Leaked source code of windows server 2003
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//+-------------------------------------------------------------------------
//
// Microsoft Windows
// Copyright (C) Microsoft Corporation, 1992 - 1992.
//
// File: fat.cxx
//
// Contents: Allocation functions for MStream
//
// Classes: None. (defined in fat.hxx)
//
//--------------------------------------------------------------------------
#include "msfhead.cxx"
#include "h/difat.hxx"
#include "h/sstream.hxx"
#include "mread.hxx"
//+-------------------------------------------------------------------------
//
// Method: CFatSect::Init, public
//
// Synopsis: CFatSect initialization function
//
// Effects: [uEntries] -- Number of entries in sector
//
// Algorithm: Allocate an array of SECT with size uEntries from
// the heap.
//
//--------------------------------------------------------------------------
SCODE CFatSect::Init(FSOFFSET uEntries)
{
msfDebugOut((DEB_FAT,"In CFatSect constructor\n"));
//This assumes that FREESECT is always 0xFFFFFFFF
memset(_asectEntry, 0xFF, uEntries * sizeof(SECT));
msfDebugOut((DEB_FAT,"Out CFatSect constructor\n"));
return S_OK;
}
//+-------------------------------------------------------------------------
//
// Method: CFatSect::InitCopy, public
//
// Synopsis: Initialization function for copying FatSects
//
// Arguments: [fsOld] -- Reference to FatSect to be copies
//
// Returns: S_OK if call completed successfully.
//
// Algorithm: Allocate a new array of SECT and copy old
// information in.
//
//--------------------------------------------------------------------------
SCODE CFatSect::InitCopy(USHORT uSize, CFatSect& fsOld)
{
msfDebugOut((DEB_FAT,"In CFatSect copy constructor\n"));
msfDebugOut((DEB_FAT,"This = %p, fsOld = %p\n",this,&fsOld));
msfDebugOut((DEB_FAT,"Sector size is %u sectors\n",uSize));
memcpy(_asectEntry,fsOld._asectEntry,sizeof(SECT)*uSize);
msfDebugOut((DEB_FAT,"Out CFatSect copy constructor\n"));
return S_OK;
}
//+-------------------------------------------------------------------------
//
// Method: CFat::CFat, public
//
// Synopsis: CFat constructor.
//
// Arguments: [pmsParent] -- Pointer to parent multistream.
//
// Algorithm: Set uFatEntries to match parent MS header info.
// Initialize all member variables.
//
// Notes:
//
//--------------------------------------------------------------------------
CFat::CFat(SID sid, USHORT cbSector, USHORT uSectorShift)
: _fv( sid,
(USHORT) (cbSector >> 2), // 4 bytes per entry
(USHORT) (cbSector >> 2) ),
// left shift this amount for FAT
_uFatShift((USHORT) (uSectorShift - 2) ),
// (# entries per sector) - 1
_uFatMask( (USHORT) ((cbSector >> 2) - 1)),
_sid(sid),
_pmsParent(NULL),
_sectFirstFree( (SECT) 0),
_sectMax(ENDOFCHAIN)
{
}
//+---------------------------------------------------------------------------
//
// Member: CFat::Empty, public
//
// Synopsis: Empty all the control structures of this instance
//
// Arguments: None.
//
// Returns: void.
//
//----------------------------------------------------------------------------
void CFat::Empty(void)
{
_fv.Empty();
_pmsParent = NULL;
_cfsTable = 0;
_ulFreeSects = MAX_ULONG;
_sectFirstFree = 0;
_sectMax = ENDOFCHAIN;
}
//+-------------------------------------------------------------------------
//
// Method: CFat::~CFat, public
//
// Synopsis: CFat Destructor
//
// Algorithm: delete dynamically allocated storage
//
// Notes:
//
//--------------------------------------------------------------------------
CFat::~CFat()
{
msfDebugOut((DEB_FAT,"In CFat destructor. Size of fat is %lu\n",_cfsTable));
msfDebugOut((DEB_FAT,"Exiting CFat destructor\n"));
}
//+-------------------------------------------------------------------------
//
// Member: CFat::GetFree, private
//
// Synposis: Locate and return a free sector in the FAT
//
// Effects: May modify full bit on full sectors
//
// Arguments: [psectRet] -- Pointer to return value
//
// Returns: S_OK if call completed successfully.
//
// Algorithm: Do a linear search of all tables until a free sector is
// found. If all tables are full, extend the FAT by one
// sector.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::GetFree(ULONG ulCount, SECT *psectRet)
{
FSINDEX ipfs;
FSOFFSET isect;
SECT sectRetval = ENDOFCHAIN;
SCODE sc;
SECT sectLast = ENDOFCHAIN;
FSINDEX ipfsLast;
FSOFFSET isectLast;
*psectRet = ENDOFCHAIN;
while (TRUE)
{
if (_ulFreeSects == MAX_ULONG)
{
msfChk(CountFree(&_ulFreeSects));
}
#if DBG == 1
else
{
ULONG ulFree;
msfChk(CountFree(&ulFree));
msfAssert((ulFree == _ulFreeSects) &&
aMsg("Free count doesn't match cached value."));
}
#endif
while (ulCount > _ulFreeSects)
{
#if DBG == 1
ULONG ulFree = _ulFreeSects;
#endif
msfChk(Resize(_cfsTable +
((ulCount - _ulFreeSects + _fv.GetSectTable() - 1) >>
_uFatShift)));
#if DBG == 1
msfAssert(_ulFreeSects > ulFree &&
aMsg("Number of free sectors didn't increase after Resize."));
#endif
}
FSOFFSET isectStart;
FSINDEX ipfsStart;
SectToPair(_sectFirstFree, &ipfsStart, &isectStart);
for (ipfs = ipfsStart; ipfs < _cfsTable; ipfs++)
{
CVectBits *pfb = _fv.GetBits(ipfs);
if ((pfb == NULL) || (!pfb->full))
{
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_NONE, &pfs));
if (pfb != NULL)
{
isectStart = pfb->firstfree;
}
for (isect = isectStart; isect < _fv.GetSectTable(); isect++)
{
SECT sectCurrent = pfs->GetSect(isect);
SECT sectNew = PairToSect(ipfs, isect);
if (sectCurrent == FREESECT)
{
msfAssert(_ulFreeSects != MAX_ULONG &&
aMsg("Free sect count not set"));
_ulFreeSects--;
sectRetval = sectNew;
if (pfb != NULL)
{
olAssert(isect+1 < USHRT_MAX);
pfb->firstfree = (USHORT) (isect + 1);
}
msfAssert(sectRetval >= _sectFirstFree &&
aMsg("Found free sector before _sectFirstFree"));
_sectFirstFree = sectRetval + 1;
pfs->SetSect(isect, ENDOFCHAIN);
msfChkTo(Err_Rel, _fv.SetDirty(ipfs));
if (sectLast != ENDOFCHAIN)
{
if (ipfsLast == ipfs)
{
pfs->SetSect(isectLast, sectRetval);
}
else
{
CFatSect *pfsLast;
msfChkTo(Err_Rel, _fv.GetTable(
ipfsLast,
FB_DIRTY,
&pfsLast));
pfsLast->SetSect(isectLast, sectRetval);
_fv.ReleaseTable(ipfsLast);
}
}
if (*psectRet == ENDOFCHAIN)
{
*psectRet = sectRetval;
}
ulCount--;
if (ulCount == 0)
{
_fv.ReleaseTable(ipfs);
if (sectRetval >= _sectMax)
{
_sectMax = sectRetval + 1;
}
return S_OK;
}
else
{
sectLast = sectRetval;
ipfsLast = ipfs;
isectLast = isect;
}
}
}
_fv.ReleaseTable(ipfs);
if (pfb != NULL)
{
pfb->full = TRUE;
}
}
isectStart = 0;
}
if (sectRetval >= _sectMax)
{
_sectMax = sectRetval + 1;
}
}
msfAssert(0 &&
aMsg("GetFree exited improperly."));
sc = STG_E_ABNORMALAPIEXIT;
Err:
return sc;
Err_Rel:
_fv.ReleaseTable(ipfs);
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::GetLength, public
//
// Synposis: Return the length of a fat chain.
//
// Arguments: [sect] -- Sector to begin count at.
//
// Returns: Length of the chain, in sectors
//
// Algorithm: Traverse the chain until ENDOFCHAIN is reached.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::GetLength(SECT sect, ULONG * pulRet)
{
msfDebugOut((DEB_FAT,"In CFat::GetLength(%lu)\n",sect));
SCODE sc = S_OK;
ULONG csect = 0;
while (sect != ENDOFCHAIN)
{
msfChk(GetNext(sect, &sect));
csect++;
}
msfDebugOut((DEB_FAT,"FAT: GetLength returned %u\n",csect));
*pulRet = csect;
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::Init, public
//
// Synposis: Sets up a FAT, reading data from an existing stream
//
// Effects: Changes all _apfsTable entries, _cfsTable, and all
// flags fields
//
// Arguments: None.
//
// Returns: S_OK if call completed OK.
//
// Algorithm: Read size from first FAT in stream.
// Resize array to necessary size.
// Read in FAT sectors sequentially.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::Init(CMStream *pmsParent, FSINDEX cFatSect, BOOL fConvert)
{
SCODE sc;
UNREFERENCED_PARM(fConvert);
msfDebugOut((DEB_FAT,"CFat::setup thinks the FAT is size %lu\n",cFatSect));
_pmsParent = pmsParent;
msfChk(_fv.Init(_pmsParent, cFatSect));
_cfsTable = cFatSect;
USHORT cbSectorSize;
cbSectorSize = _pmsParent->GetSectorSize();
InitRangeLocksSector();
_ulFreeSects = MAX_ULONG;
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Method: CFat::InitConvert, public
//
// Synopsis: Init function used for conversion
//
// Arguments: [sectData] -- number of sectors used by file
//
// Returns: S_OK if call completed OK.
//
// Algorithm: *Finish This*
//
// Notes:
//
//--------------------------------------------------------------------------
SCODE CFat::InitConvert(CMStream *pmsParent, SECT sectData)
{
SCODE sc;
msfDebugOut((DEB_FAT,"Doing conversion\n"));
_pmsParent = pmsParent;
msfAssert((sectData != 0) &&
aMsg("Attempt to convert zero length file."));
SECT sectMax = 0;
FSINDEX csectFat = 0;
FSINDEX csectLast;
InitRangeLocksSector();
if (_sid == SIDFAT)
{
SECT sectTotal;
//Since the fat needs to represent itself, we can't determine
// the actual number of sectors needed in one pass. We
// therefore loop, factoring in the number of fat sectors
// at each iteration, until we reach a stable state.
//
//As an example, consider the case where each fat sector represents
// 128 sectors and the file being converted is 128 sectors long.
// There will be no DIFat - therefore, we have 128 sectors needed
// on the first pass, which will require 1 fat sector to
// represent them. On the second pass, we discover that we
// actually need 2 fat sectors, since we now have 129 total
// sectors to allocate space for. The third pass will result
// in a stable state.
do
{
csectLast = csectFat;
sectTotal = sectData + _pmsParent->GetHeader()->GetDifLength() +
csectFat + 1;
csectFat = (sectTotal + _fv.GetSectTable() - 1) >> _uFatShift;
}
while (csectLast != csectFat);
sectMax = sectData + _pmsParent->GetHeader()->GetDifLength();
}
else
{
//The minifat doesn't need to represent itself, so we can
// compute the number of sectors needed in one pass.
sectMax = sectData;
csectFat = (sectMax + _fv.GetSectTable() -1) >> _uFatShift;
}
msfChk(_fv.Init(_pmsParent, csectFat));
FSINDEX i;
if (_sid == SIDMINIFAT)
{
SECT sectFirst;
msfChk(_pmsParent->GetFat()->Allocate(csectFat, &sectFirst));
_pmsParent->GetHeader()->SetMiniFatStart(sectFirst);
_pmsParent->GetHeader()->SetMiniFatLength(csectFat);
}
for (i = 0; i < csectFat; i++)
{
CFatSect *pfs;
msfChk(_fv.GetTable(i, FB_NEW, &pfs));
if (_sid == SIDFAT)
{
_fv.SetSect(i, sectMax + i);
_pmsParent->GetDIFat()->SetFatSect(i, sectMax + i);
}
else
{
SECT sect;
msfChk(_pmsParent->GetESect(_sid, i, &sect));
_fv.SetSect(i, sect);
}
_fv.ReleaseTable(i);
}
_cfsTable = csectFat;
if (_sid != SIDMINIFAT)
{
_pmsParent->GetHeader()->SetFatLength(_cfsTable);
SECT sect;
if (sectData > 1)
{
for (sect = 0; sect < sectData - 2; sect++)
{
msfChk(SetNext(sect, sect + 1));
}
msfChk(SetNext(sectData - 2, ENDOFCHAIN));
msfChk(SetNext(sectData - 1, 0));
}
else
{
//In the event that the file to be converted is less
// than one sector long, we don't need to create a
// real chain, just a single terminated sector.
msfChk(SetNext(0, ENDOFCHAIN));
}
for (sect = sectData; sect < sectMax; sect++)
{
msfChk(SetNext(sect, DIFSECT));
}
for (ULONG j = 0; j < csectFat; j++)
{
msfChk(SetNext(sectMax + j, FATSECT));
}
//Set up directory chain.
msfChk(SetNext(sectMax + i, ENDOFCHAIN));
_pmsParent->GetHeader()->SetDirStart(sectMax + i);
_ulFreeSects = (_cfsTable << _uFatShift) - (sectMax + csectFat + 1);
}
else
{
for (SECT sect = 0; sect < sectData -1; sect++)
{
msfChk(SetNext(sect, sect + 1));
}
msfChk(SetNext(sectData - 1, ENDOFCHAIN));
_ulFreeSects = (_cfsTable << _uFatShift) - sectData;
}
msfChk(_pmsParent->SetSize());
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::InitNew, public
//
// Synposis: Sets up a FAT for a newly created multi-strean
//
// Effects: Changes all _apfsTable entries, _cfsTable, and all
// flags fields
//
// Arguments: [pmsparent] -- pointer to parent Mstream
//
// Returns: S_OK if call completed OK.
//
// Algorithm: Set parent pointer.
// Allocate 1 sector for FAT and 1 for Directory.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::InitNew(CMStream *pmsParent)
{
msfDebugOut((DEB_FAT,"In CFat::InitNew()\n"));
SCODE sc;
_pmsParent = pmsParent;
FSINDEX count;
if (SIDMINIFAT == _sid)
count = _pmsParent->GetHeader()->GetMiniFatLength();
else
count = _pmsParent->GetHeader()->GetFatLength();
msfDebugOut((DEB_FAT,"Setting up Fat of size %lu\n",count));
msfChk(_fv.Init(_pmsParent, count));
_cfsTable = count;
InitRangeLocksSector();
if (SIDFAT == _sid)
{
FSINDEX ipfs;
FSOFFSET isect;
CFatSect *pfs;
SectToPair(_pmsParent->GetHeader()->GetFatStart(), &ipfs, &isect);
msfChk(_fv.GetTable(ipfs, FB_NEW, &pfs));
_fv.SetSect(ipfs, _pmsParent->GetHeader()->GetFatStart());
_fv.ReleaseTable(ipfs);
msfChk(SetNext(_pmsParent->GetHeader()->GetFatStart(), FATSECT));
msfDebugOut((DEB_ITRACE,"Set sector %lu (FAT) to ENDOFCHAIN\n",_pmsParent->GetHeader()->GetFatStart()));
msfChk(SetNext(_pmsParent->GetHeader()->GetDirStart(), ENDOFCHAIN));
msfDebugOut((DEB_ITRACE,"Set sector %lu (DIR) to ENDOFCHAIN\n",_pmsParent->GetHeader()->GetDirStart()));
_ulFreeSects = (count << _uFatShift) - 2;
}
else
{
_ulFreeSects = 0;
}
msfChk(_pmsParent->SetSize());
msfDebugOut((DEB_FAT,"Exiting CFat::setupnew()\n"));
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::Resize, private
//
// Synposis: Resize FAT, both in memory and in the file
//
// Effects: Modifies _cfsTable, _apfsTable, and all flags fields
//
// Arguments: [ulSize] -- New size (in # of tables) for FAT
//
// Returns: S_OK if call completed OK.
//
// Algorithm: Allocate new array of new size.
// Copy over all old pointers.
// Allocate new tables for any necessary.
//
// Notes: This routine currently cannot reduce the size of a fat
//---------------------------------------------------------------------------
SCODE CFat::Resize(ULONG ulSize)
{
msfDebugOut((DEB_FAT,"In CFat::Resize(%lu)\n",ulSize));
SCODE sc;
if (ulSize == _cfsTable)
{
return S_OK;
}
ULONG csect = _cfsTable;
msfAssert(ulSize > _cfsTable &&
aMsg("Attempted to shrink Fat"));
// 512byte sector docfiles are restricted to 2G for now
if (_pmsParent->GetSectorShift() == SECTORSHIFT512 &&
ulSize > _ipfsRangeLocks)
return STG_E_DOCFILETOOLARGE;
ULONG ipfs;
SECT sectNew = ENDOFCHAIN;
CFat *pfat = _pmsParent->GetFat();
if (_sid == SIDFAT)
{
//Make sure we have enough space for all of the sectors
// to be allocated.
ULONG csectFat = ulSize - _cfsTable;
ULONG csectPerDif = (1 << _uFatShift) - 1;
ULONG csectDif = (csectFat + csectPerDif - 1) / csectPerDif;
//Assuming all the free sectors are at the end of the file,
// we need a file csectNew sectors long to hold them.
ULONG csectOld, csectNew;
msfChk(FindMaxSect(&csectOld));
csectNew = csectOld + csectFat + csectDif;
ULARGE_INTEGER cbSize;
cbSize.QuadPart = ConvertSectOffset(
csectNew,
0,
_pmsParent->GetSectorShift());
msfHChk(_pmsParent->GetILB()->SetSize(cbSize));
//If we are the fat, we have enough space in the file for
// ourselves at this point.
}
else
{
if (_cfsTable == 0)
{
msfChk(pfat->Allocate(ulSize, &sectNew));
_pmsParent->GetHeader()->SetMiniFatStart(sectNew);
}
else
{
sectNew = _pmsParent->GetHeader()->GetMiniFatStart();
SECT sectLast;
msfChk(pfat->GetESect(sectNew, ulSize - 1, &sectLast));
}
msfChk(_pmsParent->SetSize());
msfChk(pfat->GetSect(sectNew, csect, &sectNew));
//If we are the Minifat, we have enough space in the underlying
// file for ourselves at this point.
}
_fv.Resize(ulSize);
for (ipfs = csect; ipfs < ulSize; ipfs++)
{
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_NEW, &pfs));
_cfsTable = ipfs + 1;
_ulFreeSects += (1 << _uFatShift);
if (_sid == SIDFAT)
{
if (ipfs == _ipfsRangeLocks)
{
CVectBits *pfb;
pfs->SetSect(_isectRangeLocks, ENDOFCHAIN);
pfb = _fv.GetBits(_ipfsRangeLocks);
if (pfb != NULL && pfb->full == FALSE &&
_isectRangeLocks == pfb->firstfree)
{
pfb->firstfree = _isectRangeLocks + 1;
}
_ulFreeSects--;
}
msfChk(pfat->GetFree(1, &sectNew));
msfChk(_pmsParent->GetDIFat()->SetFatSect(ipfs, sectNew));
msfChk(pfat->SetNext(sectNew, FATSECT));
}
msfAssert(sectNew != ENDOFCHAIN &&
aMsg("Bad sector returned for fatsect."));
_fv.SetSect(ipfs, sectNew);
_fv.ReleaseTable(ipfs);
if (_sid == SIDMINIFAT)
{
msfChk(pfat->GetNext(sectNew, &sectNew));
}
}
msfDebugOut((DEB_FAT,"CFat::Resize() - all new objects allocated\n"));
if (SIDMINIFAT == _sid)
_pmsParent->GetHeader()->SetMiniFatLength(_cfsTable);
else
_pmsParent->GetHeader()->SetFatLength(_cfsTable);
//This setsize should only shrink the file.
#if DBG == 1
STATSTG stat;
msfHChk(_pmsParent->GetILB()->Stat(&stat, STATFLAG_NONAME));
#endif
msfChk(_pmsParent->SetSize());
#if DBG == 1
STATSTG statNew;
msfHChk(_pmsParent->GetILB()->Stat(&statNew, STATFLAG_NONAME));
msfAssert(statNew.cbSize.QuadPart <= stat.cbSize.QuadPart);
#endif
msfDebugOut((DEB_FAT,"Out CFat::Resize(%lu)\n",ulSize));
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::Extend, private
//
// Synposis: Increase the size of an existing chain
//
// Effects: Modifies ulSize sectors within the fat. Causes one or
// more sector writes.
//
// Arguments: [sect] -- Sector ID of last sector in chain to be extended
// [ulSize] -- Number of sectors to add to chain
//
// Requires: sect must be at the end of a chain.
//
// Returns: S_OK if call completed OK.
//
// Algorithm: Use calls to GetFree to allocate chain.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::Extend(SECT sect, ULONG ulSize)
{
SCODE sc;
msfDebugOut((DEB_FAT,"In CFat::Extend(%lu,%lu)\n",sect,ulSize));
SECT sectTemp;
msfChk(GetFree(ulSize, &sectTemp));
msfChk(SetNext(sect, sectTemp));
msfDebugOut((DEB_FAT,"Out CFat::Extend()\n"));
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::GetNext, public
//
// Synposis: Returns the next sector in a chain, given a sector
//
// Arguments: [sect] -- Sector ID of any sector in a chain.
//
// Returns: Sector ID of next sector in chain, ENDOFCHAIN if at end
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::GetNext(const SECT sect, SECT * psRet)
{
SCODE sc;
FSINDEX ipfs;
FSOFFSET isect;
msfAssert(sect <= MAXREGSECT &&
aMsg("Called GetNext() on invalid sector"));
SectToPair(sect, &ipfs, &isect);
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_NONE, &pfs));
*psRet = pfs->GetSect(isect);
_fv.ReleaseTable(ipfs);
msfAssert(sect != *psRet &&
aMsg("Detected loop in fat chain."));
return S_OK;
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::SetNext, private
//
// Synposis: Set the next sector in a chain
//
// Effects: Modifies a single entry within the fat.
//
// Arguments: [sectFirst] -- Sector ID of first sector
// [sectNext] -- Sector ID of next sector
//
// Returns: void
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::SetNext(SECT sectFirst, SECT sectNext)
{
FSINDEX ipfs;
FSOFFSET isect;
SCODE sc;
// creating infinite loops is a no-no
msfAssert(sectFirst != sectNext &&
aMsg("Attempted to create loop in Fat chain"));
msfAssert(sectFirst <= MAXREGSECT &&
aMsg("Called SetNext on invalid sector"));
SectToPair(sectFirst, &ipfs, &isect);
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_DIRTY, &pfs));
pfs->SetSect(isect,sectNext);
_fv.ReleaseTable(ipfs);
if (sectNext == FREESECT)
{
CVectBits *pfb;
pfb = _fv.GetBits(ipfs);
if ((pfb != NULL) &&
((pfb->full == TRUE) || (isect < pfb->firstfree)))
{
pfb->full = FALSE;
pfb->firstfree = isect;
}
if (sectFirst == _sectMax - 1)
{
_sectMax = ENDOFCHAIN;
}
if (sectFirst < _sectFirstFree)
{
_sectFirstFree = sectFirst;
}
if (_ulFreeSects != MAX_ULONG)
{
_ulFreeSects++;
}
}
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::CountFree, private
//
// Synposis: Count and return the number of free sectors in the Fat
//
// Arguments: void.
//
// Returns: void.
//
// Algorithm: Do a linear search of the Fat, counting free sectors.
// If a FatSect has its full bit set, it is not necessary
// to search that FatSect.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::CountFree(ULONG * pulRet)
{
msfDebugOut((DEB_FAT,"In CFat::CountFree()\n"));
SCODE sc = S_OK;
FSINDEX ipfs;
ULONG csectFree=0;
FSOFFSET isectStart;
FSINDEX ipfsStart;
SectToPair(_sectFirstFree, &ipfsStart, &isectStart);
for (ipfs = ipfsStart; ipfs < _cfsTable; ipfs++)
{
CVectBits *pfb = _fv.GetBits(ipfs);
if ((pfb == NULL) || (!pfb->full))
{
msfDebugOut((DEB_FAT,"Checking table %lu\n",ipfs));
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_NONE, &pfs));
if (pfb != NULL)
{
isectStart = pfb->firstfree;
}
FSOFFSET isect;
for (isect = isectStart; isect < _fv.GetSectTable(); isect++)
{
SECT sectCurrent = pfs->GetSect(isect);
if (sectCurrent == FREESECT)
{
csectFree++;
}
}
_fv.ReleaseTable(ipfs);
}
isectStart = 0;
}
msfDebugOut((DEB_FAT,"Countfree returned %lu\n",csectFree));
*pulRet = csectFree;
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::GetSect, public
//
// Synposis: Return the nth sector in a chain
//
// Arguments: [sect] -- Sector ID of beginning of chain
// [uNum] -- indicator of which sector is to be returned
// [psectReturn] -- Pointer to storage for return value
//
// Returns: S_OK.
//
// Algorithm: Linearly traverse chain until numth sector
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::GetSect(SECT sect, ULONG ulNum, SECT * psectReturn)
{
msfDebugOut((DEB_FAT,"In CFat::GetSect(%lu,%lu)\n",sect,ulNum));
SCODE sc = S_OK;
if (ulNum == 0)
{
msfDebugOut((DEB_FAT,"Out CFat::GetSect()=>%lu\n",sect));
}
else if ((SIDFAT == _sid) &&
(_pmsParent->GetHeader()->GetFatStart() == sect))
{
msfChk(_pmsParent->GetDIFat()->GetFatSect(ulNum, &sect));
}
else for (ULONG i = 0; i < ulNum; i++)
{
msfChk(GetNext(sect, &sect));
if (sect > MAXREGSECT)
{
//The stream isn't long enough, so stop.
msfAssert(sect == ENDOFCHAIN &&
aMsg("Found invalid sector in fat chain."));
break;
}
}
*psectReturn = sect;
msfDebugOut((DEB_FAT,"Out CFat::GetSect()=>%lu\n",sect));
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::GetESect
//
// Synposis: Return the nth sector in a chain, extending the chain
// if necessary.
//
// Effects: Modifies fat (via Extend) if necessary
//
// Arguments: [sect] -- Sector ID of beginning of chain
// [ulNum] -- Indicates which sector is to be returned
// [psectReturn] -- Pointer to storage for return value
//
// Returns: S_OK if call completed OK.
//
// Algorithm: Linearly search chain until numth sector is found. If
// the chain terminates early, extend it as necessary.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::GetESect(SECT sect, ULONG ulNum, SECT *psectReturn)
{
msfDebugOut((DEB_FAT,"In CFat::GetESect(%lu,%lu)\n",sect,ulNum));
SCODE sc = S_OK;
ULONG i = 0;
while (i < ulNum)
{
SECT temp;
msfChk(GetNext(sect, &temp));
msfAssert(temp != FREESECT &&
aMsg("FREESECT found in chain."));
if (temp == ENDOFCHAIN)
{
//The stream isn't long enough, so extend it somehow.
ULONG need = ulNum - i;
msfAssert((SIDMINIFAT == _sid ||
sect != _pmsParent->GetHeader()->GetFatStart()) &&
aMsg("Called GetESect on Fat chain"));
msfChk(Extend(sect,need));
}
else
{
sect = temp;
i++;
}
}
msfDebugOut((DEB_FAT,"Exiting GetESect with result %lu\n",sect));
*psectReturn = sect;
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::SetChainLength, private
//
// Synposis: Set the length of a fat chain. This is used to reduce
// the length of the chain only. To extend a chain, use
// Extend or GetESect
//
// Effects: Modifies the fat
//
// Arguments: [sectStart] -- Sector to begin at (head of chain)
// [uLength] -- New length for chain
//
// Returns: void.
//
// Algorithm: Traverse chain until uLength is reached or the chain
// terminates. If it terminates prematurely, return with
// no other action. Otherwise, deallocate all remaining
// sectors in the chain.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::SetChainLength(SECT sectStart, ULONG ulLength)
{
msfDebugOut((DEB_FAT,"In CFat::SetChainLength(%lu,%lu)\n",sectStart,ulLength));
SCODE sc;
if (sectStart == ENDOFCHAIN) return S_OK;
for (ULONG ui = 0; ui < ulLength; ui++)
{
msfChk(GetNext(sectStart, &sectStart));
if (sectStart == ENDOFCHAIN) return S_OK;
}
msfAssert(sectStart != ENDOFCHAIN &&
aMsg("Called SetChainLength is ENDOFCHAIN start"));
SECT sectEnd;
sectEnd = sectStart;
msfChk(GetNext(sectStart, &sectStart));
if (ulLength != 0)
{
msfChk(SetNext(sectEnd, ENDOFCHAIN));
}
else
{
msfChk(SetNext(sectEnd, FREESECT));
}
while (sectStart != ENDOFCHAIN)
{
SECT sectTemp;
msfChk(GetNext(sectStart, &sectTemp));
msfChk(SetNext(sectStart, FREESECT));
sectStart = sectTemp;
}
msfDebugOut((DEB_FAT,"Out CFat::SetChainLength()\n"));
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Method: CFat::FindLast, private
//
// Synopsis: Find last used sector in a fat
//
// Returns: Location of last used sector
//
// Algorithm: Perform a backward linear search until a non-free
// sector is found.
//
// Notes: Used for shadow fats only.
//
//--------------------------------------------------------------------------
SCODE CFat::FindLast(SECT * psectRet)
{
SCODE sc = S_OK;
FSINDEX ipfs = _cfsTable;
SECT sect = 0;
while (ipfs > 0)
{
ipfs--;
FSOFFSET isect = _fv.GetSectTable();
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_NONE, &pfs));
while (isect > 0)
{
isect--;
SECT sectCurrent = pfs->GetSect(isect);
if (ipfs == _ipfsRangeLocks && isect == _isectRangeLocks)
sectCurrent = FREESECT;
if (sectCurrent != FREESECT)
{
msfDebugOut((DEB_FAT,"FindLast returns %lu\n",PairToSect(ipfs,isect)));
sect = PairToSect(ipfs, (FSOFFSET) (isect + 1));
break;
}
}
_fv.ReleaseTable(ipfs);
if (sect != 0)
break;
}
*psectRet = sect;
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Method: CFat::FindMaxSect, private
//
// Synopsis: Return last used sector in current Fat.
//
// Arguments: None.
//
// Returns: Last used sector in current Fat
//
//--------------------------------------------------------------------------
SCODE CFat::FindMaxSect(SECT *psectRet)
{
SCODE sc = S_OK;
if (_sectMax == ENDOFCHAIN)
{
msfChk(FindLast(psectRet));
}
else
{
#if DBG == 1
SECT sectLast;
msfChk(FindLast(&sectLast));
#endif
*psectRet = _sectMax;
}
Err:
return sc;
}
//+-------------------------------------------------------------------------
//
// Member: CFat::Contig, public
//
// Synposis: Create contiguous sector table
//
// Effects: Creates new CSegment.
//
// Arguments: [sect] -- Starting sector for table to begin
// [ulength] -- Runlength in sectors of table to produce
//
// Returns: Pointer to a Segment table
//
// Algorithm: Perform calls to CFat::GetNext(). Any call that is
// 1 higher than the previous represents contiguous blocks.
// Construct the Segment table on that basis.
//
// Notes:
//
//---------------------------------------------------------------------------
SCODE CFat::Contig(
SSegment STACKBASED *aseg,
SECT sect,
ULONG ulLength)
{
msfDebugOut((DEB_ITRACE,"In CFat::Contig(%lu,%lu)\n",sect,ulLength));
SCODE sc = S_OK;
SECT stemp = sect;
ULONG ulCount = 1;
USHORT iseg = 0;
msfAssert(sect != ENDOFCHAIN &&
aMsg("Called Contig with ENDOFCHAIN start"));
aseg[iseg].sectStart = sect;
aseg[iseg].cSect = 1;
while ((ulLength > 1) && (iseg < CSEG))
{
msfAssert(sect != ENDOFCHAIN &&
aMsg("Contig found premature ENDOFCHAIN"));
FSINDEX ipfs;
FSOFFSET isect;
SectToPair(sect, &ipfs, &isect);
CFatSect *pfs;
msfChk(_fv.GetTable(ipfs, FB_NONE, &pfs));
sect = pfs->GetSect(isect);
_fv.ReleaseTable(ipfs);
if (sect == ENDOFCHAIN)
{
//Allocate new sectors.
SECT sectNew;
msfChk(GetFree(ulLength - 1, &sectNew));
msfChk(SetNext(stemp, sectNew));
sect = sectNew;
}
if (sect != (stemp + 1))
{
aseg[iseg].cSect = ulCount;
ulCount = 1;
iseg++;
aseg[iseg].sectStart = sect;
stemp = sect;
}
else
{
ulCount++;
stemp = sect;
}
ulLength--;
}
if (iseg < CSEG)
{
aseg[iseg].cSect = ulCount;
aseg[iseg + 1].sectStart = ENDOFCHAIN;
}
else
{
aseg[iseg].sectStart = FREESECT;
}
msfDebugOut((DEB_ITRACE,"Exiting Contig()\n"));
Err:
return sc;
}