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rockbox/firmware/drivers/fat.c
Björn Stenberg e8bcc01edf Added fat_open() and fat_read(). 
Renamed BLOCK_SIZE to SECTOR_SIZE.
Added #ifdef DISK_WRITE to all write code.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@269 a1c6a512-1295-4272-9138-f99709370657
2002-04-27 19:37:41 +00:00

976 lines
26 KiB
C
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* 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 <time.h>
#include <sys/timeb.h>
#include "fat.h"
#include "ata.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 NUM_ROOT_DIR_ENTRIES 512
#define NUM_FATS 2
#define NUM_RESERVED_SECTORS 1
#define NUM_BLOCKS 10000
#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
struct fsinfo {
int freecount; /* last known free cluster count */
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
static int first_sector_of_cluster(struct bpb *bpb, unsigned int cluster);
static int get_bpb(struct bpb *bpb);
static int bpb_is_sane(struct bpb *bpb);
static void *cache_fat_sector(struct bpb *bpb, int secnum);
#ifdef DISK_WRITE
static unsigned int getcurrdostime(unsigned short *dosdate,
unsigned short *dostime,
unsigned char *dostenth);
static int create_dos_name(unsigned char *name, unsigned char *newname);
#endif
static unsigned char *fat_cache[256];
static int fat_cache_dirty[256];
#ifdef TEST_FAT
#include "debug.h"
#define DEBUG(x) printf(x)
#define DEBUG1(x,y) printf(x,y)
#define DEBUG2(x,y1,y2) printf(x,y1,y2)
#define DEBUG3(x,y1,y2,y3) printf(x,y1,y2,y3)
int main(int argc, char *argv[])
{
struct bpb bpb;
memset(fat_cache, 0, sizeof(fat_cache));
memset(fat_cache_dirty, 0, sizeof(fat_cache_dirty));
if(ata_init())
DEBUG("*** Warning! The disk is uninitialized\n");
else
get_bpb(&bpb);
dbg_console(&bpb);
return 0;
}
#else
#define DEBUG(x);
#define DEBUG1(x,y);
#define DEBUG2(x,y1,y2);
#define DEBUG3(x,y1,y2,y3);
#endif
static int sec2cluster(struct bpb *bpb, unsigned int sec)
{
if ( sec < bpb->firstdatasector )
{
DEBUG1( "sec2cluster() - Bad sector number (%d)\n", sec);
return -1;
}
return ((sec - bpb->firstdatasector) / bpb->bpb_secperclus) + 2;
}
static int cluster2sec(struct bpb *bpb, unsigned int cluster)
{
int max_cluster = bpb->totalsectors -
bpb->firstdatasector / bpb->bpb_secperclus + 1;
if(cluster > max_cluster)
{
DEBUG1( "cluster2sec() - Bad cluster number (%d)\n",
cluster);
return -1;
}
return first_sector_of_cluster(bpb, cluster);
}
static int first_sector_of_cluster(struct bpb *bpb, unsigned int cluster)
{
return (cluster - 2) * bpb->bpb_secperclus + bpb->firstdatasector;
}
static int get_bpb(struct bpb *bpb)
{
unsigned char buf[SECTOR_SIZE];
int err;
int datasec;
int countofclusters;
/* Read the sector */
err = ata_read_sectors(0,1,buf);
if(err)
{
DEBUG1( "get_bpb() - Couldn't read BPB (error code %i)\n",
err);
return -1;
}
memset(bpb, 0, sizeof(struct bpb));
strncpy(bpb->bs_oemname, &buf[BS_OEMNAME], 8);
bpb->bs_oemname[8] = 0;
bpb->bpb_bytspersec = BYTES2INT16(buf,BPB_BYTSPERSEC);
bpb->bpb_secperclus = buf[BPB_SECPERCLUS];
bpb->bpb_rsvdseccnt = BYTES2INT16(buf,BPB_RSVDSECCNT);
bpb->bpb_numfats = buf[BPB_NUMFATS];
bpb->bpb_rootentcnt = BYTES2INT16(buf,BPB_ROOTENTCNT);
bpb->bpb_totsec16 = BYTES2INT16(buf,BPB_TOTSEC16);
bpb->bpb_media = buf[BPB_MEDIA];
bpb->bpb_fatsz16 = BYTES2INT16(buf,BPB_FATSZ16);
bpb->bpb_fatsz32 = BYTES2INT32(buf,BPB_FATSZ32);
bpb->bpb_secpertrk = BYTES2INT16(buf,BPB_SECPERTRK);
bpb->bpb_numheads = BYTES2INT16(buf,BPB_NUMHEADS);
bpb->bpb_hiddsec = BYTES2INT32(buf,BPB_HIDDSEC);
bpb->bpb_totsec32 = BYTES2INT32(buf,BPB_TOTSEC32);
bpb->last_word = BYTES2INT16(buf,BPB_LAST_WORD);
/* calculate a few commonly used values */
if (bpb->bpb_fatsz16 != 0)
bpb->fatsize = bpb->bpb_fatsz16;
else
bpb->fatsize = bpb->bpb_fatsz32;
if (bpb->bpb_totsec16 != 0)
bpb->totalsectors = bpb->bpb_totsec16;
else
bpb->totalsectors = bpb->bpb_totsec32;
bpb->firstdatasector = bpb->bpb_rsvdseccnt +
bpb->bpb_numfats * bpb->fatsize;
/* Determine FAT type */
datasec = bpb->totalsectors - bpb->firstdatasector;
countofclusters = datasec / 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 ( bpb->bpb_fatsz16 )
#else
if ( countofclusters < 65525 )
#endif
{
DEBUG("This is not FAT32. Go away!\n");
return -1;
}
bpb->bpb_extflags = BYTES2INT16(buf,BPB_EXTFLAGS);
bpb->bpb_fsver = BYTES2INT16(buf,BPB_FSVER);
bpb->bpb_rootclus = BYTES2INT32(buf,BPB_ROOTCLUS);
bpb->bpb_fsinfo = BYTES2INT16(buf,BPB_FSINFO);
bpb->bpb_bkbootsec = BYTES2INT16(buf,BPB_BKBOOTSEC);
bpb->bs_drvnum = buf[BS_32_DRVNUM];
bpb->bs_bootsig = buf[BS_32_BOOTSIG];
if(bpb->bs_bootsig == 0x29)
{
bpb->bs_volid = BYTES2INT32(buf,BS_32_VOLID);
strncpy(bpb->bs_vollab, &buf[BS_32_VOLLAB], 11);
strncpy(bpb->bs_filsystype, &buf[BS_32_FILSYSTYPE], 8);
}
if (bpb_is_sane(bpb) < 0)
{
DEBUG( "get_bpb() - BPB is not sane\n");
return -1;
}
bpb->rootdirsector = cluster2sec(bpb,bpb->bpb_rootclus);
return 0;
}
static int bpb_is_sane(struct bpb *bpb)
{
if(bpb->bpb_bytspersec != 512)
{
DEBUG1( "bpb_is_sane() - Error: sector size is not 512 (%i)\n",
bpb->bpb_bytspersec);
return -1;
}
if(bpb->bpb_secperclus * bpb->bpb_bytspersec > 32768)
{
DEBUG3( "bpb_is_sane() - Warning: cluster size is larger than 32K "
"(%i * %i = %i)\n",
bpb->bpb_bytspersec, bpb->bpb_secperclus,
bpb->bpb_bytspersec * bpb->bpb_secperclus);
}
if(bpb->bpb_rsvdseccnt != 1)
{
DEBUG1( "bpb_is_sane() - Warning: Reserved sectors is not 1 (%i)\n",
bpb->bpb_rsvdseccnt);
}
if(bpb->bpb_numfats != 2)
{
DEBUG1( "bpb_is_sane() - Warning: NumFATS is not 2 (%i)\n",
bpb->bpb_numfats);
}
if(bpb->bpb_rootentcnt != 512)
{
DEBUG1( "bpb_is_sane() - Warning: RootEntCnt is not 512 (%i)\n",
bpb->bpb_rootentcnt);
}
if(bpb->bpb_totsec16 < 200)
{
if(bpb->bpb_totsec16 == 0)
{
DEBUG( "bpb_is_sane() - Error: TotSec16 is 0\n");
return -1;
}
else
{
DEBUG1( "bpb_is_sane() - Warning: TotSec16 "
"is quite small (%i)\n",
bpb->bpb_totsec16);
}
}
if(bpb->bpb_media != 0xf0 && bpb->bpb_media < 0xf8)
{
DEBUG1( "bpb_is_sane() - Warning: Non-standard "
"media type (0x%02x)\n",
bpb->bpb_media);
}
if(bpb->last_word != 0xaa55)
{
DEBUG1( "bpb_is_sane() - Error: Last word is not "
"0xaa55 (0x%04x)\n", bpb->last_word);
return -1;
}
return 0;
}
static void *cache_fat_sector(struct bpb *bpb, int secnum)
{
unsigned char *sec;
sec = fat_cache[secnum];
/* Load the sector if it is not cached */
if(!sec)
{
sec = malloc(bpb->bpb_bytspersec);
if(!sec)
{
DEBUG( "cache_fat_sector() - Out of memory\n");
return NULL;
}
if(ata_read_sectors(secnum,1,sec))
{
DEBUG1( "cache_fat_sector() - Could"
" not read sector %d\n",
secnum);
free(sec);
return NULL;
}
fat_cache[secnum] = sec;
}
return sec;
}
#ifdef DISK_WRITE
static int update_entry(struct bpb *bpb, int entry, unsigned int val)
{
unsigned long *sec;
int fatoffset;
int thisfatsecnum;
int thisfatentoffset;
fatoffset = entry * 4;
thisfatsecnum = fatoffset / bpb->bpb_bytspersec + bpb->bpb_rsvdseccnt;
thisfatentoffset = fatoffset % bpb->bpb_bytspersec;
/* Load the sector if it is not cached */
sec = cache_fat_sector(bpb, thisfatsecnum);
if(!sec)
{
DEBUG1( "update_entry() - Could not cache sector %d\n",
thisfatsecnum);
return -1;
}
fat_cache_dirty[thisfatsecnum] = 1;
/* don't change top 4 bits */
sec[thisfatentoffset/sizeof(int)] &= 0xf000000;
sec[thisfatentoffset/sizeof(int)] |= val & 0x0fffffff;
return 0;
}
#endif
static int read_entry(struct bpb *bpb, int entry)
{
unsigned long *sec;
int fatoffset;
int thisfatsecnum;
int thisfatentoffset;
int val = -1;
fatoffset = entry * 4;
thisfatsecnum = fatoffset / bpb->bpb_bytspersec + bpb->bpb_rsvdseccnt;
thisfatentoffset = fatoffset % bpb->bpb_bytspersec;
/* Load the sector if it is not cached */
sec = cache_fat_sector(bpb, thisfatsecnum);
if(!sec)
{
DEBUG1( "update_entry() - Could not cache sector %d\n",
thisfatsecnum);
return -1;
}
val = sec[thisfatentoffset/sizeof(int)];
return val;
}
static int get_next_cluster(struct bpb *bpb, unsigned int cluster)
{
int next_cluster = read_entry(bpb, cluster);
/* is this last cluster in chain? */
if ( next_cluster >= 0x0ffffff8 )
return 0;
else
return next_cluster;
}
#ifdef DISK_WRITE
static int flush_fat(struct bpb *bpb)
{
int i;
int err;
unsigned char *sec;
int fatsz;
unsigned short d, t;
char m;
fatsz = bpb->fatsize;
for(i = 0;i < 256;i++)
{
if(fat_cache[i] && fat_cache_dirty[i])
{
DEBUG1("Flushing FAT sector %d\n", i);
sec = fat_cache[i];
err = ata_write_sectors(i + bpb->bpb_rsvdseccnt,1,sec);
if(err)
{
DEBUG1( "flush_fat() - Couldn't write"
" sector (%d)\n", i + bpb->bpb_rsvdseccnt);
return -1;
}
err = ata_write_sectors(i + bpb->bpb_rsvdseccnt + fatsz,1,sec);
if(err)
{
DEBUG1( "flush_fat() - Couldn't write"
" sector (%d)\n", i + bpb->bpb_rsvdseccnt + fatsz);
return -1;
}
fat_cache_dirty[i] = 0;
}
}
getcurrdostime(&d, &t, &m);
return 0;
}
unsigned int getcurrdostime(unsigned short *dosdate,
unsigned short *dostime,
unsigned char *dostenth)
{
struct timeb tb;
struct tm *tm;
ftime(&tb);
tm = localtime(&tb.time);
*dosdate = ((tm->tm_year - 80) << 9) |
((tm->tm_mon + 1) << 5) |
(tm->tm_mday);
*dostime = (tm->tm_hour << 11) |
(tm->tm_min << 5) |
(tm->tm_sec >> 1);
*dostenth = (tm->tm_sec & 1) * 100 + tb.millitm / 10;
return 0;
}
static int add_dir_entry(struct bpb *bpb,
unsigned int currdir,
struct fat_direntry *de)
{
unsigned char buf[SECTOR_SIZE];
unsigned char *eptr;
int i;
int err;
unsigned int sec;
unsigned int sec_cnt;
int need_to_update_last_empty_marker = 0;
int is_rootdir = (currdir == 0);
int done = 0;
unsigned char firstbyte;
if(is_rootdir)
{
sec = bpb->rootdirsector;
}
else
{
sec = first_sector_of_cluster(bpb, currdir);
}
sec_cnt = 0;
while(!done)
{
/* The root dir has a fixed size */
if(is_rootdir)
{
if(sec_cnt >= bpb->bpb_rootentcnt * 32 / bpb->bpb_bytspersec)
{
/* We have reached the last sector of the root dir */
if(need_to_update_last_empty_marker)
{
/* Since the directory is full, there is no room for
a marker, so we just exit */
return 0;
}
else
{
DEBUG( "add_dir_entry() -"
" Root dir is full\n");
return -1;
}
}
}
else
{
if(sec_cnt >= bpb->bpb_secperclus)
{
/* We have reached the end of this cluster */
DEBUG("Moving to the next cluster...");
currdir = get_next_cluster(bpb, currdir);
DEBUG1("new cluster is %d\n", currdir);
if(!currdir)
{
/* This was the last in the chain,
we have to allocate a new cluster */
/* TODO */
}
}
}
DEBUG1("Reading sector %d...\n", sec);
/* Read the next sector in the current dir */
err = ata_read_sectors(sec,1,buf);
if(err)
{
DEBUG1( "add_dir_entry() - Couldn't read dir sector"
" (error code %i)\n", err);
return -1;
}
if(need_to_update_last_empty_marker)
{
/* All we need to do is to set the first entry to 0 */
DEBUG1("Clearing the first entry in sector %d\n", sec);
buf[0] = 0;
done = 1;
}
else
{
/* Look for a free slot */
for(i = 0;i < SECTOR_SIZE;i+=32)
{
firstbyte = buf[i];
if(firstbyte == 0xe5 || firstbyte == 0)
{
DEBUG2("Found free slot at entry %d in sector %d\n",
i/32, sec);
eptr = &buf[i];
memset(eptr, 0, 32);
strncpy(&eptr[FATDIR_NAME], de->name, 11);
eptr[FATDIR_ATTR] = de->attr;
eptr[FATDIR_NTRES] = 0;
eptr[FATDIR_CRTTIMETENTH] = de->crttimetenth;
eptr[FATDIR_CRTDATE] = de->crtdate & 0xff;
eptr[FATDIR_CRTDATE+1] = de->crtdate >> 8;
eptr[FATDIR_CRTTIME] = de->crttime & 0xff;
eptr[FATDIR_CRTTIME+1] = de->crttime >> 8;
eptr[FATDIR_WRTDATE] = de->wrtdate & 0xff;
eptr[FATDIR_WRTDATE+1] = de->wrtdate >> 8;
eptr[FATDIR_WRTTIME] = de->wrttime & 0xff;
eptr[FATDIR_WRTTIME+1] = de->wrttime >> 8;
eptr[FATDIR_FILESIZE] = de->filesize & 0xff;
eptr[FATDIR_FILESIZE+1] = (de->filesize >> 8) & 0xff;
eptr[FATDIR_FILESIZE+2] = (de->filesize >> 16) & 0xff;
eptr[FATDIR_FILESIZE+3] = (de->filesize >> 24) & 0xff;
/* Advance the last_empty_entry marker */
if(firstbyte == 0)
{
i += 32;
if(i < SECTOR_SIZE)
{
buf[i] = 0;
/* We are done */
done = 1;
}
else
{
/* We must fill in the first entry
in the next sector */
need_to_update_last_empty_marker = 1;
}
}
err = ata_write_sectors(sec,1,buf);
if(err)
{
DEBUG1( "add_dir_entry() - "
" Couldn't write dir"
" sector (error code %i)\n", err);
return -1;
}
break;
}
}
}
sec++;
sec_cnt++;
}
return 0;
}
unsigned char char2dos(unsigned char c)
{
switch(c)
{
case 0xe5: /* Special kanji character */
c = 0x05;
break;
case 0x22:
case 0x2a:
case 0x2b:
case 0x2c:
case 0x2e:
case 0x3a:
case 0x3b:
case 0x3c:
case 0x3d:
case 0x3e:
case 0x3f:
case 0x5b:
case 0x5c:
case 0x5d:
case 0x7c:
/* Illegal name */
c = 0;
break;
default:
if(c < 0x20)
{
/* Illegal name */
c = 0;
}
break;
}
return c;
}
static int create_dos_name(unsigned char *name, unsigned char *newname)
{
unsigned char n[12];
unsigned char c;
int i;
char *ext;
if(strlen(name) > 12)
{
return -1;
}
strcpy(n, name);
ext = strchr(n, '.');
if(ext)
{
*ext++ = 0;
}
/* The file name is either empty, or there was only an extension.
In either case it is illegal. */
if(n[0] == 0)
{
return -1;
}
/* Name part */
for(i = 0;n[i] && (i < 8);i++)
{
c = char2dos(n[i]);
if(c)
{
newname[i] = toupper(c);
}
}
while(i < 8)
{
newname[i++] = ' ';
}
/* Extension part */
for(i = 0;ext && ext[i] && (i < 3);i++)
{
c = char2dos(ext[i]);
if(c)
{
newname[8+i] = toupper(c);
}
}
while(i < 3)
{
newname[8+i++] = ' ';
}
return 0;
}
int fat_create_dir(struct bpb *bpb, unsigned int currdir, char *name)
{
struct fat_direntry de;
int err;
DEBUG("fat_create_file()\n");
memset(&de, 0, sizeof(struct fat_direntry));
if(create_dos_name(name, de.name) < 0)
{
DEBUG1( "fat_create_file() - Illegal file name (%s)\n", name);
return -1;
}
getcurrdostime(&de.crtdate, &de.crttime, &de.crttimetenth);
de.wrtdate = de.crtdate;
de.wrttime = de.crttime;
de.filesize = 0;
de.attr = FAT_ATTR_DIRECTORY;
err = add_dir_entry(bpb, currdir, &de);
return 0;
}
int fat_create_file(struct bpb *bpb, unsigned int currdir, char *name)
{
struct fat_direntry de;
int err;
DEBUG("fat_create_file()\n");
memset(&de, 0, sizeof(struct fat_direntry));
if(create_dos_name(name, de.name) < 0)
{
DEBUG1( "fat_create_file() - Illegal file name (%s)\n", name);
return -1;
}
getcurrdostime(&de.crtdate, &de.crttime, &de.crttimetenth);
de.wrtdate = de.crtdate;
de.wrttime = de.crttime;
de.filesize = 0;
err = add_dir_entry(bpb, currdir, &de);
return err;
}
#endif
static int parse_direntry(struct fat_direntry *de, unsigned char *buf)
{
/* is this a long filename entry? */
if ( ( buf[FATDIR_ATTR] & FAT_ATTR_LONG_NAME_MASK ) ==
FAT_ATTR_LONG_NAME )
{
return 0;
}
memset(de, 0, sizeof(struct fat_direntry));
de->attr = buf[FATDIR_ATTR];
de->crttimetenth = buf[FATDIR_CRTTIMETENTH];
de->crtdate = BYTES2INT16(buf,FATDIR_CRTDATE);
de->crttime = BYTES2INT16(buf,FATDIR_CRTTIME);
de->wrtdate = BYTES2INT16(buf,FATDIR_WRTDATE);
de->wrttime = BYTES2INT16(buf,FATDIR_WRTTIME);
de->filesize = BYTES2INT32(buf,FATDIR_FILESIZE);
de->firstcluster = BYTES2INT16(buf,FATDIR_FSTCLUSLO) |
(BYTES2INT16(buf,FATDIR_FSTCLUSHI) << 16);
strncpy(de->name, &buf[FATDIR_NAME], 11);
return 1;
}
int fat_open(struct bpb *bpb,
unsigned int startcluster,
struct fat_fileent *ent)
{
ent->firstcluster = startcluster;
ent->nextcluster = startcluster;
ent->nextsector = cluster2sec(bpb,startcluster);
ent->sectornum = 0;
return 0;
}
int fat_read(struct bpb *bpb,
struct fat_fileent *ent,
int sectorcount,
void* buf )
{
int cluster = ent->nextcluster;
int sector = ent->nextsector;
int numsec = ent->sectornum;
int err, i;
for ( i=0; i<sectorcount; i++ ) {
err = ata_read_sectors(sector,1,(char*)buf+(i*SECTOR_SIZE));
if(err) {
DEBUG2( "fat_read() - Couldn't read sector %d"
" (error code %i)\n", sector,err);
return -1;
}
numsec++;
if ( numsec >= bpb->bpb_secperclus ) {
cluster = get_next_cluster(bpb,cluster);
if (!cluster)
break; /* end of file */
sector = cluster2sec(bpb,cluster);
if (sector<0)
return -1;
numsec=0;
}
else
sector++;
}
ent->nextcluster = cluster;
ent->nextsector = sector;
ent->sectornum = numsec;
return sectorcount;
}
int fat_opendir(struct bpb *bpb,
struct fat_dirent *ent,
unsigned int currdir)
{
int is_rootdir = (currdir == 0);
unsigned int sec;
int err;
if(is_rootdir)
{
sec = bpb->rootdirsector;
}
else
{
sec = first_sector_of_cluster(bpb, currdir);
}
/* Read the first sector in the current dir */
err = ata_read_sectors(sec,1,ent->cached_buf);
if(err)
{
DEBUG1( "fat_getfirst() - Couldn't read dir sector"
" (error code %i)\n", err);
return -1;
}
ent->entry = 0;
ent->cached_sec = sec;
ent->num_sec = 0;
return 0;
}
int fat_getnext(struct bpb *bpb,
struct fat_dirent *ent,
struct fat_direntry *entry)
{
int done = 0;
int i;
int err;
unsigned char firstbyte;
while(!done)
{
/* Look for a free slot */
for(i = ent->entry;i < SECTOR_SIZE/32;i++)
{
firstbyte = ent->cached_buf[i*32];
if(firstbyte == 0xe5)
continue;
if(firstbyte == 0)
/* no more entries */
return -1;
if ( parse_direntry(entry, &ent->cached_buf[i*32]) ) {
done = 1;
break;
}
}
/* Next sector? */
if(i < SECTOR_SIZE/32)
{
i++;
}
else
{
ent->num_sec++;
/* Do we need to advance one cluster? */
if(ent->num_sec < bpb->bpb_secperclus)
{
ent->cached_sec++;
}
else
{
int cluster = sec2cluster(bpb, ent->cached_sec);
if ( cluster < 0 ) {
DEBUG("sec2cluster failed\n");
return -1;
}
ent->num_sec = 0;
cluster = get_next_cluster( bpb, cluster );
if(!cluster)
{
DEBUG("End of cluster chain.\n");
return -1;
}
ent->cached_sec = cluster2sec(bpb,cluster);
if ( ent->cached_sec < 0 )
{
DEBUG1("Invalid cluster: %d\n",cluster);
return -1;
}
}
/* Read the next sector */
err = ata_read_sectors(ent->cached_sec,1,ent->cached_buf);
if(err)
{
DEBUG1( "fat_getnext() - Couldn't read dir sector"
" (error code %i)\n", err);
return -1;
}
i = 0;
}
ent->entry = i;
}
return 0;
}
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