] = fs->rdcl & 0xff;
220 fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
221 fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
222 fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
223 }
224 return (0);
225 }
226
227 static int
dos_mount(const char * dev,const char * path,void ** data)228 dos_mount(const char *dev, const char *path, void **data)
229 {
230 char *fs;
231 dos_mnt_t *mnt;
232 struct open_file *f;
233 DOS_FILE *df;
234
235 errno = 0;
236 mnt = calloc(1, sizeof(*mnt));
237 if (mnt == NULL)
238 return (errno);
239 mnt->dos_fd = -1;
240 mnt->dos_dev = strdup(dev);
241 if (mnt->dos_dev == NULL)
242 goto done;
243
244 if (asprintf(&fs, "%s%s", dev, path) < 0)
245 goto done;
246
247 mnt->dos_fd = open(fs, O_RDONLY);
248 free(fs);
249 if (mnt->dos_fd == -1)
250 goto done;
251
252 f = fd2open_file(mnt->dos_fd);
253 if (strcmp(f->f_ops->fs_name, "dosfs") == 0) {
254 df = f->f_fsdata;
255 mnt->dos_fs = df->fs;
256 STAILQ_INSERT_TAIL(&mnt_list, mnt, dos_link);
257 } else {
258 errno = ENXIO;
259 }
260
261 done:
262 if (errno != 0) {
263 free(mnt->dos_dev);
264 if (mnt->dos_fd >= 0)
265 close(mnt->dos_fd);
266 free(mnt);
267 } else {
268 *data = mnt;
269 }
270
271 return (errno);
272 }
273
274 static int
dos_unmount(const char * dev __unused,void * data)275 dos_unmount(const char *dev __unused, void *data)
276 {
277 dos_mnt_t *mnt = data;
278
279 STAILQ_REMOVE(&mnt_list, mnt, dos_mnt, dos_link);
280 free(mnt->dos_dev);
281 close(mnt->dos_fd);
282 free(mnt);
283 return (0);
284 }
285
286 /*
287 * Unmount mounted filesystem
288 */
289 static int
dos_unmount_impl(DOS_FS * fs)290 dos_unmount_impl(DOS_FS *fs)
291 {
292 if (fs->links)
293 return (EBUSY);
294 free(fs->fatbuf);
295 free(fs);
296 return (0);
297 }
298
299 /*
300 * Open DOS file
301 */
302 static int
dos_open(const char * path,struct open_file * fd)303 dos_open(const char *path, struct open_file *fd)
304 {
305 DOS_DE *de;
306 DOS_FILE *f;
307 DOS_FS *fs;
308 dos_mnt_t *mnt;
309 const char *dev;
310 u_int size, clus;
311 int err;
312
313 dev = devformat((struct devdesc *)fd->f_devdata);
314 STAILQ_FOREACH(mnt, &mnt_list, dos_link) {
315 if (strcmp(dev, mnt->dos_dev) == 0)
316 break;
317 }
318
319 if (mnt == NULL) {
320 /* Allocate mount structure, associate with open */
321 if ((fs = calloc(1, sizeof(DOS_FS))) == NULL)
322 return (errno);
323 if ((err = dos_mount_impl(fs, fd))) {
324 free(fs);
325 return (err);
326 }
327 } else {
328 fs = mnt->dos_fs;
329 }
330
331 if ((err = namede(fs, path, &de))) {
332 if (mnt == NULL)
333 dos_unmount_impl(fs);
334 return (err);
335 }
336
337 clus = stclus(fs->fatsz, de);
338 size = cv4(de->size);
339
340 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
341 ((de->attr & FA_DIR) && size) ||
342 (clus && !okclus(fs, clus))) {
343 if (mnt == NULL)
344 dos_unmount_impl(fs);
345 return (EINVAL);
346 }
347 if ((f = calloc(1, sizeof(DOS_FILE))) == NULL) {
348 err = errno;
349 if (mnt == NULL)
350 dos_unmount_impl(fs);
351 return (err);
352 }
353 f->fs = fs;
354 fs->links++;
355 f->de = *de;
356 fd->f_fsdata = f;
357 return (0);
358 }
359
360 /*
361 * Read from file
362 */
363 static int
dos_read(struct open_file * fd,void * buf,size_t nbyte,size_t * resid)364 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
365 {
366 off_t size;
367 u_int nb, off, clus, c, cnt, n;
368 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
369 int err = 0;
370
371 /*
372 * as ioget() can be called *a lot*, use twiddle here.
373 * also 4 seems to be good value not to slow loading down too much:
374 * with 270MB file (~540k ioget() calls, twiddle can easily waste
375 * 4-5 sec.
376 */
377 twiddle(4);
378 nb = (u_int)nbyte;
379 if ((size = fsize(f->fs, &f->de)) == -1)
380 return (EINVAL);
381 if (nb > (n = size - f->offset))
382 nb = n;
383 off = f->offset;
384 if ((clus = stclus(f->fs->fatsz, &f->de)))
385 off &= f->fs->bsize - 1;
386 c = f->c;
387 cnt = nb;
388 while (cnt) {
389 n = 0;
390 if (!c) {
391 if ((c = clus))
392 n = bytblk(f->fs, f->offset);
393 } else if (!off)
394 n++;
395 while (n--) {
396 if ((err = fatget(f->fs, &c)))
397 goto out;
398 if (!okclus(f->fs, c)) {
399 err = EINVAL;
400 goto out;
401 }
402 }
403 if (!clus || (n = f->fs->bsize - off) > cnt)
404 n = cnt;
405 if ((err = ioread(f->fs, (c ? blkoff(f->fs, c) :
406 secbyt(f->fs->lsndir)) + off, buf, n)))
407 goto out;
408 f->offset += n;
409 f->c = c;
410 off = 0;
411 buf = (char *)buf + n;
412 cnt -= n;
413 }
414 out:
415 if (resid)
416 *resid = nbyte - nb + cnt;
417 return (err);
418 }
419
420 /*
421 * Reposition within file
422 */
423 static off_t
dos_seek(struct open_file * fd,off_t offset,int whence)424 dos_seek(struct open_file *fd, off_t offset, int whence)
425 {
426 off_t off;
427 u_int size;
428 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
429
430 size = cv4(f->de.size);
431 switch (whence) {
432 case SEEK_SET:
433 off = 0;
434 break;
435 case SEEK_CUR:
436 off = f->offset;
437 break;
438 case SEEK_END:
439 off = size;
440 break;
441 default:
442 errno = EINVAL;
443 return (-1);
444 }
445 off += offset;
446 if (off < 0 || off > size) {
447 errno = EINVAL;
448 return (-1);
449 }
450 f->offset = (u_int)off;
451 f->c = 0;
452 return (off);
453 }
454
455 /*
456 * Close open file
457 */
458 static int
dos_close(struct open_file * fd)459 dos_close(struct open_file *fd)
460 {
461 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
462 DOS_FS *fs = f->fs;
463
464 f->fs->links--;
465 free(f);
466 dos_unmount_impl(fs);
467 return (0);
468 }
469
470 /*
471 * Return some stat information on a file.
472 */
473 static int
dos_stat(struct open_file * fd,struct stat * sb)474 dos_stat(struct open_file *fd, struct stat *sb)
475 {
476 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
477
478 /* only important stuff */
479 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
480 sb->st_nlink = 1;
481 sb->st_uid = 0;
482 sb->st_gid = 0;
483 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
484 return (EINVAL);
485 return (0);
486 }
487
488 static int
dos_checksum(unsigned char * name,unsigned char * ext)489 dos_checksum(unsigned char *name, unsigned char *ext)
490 {
491 int x, i;
492 char buf[11];
493
494 bcopy(name, buf, 8);
495 bcopy(ext, buf+8, 3);
496 x = 0;
497 for (i = 0; i < 11; i++) {
498 x = ((x & 1) << 7) | (x >> 1);
499 x += buf[i];
500 x &= 0xff;
501 }
502 return (x);
503 }
504
505 static int
dos_readdir(struct open_file * fd,struct dirent * d)506 dos_readdir(struct open_file *fd, struct dirent *d)
507 {
508 /* DOS_FILE *f = (DOS_FILE *)fd->f_fsdata; */
509 u_char fn[261];
510 DOS_DIR dd;
511 size_t res;
512 u_int chk, x, xdn;
513 int err;
514
515 x = chk = 0;
516 for (;;) {
517 xdn = x;
518 x = 0;
519 err = dos_read(fd, &dd, sizeof(dd), &res);
520 if (err)
521 return (err);
522 if (res == sizeof(dd))
523 return (ENOENT);
524 if (dd.de.name[0] == 0)
525 return (ENOENT);
526
527 /* Skip deleted entries */
528 if (dd.de.name[0] == 0xe5)
529 continue;
530
531 /* Check if directory entry is volume label */
532 if (dd.de.attr & FA_LABEL) {
533 /*
534 * If volume label set, check if the current entry is
535 * extended entry (FA_XDE) for long file names.
536 */
537 if ((dd.de.attr & FA_MASK) == FA_XDE) {
538 /*
539 * Read through all following extended entries
540 * to get the long file name. 0x40 marks the
541 * last entry containing part of long file name.
542 */
543 if (dd.xde.seq & 0x40)
544 chk = dd.xde.chk;
545 else if (dd.xde.seq != xdn - 1 ||
546 dd.xde.chk != chk)
547 continue;
548 x = dd.xde.seq & ~0x40;
549 if (x < 1 || x > 20) {
550 x = 0;
551 continue;
552 }
553 cp_xdnm(fn, &dd.xde);
554 } else {
555 /* skip only volume label entries */
556 continue;
557 }
558 } else {
559 if (xdn == 1) {
560 x = dos_checksum(dd.de.name, dd.de.ext);
561 if (x == chk)
562 break;
563 } else {
564 cp_sfn(fn, &dd.de);
565 break;
566 }
567 x = 0;
568 }
569 }
570
571 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
572 d->d_reclen = sizeof(*d);
573 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
574 memcpy(d->d_name, fn, sizeof(d->d_name));
575 return (0);
576 }
577
578 /*
579 * Parse DOS boot sector
580 */
581 static int
parsebs(DOS_FS * fs,DOS_BS * bs)582 parsebs(DOS_FS *fs, DOS_BS *bs)
583 {
584 u_int sc;
585
586 if ((bs->jmp[0] != 0x69 &&
587 bs->jmp[0] != 0xe9 &&
588 (bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
589 bs->bpb.media < 0xf0)
590 return (EINVAL);
591 if (cv2(bs->bpb.secsiz) != SECSIZ)
592 return (EINVAL);
593 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
594 return (EINVAL);
595 fs->bsize = secbyt(fs->spc);
596 fs->bshift = ffs(fs->bsize) - 1;
597 if ((fs->spf = cv2(bs->bpb.spf))) {
598 if (bs->bpb.fats != 2)
599 return (EINVAL);
600 if (!(fs->dirents = cv2(bs->bpb.dirents)))
601 return (EINVAL);
602 } else {
603 if (!(fs->spf = cv4(bs->bpb.lspf)))
604 return (EINVAL);
605 if (!bs->bpb.fats || bs->bpb.fats > 16)
606 return (EINVAL);
607 if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
608 return (EINVAL);
609 }
610 if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
611 return (EINVAL);
612 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
613 fs->lsndta = fs->lsndir + entsec(fs->dirents);
614 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
615 return (EINVAL);
616 if (fs->lsndta > sc)
617 return (EINVAL);
618 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
619 return (EINVAL);
620 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
621 sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
622 if (fs->xclus > sc)
623 fs->xclus = sc;
624 return (0);
625 }
626
627 /*
628 * Return directory entry from path
629 */
630 static int
namede(DOS_FS * fs,const char * path,DOS_DE ** dep)631 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
632 {
633 char name[256];
634 DOS_DE *de;
635 char *s;
636 size_t n;
637 int err;
638
639 err = 0;
640 de = &fs->root;
641 while (*path) {
642 while (*path == '/')
643 path++;
644 if (*path == '\0')
645 break;
646 if (!(s = strchr(path, '/')))
647 s = strchr(path, 0);
648 if ((n = s - path) > 255)
649 return (ENAMETOOLONG);
650 memcpy(name, path, n);
651 name[n] = 0;
652 path = s;
653 if (!(de->attr & FA_DIR))
654 return (ENOTDIR);
655 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
656 return (err);
657 }
658 *dep = de;
659 return (0);
660 }
661
662 /*
663 * Lookup path segment
664 */
665 static int
lookup(DOS_FS * fs,u_int clus,const char * name,DOS_DE ** dep)666 lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
667 {
668 static DOS_DIR dir[DEPSEC];
669 u_char lfn[261];
670 u_char sfn[13];
671 u_int nsec, lsec, xdn, chk, sec, ent, x;
672 int err, ok;
673
674 if (!clus)
675 for (ent = 0; ent < 2; ent++)
676 if (!strcasecmp(name, dotstr[ent])) {
677 *dep = dot + ent;
678 return (0);
679 }
680 if (!clus && fs->fatsz == 32)
681 clus = fs->rdcl;
682 nsec = !clus ? entsec(fs->dirents) : fs->spc;
683 lsec = 0;
684 xdn = chk = 0;
685 for (;;) {
686 if (!clus && !lsec)
687 lsec = fs->lsndir;
688 else if (okclus(fs, clus))
689 lsec = blklsn(fs, clus);
690 else
691 return (EINVAL);
692 for (sec = 0; sec < nsec; sec++) {
693 if ((err = ioget(fs->fd, lsec + sec, dir, secbyt(1))))
694 return (err);
695 for (ent = 0; ent < DEPSEC; ent++) {
696 if (!*dir[ent].de.name)
697 return (ENOENT);
698 if (*dir[ent].de.name != 0xe5) {
699 if ((dir[ent].de.attr & FA_MASK) ==
700 FA_XDE) {
701 x = dir[ent].xde.seq;
702 if (x & 0x40 || (x + 1 == xdn &&
703 dir[ent].xde.chk == chk)) {
704 if (x & 0x40) {
705 chk = dir[ent].xde.chk;
706 x &= ~0x40;
707 }
708 if (x >= 1 && x <= 20) {
709 cp_xdnm(lfn, &dir[ent].xde);
710 xdn = x;
711 continue;
712 }
713 }
714 } else if (!(dir[ent].de.attr &
715 FA_LABEL)) {
716 if ((ok = xdn == 1)) {
717 x = dos_checksum(
718 dir[ent].de.name,
719 dir[ent].de.ext);
720 ok = chk == x &&
721 !strcasecmp(name,
722 (const char *)lfn);
723 }
724 if (!ok) {
725 cp_sfn(sfn,
726 &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 }
736 xdn = 0;
737 }
738 }
739 if (!clus)
740 break;
741 if ((err = fatget(fs, &clus)))
742 return (err);
743 if (fatend(fs->fatsz, clus))
744 break;
745 }
746 return (ENOENT);
747 }
748
749 /*
750 * Copy name from extended directory entry
751 */
752 static void
cp_xdnm(u_char * lfn,DOS_XDE * xde)753 cp_xdnm(u_char *lfn, DOS_XDE *xde)
754 {
755 static struct {
756 u_int off;
757 u_int dim;
758 } ix[3] = {
759 {offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
760 {offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
761 {offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
762 };
763 u_char *p;
764 u_int n, x, c;
765
766 lfn += 13 * ((xde->seq & ~0x40) - 1);
767 for (n = 0; n < 3; n++)
768 for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
769 p += 2, x--) {
770 if ((c = cv2(p)) && (c < 32 || c > 127))
771 c = '?';
772 if (!(*lfn++ = c))
773 return;
774 }
775 if (xde->seq & 0x40)
776 *lfn = 0;
777 }
778
779 /*
780 * Copy short filename
781 */
782 static void
cp_sfn(u_char * sfn,DOS_DE * de)783 cp_sfn(u_char *sfn, DOS_DE *de)
784 {
785 u_char *p;
786 int j, i;
787
788 p = sfn;
789 if (*de->name != ' ') {
790 for (j = 7; de->name[j] == ' '; j--)
791 ;
792 for (i = 0; i <= j; i++)
793 *p++ = de->name[i];
794 if (*de->ext != ' ') {
795 *p++ = '.';
796 for (j = 2; de->ext[j] == ' '; j--)
797 ;
798 for (i = 0; i <= j; i++)
799 *p++ = de->ext[i];
800 }
801 }
802 *p = 0;
803 if (*sfn == 5)
804 *sfn = 0xe5;
805 }
806
807 /*
808 * Return size of file in bytes
809 */
810 static off_t
fsize(DOS_FS * fs,DOS_DE * de)811 fsize(DOS_FS *fs, DOS_DE *de)
812 {
813 u_long size;
814 u_int c;
815 int n;
816
817 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
818 if (!(c = cv2(de->clus))) {
819 size = fs->dirents * sizeof(DOS_DE);
820 } else {
821 if ((n = fatcnt(fs, c)) == -1)
822 return (n);
823 size = blkbyt(fs, n);
824 }
825 }
826 return (size);
827 }
828
829 /*
830 * Count number of clusters in chain
831 */
832 static int
fatcnt(DOS_FS * fs,u_int c)833 fatcnt(DOS_FS *fs, u_int c)
834 {
835 int n;
836
837 for (n = 0; okclus(fs, c); n++)
838 if (fatget(fs, &c))
839 return (-1);
840 return (fatend(fs->fatsz, c) ? n : -1);
841 }
842
843 /*
844 * Get next cluster in cluster chain. Use in core fat cache unless
845 * the number of current 128K block in FAT has changed.
846 */
847 static int
fatget(DOS_FS * fs,u_int * c)848 fatget(DOS_FS *fs, u_int *c)
849 {
850 u_int val_in, val_out, offset, blknum, nbyte;
851 const u_char *p_entry;
852 int err;
853
854 /* check input value to prevent overflow in fatoff() */
855 val_in = *c;
856 if (val_in & 0xf0000000)
857 return (EINVAL);
858
859 /* ensure that current 128K FAT block is cached */
860 offset = fatoff(fs->fatsz, val_in);
861 nbyte = fs->fatsz != 32 ? 2 : 4;
862 if (offset + nbyte > secbyt(fs->spf))
863 return (EINVAL);
864 blknum = offset / FATBLKSZ;
865 offset %= FATBLKSZ;
866 if (offset + nbyte > FATBLKSZ)
867 return (EINVAL);
868 if (blknum != fs->fatbuf_blknum) {
869 err = dos_read_fatblk(fs, fs->fd, blknum);
870 if (err != 0)
871 return (err);
872 }
873 p_entry = fs->fatbuf + offset;
874
875 /* extract cluster number from FAT entry */
876 switch (fs->fatsz) {
877 case 32:
878 val_out = cv4(p_entry);
879 val_out &= 0x0fffffff;
880 break;
881 case 16:
882 val_out = cv2(p_entry);
883 break;
884 case 12:
885 val_out = cv2(p_entry);
886 if (val_in & 1)
887 val_out >>= 4;
888 else
889 val_out &= 0xfff;
890 break;
891 default:
892 return (EINVAL);
893 }
894 *c = val_out;
895 return (0);
896 }
897
898 /*
899 * Is cluster an end-of-chain marker?
900 */
901 static int
fatend(u_int sz,u_int c)902 fatend(u_int sz, u_int c)
903 {
904 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
905 }
906
907 /*
908 * Offset-based I/O primitive
909 */
910 static int
ioread(DOS_FS * fs,u_int offset,void * buf,size_t nbyte)911 ioread(DOS_FS *fs, u_int offset, void *buf, size_t nbyte)
912 {
913 char *s;
914 u_int off, n;
915 int err;
916 u_char local_buf[SECSIZ];
917
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->fd, bytsec(offset), local_buf,
924 sizeof(local_buf));
925 if (err != 0)
926 return (err);
927 memcpy(s, local_buf + off, n);
928 offset += SECSIZ;
929 s += n;
930 nbyte -= n;
931 }
932 n = nbyte & (SECSIZ - 1);
933 if (nbyte -= n) {
934 if ((err = ioget(fs->fd, bytsec(offset), s, nbyte)))
935 return (err);
936 offset += nbyte;
937 s += nbyte;
938 }
939 if (n != 0) {
940 err = ioget(fs->fd, bytsec(offset), local_buf,
941 sizeof(local_buf));
942 if (err != 0)
943 return (err);
944 memcpy(s, local_buf, n);
945 }
946 return (0);
947 }
948
949 /*
950 * Sector-based I/O primitive
951 */
952 static int
ioget(struct open_file * fd,daddr_t lsec,void * buf,size_t size)953 ioget(struct open_file *fd, daddr_t lsec, void *buf, size_t size)
954 {
955 size_t rsize;
956 int rv;
957
958 /* Make sure we get full read or error. */
959 rsize = 0;
960 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
961 size, buf, &rsize);
962 if ((rv == 0) && (size != rsize))
963 rv = EIO;
964 return (rv);
965 }
966