796 lines
20 KiB
C
796 lines
20 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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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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#include "dosfs.h"
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static int dos_open(const 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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static int dos_readdir(struct open_file *fd, struct dirent *d);
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struct fs_ops dosfs_fsops = {
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"dosfs",
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dos_open,
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dos_close,
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dos_read,
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null_write,
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dos_seek,
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dos_stat,
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dos_readdir
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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 off_t fsize(DOS_FS *, DOS_DE *);
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static int fatcnt(DOS_FS *, u_int);
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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 = malloc(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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fs->root = dot[0];
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fs->root.name[0] = ' ';
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if (fs->fatsz == 32) {
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fs->root.clus[0] = fs->rdcl & 0xff;
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fs->root.clus[1] = (fs->rdcl >> 8) & 0xff;
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fs->root.dex.h_clus[0] = (fs->rdcl >> 16) & 0xff;
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fs->root.dex.h_clus[1] = (fs->rdcl >> 24) & 0xff;
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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);
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free(fs);
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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(const 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 = malloc(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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clus = stclus(fs->fatsz, de);
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size = cv4(de->size);
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if ((!(de->attr & FA_DIR) && (!clus != !size)) ||
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((de->attr & FA_DIR) && size) ||
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(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 = malloc(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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off_t size;
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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 ((size = fsize(f->fs, &f->de)) == -1)
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return EINVAL;
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if (nb > (n = 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, (c ? blkoff(f->fs, c) :
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secbyt(f->fs->lsndir)) + off,
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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 = (char *)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 = nbyte - nb + 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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errno = EINVAL;
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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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errno = EINVAL;
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return(-1);
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}
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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);
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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 = f->de.attr & FA_DIR ? S_IFDIR | 0555 : S_IFREG | 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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if ((sb->st_size = fsize(f->fs, &f->de)) == -1)
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return EINVAL;
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return (0);
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}
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static int
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dos_readdir(struct open_file *fd, struct dirent *d)
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{
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/* DOS_FILE *f = (DOS_FILE *)fd->f_fsdata; */
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u_char fn[261];
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DOS_DIR dd;
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size_t res;
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u_int chk, i, x, xdn;
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int err;
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x = chk = 0;
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while (1) {
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xdn = x;
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x = 0;
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err = dos_read(fd, &dd, sizeof(dd), &res);
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if (err)
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return (err);
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if (res == sizeof(dd))
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return (ENOENT);
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if (dd.de.name[0] == 0)
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return (ENOENT);
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/* Skip deleted entries */
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if (dd.de.name[0] == 0xe5)
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continue;
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/* Check if directory entry is volume label */
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if (dd.de.attr & FA_LABEL) {
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/*
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* If volume label set, check if the current entry is
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* extended entry (FA_XDE) for long file names.
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*/
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if ((dd.de.attr & FA_MASK) == FA_XDE) {
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/*
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* Read through all following extended entries
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* to get the long file name. 0x40 marks the
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* last entry containing part of long file name.
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*/
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if (dd.xde.seq & 0x40)
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chk = dd.xde.chk;
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else if (dd.xde.seq != xdn - 1 || dd.xde.chk != chk)
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continue;
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x = dd.xde.seq & ~0x40;
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if (x < 1 || x > 20) {
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x = 0;
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continue;
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}
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cp_xdnm(fn, &dd.xde);
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} else {
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/* skip only volume label entries */
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continue;
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}
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} else {
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if (xdn == 1) {
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x = 0;
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for (i = 0; i < 11; i++) {
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x = ((x & 1) << 7) | (x >> 1);
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x += dd.de.name[i];
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x &= 0xff;
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}
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if (x == chk)
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break;
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} else {
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cp_sfn(fn, &dd.de);
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break;
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}
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x = 0;
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}
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}
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d->d_fileno = (dd.de.clus[1] << 8) + dd.de.clus[0];
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d->d_reclen = sizeof(*d);
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d->d_type = (dd.de.attr & FA_DIR) ? DT_DIR : DT_REG;
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memcpy(d->d_name, fn, sizeof(d->d_name));
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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 = &fs->root;
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while (*path) {
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while (*path == '/')
|
|
path++;
|
|
if (*path == '\0')
|
|
break;
|
|
if (!(s = strchr(path, '/')))
|
|
s = strchr(path, 0);
|
|
if ((n = s - path) > 255)
|
|
return ENAMETOOLONG;
|
|
memcpy(name, path, n);
|
|
name[n] = 0;
|
|
path = s;
|
|
if (!(de->attr & FA_DIR))
|
|
return ENOTDIR;
|
|
if ((err = lookup(fs, stclus(fs->fatsz, de), name, &de)))
|
|
return err;
|
|
}
|
|
*dep = de;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Lookup path segment
|
|
*/
|
|
static int
|
|
lookup(DOS_FS *fs, u_int clus, const char *name, DOS_DE **dep)
|
|
{
|
|
static DOS_DIR dir[DEPSEC];
|
|
u_char lfn[261];
|
|
u_char sfn[13];
|
|
u_int nsec, lsec, xdn, chk, sec, ent, x;
|
|
int err, ok, i;
|
|
|
|
if (!clus)
|
|
for (ent = 0; ent < 2; ent++)
|
|
if (!strcasecmp(name, dotstr[ent])) {
|
|
*dep = dot + ent;
|
|
return 0;
|
|
}
|
|
if (!clus && fs->fatsz == 32)
|
|
clus = fs->rdcl;
|
|
nsec = !clus ? entsec(fs->dirents) : fs->spc;
|
|
lsec = 0;
|
|
xdn = chk = 0;
|
|
for (;;) {
|
|
if (!clus && !lsec)
|
|
lsec = fs->lsndir;
|
|
else if (okclus(fs, clus))
|
|
lsec = blklsn(fs, clus);
|
|
else
|
|
return EINVAL;
|
|
for (sec = 0; sec < nsec; sec++) {
|
|
if ((err = ioget(fs->fd, lsec + sec, dir, 1)))
|
|
return err;
|
|
for (ent = 0; ent < DEPSEC; ent++) {
|
|
if (!*dir[ent].de.name)
|
|
return ENOENT;
|
|
if (*dir[ent].de.name != 0xe5) {
|
|
if ((dir[ent].de.attr & FA_MASK) == FA_XDE) {
|
|
x = dir[ent].xde.seq;
|
|
if (x & 0x40 || (x + 1 == xdn &&
|
|
dir[ent].xde.chk == chk)) {
|
|
if (x & 0x40) {
|
|
chk = dir[ent].xde.chk;
|
|
x &= ~0x40;
|
|
}
|
|
if (x >= 1 && x <= 20) {
|
|
cp_xdnm(lfn, &dir[ent].xde);
|
|
xdn = x;
|
|
continue;
|
|
}
|
|
}
|
|
} else if (!(dir[ent].de.attr & FA_LABEL)) {
|
|
if ((ok = xdn == 1)) {
|
|
for (x = 0, i = 0; i < 11; i++)
|
|
x = ((((x & 1) << 7) | (x >> 1)) +
|
|
dir[ent].de.name[i]) & 0xff;
|
|
ok = chk == x &&
|
|
!strcasecmp(name, (const char *)lfn);
|
|
}
|
|
if (!ok) {
|
|
cp_sfn(sfn, &dir[ent].de);
|
|
ok = !strcasecmp(name, (const char *)sfn);
|
|
}
|
|
if (ok) {
|
|
*dep = &dir[ent].de;
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
xdn = 0;
|
|
}
|
|
}
|
|
if (!clus)
|
|
break;
|
|
if ((err = fatget(fs, &clus)))
|
|
return err;
|
|
if (fatend(fs->fatsz, clus))
|
|
break;
|
|
}
|
|
return ENOENT;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/*
|
|
* Return size of file in bytes
|
|
*/
|
|
static off_t
|
|
fsize(DOS_FS *fs, DOS_DE *de)
|
|
{
|
|
u_long size;
|
|
u_int c;
|
|
int n;
|
|
|
|
if (!(size = cv4(de->size)) && de->attr & FA_DIR) {
|
|
if (!(c = cv2(de->clus)))
|
|
size = fs->dirents * sizeof(DOS_DE);
|
|
else {
|
|
if ((n = fatcnt(fs, c)) == -1)
|
|
return n;
|
|
size = blkbyt(fs, n);
|
|
}
|
|
}
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* Count number of clusters in chain
|
|
*/
|
|
static int
|
|
fatcnt(DOS_FS *fs, u_int c)
|
|
{
|
|
int n;
|
|
|
|
for (n = 0; okclus(fs, c); n++)
|
|
if (fatget(fs, &c))
|
|
return -1;
|
|
return fatend(fs->fatsz, c) ? n : -1;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
twiddle(1);
|
|
if ((err = (fd->f_dev->dv_strategy)(fd->f_devdata, F_READ, lsec,
|
|
secbyt(nsec), buf, NULL)))
|
|
return(err);
|
|
return(0);
|
|
}
|