661 lines
17 KiB
C
661 lines
17 KiB
C
/*
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* Copyright (c) 1996, 1998 Robert Nordier
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Readonly filesystem for Microsoft FAT12/FAT16/FAT32 filesystems,
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* also supports VFAT.
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*/
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#include <sys/types.h>
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#include <string.h>
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#include <stddef.h>
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#include "stand.h"
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#if 0
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#include <unistd.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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#endif
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#include "dosfs.h"
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static int dos_open(char *path, struct open_file *fd);
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static int dos_close(struct open_file *fd);
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static int dos_read(struct open_file *fd, void *buf, size_t size, size_t *resid);
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static off_t dos_seek(struct open_file *fd, off_t offset, int whence);
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static int dos_stat(struct open_file *fd, struct stat *sb);
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struct fs_ops dos_fsops = {
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"dosfs", dos_open, dos_close, dos_read, null_write, dos_seek, dos_stat
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};
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#define SECSIZ 512 /* sector size */
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#define SSHIFT 9 /* SECSIZ shift */
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#define DEPSEC 16 /* directory entries per sector */
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#define DSHIFT 4 /* DEPSEC shift */
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#define LOCLUS 2 /* lowest cluster number */
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/* DOS "BIOS Parameter Block" */
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typedef struct {
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u_char secsiz[2]; /* sector size */
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u_char spc; /* sectors per cluster */
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u_char ressec[2]; /* reserved sectors */
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u_char fats; /* FATs */
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u_char dirents[2]; /* root directory entries */
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u_char secs[2]; /* total sectors */
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u_char media; /* media descriptor */
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u_char spf[2]; /* sectors per FAT */
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u_char spt[2]; /* sectors per track */
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u_char heads[2]; /* drive heads */
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u_char hidsec[4]; /* hidden sectors */
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u_char lsecs[4]; /* huge sectors */
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u_char lspf[4]; /* huge sectors per FAT */
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u_char xflg[2]; /* flags */
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u_char vers[2]; /* filesystem version */
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u_char rdcl[4]; /* root directory start cluster */
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u_char infs[2]; /* filesystem info sector */
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u_char bkbs[2]; /* backup boot sector */
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} DOS_BPB;
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/* Initial portion of DOS boot sector */
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typedef struct {
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u_char jmp[3]; /* usually 80x86 'jmp' opcode */
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u_char oem[8]; /* OEM name and version */
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DOS_BPB bpb; /* BPB */
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} DOS_BS;
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/* Supply missing "." and ".." root directory entries */
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static const char *const dotstr[2] = {".", ".."};
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static DOS_DE dot[2] = {
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{". ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
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{0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}},
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{".. ", " ", FA_DIR, {0, 0, {0, 0}, {0, 0}, {0, 0}, {0, 0}},
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{0, 0}, {0x21, 0}, {0, 0}, {0, 0, 0, 0}}
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};
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/* The usual conversion macros to avoid multiplication and division */
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#define bytsec(n) ((n) >> SSHIFT)
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#define secbyt(s) ((s) << SSHIFT)
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#define entsec(e) ((e) >> DSHIFT)
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#define bytblk(fs, n) ((n) >> (fs)->bshift)
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#define blkbyt(fs, b) ((b) << (fs)->bshift)
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#define secblk(fs, s) ((s) >> ((fs)->bshift - SSHIFT))
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#define blksec(fs, b) ((b) << ((fs)->bshift - SSHIFT))
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/* Convert cluster number to offset within filesystem */
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#define blkoff(fs, b) (secbyt((fs)->lsndta) + blkbyt(fs, (b) - LOCLUS))
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/* Convert cluster number to logical sector number */
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#define blklsn(fs, b) ((fs)->lsndta + blksec(fs, (b) - LOCLUS))
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/* Convert cluster number to offset within FAT */
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#define fatoff(sz, c) ((sz) == 12 ? (c) + ((c) >> 1) : \
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(sz) == 16 ? (c) << 1 : \
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(c) << 2)
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/* Does cluster number reference a valid data cluster? */
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#define okclus(fs, c) ((c) >= LOCLUS && (c) <= (fs)->xclus)
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/* Get start cluster from directory entry */
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#define stclus(sz, de) ((sz) != 32 ? cv2((de)->clus) : \
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((u_int)cv2((de)->dex.h_clus) << 16) | \
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cv2((de)->clus))
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static int dosunmount(DOS_FS *);
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static int parsebs(DOS_FS *, DOS_BS *);
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static int namede(DOS_FS *, const char *, DOS_DE **);
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static int lookup(DOS_FS *, u_int, const char *, DOS_DE **);
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static void cp_xdnm(u_char *, DOS_XDE *);
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static void cp_sfn(u_char *, DOS_DE *);
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static int fatget(DOS_FS *, u_int *);
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static int fatend(u_int, u_int);
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static int ioread(DOS_FS *, u_int, void *, u_int);
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static int iobuf(DOS_FS *, u_int);
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static int ioget(struct open_file *, u_int, void *, u_int);
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/*
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* Mount DOS filesystem
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*/
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static int
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dos_mount(DOS_FS *fs, struct open_file *fd)
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{
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int err;
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bzero(fs, sizeof(DOS_FS));
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fs->fd = fd;
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if ((err = !(fs->buf = alloc(SECSIZ)) ? errno : 0) ||
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(err = ioget(fs->fd, 0, fs->buf, 1)) ||
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(err = parsebs(fs, (DOS_BS *)fs->buf))) {
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(void)dosunmount(fs);
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return(err);
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}
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return 0;
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}
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/*
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* Unmount mounted filesystem
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*/
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static int
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dos_unmount(DOS_FS *fs)
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{
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int err;
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if (fs->links)
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return(EBUSY);
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if ((err = dosunmount(fs)))
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return(err);
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return 0;
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}
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/*
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* Common code shared by dos_mount() and dos_unmount()
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*/
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static int
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dosunmount(DOS_FS *fs)
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{
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if (fs->buf)
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free(fs->buf, 0);
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free(fs, 0);
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return(0);
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}
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/*
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* Open DOS file
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*/
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static int
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dos_open(char *path, struct open_file *fd)
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{
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DOS_DE *de;
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DOS_FILE *f;
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DOS_FS *fs;
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u_int size, clus;
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int err = 0;
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/* Allocate mount structure, associate with open */
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fs = alloc(sizeof(DOS_FS));
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if ((err = dos_mount(fs, fd)))
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goto out;
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if ((err = namede(fs, path, &de)))
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goto out;
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/* XXX we need to be able to open directories */
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if (de->attr & FA_DIR) {
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err = EISDIR;
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goto out;
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}
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clus = stclus(fs->fatsz, de);
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size = cv4(de->size);
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if (!clus ^ !size || (clus && !okclus(fs, clus))) {
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err = EINVAL;
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goto out;
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}
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f = alloc(sizeof(DOS_FILE));
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bzero(f, sizeof(DOS_FILE));
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f->fs = fs;
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fs->links++;
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f->de = *de;
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fd->f_fsdata = (void *)f;
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out:
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return(err);
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}
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/*
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* Read from file
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*/
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static int
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dos_read(struct open_file *fd, void *buf, size_t nbyte, size_t *resid)
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{
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u_int nb, off, clus, c, cnt, n;
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DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
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int err = 0;
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nb = (u_int)nbyte;
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if (nb > (n = cv4(f->de.size) - f->offset))
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nb = n;
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off = f->offset;
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if ((clus = stclus(f->fs->fatsz, &f->de)))
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off &= f->fs->bsize - 1;
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c = f->c;
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cnt = nb;
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while (cnt) {
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n = 0;
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if (!c) {
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if ((c = clus))
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n = bytblk(f->fs, f->offset);
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} else if (!off)
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n++;
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while (n--) {
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if ((err = fatget(f->fs, &c)))
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goto out;
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if (!okclus(f->fs, c)) {
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err = EINVAL;
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goto out;
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}
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}
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if (!clus || (n = f->fs->bsize - off) > cnt)
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n = cnt;
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if ((err = ioread(f->fs, blkoff(f->fs, c) + off, buf, n)))
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goto out;
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f->offset += n;
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f->c = c;
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off = 0;
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buf += n;
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cnt -= n;
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}
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out:
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if (resid)
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*resid = cnt;
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return(err);
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}
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/*
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* Reposition within file
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*/
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static off_t
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dos_seek(struct open_file *fd, off_t offset, int whence)
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{
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off_t off;
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u_int size;
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DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
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size = cv4(f->de.size);
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switch (whence) {
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case SEEK_SET:
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off = 0;
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break;
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case SEEK_CUR:
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off = f->offset;
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break;
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case SEEK_END:
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off = size;
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break;
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default:
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return(-1);
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}
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off += offset;
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if (off < 0 || off > size)
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return(-1);
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f->offset = (u_int)off;
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f->c = 0;
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return(off);
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}
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/*
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* Close open file
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*/
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static int
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dos_close(struct open_file *fd)
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{
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DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
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DOS_FS *fs = f->fs;
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f->fs->links--;
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free(f, 0);
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dos_unmount(fs);
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return 0;
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}
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/*
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* Return some stat information on a file.
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*/
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static int
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dos_stat(struct open_file *fd, struct stat *sb)
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{
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DOS_FILE *f = (DOS_FILE *)fd->f_fsdata;
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/* only important stuff */
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sb->st_mode = 0444;
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sb->st_nlink = 1;
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sb->st_uid = 0;
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sb->st_gid = 0;
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sb->st_size = cv4(f->de.size);
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return (0);
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}
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/*
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* Parse DOS boot sector
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*/
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static int
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parsebs(DOS_FS *fs, DOS_BS *bs)
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{
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u_int sc;
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if ((bs->jmp[0] != 0x69 &&
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bs->jmp[0] != 0xe9 &&
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(bs->jmp[0] != 0xeb || bs->jmp[2] != 0x90)) ||
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bs->bpb.media < 0xf0)
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return EINVAL;
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if (cv2(bs->bpb.secsiz) != SECSIZ)
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return EINVAL;
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if (!(fs->spc = bs->bpb.spc) || fs->spc & (fs->spc - 1))
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return EINVAL;
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fs->bsize = secbyt(fs->spc);
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fs->bshift = ffs(fs->bsize) - 1;
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if ((fs->spf = cv2(bs->bpb.spf))) {
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if (bs->bpb.fats != 2)
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return EINVAL;
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if (!(fs->dirents = cv2(bs->bpb.dirents)))
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return EINVAL;
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} else {
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if (!(fs->spf = cv4(bs->bpb.lspf)))
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return EINVAL;
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if (!bs->bpb.fats || bs->bpb.fats > 16)
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return EINVAL;
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if ((fs->rdcl = cv4(bs->bpb.rdcl)) < LOCLUS)
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return EINVAL;
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}
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if (!(fs->lsnfat = cv2(bs->bpb.ressec)))
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return EINVAL;
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fs->lsndir = fs->lsnfat + fs->spf * bs->bpb.fats;
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fs->lsndta = fs->lsndir + entsec(fs->dirents);
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if (!(sc = cv2(bs->bpb.secs)) && !(sc = cv4(bs->bpb.lsecs)))
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return EINVAL;
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if (fs->lsndta > sc)
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return EINVAL;
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if ((fs->xclus = secblk(fs, sc - fs->lsndta) + 1) < LOCLUS)
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return EINVAL;
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fs->fatsz = fs->dirents ? fs->xclus < 0xff6 ? 12 : 16 : 32;
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sc = (secbyt(fs->spf) << 1) / (fs->fatsz >> 2) - 1;
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if (fs->xclus > sc)
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fs->xclus = sc;
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return 0;
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}
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/*
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* Return directory entry from path
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*/
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static int
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namede(DOS_FS *fs, const char *path, DOS_DE **dep)
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{
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char name[256];
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DOS_DE *de;
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char *s;
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size_t n;
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int err;
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err = 0;
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de = dot;
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if (*path == '/')
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path++;
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while (*path) {
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if (!(s = strchr(path, '/')))
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s = strchr(path, 0);
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if ((n = s - path) > 255)
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return ENAMETOOLONG;
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memcpy(name, path, n);
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name[n] = 0;
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path = s;
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if (!(de->attr & FA_DIR))
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return ENOTDIR;
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if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
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return err;
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if (*path == '/')
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path++;
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}
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*dep = de;
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return 0;
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}
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/*
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* Lookup path segment
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*/
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static int
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lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
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{
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static DOS_DIR dir[DEPSEC];
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u_char lfn[261];
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u_char sfn[13];
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u_int nsec, lsec, xdn, chk, sec, ent, x;
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int err, ok, i;
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if (!clus)
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for (ent = 0; ent < 2; ent++)
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if (!strcasecmp(name, dotstr[ent])) {
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*dep = dot + ent;
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return 0;
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}
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if (!clus && fs->fatsz == 32)
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clus = fs->rdcl;
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nsec = !clus ? entsec(fs->dirents) : fs->spc;
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lsec = 0;
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xdn = chk = 0;
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for (;;) {
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if (!clus && !lsec)
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lsec = fs->lsndir;
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else if (okclus(fs, clus))
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lsec = blklsn(fs, clus);
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else
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return EINVAL;
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for (sec = 0; sec < nsec; sec++) {
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if ((err = ioget(fs->fd, lsec + sec, dir, 1)))
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return err;
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for (ent = 0; ent < DEPSEC; ent++) {
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if (!*dir[ent].de.name)
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return ENOENT;
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if (*dir[ent].de.name != 0xe5)
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if ((dir[ent].de.attr & FA_MASK) == FA_XDE) {
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x = dir[ent].xde.seq;
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if (x & 0x40 || (x + 1 == xdn &&
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dir[ent].xde.chk == chk)) {
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if (x & 0x40) {
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chk = dir[ent].xde.chk;
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x &= ~0x40;
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}
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if (x >= 1 && x <= 20) {
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cp_xdnm(lfn, &dir[ent].xde);
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xdn = x;
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continue;
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}
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}
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} else if (!(dir[ent].de.attr & FA_LABEL)) {
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if ((ok = xdn == 1)) {
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for (x = 0, i = 0; i < 11; i++)
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x = ((((x & 1) << 7) | (x >> 1)) +
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dir[ent].de.name[i]) & 0xff;
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ok = chk == x &&
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!strcasecmp(name, (const char *)lfn);
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}
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if (!ok) {
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cp_sfn(sfn, &dir[ent].de);
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ok = !strcasecmp(name, (const char *)sfn);
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}
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if (ok) {
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*dep = &dir[ent].de;
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return 0;
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}
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}
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xdn = 0;
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}
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}
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if (!clus)
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break;
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if ((err = fatget(fs, &clus)))
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return err;
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if (fatend(fs->fatsz, clus))
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break;
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}
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return ENOENT;
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}
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/*
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|
* Copy name from extended directory entry
|
|
*/
|
|
static void
|
|
cp_xdnm(u_char *lfn, DOS_XDE *xde)
|
|
{
|
|
static struct {
|
|
u_int off;
|
|
u_int dim;
|
|
} ix[3] = {
|
|
{offsetof(DOS_XDE, name1), sizeof(xde->name1) / 2},
|
|
{offsetof(DOS_XDE, name2), sizeof(xde->name2) / 2},
|
|
{offsetof(DOS_XDE, name3), sizeof(xde->name3) / 2}
|
|
};
|
|
u_char *p;
|
|
u_int n, x, c;
|
|
|
|
lfn += 13 * ((xde->seq & ~0x40) - 1);
|
|
for (n = 0; n < 3; n++)
|
|
for (p = (u_char *)xde + ix[n].off, x = ix[n].dim; x;
|
|
p += 2, x--) {
|
|
if ((c = cv2(p)) && (c < 32 || c > 127))
|
|
c = '?';
|
|
if (!(*lfn++ = c))
|
|
return;
|
|
}
|
|
if (xde->seq & 0x40)
|
|
*lfn = 0;
|
|
}
|
|
|
|
/*
|
|
* Copy short filename
|
|
*/
|
|
static void
|
|
cp_sfn(u_char *sfn, DOS_DE *de)
|
|
{
|
|
u_char *p;
|
|
int j, i;
|
|
|
|
p = sfn;
|
|
if (*de->name != ' ') {
|
|
for (j = 7; de->name[j] == ' '; j--);
|
|
for (i = 0; i <= j; i++)
|
|
*p++ = de->name[i];
|
|
if (*de->ext != ' ') {
|
|
*p++ = '.';
|
|
for (j = 2; de->ext[j] == ' '; j--);
|
|
for (i = 0; i <= j; i++)
|
|
*p++ = de->ext[i];
|
|
}
|
|
}
|
|
*p = 0;
|
|
if (*sfn == 5)
|
|
*sfn = 0xe5;
|
|
}
|
|
|
|
/*
|
|
* Get next cluster in cluster chain
|
|
*/
|
|
static int
|
|
fatget(DOS_FS *fs, u_int *c)
|
|
{
|
|
u_char buf[4];
|
|
u_int x;
|
|
int err;
|
|
|
|
err = ioread(fs, secbyt(fs->lsnfat) + fatoff(fs->fatsz, *c), buf,
|
|
fs->fatsz != 32 ? 2 : 4);
|
|
if (err)
|
|
return err;
|
|
x = fs->fatsz != 32 ? cv2(buf) : cv4(buf);
|
|
*c = fs->fatsz == 12 ? *c & 1 ? x >> 4 : x & 0xfff : x;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Is cluster an end-of-chain marker?
|
|
*/
|
|
static int
|
|
fatend(u_int sz, u_int c)
|
|
{
|
|
return c > (sz == 12 ? 0xff7U : sz == 16 ? 0xfff7U : 0xffffff7);
|
|
}
|
|
|
|
/*
|
|
* Offset-based I/O primitive
|
|
*/
|
|
static int
|
|
ioread(DOS_FS *fs, u_int offset, void *buf, u_int nbyte)
|
|
{
|
|
char *s;
|
|
u_int off, n;
|
|
int err;
|
|
|
|
s = buf;
|
|
if ((off = offset & (SECSIZ - 1))) {
|
|
offset -= off;
|
|
if ((err = iobuf(fs, bytsec(offset))))
|
|
return err;
|
|
offset += SECSIZ;
|
|
if ((n = SECSIZ - off) > nbyte)
|
|
n = nbyte;
|
|
memcpy(s, fs->buf + off, n);
|
|
s += n;
|
|
nbyte -= n;
|
|
}
|
|
n = nbyte & (SECSIZ - 1);
|
|
if (nbyte -= n) {
|
|
if ((err = ioget(fs->fd, bytsec(offset), s, bytsec(nbyte))))
|
|
return err;
|
|
offset += nbyte;
|
|
s += nbyte;
|
|
}
|
|
if (n) {
|
|
if ((err = iobuf(fs, bytsec(offset))))
|
|
return err;
|
|
memcpy(s, fs->buf, n);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Buffered sector-based I/O primitive
|
|
*/
|
|
static int
|
|
iobuf(DOS_FS *fs, u_int lsec)
|
|
{
|
|
int err;
|
|
|
|
if (fs->bufsec != lsec) {
|
|
if ((err = ioget(fs->fd, lsec, fs->buf, 1)))
|
|
return err;
|
|
fs->bufsec = lsec;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Sector-based I/O primitive
|
|
*/
|
|
static int
|
|
ioget(struct open_file *fd, u_int lsec, void *buf, u_int nsec)
|
|
{
|
|
int err;
|
|
|
|
if ((err = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
|
|
secbyt(nsec), buf, NULL)))
|
|
return(err);
|
|
return(0);
|
|
}
|