fat.c

编译后直接运行的ＭＰ３播放器全部Ｃ语言源代码 一个包含FAT文件系统、系统引导 Boot、FLASH Driver等内容的

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id: fat.c,v 1.84 2004/01/26 10:14:46 linusnielsen Exp $
 *
 * Copyright (C) 2002 by Linus Nielsen Feltzing
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdbool.h>
#include "fat.h"
#include "ata.h"
#include "debug.h"
#include "panic.h"
#include "system.h"
#include "timefuncs.h"

#define BYTES2INT16(array,pos) \
          (array[pos] | (array[pos+1] << 8 ))
#define BYTES2INT32(array,pos) \
          (array[pos] | (array[pos+1] << 8 ) | \
          (array[pos+2] << 16 ) | (array[pos+3] << 24 ))

#define FATTYPE_FAT12       0
#define FATTYPE_FAT16       1
#define FATTYPE_FAT32       2

/* BPB offsets; generic */
#define BS_JMPBOOT          0
#define BS_OEMNAME          3
#define BPB_BYTSPERSEC      11
#define BPB_SECPERCLUS      13
#define BPB_RSVDSECCNT      14
#define BPB_NUMFATS         16
#define BPB_ROOTENTCNT      17
#define BPB_TOTSEC16        19
#define BPB_MEDIA           21
#define BPB_FATSZ16         22
#define BPB_SECPERTRK       24
#define BPB_NUMHEADS        26
#define BPB_HIDDSEC         28
#define BPB_TOTSEC32        32

/* fat12/16 */
#define BS_DRVNUM           36
#define BS_RESERVED1        37
#define BS_BOOTSIG          38
#define BS_VOLID            39
#define BS_VOLLAB           43
#define BS_FILSYSTYPE       54

/* fat32 */
#define BPB_FATSZ32         36
#define BPB_EXTFLAGS        40
#define BPB_FSVER           42
#define BPB_ROOTCLUS        44
#define BPB_FSINFO          48
#define BPB_BKBOOTSEC       50
#define BS_32_DRVNUM        64
#define BS_32_BOOTSIG       66
#define BS_32_VOLID         67
#define BS_32_VOLLAB        71
#define BS_32_FILSYSTYPE    82

#define BPB_LAST_WORD       510


/* attributes */
#define FAT_ATTR_LONG_NAME   (FAT_ATTR_READ_ONLY | FAT_ATTR_HIDDEN | \
                              FAT_ATTR_SYSTEM | FAT_ATTR_VOLUME_ID)
#define FAT_ATTR_LONG_NAME_MASK (FAT_ATTR_READ_ONLY | FAT_ATTR_HIDDEN | \
                                 FAT_ATTR_SYSTEM | FAT_ATTR_VOLUME_ID | \
                                 FAT_ATTR_DIRECTORY | FAT_ATTR_ARCHIVE )

#define FATDIR_NAME          0
#define FATDIR_ATTR          11
#define FATDIR_NTRES         12
#define FATDIR_CRTTIMETENTH  13
#define FATDIR_CRTTIME       14
#define FATDIR_CRTDATE       16
#define FATDIR_LSTACCDATE    18
#define FATDIR_FSTCLUSHI     20
#define FATDIR_WRTTIME       22
#define FATDIR_WRTDATE       24
#define FATDIR_FSTCLUSLO     26
#define FATDIR_FILESIZE      28

#define FATLONG_ORDER        0
#define FATLONG_TYPE         12
#define FATLONG_CHKSUM       13

#define CLUSTERS_PER_FAT_SECTOR (SECTOR_SIZE / 4)
#define DIR_ENTRIES_PER_SECTOR  (SECTOR_SIZE / DIR_ENTRY_SIZE)
#define DIR_ENTRY_SIZE       32
#define NAME_BYTES_PER_ENTRY 13
#define FAT_BAD_MARK         0x0ffffff7
#define FAT_EOF_MARK         0x0ffffff8

/* filename charset conversion table */
static const unsigned char unicode2iso8859_2[] = {
    0x00, 0x00, 0xc3, 0xe3, 0xa1, 0xb1, 0xc6, 0xe6,  /* 0x0100 */
    0x00, 0x00, 0x00, 0x00, 0xc8, 0xe8, 0xcf, 0xef,  /* 0x0108 */
    0xd0, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0110 */
    0xca, 0xea, 0xcc, 0xec, 0x00, 0x00, 0x00, 0x00,  /* 0x0118 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0120 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0128 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0130 */
    0x00, 0xc5, 0xe5, 0x00, 0x00, 0xa5, 0xb5, 0x00,  /* 0x0138 */
    0x00, 0xa3, 0xb3, 0xd1, 0xf1, 0x00, 0x00, 0xd2,  /* 0x0140 */
    0xf2, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0148 */
    0xd5, 0xf5, 0x00, 0x00, 0xc0, 0xe0, 0x00, 0x00,  /* 0x0150 */
    0xd8, 0xf8, 0xa6, 0xb6, 0x00, 0x00, 0xaa, 0xba,  /* 0x0158 */
    0xa9, 0xb9, 0xde, 0xfe, 0xab, 0xbb, 0x00, 0x00,  /* 0x0160 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd9, 0xf9,  /* 0x0168 */
    0xdb, 0xfb, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0170 */
    0x00, 0xac, 0xbc, 0xaf, 0xbf, 0xae, 0xbe, 0x00,  /* 0x0178 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0180 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0188 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0190 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0198 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01a0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01a8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01b0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01b8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01c0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01c8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01d0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01d8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01e0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01e8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01f0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x01f8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0200 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0208 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0210 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0218 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0220 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0228 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0230 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0238 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0240 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0248 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0250 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0258 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0260 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0268 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0270 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0278 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0280 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0288 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0290 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x0298 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02a0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02a8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02b0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02b8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xb7,  /* 0x02c0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02c8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02d0 */
    0xa2, 0xff, 0x00, 0xb2, 0x00, 0xbd, 0x00, 0x00,  /* 0x02d8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02e0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02e8 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 0x02f0 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00   /* 0x02f8 */
};

struct fsinfo {
    unsigned int freecount; /* last known free cluster count */
    unsigned int nextfree;  /* first cluster to start looking for free
                               clusters, or 0xffffffff for no hint */
};
/* fsinfo offsets */
#define FSINFO_FREECOUNT 488
#define FSINFO_NEXTFREE  492

struct bpb
{
    char bs_oemname[9];  /* OEM string, ending with \0 */
    int bpb_bytspersec;  /* Bytes per sectory, typically 512 */
    unsigned int bpb_secperclus;  /* Sectors per cluster */
    int bpb_rsvdseccnt;  /* Number of reserved sectors */
    int bpb_numfats;     /* Number of FAT structures, typically 2 */
    int bpb_rootentcnt;  /* Number of dir entries in the root */
    int bpb_totsec16;    /* Number of sectors on the volume (old 16-bit) */
    int bpb_media;       /* Media type (typically 0xf0 or 0xf8) */
    int bpb_fatsz16;     /* Number of used sectors per FAT structure */
    int bpb_secpertrk;   /* Number of sectors per track */
    int bpb_numheads;    /* Number of heads */
    int bpb_hiddsec;     /* Hidden sectors before the volume */
    unsigned int bpb_totsec32;    /* Number of sectors on the volume
                                     (new 32-bit) */
    int last_word;       /* 0xAA55 */

    /**** FAT12/16 specific *****/
    int bs_drvnum;       /* Drive number */
    int bs_bootsig;      /* Is 0x29 if the following 3 fields are valid */
    unsigned int bs_volid; /* Volume ID */
    char bs_vollab[12];    /* Volume label, 11 chars plus \0 */
    char bs_filsystype[9]; /* File system type, 8 chars plus \0 */

    /**** FAT32 specific *****/
    int bpb_fatsz32;
    int bpb_extflags;
    int bpb_fsver;
    int bpb_rootclus;
    int bpb_fsinfo;
    int bpb_bkbootsec;

    /* variables for internal use */
    unsigned int fatsize;
    unsigned int totalsectors;
    unsigned int rootdirsector;
    unsigned int firstdatasector;
    unsigned int startsector;
    unsigned int dataclusters;
    struct fsinfo fsinfo;
};

static struct bpb fat_bpb;

static int update_fsinfo(void);
static int first_sector_of_cluster(int cluster);
static int bpb_is_sane(void);
static void *cache_fat_sector(int secnum);
static int create_dos_name(unsigned char *name, unsigned char *newname);
static unsigned int find_free_cluster(unsigned int start);
static int transfer( unsigned int start, int count, char* buf, bool write );

#define FAT_CACHE_SIZE 0x20
#define FAT_CACHE_MASK (FAT_CACHE_SIZE-1)

struct fat_cache_entry
{
    int secnum;
    bool inuse;
    bool dirty;
};

static char fat_cache_sectors[FAT_CACHE_SIZE][SECTOR_SIZE];
static struct fat_cache_entry fat_cache[FAT_CACHE_SIZE];

static int sec2cluster(unsigned int sec)
{
    if ( sec < fat_bpb.firstdatasector )
    {
        DEBUGF( "sec2cluster() - Bad sector number (%d)\n", sec);
        return -1;
    }

    return ((sec - fat_bpb.firstdatasector) / fat_bpb.bpb_secperclus) + 2;
}

static int cluster2sec(int cluster)
{
    int max_cluster = fat_bpb.totalsectors -
        fat_bpb.firstdatasector / fat_bpb.bpb_secperclus + 1;
    
    if(cluster > max_cluster)
    {
        DEBUGF( "cluster2sec() - Bad cluster number (%d)\n",
                cluster);
        return -1;
    }

    return first_sector_of_cluster(cluster);
}

static int first_sector_of_cluster(int cluster)
{
    return (cluster - 2) * fat_bpb.bpb_secperclus + fat_bpb.firstdatasector;
}

int fat_startsector(void)
{
    return fat_bpb.startsector;
}

void fat_size(unsigned int* size, unsigned int* free)
{
    if (size)
        *size = fat_bpb.dataclusters * fat_bpb.bpb_secperclus / 2;
    if (free)
        *free = fat_bpb.fsinfo.freecount * fat_bpb.bpb_secperclus / 2;
}

int fat_mount(int startsector)
{
    unsigned char buf[SECTOR_SIZE];
    int rc;
    int datasec;
    unsigned int i;

    for(i = 0;i < FAT_CACHE_SIZE;i++)
    {
        fat_cache[i].secnum = 8; /* We use a "safe" sector just in case */
        fat_cache[i].inuse = false;
        fat_cache[i].dirty = false;
    }

    /* Read the sector */
    rc = ata_read_sectors(startsector,1,buf);
    if(rc)
    {
        DEBUGF( "fat_mount() - Couldn't read BPB (error code %d)\n", rc);
        return rc * 10 - 1;
    }

    memset(&fat_bpb, 0, sizeof(struct bpb));
    fat_bpb.startsector = startsector;
    
    strncpy(fat_bpb.bs_oemname, &buf[BS_OEMNAME], 8);
    fat_bpb.bs_oemname[8] = 0;

    fat_bpb.bpb_bytspersec = BYTES2INT16(buf,BPB_BYTSPERSEC);
    fat_bpb.bpb_secperclus = buf[BPB_SECPERCLUS];
    fat_bpb.bpb_rsvdseccnt = BYTES2INT16(buf,BPB_RSVDSECCNT);
    fat_bpb.bpb_numfats    = buf[BPB_NUMFATS];
    fat_bpb.bpb_totsec16   = BYTES2INT16(buf,BPB_TOTSEC16);
    fat_bpb.bpb_media      = buf[BPB_MEDIA];
    fat_bpb.bpb_fatsz16    = BYTES2INT16(buf,BPB_FATSZ16);
    fat_bpb.bpb_fatsz32    = BYTES2INT32(buf,BPB_FATSZ32);
    fat_bpb.bpb_secpertrk  = BYTES2INT16(buf,BPB_SECPERTRK);
    fat_bpb.bpb_numheads   = BYTES2INT16(buf,BPB_NUMHEADS);
    fat_bpb.bpb_hiddsec    = BYTES2INT32(buf,BPB_HIDDSEC);
    fat_bpb.bpb_totsec32   = BYTES2INT32(buf,BPB_TOTSEC32);
    fat_bpb.last_word      = BYTES2INT16(buf,BPB_LAST_WORD);

    /* calculate a few commonly used values */
    if (fat_bpb.bpb_fatsz16 != 0)
        fat_bpb.fatsize = fat_bpb.bpb_fatsz16;
    else
        fat_bpb.fatsize = fat_bpb.bpb_fatsz32;

    if (fat_bpb.bpb_totsec16 != 0)
        fat_bpb.totalsectors = fat_bpb.bpb_totsec16;
    else
        fat_bpb.totalsectors = fat_bpb.bpb_totsec32;
    fat_bpb.firstdatasector = fat_bpb.bpb_rsvdseccnt +
        fat_bpb.bpb_numfats * fat_bpb.fatsize;

    /* Determine FAT type */
    datasec = fat_bpb.totalsectors - fat_bpb.firstdatasector;
    fat_bpb.dataclusters = datasec / fat_bpb.bpb_secperclus;

#ifdef TEST_FAT
    /*
      we are sometimes testing with "illegally small" fat32 images,
      so we don't use the proper fat32 test case for test code
    */
    if ( fat_bpb.bpb_fatsz16 )
#else
    if ( fat_bpb.dataclusters < 65525 )
#endif
    {
        DEBUGF("This is not FAT32. Go away!\n");
        return -2;
    }

    fat_bpb.bpb_extflags  = BYTES2INT16(buf,BPB_EXTFLAGS);
    fat_bpb.bpb_fsver     = BYTES2INT16(buf,BPB_FSVER);
    fat_bpb.bpb_rootclus  = BYTES2INT32(buf,BPB_ROOTCLUS);
    fat_bpb.bpb_fsinfo    = BYTES2INT16(buf,BPB_FSINFO);
    fat_bpb.bpb_bkbootsec = BYTES2INT16(buf,BPB_BKBOOTSEC);
    fat_bpb.bs_drvnum     = buf[BS_32_DRVNUM];
    fat_bpb.bs_bootsig    = buf[BS_32_BOOTSIG];

    if(fat_bpb.bs_bootsig == 0x29)
    {
        fat_bpb.bs_volid = BYTES2INT32(buf,BS_32_VOLID);
        strncpy(fat_bpb.bs_vollab, &buf[BS_32_VOLLAB], 11);
        strncpy(fat_bpb.bs_filsystype, &buf[BS_32_FILSYSTYPE], 8);
    }

    rc = bpb_is_sane();
    if (rc < 0)
    {
        DEBUGF( "fat_mount() - BPB is not sane\n");
        return rc * 10 - 3;
    }

    fat_bpb.rootdirsector = cluster2sec(fat_bpb.bpb_rootclus);

    /* Read the fsinfo sector */
    rc = ata_read_sectors(startsector + fat_bpb.bpb_fsinfo, 1, buf);
    if (rc < 0)