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/*
File: fat_common.h
Copyright (C) 2013 Christophe GRENIER <grenier@cgsecurity.org>
This software is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write the Free Software Foundation, Inc., 51
Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _FAT_COMMON_H
#define _FAT_COMMON_H
#ifdef __cplusplus
extern "C" {
#endif
#define FAT1X_PART_NAME 0x2B
#define FAT32_PART_NAME 0x47
#define FAT_NAME1 0x36
#define FAT_NAME2 0x52 /* FAT32 only */
#define DELETED_FLAG 0xe5 /* marks file as deleted when in name[0] */
#define IS_FREE(n) (!*(n) || *(const unsigned char *) (n) == DELETED_FLAG)
#define ATTR_RO 1 /* read-only */
#define ATTR_HIDDEN 2 /* hidden */
#define ATTR_SYS 4 /* system */
#define ATTR_VOLUME 8 /* volume label */
#define ATTR_DIR 16 /* directory */
#define ATTR_ARCH 32 /* archived */
#define ATTR_NONE 0 /* no attribute bits */
#define ATTR_UNUSED (ATTR_VOLUME | ATTR_ARCH | ATTR_SYS | ATTR_HIDDEN)
/* attribute bits that are copied "as is" */
#define ATTR_EXT (ATTR_RO | ATTR_HIDDEN | ATTR_SYS | ATTR_VOLUME)
#define ATTR_EXT_MASK (ATTR_RO | ATTR_HIDDEN | ATTR_SYS | ATTR_VOLUME | ATTR_DIR | ATTR_ARCH)
/* bits that are used by the Windows 95/Windows NT extended FAT */
#define FAT12_BAD 0x0FF7
#define FAT12_EOC 0x0FF8
#define FAT16_BAD 0xFFF7
#define FAT16_EOC 0xFFF8
#define FAT32_BAD 0x0FFFFFF7
#define FAT32_EOC 0x0FFFFFF8
#define FAT1x_BOOT_SECTOR_SIZE 0x200
/*
* FAT partition boot sector information, taken from the Linux
* kernel sources.
*/
struct fat_boot_sector {
uint8_t ignored[3]; /* 0x00 Boot strap short or near jump */
int8_t system_id[8]; /* 0x03 Name - can be used to special case
partition manager volumes */
uint8_t sector_size[2]; /* 0x0B bytes per logical sector */
uint8_t sectors_per_cluster; /* 0x0D sectors/cluster */
uint16_t reserved; /* 0x0E reserved sectors */
uint8_t fats; /* 0x10 number of FATs */
uint8_t dir_entries[2]; /* 0x11 root directory entries */
uint8_t sectors[2]; /* 0x13 number of sectors */
uint8_t media; /* 0x15 media code (unused) */
uint16_t fat_length; /* 0x16 sectors/FAT */
uint16_t secs_track; /* 0x18 sectors per track */
uint16_t heads; /* 0x1A number of heads */
uint32_t hidden; /* 0x1C hidden sectors (unused) */
uint32_t total_sect; /* 0x20 number of sectors (if sectors == 0) */
/* The following fields are only used by FAT32 */
uint32_t fat32_length; /* 0x24=36 sectors/FAT */
uint16_t flags; /* 0x28 bit 8: fat mirroring, low 4: active fat */
uint8_t version[2]; /* 0x2A major, minor filesystem version */
uint32_t root_cluster; /* 0x2C first cluster in root directory */
uint16_t info_sector; /* 0x30 filesystem info sector */
uint16_t backup_boot; /* 0x32 backup boot sector */
uint8_t BPB_Reserved[12]; /* 0x34 Unused */
uint8_t BS_DrvNum; /* 0x40 */
uint8_t BS_Reserved1; /* 0x41 */
uint8_t BS_BootSig; /* 0x42 */
uint8_t BS_VolID[4]; /* 0x43 */
uint8_t BS_VolLab[11]; /* 0x47 */
uint8_t BS_FilSysType[8]; /* 0x52=82*/
/* */
uint8_t nothing[420]; /* 0x5A */
uint16_t marker;
} __attribute__ ((gcc_struct, __packed__));
struct fat_fsinfo {
uint32_t leadsig; /* 0x41615252 */
uint8_t reserved1[480];
uint32_t strucsig; /* 0x61417272 */
uint32_t freecnt; /* free clusters 0xfffffffff if unknown */
uint32_t nextfree; /* next free cluster */
uint8_t reserved3[12];
uint32_t magic3; /* 0xAA550000 */
} __attribute__ ((gcc_struct, __packed__));
struct msdos_dir_entry {
uint8_t name[8]; /* 00 name and extension */
uint8_t ext[3];
uint8_t attr; /* 0B attribute bits */
uint8_t lcase; /* 0C Case for base and extension */
uint8_t ctime_ms; /* 0D Creation time, milliseconds */
uint16_t ctime; /* 0E Creation time */
uint16_t cdate; /* 10 Creation date */
uint16_t adate; /* 12 Last access date */
uint16_t starthi; /* 14 High 16 bits of cluster in FAT32 */
uint16_t time; /* 16 time, date and first cluster */
uint16_t date; /* 18 */
uint16_t start; /* 1A */
uint32_t size; /* 1C file size (in bytes) */
} __attribute__ ((gcc_struct, __packed__));
/* Up to 13 characters of the name */
struct msdos_dir_slot {
uint8_t id; /* 00 sequence number for slot */
uint8_t name0_4[10]; /* 01 first 5 characters in name */
uint8_t attr; /* 0B attribute byte */
uint8_t reserved; /* 0C always 0 */
uint8_t alias_checksum; /* 0D checksum for 8.3 alias */
uint8_t name5_10[12]; /* 0E 6 more characters in name */
uint16_t start; /* 1A starting cluster number, 0 in long slots */
uint8_t name11_12[4]; /* 1C last 2 characters in name */
};
/*@
@ requires \valid_read(entry);
@ requires \initialized(entry);
@ terminates \true;
@ assigns \nothing;
@ */
unsigned int fat_get_cluster_from_entry(const struct msdos_dir_entry *entry);
/*@
@ requires \valid_read(buffer + (0 .. 0x40-1));
@ assigns \nothing;
@ */
int is_fat_directory(const unsigned char *buffer);
/*@
@ requires \valid_read(fat_header);
@ requires \initialized(fat_header);
@ terminates \true;
@ ensures \result <= 65535;
@ assigns \nothing;
@ */
unsigned int get_dir_entries(const struct fat_boot_sector *fat_header);
/*@
@ requires \valid_read(fat_header);
@ requires \initialized(fat_header);
@ terminates \true;
@ ensures \result <= 65535;
@ assigns \nothing;
@ */
unsigned int fat_sector_size(const struct fat_boot_sector *fat_header);
/*@
@ requires \valid_read(fat_header);
@ requires \initialized(fat_header);
@ terminates \true;
@ ensures \result <= 65535;
@ assigns \nothing;
@ */
unsigned int fat_sectors(const struct fat_boot_sector *fat_header);
#ifdef __cplusplus
} /* closing brace for extern "C" */
#endif
#endif
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