libfat/fat.h

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2001-2008 H. Peter Anvin - All Rights Reserved
 *
 *   This program 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, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * fat.h
 *
 * Basic data structures for a FAT filesystem
 */

#ifndef FAT_H
#define FAT_H

#include "ulint.h"

/* The poor excuse FAT has for a superblock -- in the boot sector */
struct fat_bootsect {
    le8_t bsJump[3];		/* Jump to code */
    char bsOemName[8];		/* Formatting program */
    le16_t bsBytesPerSec;	/* Bytes/sector */
    le8_t bsSecPerClust;	/* Sectors/cluster */
    le16_t bsResSectors;	/* Reserved sectors */
    le8_t bsFATs;		/* Number of FATs */
    le16_t bsRootDirEnts;	/* Number of entries/root directory */
    le16_t bsSectors;		/* Number of sectors [1] */
    le8_t bsMedia;		/* Magic media type byte */
    le16_t bsFATsecs;		/* Sectors/FAT */
    le16_t bsSecPerTrack;	/* Sectors/track */
    le16_t bsHeads;		/* Number of heads */
    le32_t bsHiddenSecs;	/* Number of hidden sectors */
    le32_t bsHugeSectors;	/* Number of sectors [2] */
    union {
	/* FAT12/16 */
	struct {
	    le8_t bsDriveNumber;	/* Drive number */
	    le8_t bsReserved1;	/* Reserved */
	    le8_t bsBootSignature;	/* 0x29 */
	    le32_t bsVolumeID;	/* Volume serial number */
	    char bsVolumeLabel[11];	/* Volume name */
	    char bsFileSysType[8];	/* File system type */

	    le8_t bsCode[448];	/* Boot sector code */
	} fat16;

	/* FAT32 */
	struct {
	    le32_t bpb_fatsz32;	/* Sectors/FAT */
	    le16_t bpb_extflags;	/* Extended flags */
	    le16_t bpb_fsver;	/* Filesystem version */
	    le32_t bpb_rootclus;	/* Root directory cluster */
	    le16_t bpb_fsinfo;	/* FSINFO sector number */
	    le16_t bpb_bkbootsec;	/* Backup boot sector (superblock) */
	    char bpb_reserved[12];

	    /* Same shit, different offset! */
	    le8_t bsDriveNumber;	/* Drive number */
	    le8_t bsReserved1;	/* Reserved */
	    le8_t bsBootSignature;	/* 0x29 */
	    le32_t bsVolumeID;	/* Volume serial number */
	    char bsVolumeLabel[11];	/* Volume name */
	    char bsFileSysType[8];	/* File system type */

	    le8_t bsCode[420];	/* Boot sector code */
	} fat32;
    } u;

    le16_t bsSignature;		/* 0xAA55 */
};

#define BS_BOOTSIGNATURE	0x29
#define BS_SIGNATURE		0xAA55

/* A FAT filesystem directory entry */

struct fat_dirent {
    le8_t name[11];		/* Mangled filename */
    le8_t attribute;		/* File type/attribute */
    le8_t caseflags;		/* VFAT: case for basis and extension */
    le8_t ctime_ms;		/* ms of creation time */
    le32_t ctime;		/* Creation time */
    le16_t atime;		/* Date portion (high 16 bits) of atime */
    le16_t clusthi;		/* FAT32: high 16 bits of cluster */
    le32_t mtime;		/* Modification time */
    le16_t clustlo;		/* First cluster pointer */
    le32_t size;		/* File size (bytes) */
};

/* A VFAT filesystem continuation entry */
struct fat_vfat_slot {
    le8_t id;			/* Sequence number for slot */
    le16_t name0[5];		/* 5 characters */
    le8_t attribute;		/* Attribute byte */
    le8_t reserved;		/* Reserved, MBZ */
    le8_t alias_csum;		/* Short name checksum */
    le16_t name5[6];		/* 6 characters */
    le16_t firstclust;		/* MBZ */
    le16_t name11[2];		/* 2 characters */
};

#endif /* FAT_H */