Boot loader fixes - fix recursive malloc()/free() errors, NULL freed fields
[dragonfly.git] / lib / libstand / dosfs.c
CommitLineData
984263bc
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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 * $FreeBSD: src/lib/libstand/dosfs.c,v 1.4.2.1 2000/05/04 13:47:49 ps Exp $
1de703da 28 * $DragonFly: src/lib/libstand/dosfs.c,v 1.2 2003/06/17 04:26:51 dillon Exp $
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29 */
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
45static int dos_open(const char *path, struct open_file *fd);
46static int dos_close(struct open_file *fd);
47static int dos_read(struct open_file *fd, void *buf, size_t size, size_t *resid);
48static off_t dos_seek(struct open_file *fd, off_t offset, int whence);
49static int dos_stat(struct open_file *fd, struct stat *sb);
50
51struct fs_ops dosfs_fsops = {
52 "dosfs",
53 dos_open,
54 dos_close,
55 dos_read,
56 null_write,
57 dos_seek,
58 dos_stat,
59 null_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
68/* DOS "BIOS Parameter Block" */
69typedef struct {
70 u_char secsiz[2]; /* sector size */
71 u_char spc; /* sectors per cluster */
72 u_char ressec[2]; /* reserved sectors */
73 u_char fats; /* FATs */
74 u_char dirents[2]; /* root directory entries */
75 u_char secs[2]; /* total sectors */
76 u_char media; /* media descriptor */
77 u_char spf[2]; /* sectors per FAT */
78 u_char spt[2]; /* sectors per track */
79 u_char heads[2]; /* drive heads */
80 u_char hidsec[4]; /* hidden sectors */
81 u_char lsecs[4]; /* huge sectors */
82 u_char lspf[4]; /* huge sectors per FAT */
83 u_char xflg[2]; /* flags */
84 u_char vers[2]; /* filesystem version */
85 u_char rdcl[4]; /* root directory start cluster */
86 u_char infs[2]; /* filesystem info sector */
87 u_char bkbs[2]; /* backup boot sector */
88} DOS_BPB;
89
90/* Initial portion of DOS boot sector */
91typedef struct {
92 u_char jmp[3]; /* usually 80x86 'jmp' opcode */
93 u_char oem[8]; /* OEM name and version */
94 DOS_BPB bpb; /* BPB */
95} DOS_BS;
96
97/* Supply missing "." and ".." root directory entries */
98static const char *const dotstr[2] = {".", ".."};
99static DOS_DE dot[2] = {
100 {". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
101 {0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
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};
105
106/* The usual conversion macros to avoid multiplication and division */
107#define bytsec(n) ((n) >> SSHIFT)
108#define secbyt(s) ((s) << SSHIFT)
109#define entsec(e) ((e) >> DSHIFT)
110#define bytblk(fs, n) ((n) >> (fs)->bshift)
111#define blkbyt(fs, b) ((b) << (fs)->bshift)
112#define secblk(fs, s) ((s) >> ((fs)->bshift - SSHIFT))
113#define blksec(fs, b) ((b) << ((fs)->bshift - SSHIFT))
114
115/* Convert cluster number to offset within filesystem */
116#define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
117
118/* Convert cluster number to logical sector number */
119#define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
120
121/* Convert cluster number to offset within FAT */
122#define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
123 (sz) == 16 ? (c) << 1 : \
124 (c) << 2)
125
126/* Does cluster number reference a valid data cluster? */
127#define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
128
129/* Get start cluster from directory entry */
130#define stclus(sz, de) ((sz) != 32 ? cv2((de)->clus) : \
131 ((u_int)cv2((de)->dex.h_clus) << 16) | \
132 cv2((de)->clus))
133
134static int dosunmount(DOS_FS *);
135static int parsebs(DOS_FS *, DOS_BS *);
136static int namede(DOS_FS *, const char *, DOS_DE **);
137static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
138static void cp_xdnm(u_char *, DOS_XDE *);
139static void cp_sfn(u_char *, DOS_DE *);
140static off_t fsize(DOS_FS *, DOS_DE *);
141static int fatcnt(DOS_FS *, u_int);
142static int fatget(DOS_FS *, u_int *);
143static int fatend(u_int, u_int);
144static int ioread(DOS_FS *, u_int, void *, u_int);
145static int iobuf(DOS_FS *, u_int);
146static int ioget(struct open_file *, u_int, void *, u_int);
147
148/*
149 * Mount DOS filesystem
150 */
151static int
152dos_mount(DOS_FS *fs, struct open_file *fd)
153{
154 int err;
155
156 bzero(fs, sizeof(DOS_FS));
157 fs->fd = fd;
158 if ((err = !(fs->buf = malloc(SECSIZ)) ? errno : 0) ||
159 (err = ioget(fs->fd, 0, fs->buf, 1)) ||
160 (err = parsebs(fs, (DOS_BS *)fs->buf))) {
161 (void)dosunmount(fs);
162 return(err);
163 }
164 return 0;
165}
166
167/*
168 * Unmount mounted filesystem
169 */
170static int
171dos_unmount(DOS_FS *fs)
172{
173 int err;
174
175 if (fs->links)
176 return(EBUSY);
177 if ((err = dosunmount(fs)))
178 return(err);
179 return 0;
180}
181
182/*
183 * Common code shared by dos_mount() and dos_unmount()
184 */
185static int
186dosunmount(DOS_FS *fs)
187{
188 if (fs->buf)
189 free(fs->buf);
190 free(fs);
191 return(0);
192}
193
194/*
195 * Open DOS file
196 */
197static int
198dos_open(const char *path, struct open_file *fd)
199{
200 DOS_DE *de;
201 DOS_FILE *f;
202 DOS_FS *fs;
203 u_int size, clus;
204 int err = 0;
205
206 /* Allocate mount structure, associate with open */
207 fs = malloc(sizeof(DOS_FS));
208
209 if ((err = dos_mount(fs, fd)))
210 goto out;
211
212 if ((err = namede(fs, path, &de)))
213 goto out;
214
215 clus = stclus(fs->fatsz, de);
216 size = cv4(de->size);
217
218 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
219 ((de->attr & FA_DIR) && size) ||
220 (clus && !okclus(fs, clus))) {
221 err = EINVAL;
222 goto out;
223 }
224 f = malloc(sizeof(DOS_FILE));
225 bzero(f, sizeof(DOS_FILE));
226 f->fs = fs;
227 fs->links++;
228 f->de = *de;
229 fd->f_fsdata = (void *)f;
230
231 out:
232 return(err);
233}
234
235/*
236 * Read from file
237 */
238static int
239dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
240{
241 off_t size;
242 u_int nb, off, clus, c, cnt, n;
243 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
244 int err = 0;
245
246 nb = (u_int)nbyte;
247 if ((size = fsize(f->fs, &f->de)) == -1)
248 return EINVAL;
249 if (nb > (n = size - f->offset))
250 nb = n;
251 off = f->offset;
252 if ((clus = stclus(f->fs->fatsz, &f->de)))
253 off &= f->fs->bsize - 1;
254 c = f->c;
255 cnt = nb;
256 while (cnt) {
257 n = 0;
258 if (!c) {
259 if ((c = clus))
260 n = bytblk(f->fs, f->offset);
261 } else if (!off)
262 n++;
263 while (n--) {
264 if ((err = fatget(f->fs, &c)))
265 goto out;
266 if (!okclus(f->fs, c)) {
267 err = EINVAL;
268 goto out;
269 }
270 }
271 if (!clus || (n = f->fs->bsize - off) > cnt)
272 n = cnt;
273 if ((err = ioread(f->fs, (c ? blkoff(f->fs, c) :
274 secbyt(f->fs->lsndir)) + off,
275 buf, n)))
276 goto out;
277 f->offset += n;
278 f->c = c;
279 off = 0;
280 buf += n;
281 cnt -= n;
282 }
283 out:
284 if (resid)
285 *resid = nbyte - nb + cnt;
286 return(err);
287}
288
289/*
290 * Reposition within file
291 */
292static off_t
293dos_seek(struct open_file *fd, off_t offset, int whence)
294{
295 off_t off;
296 u_int size;
297 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
298
299 size = cv4(f->de.size);
300 switch (whence) {
301 case SEEK_SET:
302 off = 0;
303 break;
304 case SEEK_CUR:
305 off = f->offset;
306 break;
307 case SEEK_END:
308 off = size;
309 break;
310 default:
311 return(-1);
312 }
313 off += offset;
314 if (off < 0 || off > size)
315 return(-1);
316 f->offset = (u_int)off;
317 f->c = 0;
318 return(off);
319}
320
321/*
322 * Close open file
323 */
324static int
325dos_close(struct open_file *fd)
326{
327 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
6825e71f 328 DOS_FS *fs;
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330 fd->f_fsdata = NULL;
331 if (f) {
332 fs = f->fs;
333 f->fs = NULL;
334 fs->links--;
335 free(f);
336 dos_unmount(fs);
337 }
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338 return 0;
339}
340
341/*
342 * Return some stat information on a file.
343 */
344static int
345dos_stat(struct open_file *fd, struct stat *sb)
346{
347 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
348
349 /* only important stuff */
350 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
351 sb->st_nlink = 1;
352 sb->st_uid = 0;
353 sb->st_gid = 0;
354 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
355 return EINVAL;
356 return (0);
357}
358
359/*
360 * Parse DOS boot sector
361 */
362static int
363parsebs(DOS_FS *fs, DOS_BS *bs)
364{
365 u_int sc;
366
367 if ((bs->jmp[0] != 0x69 &&
368 bs->jmp[0] != 0xe9 &&
369 (bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
370 bs->bpb.media < 0xf0)
371 return EINVAL;
372 if (cv2(bs->bpb.secsiz) != SECSIZ)
373 return EINVAL;
374 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
375 return EINVAL;
376 fs->bsize = secbyt(fs->spc);
377 fs->bshift = ffs(fs->bsize) - 1;
378 if ((fs->spf = cv2(bs->bpb.spf))) {
379 if (bs->bpb.fats != 2)
380 return EINVAL;
381 if (!(fs->dirents = cv2(bs->bpb.dirents)))
382 return EINVAL;
383 } else {
384 if (!(fs->spf = cv4(bs->bpb.lspf)))
385 return EINVAL;
386 if (!bs->bpb.fats || bs->bpb.fats > 16)
387 return EINVAL;
388 if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
389 return EINVAL;
390 }
391 if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
392 return EINVAL;
393 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
394 fs->lsndta = fs->lsndir + entsec(fs->dirents);
395 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
396 return EINVAL;
397 if (fs->lsndta > sc)
398 return EINVAL;
399 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
400 return EINVAL;
401 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
402 sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
403 if (fs->xclus > sc)
404 fs->xclus = sc;
405 return 0;
406}
407
408/*
409 * Return directory entry from path
410 */
411static int
412namede(DOS_FS *fs, const char *path, DOS_DE **dep)
413{
414 char name[256];
415 DOS_DE *de;
416 char *s;
417 size_t n;
418 int err;
419
420 err = 0;
421 de = dot;
422 if (*path == '/')
423 path++;
424 while (*path) {
425 if (!(s = strchr(path, '/')))
426 s = strchr(path, 0);
427 if ((n = s - path) > 255)
428 return ENAMETOOLONG;
429 memcpy(name, path, n);
430 name[n] = 0;
431 path = s;
432 if (!(de->attr & FA_DIR))
433 return ENOTDIR;
434 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
435 return err;
436 if (*path == '/')
437 path++;
438 }
439 *dep = de;
440 return 0;
441}
442
443/*
444 * Lookup path segment
445 */
446static int
447lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
448{
449 static DOS_DIR dir[DEPSEC];
450 u_char lfn[261];
451 u_char sfn[13];
452 u_int nsec, lsec, xdn, chk, sec, ent, x;
453 int err, ok, i;
454
455 if (!clus)
456 for (ent = 0; ent < 2; ent++)
457 if (!strcasecmp(name, dotstr[ent])) {
458 *dep = dot + ent;
459 return 0;
460 }
461 if (!clus && fs->fatsz == 32)
462 clus = fs->rdcl;
463 nsec = !clus ? entsec(fs->dirents) : fs->spc;
464 lsec = 0;
465 xdn = chk = 0;
466 for (;;) {
467 if (!clus && !lsec)
468 lsec = fs->lsndir;
469 else if (okclus(fs, clus))
470 lsec = blklsn(fs, clus);
471 else
472 return EINVAL;
473 for (sec = 0; sec < nsec; sec++) {
474 if ((err = ioget(fs->fd, lsec + sec, dir, 1)))
475 return err;
476 for (ent = 0; ent < DEPSEC; ent++) {
477 if (!*dir[ent].de.name)
478 return ENOENT;
479 if (*dir[ent].de.name != 0xe5) {
480 if ((dir[ent].de.attr & FA_MASK) == FA_XDE) {
481 x = dir[ent].xde.seq;
482 if (x & 0x40 || (x + 1 == xdn &&
483 dir[ent].xde.chk == chk)) {
484 if (x & 0x40) {
485 chk = dir[ent].xde.chk;
486 x &= ~0x40;
487 }
488 if (x >= 1 && x <= 20) {
489 cp_xdnm(lfn, &dir[ent].xde);
490 xdn = x;
491 continue;
492 }
493 }
494 } else if (!(dir[ent].de.attr & FA_LABEL)) {
495 if ((ok = xdn == 1)) {
496 for (x = 0, i = 0; i < 11; i++)
497 x = ((((x & 1) << 7) | (x >> 1)) +
498 dir[ent].de.name[i]) & 0xff;
499 ok = chk == x &&
500 !strcasecmp(name, (const char *)lfn);
501 }
502 if (!ok) {
503 cp_sfn(sfn, &dir[ent].de);
504 ok = !strcasecmp(name, (const char *)sfn);
505 }
506 if (ok) {
507 *dep = &dir[ent].de;
508 return 0;
509 }
510 }
511 }
512 xdn = 0;
513 }
514 }
515 if (!clus)
516 break;
517 if ((err = fatget(fs, &clus)))
518 return err;
519 if (fatend(fs->fatsz, clus))
520 break;
521 }
522 return ENOENT;
523}
524
525/*
526 * Copy name from extended directory entry
527 */
528static void
529cp_xdnm(u_char *lfn, DOS_XDE *xde)
530{
531 static struct {
532 u_int off;
533 u_int dim;
534 } ix[3] = {
535 {offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
536 {offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
537 {offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
538 };
539 u_char *p;
540 u_int n, x, c;
541
542 lfn += 13 * ((xde->seq & ~0x40) - 1);
543 for (n = 0; n < 3; n++)
544 for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
545 p += 2, x--) {
546 if ((c = cv2(p)) && (c < 32 || c > 127))
547 c = '?';
548 if (!(*lfn++ = c))
549 return;
550 }
551 if (xde->seq & 0x40)
552 *lfn = 0;
553}
554
555/*
556 * Copy short filename
557 */
558static void
559cp_sfn(u_char *sfn, DOS_DE *de)
560{
561 u_char *p;
562 int j, i;
563
564 p = sfn;
565 if (*de->name != ' ') {
566 for (j = 7; de->name[j] == ' '; j--);
567 for (i = 0; i <= j; i++)
568 *p++ = de->name[i];
569 if (*de->ext != ' ') {
570 *p++ = '.';
571 for (j = 2; de->ext[j] == ' '; j--);
572 for (i = 0; i <= j; i++)
573 *p++ = de->ext[i];
574 }
575 }
576 *p = 0;
577 if (*sfn == 5)
578 *sfn = 0xe5;
579}
580
581/*
582 * Return size of file in bytes
583 */
584static off_t
585fsize(DOS_FS *fs, DOS_DE *de)
586{
587 u_long size;
588 u_int c;
589 int n;
590
591 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
592 if (!(c = cv2(de->clus)))
593 size = fs->dirents * sizeof(DOS_DE);
594 else {
595 if ((n = fatcnt(fs, c)) == -1)
596 return n;
597 size = blkbyt(fs, n);
598 }
599 }
600 return size;
601}
602
603/*
604 * Count number of clusters in chain
605 */
606static int
607fatcnt(DOS_FS *fs, u_int c)
608{
609 int n;
610
611 for (n = 0; okclus(fs, c); n++)
612 if (fatget(fs, &c))
613 return -1;
614 return fatend(fs->fatsz, c) ? n : -1;
615}
616
617/*
618 * Get next cluster in cluster chain
619 */
620static int
621fatget(DOS_FS *fs, u_int *c)
622{
623 u_char buf[4];
624 u_int x;
625 int err;
626
627 err = ioread(fs, secbyt(fs->lsnfat) + fatoff(fs->fatsz, *c), buf,
628 fs->fatsz != 32 ? 2 : 4);
629 if (err)
630 return err;
631 x = fs->fatsz != 32 ? cv2(buf) : cv4(buf);
632 *c = fs->fatsz == 12 ? *c & 1 ? x >> 4 : x & 0xfff : x;
633 return 0;
634}
635
636/*
637 * Is cluster an end-of-chain marker?
638 */
639static int
640fatend(u_int sz, u_int c)
641{
642 return c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7);
643}
644
645/*
646 * Offset-based I/O primitive
647 */
648static int
649ioread(DOS_FS *fs, u_int offset, void *buf, u_int nbyte)
650{
651 char *s;
652 u_int off, n;
653 int err;
654
655 s = buf;
656 if ((off = offset & (SECSIZ - 1))) {
657 offset -= off;
658 if ((err = iobuf(fs, bytsec(offset))))
659 return err;
660 offset += SECSIZ;
661 if ((n = SECSIZ - off) > nbyte)
662 n = nbyte;
663 memcpy(s, fs->buf + off, n);
664 s += n;
665 nbyte -= n;
666 }
667 n = nbyte & (SECSIZ - 1);
668 if (nbyte -= n) {
669 if ((err = ioget(fs->fd, bytsec(offset), s, bytsec(nbyte))))
670 return err;
671 offset += nbyte;
672 s += nbyte;
673 }
674 if (n) {
675 if ((err = iobuf(fs, bytsec(offset))))
676 return err;
677 memcpy(s, fs->buf, n);
678 }
679 return 0;
680}
681
682/*
683 * Buffered sector-based I/O primitive
684 */
685static int
686iobuf(DOS_FS *fs, u_int lsec)
687{
688 int err;
689
690 if (fs->bufsec != lsec) {
691 if ((err = ioget(fs->fd, lsec, fs->buf, 1)))
692 return err;
693 fs->bufsec = lsec;
694 }
695 return 0;
696}
697
698/*
699 * Sector-based I/O primitive
700 */
701static int
702ioget(struct open_file *fd, u_int lsec, void *buf, u_int nsec)
703{
704 int err;
705
706 if ((err = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
707 secbyt(nsec), buf, NULL)))
708 return(err);
709 return(0);
710}