2 * Copyright (c) 1996, 1998 Robert Nordier
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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
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.
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
32 * Readonly filesystem for Microsoft FAT12/FAT16/FAT32 filesystems,
36 #include <sys/types.h>
45 static int dos_open(const char *path, struct open_file *fd);
46 static int dos_close(struct open_file *fd);
47 static int dos_read(struct open_file *fd, void *buf, size_t size, size_t *resid);
48 static off_t dos_seek(struct open_file *fd, off_t offset, int whence);
49 static int dos_stat(struct open_file *fd, struct stat *sb);
50 static int dos_readdir(struct open_file *fd, struct dirent *d);
52 struct fs_ops dosfs_fsops = {
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 */
70 /* DOS "BIOS Parameter Block" */
72 u_char secsiz[2]; /* sector size */
73 u_char spc; /* sectors per cluster */
74 u_char ressec[2]; /* reserved sectors */
75 u_char fats; /* FATs */
76 u_char dirents[2]; /* root directory entries */
77 u_char secs[2]; /* total sectors */
78 u_char media; /* media descriptor */
79 u_char spf[2]; /* sectors per FAT */
80 u_char spt[2]; /* sectors per track */
81 u_char heads[2]; /* drive heads */
82 u_char hidsec[4]; /* hidden sectors */
83 u_char lsecs[4]; /* huge sectors */
84 u_char lspf[4]; /* huge sectors per FAT */
85 u_char xflg[2]; /* flags */
86 u_char vers[2]; /* filesystem version */
87 u_char rdcl[4]; /* root directory start cluster */
88 u_char infs[2]; /* filesystem info sector */
89 u_char bkbs[2]; /* backup boot sector */
92 /* Initial portion of DOS boot sector */
94 u_char jmp[3]; /* usually 80x86 'jmp' opcode */
95 u_char oem[8]; /* OEM name and version */
96 DOS_BPB bpb; /* BPB */
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}}
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))
117 /* Convert cluster number to offset within filesystem */
118 #define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
120 /* Convert cluster number to logical sector number */
121 #define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
123 /* Convert cluster number to offset within FAT */
124 #define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
125 (sz) == 16 ? (c) << 1 : \
128 /* Does cluster number reference a valid data cluster? */
129 #define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
131 /* Get start cluster from directory entry */
132 #define stclus(sz, de) ((sz) != 32 ? cv2((de)->clus) : \
133 ((u_int)cv2((de)->dex.h_clus) << 16) | \
136 static int parsebs(DOS_FS *, DOS_BS *);
137 static int namede(DOS_FS *, const char *, DOS_DE **);
138 static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
139 static void cp_xdnm(u_char *, DOS_XDE *);
140 static void cp_sfn(u_char *, DOS_DE *);
141 static off_t fsize(DOS_FS *, DOS_DE *);
142 static int fatcnt(DOS_FS *, u_int);
143 static int fatget(DOS_FS *, u_int *);
144 static int fatend(u_int, u_int);
145 static int ioread(DOS_FS *, u_int, void *, size_t);
146 static int ioget(struct open_file *, daddr_t, void *, size_t);
149 dos_read_fatblk(DOS_FS *fs, struct open_file *fd, u_int blknum)
153 daddr_t offset_in_fat, max_offset_in_fat;
155 offset_in_fat = ((daddr_t)blknum) * FATBLKSZ;
156 max_offset_in_fat = secbyt(fs->spf);
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));
164 err = ioget(fd, fs->lsnfat + bytsec(offset_in_fat),
165 fs->fatbuf, io_size);
167 fs->fatbuf_blknum = ((u_int)(-1));
171 if (io_size < FATBLKSZ)
172 memset(fs->fatbuf + io_size, 0, FATBLKSZ - io_size);
174 fs->fatbuf_blknum = blknum;
179 * Mount DOS filesystem
182 dos_mount(DOS_FS *fs, struct open_file *fd)
187 bzero(fs, sizeof(DOS_FS));
190 if ((buf = malloc(secbyt(1))) == NULL)
192 if ((err = ioget(fs->fd, 0, buf, secbyt(1))) ||
193 (err = parsebs(fs, (DOS_BS *)buf))) {
199 if ((fs->fatbuf = malloc(FATBLKSZ)) == NULL)
201 err = dos_read_fatblk(fs, fd, 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;
219 * Unmount mounted filesystem
222 dos_unmount(DOS_FS *fs)
235 dos_open(const char *path, struct open_file *fd)
243 /* Allocate mount structure, associate with open */
244 if ((fs = malloc(sizeof(DOS_FS))) == NULL)
246 if ((err = dos_mount(fs, fd))) {
251 if ((err = namede(fs, path, &de))) {
256 clus = stclus(fs->fatsz, de);
257 size = cv4(de->size);
259 if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
260 ((de->attr & FA_DIR) && size) ||
261 (clus && !okclus(fs, clus))) {
265 if ((f = malloc(sizeof(DOS_FILE))) == NULL) {
270 bzero(f, sizeof(DOS_FILE));
274 fd->f_fsdata = (void *)f;
282 dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
285 u_int nb, off, clus, c, cnt, n;
286 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
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
297 if ((size = fsize(f->fs, &f->de)) == -1)
299 if (nb > (n = size - f->offset))
302 if ((clus = stclus(f->fs->fatsz, &f->de)))
303 off &= f->fs->bsize - 1;
310 n = bytblk(f->fs, f->offset);
314 if ((err = fatget(f->fs, &c)))
316 if (!okclus(f->fs, c)) {
321 if (!clus || (n = f->fs->bsize - off) > cnt)
323 if ((err = ioread(f->fs, (c ? blkoff(f->fs, c) :
324 secbyt(f->fs->lsndir)) + off, buf, n)))
329 buf = (char *)buf + n;
334 *resid = nbyte - nb + cnt;
339 * Reposition within file
342 dos_seek(struct open_file *fd, off_t offset, int whence)
346 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
348 size = cv4(f->de.size);
364 if (off < 0 || off > size) {
368 f->offset = (u_int)off;
377 dos_close(struct open_file *fd)
379 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
389 * Return some stat information on a file.
392 dos_stat(struct open_file *fd, struct stat *sb)
394 DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
396 /* only important stuff */
397 sb->st_mode = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 0444;
401 if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
407 dos_checksum(unsigned char *name, unsigned char *ext)
413 bcopy(ext, buf+8, 3);
415 for (i = 0; i < 11; i++) {
416 x = ((x & 1) << 7) | (x >> 1);
424 dos_readdir(struct open_file *fd, struct dirent *d)
426 /* DOS_FILE *f = (DOS_FILE *)fd->f_fsdata; */
437 err = dos_read(fd, &dd, sizeof(dd), &res);
440 if (res == sizeof(dd))
442 if (dd.de.name[0] == 0)
445 /* Skip deleted entries */
446 if (dd.de.name[0] == 0xe5)
449 /* Check if directory entry is volume label */
450 if (dd.de.attr & FA_LABEL) {
452 * If volume label set, check if the current entry is
453 * extended entry (FA_XDE) for long file names.
455 if ((dd.de.attr & FA_MASK) == FA_XDE) {
457 * Read through all following extended entries
458 * to get the long file name. 0x40 marks the
459 * last entry containing part of long file name.
461 if (dd.xde.seq & 0x40)
463 else if (dd.xde.seq != xdn - 1 ||
466 x = dd.xde.seq & ~0x40;
467 if (x < 1 || x > 20) {
471 cp_xdnm(fn, &dd.xde);
473 /* skip only volume label entries */
478 x = dos_checksum(dd.de.name, dd.de.ext);
489 d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
490 d->d_reclen = sizeof(*d);
491 d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
492 memcpy(d->d_name, fn, sizeof(d->d_name));
497 * Parse DOS boot sector
500 parsebs(DOS_FS *fs, DOS_BS *bs)
504 if ((bs->jmp[0] != 0x69 &&
505 bs->jmp[0] != 0xe9 &&
506 (bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
507 bs->bpb.media < 0xf0)
509 if (cv2(bs->bpb.secsiz) != SECSIZ)
511 if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
513 fs->bsize = secbyt(fs->spc);
514 fs->bshift = ffs(fs->bsize) - 1;
515 if ((fs->spf = cv2(bs->bpb.spf))) {
516 if (bs->bpb.fats != 2)
518 if (!(fs->dirents = cv2(bs->bpb.dirents)))
521 if (!(fs->spf = cv4(bs->bpb.lspf)))
523 if (!bs->bpb.fats || bs->bpb.fats > 16)
525 if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
528 if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
530 fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
531 fs->lsndta = fs->lsndir + entsec(fs->dirents);
532 if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
536 if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
538 fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
539 sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
546 * Return directory entry from path
549 namede(DOS_FS *fs, const char *path, DOS_DE **dep)
564 if (!(s = strchr(path, '/')))
566 if ((n = s - path) > 255)
567 return (ENAMETOOLONG);
568 memcpy(name, path, n);
571 if (!(de->attr & FA_DIR))
573 if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
581 * Lookup path segment
584 lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
586 static DOS_DIR dir[DEPSEC];
589 u_int nsec, lsec, xdn, chk, sec, ent, x;
593 for (ent = 0; ent < 2; ent++)
594 if (!strcasecmp(name, dotstr[ent])) {
598 if (!clus && fs->fatsz == 32)
600 nsec = !clus ? entsec(fs->dirents) : fs->spc;
606 else if (okclus(fs, clus))
607 lsec = blklsn(fs, clus);
610 for (sec = 0; sec < nsec; sec++) {
611 if ((err = ioget(fs->fd, lsec + sec, dir, secbyt(1))))
613 for (ent = 0; ent < DEPSEC; ent++) {
614 if (!*dir[ent].de.name)
616 if (*dir[ent].de.name != 0xe5) {
617 if ((dir[ent].de.attr & FA_MASK) ==
619 x = dir[ent].xde.seq;
620 if (x & 0x40 || (x + 1 == xdn &&
621 dir[ent].xde.chk == chk)) {
623 chk = dir[ent].xde.chk;
626 if (x >= 1 && x <= 20) {
627 cp_xdnm(lfn, &dir[ent].xde);
632 } else if (!(dir[ent].de.attr &
634 if ((ok = xdn == 1)) {
645 ok = !strcasecmp(name,
659 if ((err = fatget(fs, &clus)))
661 if (fatend(fs->fatsz, clus))
668 * Copy name from extended directory entry
671 cp_xdnm(u_char *lfn, DOS_XDE *xde)
677 {offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
678 {offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
679 {offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
684 lfn += 13 * ((xde->seq & ~0x40) - 1);
685 for (n = 0; n < 3; n++)
686 for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
688 if ((c = cv2(p)) && (c < 32 || c > 127))
698 * Copy short filename
701 cp_sfn(u_char *sfn, DOS_DE *de)
707 if (*de->name != ' ') {
708 for (j = 7; de->name[j] == ' '; j--)
710 for (i = 0; i <= j; i++)
712 if (*de->ext != ' ') {
714 for (j = 2; de->ext[j] == ' '; j--)
716 for (i = 0; i <= j; i++)
726 * Return size of file in bytes
729 fsize(DOS_FS *fs, DOS_DE *de)
735 if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
736 if (!(c = cv2(de->clus))) {
737 size = fs->dirents * sizeof(DOS_DE);
739 if ((n = fatcnt(fs, c)) == -1)
741 size = blkbyt(fs, n);
748 * Count number of clusters in chain
751 fatcnt(DOS_FS *fs, u_int c)
755 for (n = 0; okclus(fs, c); n++)
758 return (fatend(fs->fatsz, c) ? n : -1);
762 * Get next cluster in cluster chain. Use in core fat cache unless
763 * the number of current 128K block in FAT has changed.
766 fatget(DOS_FS *fs, u_int *c)
768 u_int val_in, val_out, offset, blknum, nbyte;
769 const u_char *p_entry;
772 /* check input value to prevent overflow in fatoff() */
774 if (val_in & 0xf0000000)
777 /* ensure that current 128K FAT block is cached */
778 offset = fatoff(fs->fatsz, val_in);
779 nbyte = fs->fatsz != 32 ? 2 : 4;
780 if (offset + nbyte > secbyt(fs->spf))
782 blknum = offset / FATBLKSZ;
784 if (offset + nbyte > FATBLKSZ)
786 if (blknum != fs->fatbuf_blknum) {
787 err = dos_read_fatblk(fs, fs->fd, blknum);
791 p_entry = fs->fatbuf + offset;
793 /* extract cluster number from FAT entry */
796 val_out = cv4(p_entry);
797 val_out &= 0x0fffffff;
800 val_out = cv2(p_entry);
803 val_out = cv2(p_entry);
817 * Is cluster an end-of-chain marker?
820 fatend(u_int sz, u_int c)
822 return (c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7));
826 * Offset-based I/O primitive
829 ioread(DOS_FS *fs, u_int offset, void *buf, size_t nbyte)
834 u_char local_buf[SECSIZ];
837 if ((off = offset & (SECSIZ - 1))) {
839 if ((n = SECSIZ - off) > nbyte)
841 err = ioget(fs->fd, bytsec(offset), local_buf,
845 memcpy(s, local_buf + off, n);
850 n = nbyte & (SECSIZ - 1);
852 if ((err = ioget(fs->fd, bytsec(offset), s, nbyte)))
858 err = ioget(fs->fd, bytsec(offset), local_buf,
862 memcpy(s, local_buf, n);
868 * Sector-based I/O primitive
871 ioget(struct open_file *fd, daddr_t lsec, void *buf, size_t size)
876 /* Make sure we get full read or error. */
878 rv = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
880 if ((rv == 0) && (size != rsize))