dosfsfmtlib.c

FAT文件系统原代码

/* dosFsFmtLib.c - MS-DOS media-compatible file system formatting library */ 

/* Copyright 1984-2002 Wind River Systems, Inc. */
#include "copyright_wrs.h"

/*
modification history
--------------------
02b,29apr02,jkf  SPR#76013, dosFsVolFormat shall cbioUnlock all it cbioLock's
02a,12dec01,jkf  fixing diab warnings
01z,10dec01,jkf  SPR#72039, MSDOS FAT32 fsInfo sector now using hard coded 
                 offsets to properly support blkSize > 512bps.
                 increase check for bytesPerBlk minimum in dosFsFmtAutoParams.
01y,15nov01,jkf  SPR#71720, avoid unaligned pointer access.
01x,09nov01,jkf  SPR#71633, dont set errno when VolFormat suceeded.
01w,20sep01,jkf  SPR#69031, common code for both AE & 5.x.
01v,08dec00,jkf  SPR#34704,FAT12/FAT16 determination, SPR#62415 sig location.
01u,15sep00,jkf  cleaning warning
01t,29feb00,jkf  T3 changes, cleanup
01s,18oct99,jkf  avoiding div by zero if nHeads*blksPerTrack = 0, SPR#29508
01r,27oct99,jkf  Documentation correction for compatibility section.
01q,03oct99,jkf  setup a pseudo LCHS translation to mimic MSDOS more.
                 This helps VxLd on large disks formatted by us.
01p,03oct99,jkf  removed random signature, breaks vxsys booting.
                 Correction from vxsys investigation, removed random
                 signature, configure hidden sectors to sec per track,
                 change nClust calculation to match Microsoft.
01o,03oct99,jkf  added sysId check to dosFsFmtReadBootBlock, 
                 changed reserved sectors setting to one in 
                 dosFsVolFormat. Disabled the ret instructions
                 being written in dosFsFmtNonFsBootInit.
01n,15sep99,jkf  changes for new CBIO API.
01m,31jul99,jkf  FAT12/FAT16 calculation per NT, SPR#28274. 
                 improved media byte support, SPR#27282. 
		 added support FSTYPE (0x36) in boot sector, SPR#28273.
01l,16jun99,jkf  correctly set FS ID for FAT32, SPR#28275.
01k,12jul99,jkf  T2 merge, tidiness & spelling.
                 (allows Windows to mount our FAT32)
01j,30nov98,lrn  changed JMP instruction to be Win98 compatible (SPR#23442)
01i,07sep98,lrn  fixed formatting of 4 MB disks to be FAT16
01h,30jul98,wlf  partial doc cleanup
01g,14jul98,lrn  replaced perror() with printErr
01f,12jul98,lrn  fixed: option may force format to FAT16
01e,22jun98,lrn  vol desc name change
01d,03jun98,lrn  Libinit, integ, increased max root dirs for small disks
01c,03jun98,lrn  polished main function and interactive params control, doc
01b,14may98,lrn  added VxLong names 
01a,12may98,lrn  initial version
*/

/*
DESCRIPTION
This module is a scaleable companion module for dosFsLib, 
and is intended to facilitate high level formatting of 
disk volumes.

There are two ways to high level format a volume:
.IP "(1)"
Directly calling dosFsVolFormat() routine allows to have complete
control over the format used, parameters and allows to supply a hook
routine which for instance could interactively prompt the user to
modify disk parameters.
.IP "(2)"
Calling ioctl command FIODISKINIT will invoke the formatting routine
via dosFsLib. This uses the default volume format and parameters.

AVAILABILITY
This routine is an optional part of the MS-DOS file system,
and may be included in a target system if it is required to
be able to format new volumes.

In order to include this option, the following function needs
to be invoked during system initialization:
.CS
void dosFsFmtLibInit( void );
.CE

See reference page dosFsVolFormat() for complete description of
supported formats, options and arguments.

SEE ALSO
dosFsLib
*/

/* includes */
#include "vxWorks.h"
#include "private/dosFsVerP.h"
#include "string.h"
#include "stdio.h"
#include "stdlib.h"
#include "ctype.h"
#include "errnoLib.h"
#include "memLib.h"
#include "tickLib.h"

#include "dosFsLib.h"
#include "private/dosFsLibP.h"
#include "private/dosDirLibP.h"

/* defines */

/* defines - FAT Boot Sector values */
#define DOS_BOOT_SEC_NUM        0       /* sector number of boot sector */
#define DOS_MIN_CLUST           2       /* lowest cluster number used */

/* most of these are old defaults which are now calculated */
#define DEFAULT_ROOT_ENTS       112     /* default # of root dir entries */
#define DEFAULT_MAX_ROOT_ENTS   512     /* default max # of root dir entries */
#define DEFAULT_SEC_PER_CLUST   2       /* default sectors per cluster */
#define DEFAULT_MEDIA_BYTE      0xF8    /* default media byte value */
#define DEFAULT_NFATS           2       /* default number FAT copies */
#define MAX_NFATS		16	/* maximum number FAT copies */
#define DEFAULT_NRESERVED       1       /* default # of reserved sec's (min=1)*/

#define DOS_FAT_12BIT_MAX       4085    /* max clusters, 12 bit FAT entries */

/* 
 * FIXME - these are not really -2, but -11, but it is ok because
 * we then should take into account the FAT sectors overhead when
 * calculating cluster size.
 */

#define DOS_FAT_16BIT_MAX   (0x10000-2) /* max clusters, 16 bit FAT */
#define DOS_FAT_32BIT_MAX (0x200000-2)  /* max clusters, 32-bit FAT entries */

#define	DOS32_INFO_SEC		1	/* FAT32 info sector location */
#define	DOS32_BACKUP_BOOT	6	/* FAT32 backup boot block location */


/*******************************************************************************
*
* dosFsFmtShow - print volume parameters to stdout
*
*/
LOCAL void dosFsFmtShow( DOS_VOL_CONFIG * pConf )
    {
    printf("Volume Parameters: FAT type: FAT%d, sectors per cluster %d\n",
	pConf->fatType, pConf->secPerClust);
    printf("  %d FAT copies, %ld clusters, %ld sectors per FAT\n",
	pConf->nFats, pConf->nClust, pConf->secPerFat );
    printf("  Sectors reserved %d, hidden %ld, FAT sectors %ld\n",
	pConf->nResrvd, pConf->nHidden, pConf->secPerFat* pConf->nFats);
    printf("  Root dir entries %d, sysId %-8s, serial number %lx\n",
	pConf->maxRootEnts, pConf->sysId, pConf->volSerial );
    printf("  Label:\"%-11s\" ...\n", pConf->volLabel );
    }

/*******************************************************************************
*
* dosFsFmtAutoParams - automatically calculate FAT formatting params
*
* This function attempts to imitate MSFT formulae for setting
* disk parameters for maximum compatibility.
* For fully automatic configuration, the configuration structure
* should be all zeroed out.
* If any of the modifiable fields are non-zero, this function will
* calculate the rest of the parameters, honoring the values filled
* in prior to the call.
*
* Note however that MSFT compatibility can not be always maintained
* unless fully automatic configuration is performed.
*
*/
LOCAL STATUS dosFsFmtAutoParams
    (
    DOS_VOL_CONFIG * pConf,	/* config params structure */
    ULONG nBlks,		/* # of secs on volume */
    int bytesPerBlk,		/* sector size */
    int opt			/* VxLongs */
    )
    {
    ULONG nClust, maxClust, minClust ;
    int rootSecs, fatBytes ;
    int dirEntrySize = DOS_DIRENT_STD_LEN;

    /* 
     * adjust the directory entry size if using vxLongnames which
     * use a unique directory entry size.
     */

    if( opt & DOS_OPT_VXLONGNAMES )
	dirEntrySize = DOS_VX_DIRENT_LEN;

    /* verify bytes per block supports the file system */

    if( (bytesPerBlk < (dirEntrySize *3))     || 
        (bytesPerBlk < 64 && nBlks > 0xfffe) )
	{
	errno = EINVAL;
	return ERROR;
	}
    
    /* setup some pConf field based on disk size */

    if( bytesPerBlk < 512 )
	{
	/* most likely a tiny RAMdisks */
	if(pConf->secPerClust == 0 )	
	    pConf->secPerClust = 1 ;
	if(pConf->mediaByte == 0 )	
	    pConf->mediaByte = 0xfd;  /* TODO, what to use for RAMDISK? */
	if(pConf->nFats == 0 )		
	    pConf->nFats = 1;
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
	minClust = 1 ;
	}

    else if (nBlks <= 720) /* i.e. 360KB 5.25" */
	{
	/* temporary value, later scaled up as needed */
	if(pConf->secPerClust == 0)	
	    pConf->secPerClust = 1 ;
	if(pConf->mediaByte == 0)	
	    pConf->mediaByte = 0xfd; /* per NT Resource Kit */
	if(pConf->fatType == _AUTO)	
	    pConf->fatType = _FAT12; /* floppies use FAT12 */
	pConf->maxRootEnts = DEFAULT_ROOT_ENTS; /* always 112 for 360KB */
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
	minClust = 2;
	}

    else if (nBlks <= 1440 ) /* i.e. 720KB 3.5" */
	{
	/* temporary value, later scaled up as needed */
	if( pConf->secPerClust == 0)	
	    pConf->secPerClust = 1 ;
	if( pConf->mediaByte == 0)	
	    pConf->mediaByte = 0xf9; /* per NT Resource Kit */ 
	if(pConf->fatType == _AUTO)	
	    pConf->fatType = _FAT12; /* floppies use FAT12 */
	pConf->maxRootEnts = DEFAULT_ROOT_ENTS; /* always 112 for 720KB */
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
	minClust = 2;
	}
    else if (nBlks <= 2400 ) /* i.e. 1.2Mb 5.25" */
	{
	/* temporary value, later scaled up as needed */
	if(pConf->secPerClust == 0)	
	    pConf->secPerClust = 1 ;
	if(pConf->mediaByte == 0)	
	   pConf->mediaByte = 0xf9;/* per NT Resource Kit */
	if(pConf->fatType == _AUTO)	
	    pConf->fatType = _FAT12; /* floppies use FAT12 */
	pConf->maxRootEnts = DEFAULT_ROOT_ENTS;
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
	minClust = 2;
	}
    else if( nBlks <= 2880 ) /* i.e. 1.44MB 3.5" floppy */
	{
	/* temporary value, later scaled up as needed */
	if(pConf->secPerClust == 0)	
	    pConf->secPerClust = 1 ;
	if(pConf->mediaByte == 0)	
	    pConf->mediaByte = 0xf0;/* Per NT Resource Kit */
	if(pConf->fatType == _AUTO)	
	    pConf->fatType = _FAT12; /* floppies use FAT12 */
	pConf->maxRootEnts = DEFAULT_ROOT_ENTS; 
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
	minClust = 2;
	}
    else if( nBlks <= 4000 ) /* probally a hard disk or PCMCIA, FLASH etc.*/
	{
	/* temporary value, later scaled up as needed */
	if(pConf->secPerClust == 0)	
	    pConf->secPerClust = 1;
	if(pConf->mediaByte == 0)	
	    pConf->mediaByte = DEFAULT_MEDIA_BYTE;
	if(pConf->fatType == _AUTO)	
	    pConf->fatType = _FAT12; /* floppies use FAT12 */
	pConf->maxRootEnts = DEFAULT_ROOT_ENTS; 
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
        minClust = 1 ;
	}
    else
	{
	/* temporary value, later scaled up as needed */
	if(pConf->secPerClust == 0)	
	    pConf->secPerClust = 2;
	if(pConf->mediaByte == 0)	
	    pConf->mediaByte = DEFAULT_MEDIA_BYTE;
	pConf->maxRootEnts = DEFAULT_MAX_ROOT_ENTS;
	rootSecs = (((DEFAULT_ROOT_ENTS * dirEntrySize) + (bytesPerBlk -1)) / 
			 bytesPerBlk);
	minClust = 2;
	}

    /* fixup root directory entries */
    if( pConf->maxRootEnts != 0 )
	{
	rootSecs = (((pConf->maxRootEnts * dirEntrySize) + (bytesPerBlk -1)) / 
		    bytesPerBlk);
	}

    if( pConf->nFats == 0 )		
	pConf->nFats = DEFAULT_NFATS;

    pConf->nFats = min( pConf->nFats, MAX_NFATS );

    /* temporary value, may be way too large */

    nClust = nBlks / pConf->secPerClust ;

    /* define FAT type first, many other params depend on it */
    if( pConf->fatType == _AUTO )
	{
	/* 
	 * Here we decide which FAT format to use.
	 */
	if(nClust < DOS_FAT_12BIT_MAX)
	    pConf->fatType = _FAT12 ;	/* <16MB volume, FAT12 */
	else if ( nBlks < 0x400000 )	
	    pConf->fatType = _FAT16 ;   /* 16MB+ <2GB, FAT16 */
	else			
	    pConf->fatType = _FAT32 ;	/* 2GB+ volume, FAT32 */
	}

    switch(pConf->fatType)
	{
	case _FAT32:
	    if( pConf->nResrvd == 0)		
		pConf->nResrvd = 32;
	    maxClust = DOS_FAT_32BIT_MAX;
	    minClust = 8;
	    break;
	default:
	case _FAT16:
	    if( pConf->nResrvd == 0)		
		pConf->nResrvd = 1;
	    maxClust = DOS_FAT_16BIT_MAX;
	    minClust = 2;
	    break;
	case _FAT12:
	    if( pConf->nResrvd == 0)		
		pConf->nResrvd = 1;
	    maxClust = DOS_FAT_12BIT_MAX;
	    minClust = 1;
	    break;
	}


    /* now, we know the FAT type, so we can really calculate secs per clust */

    while( (nClust > maxClust ) || ((ULONG)pConf->secPerClust < minClust) )
	{
	pConf->secPerClust <<= 1 ;	/* multiply secs/clust by 2 */
	nClust = nBlks / pConf->secPerClust ;	/* recalc */
	}

    /* max secs/clust is limited to 254 */

    pConf->secPerClust = min( pConf->secPerClust, 254 );
    nClust = nBlks / pConf->secPerClust ;	/* recalc */

    switch( pConf->fatType )
	{
	case _FAT32:
	    fatBytes = nClust * 4;
	    rootSecs = 0 ; /* root dir is a normal cluster */
	    if(pConf->sysId==NULL) pConf->sysId = "VX5DOS32";
	    break;
	default:
	case _FAT16:
	    fatBytes = nClust * 2;
	    if(pConf->sysId==NULL) pConf->sysId = "VXDOS16";
	    break;
	case _FAT12:
	    fatBytes = nClust * 3 / 2;
	    if(pConf->sysId==NULL) pConf->sysId = "VXDOS12";
	    break;
	}

    /* setup a special id for longnames */

    if( opt & DOS_OPT_VXLONGNAMES )
	{
	pConf->sysId = "VXEXT1.1";
	}

    /* calculate sectors per fat */

    pConf->secPerFat =  (fatBytes + bytesPerBlk - 1) / bytesPerBlk ;

    /* figure out root dir size */

    pConf->maxRootEnts = rootSecs * bytesPerBlk / dirEntrySize ;

    /* root entries are never bigger than 512 */

    if ((pConf->fatType != _FAT32) && (pConf->maxRootEnts > DEFAULT_MAX_ROOT_ENTS))