--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/userlibandfileserver/fileserver/sfat32/sl_scan32.cpp Thu Dec 17 09:24:54 2009 +0200
@@ -0,0 +1,1034 @@
+// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// f32\sfat32\sl_scan32.cpp
+// ScanDrive code, specific for EFAT32.FSY
+//
+//
+
+/**
+ @file
+ @internalTechnology
+*/
+
+//#define DEBUG_SCANDRIVE
+
+#include "sl_std.h"
+#include "sl_scandrv.h"
+
+
+
+const TInt KEndOfDirectory = 0xFFFF; ///< End of directory marker
+const TInt KMaxScanDepth = 20; ///< Maximum scan depth of to avoid stack over flow
+const TInt KClusterListGranularity = 8; ///< Granularity of cluster list used for storage of clusters when KMaxScanDepth is reached
+
+
+/**
+Creates a CScanDrive
+@param aMount The owning mount
+*/
+ CScanDrive* CScanDrive::NewL(CFatMountCB* aMount)
+ {
+ if(aMount==NULL)
+ User::Leave(KErrArgument);
+ CScanDrive* self=new (ELeave) CScanDrive();
+ CleanupStack::PushL(self);
+ self->ConstructL(aMount);
+ CleanupStack::Pop();
+ return self;
+ }
+
+
+CScanDrive::~CScanDrive()
+ {
+ for(TInt i=0;i<KMaxArrayDepth && iClusterListArray[i]!=NULL;++i)
+ {
+ iClusterListArray[i]->Close();
+ delete iClusterListArray[i];
+ }
+
+ iMediaFatBits.Close();
+ iScanFatBits.Close();
+
+ }
+
+/**
+Allocates the Cluster array, the bit packed Fats and if run in a seperate
+thread the extra CFatTable and cluster buffer
+
+@param aMount The owning mount
+*/
+void CScanDrive::ConstructL(CFatMountCB* aMount)
+ {
+ iMount=aMount;
+
+ //-- create bit vectors that will represent FAT on media and reconstructed by ScanDrive
+ //-- each bit in the vector represents 1 FAT cluster.
+ const TUint32 KClustersNum = iMount->UsableClusters()+KFatFirstSearchCluster; //-- UsableClusters() doesn't count first 2 unused clusers
+
+ CleanupClosePushL(iMediaFatBits);
+ CleanupClosePushL(iScanFatBits);
+
+ iMediaFatBits.CreateL(KClustersNum);
+ iScanFatBits.CreateL(KClustersNum);;
+
+ CleanupStack::Pop(&iScanFatBits);
+ CleanupStack::Pop(&iMediaFatBits);
+ }
+
+//----------------------------------------------------------------------------------------------------
+/**
+ FAT type-agnnostic parser. Reads whole FAT and sets up a bit vector.
+ for FAT12/16 it's OK, because the FAT12/16 is fully cached.
+*/
+void CScanDrive::DoParseFatL()
+ {
+ const TInt MaxClusters = iMount->UsableClusters()+KFatFirstSearchCluster;
+
+
+
+ iMediaFatBits.Fill(0);
+
+ for(TInt i=KFatFirstSearchCluster; i<MaxClusters; ++i)
+ {
+ const TUint32 nFatEntry = ReadFatL(i);
+
+ //-- each '1' bit represents a used cluster
+ if(nFatEntry != KSpareCluster)
+ iMediaFatBits.SetBit(i);
+ }
+ }
+
+//----------------------------------------------------------------------------------------------------
+/**
+ Parse FAT32 buffer.
+ @param aBuf buffer, containing FAT32 entries (current portion of FAT)
+ @param aCurrFatEntry current FAT entry processed
+*/
+void CScanDrive::DoParseFat32Buf(const TPtrC8& aBuf, TUint32& aCurrFatEntry)
+ {
+ ASSERT((aBuf.Size() & (sizeof(TFat32Entry)-1)) == 0);
+
+ const TInt KNumEntries = aBuf.Size() >> KFat32EntrySzLog2;
+ const TFat32Entry* const pFatEntry = (const TFat32Entry*)(aBuf.Ptr());
+
+ for(TInt i=0; i<KNumEntries; ++i)
+ {
+ if(aCurrFatEntry >= KFatFirstSearchCluster)
+ {
+ if((pFatEntry[i] & KFat32EntryMask) != KSpareCluster)
+ {//-- found a non-free FAT32 entry
+ iMediaFatBits.SetBit(aCurrFatEntry);
+ }
+ }
+ ++aCurrFatEntry;
+ }
+ }
+
+//----------------------------------------------------------------------------------------------------
+/**
+ A specialised method to read and parse FAT32 using a larger buffer.
+ 1. Larger buffer gives better read performance
+ 2. using dedicated buffer doesn't trash FAT32 LRU cache.
+*/
+void CScanDrive::DoParseFat32L()
+ {
+ ASSERT(iMount->FatType() == EFat32);
+
+ const TUint32 KNumClusters = iMount->UsableClusters()+KFatFirstSearchCluster;
+ const TUint32 KFat1StartPos = iMount->StartOfFatInBytes();
+ const TUint32 KFatSize = KNumClusters * sizeof(TFat32Entry); //-- usable size of one FAT.
+
+ const TUint32 KFatBufSz = 32*K1KiloByte; //-- buffer size for FAT reading. 32K seems to be optimal size
+
+ iMediaFatBits.Fill(0);
+
+ RBuf8 buf;
+ CleanupClosePushL(buf);
+
+ //-- allocate memory for FAT parse buffer
+ buf.CreateMaxL(KFatBufSz);
+
+ //-- read FAT directly from the media into the large buffer and parse it
+ TUint32 rem = KFatSize;
+ TUint32 mediaPos = KFat1StartPos;
+ TUint32 currFatEntry = 0;
+
+ while(rem)
+ {
+ const TUint32 bytesToRead=Min(rem, KFatBufSz);
+ TPtrC8 ptrData(buf.Ptr(), bytesToRead);
+
+ //-- read portion of the FAT into buffer
+ User::LeaveIfError(iMount->LocalDrive()->Read(mediaPos, bytesToRead, buf));
+
+ //-- parse the buffer and populate bit vector
+ DoParseFat32Buf(ptrData, currFatEntry);
+
+ mediaPos += bytesToRead;
+ rem -= bytesToRead;
+ }
+
+ buf.Close();
+ CleanupStack::PopAndDestroy(&buf);
+ }
+
+//----------------------------------------------------------------------------------------------------
+/**
+ Sets up a bit list representation of the media fat
+ Reads whole FAT and sets '1' bits in the bit vector corresponding to the occupied clusters.
+*/
+void CScanDrive::ReadMediaFatL()
+ {
+ ASSERT(iMount->ConsistentState());
+
+ if(iMount->FatType() == EFat32)
+ {//-- for FAT32 try to use specialised method of parsing
+ TInt nRes;
+ TRAP(nRes, DoParseFat32L())
+ if(nRes == KErrNone)
+ return;
+ }
+
+ //-- use old FAT-agnostic parsing
+ DoParseFatL();
+ }
+
+/**
+Set a cluster as visited in the bit packed scan Fat
+
+@param aCluster Cluster number
+*/
+void CScanDrive::SetUsedL(TUint aCluster)
+ {
+ __ASSERT_ALWAYS(aCluster >= KFatFirstSearchCluster && aCluster < (KFatFirstSearchCluster+iMount->UsableClusters()),User::Leave(KErrCorrupt));
+ iScanFatBits.SetBit(aCluster);
+ }
+
+
+/**
+Query whether a cluster is already set as used
+
+@param aCluster Cluster to query
+*/
+TBool CScanDrive::AlreadyUsedL(TUint aCluster) const
+ {
+ __ASSERT_ALWAYS(aCluster >= KFatFirstSearchCluster && aCluster < (KFatFirstSearchCluster+iMount->UsableClusters()),User::Leave(KErrCorrupt));
+
+ return iScanFatBits[aCluster];
+ }
+
+/**
+@param aPos Position in a directory cluster
+@return ETrue if aPos is the last entry in the root directory
+*/
+TBool CScanDrive::IsEndOfRootDir(const TEntryPos& aPos)const
+ {
+ return(iMount->IsRootDir(aPos)&&(iMount->StartOfRootDirInBytes()+aPos.iPos==(iMount->RootDirEnd()-KSizeOfFatDirEntry)));
+ }
+
+/**
+@param aVal Value of the cluster to be tested
+@return ETrue if aVal is the end of cluster marker
+*/
+TBool CScanDrive::IsEofF(TInt aVal) const
+ {
+ return iMount->IsEndOfClusterCh(aVal);
+ }
+
+
+/**
+@return True if a directory error has been found
+*/
+TBool CScanDrive::IsDirError() const
+ {
+ return(iDirError!=0);
+ }
+
+/**
+ After StartL() and finishing allows us to know if there were any problems at all.
+ The client may wish to remount the filesystem if there were errors.
+
+ @return EFalse if there were no problems in FS.
+*/
+TBool CScanDrive::ProblemsDiscovered() const
+{
+ return IsDirError() || iFoundProblems;
+}
+
+/**
+ Sets the flag indicating than there are errors in filesystem structure
+ See ProblemsDiscovered()
+*/
+void CScanDrive::IndicateErrorsFound()
+{
+ iFoundProblems = ETrue;
+}
+
+
+
+/**
+Start point for scan drive also fixes up errors
+
+@return The result of the scan
+@leave
+*/
+TInt CScanDrive::StartL()
+ {
+ __PRINT1(_L("CScanDrive::StartL(), drive:%d"), iMount->DriveNumber());
+
+ //-- used for measuring time
+ TTime timeStart;
+ TTime timeEnd;
+ timeStart.UniversalTime(); //-- take start time
+
+
+ ReadMediaFatL();
+
+ CheckDirStructureL();
+#if defined(DEBUG_SCANDRIVE)
+ CompareFatsL();
+#endif
+ if(IsDirError())
+ FixupDirErrorL();
+
+ WriteNewFatsL();
+#if defined(DEBUG_SCANDRIVE)
+ PrintErrors();
+#endif
+
+
+
+ timeEnd.UniversalTime(); //-- take end time
+ const TInt msScanTime = (TInt)( (timeEnd.MicroSecondsFrom(timeStart)).Int64() / K1mSec);
+ (void)msScanTime;
+
+ __PRINT1(_L("CScanDrive: Directories visisted = %d\n"),iDirsChecked);
+ __PRINT1(_L("#@@@ CScanDrive time taken:%d ms "), msScanTime);
+
+ return KErrNone;
+ }
+
+/**
+Fix errors detected by the drive scan
+
+@leave System wide error code
+*/
+void CScanDrive::FixupDirErrorL()
+ {
+ if(!IsDirError())
+ return;
+
+ if(iDirError==EScanMatchingEntry)
+ {
+ FindSameStartClusterL();
+ FixMatchingEntryL();
+ }
+ else
+ {
+ FixPartEntryL();
+ }
+
+ IndicateErrorsFound(); //-- indicate that we have found errors
+ }
+
+/**
+Find positions of entries with same start cluster for error correction, searches
+the whole volume. Starts at the root directory.
+
+@leave System wide error code
+*/
+void CScanDrive::FindSameStartClusterL()
+ {
+ TInt err=FindStartClusterL(iMount->RootIndicator());
+ if(err==KErrNone)
+ return;
+ for(TInt i=0;i<KMaxArrayDepth && iClusterListArray[i]!=NULL;++i)
+ {
+ RArray<TInt>* clusterList=iClusterListArray[i];
+ for(TInt j=0;j<clusterList->Count();++j)
+ {
+ iRecursiveDepth=0;
+ err=FindStartClusterL((*clusterList)[j]);
+ if(err==KErrNone)
+ return;
+ }
+ }
+ __ASSERT_ALWAYS(err==KErrNone,User::Leave(KErrNotFound));
+ }
+
+/**
+Scan through directory structure looking for start cluster found in iMatching
+
+@param aDirCluster Start cluster for scan to start
+@return System wide error value
+@leave
+*/
+TInt CScanDrive::FindStartClusterL(TInt aDirCluster)
+ {
+ __PRINT1(_L("CScanDrive::FindStartCluster dirCluster=%d"),aDirCluster);
+ __ASSERT_ALWAYS(aDirCluster>=iMount->RootIndicator(),User::Leave(KErrCorrupt));
+ if(++iRecursiveDepth==KMaxScanDepth)
+ {
+ --iRecursiveDepth;
+ return(KErrNotFound);
+ }
+ TEntryPos entryPos(aDirCluster,0);
+ TInt dirEntries=0;
+ FOREVER
+ {
+ TFatDirEntry entry;
+ ReadDirEntryL(entryPos,entry);
+ if(entry.IsParentDirectory()||entry.IsCurrentDirectory()||entry.IsErased())
+ {
+ if(IsEndOfRootDir(entryPos))
+ break;
+ MoveToNextEntryL(entryPos);
+ continue;
+ }
+ if(entry.IsEndOfDirectory())
+ break;
+ TBool isComplete;
+ TEntryPos vfatPos=entryPos;
+ isComplete=MoveToVFatEndL(entryPos,entry,dirEntries);
+ __ASSERT_ALWAYS(isComplete,User::Leave(KErrBadName));
+ TInt err=CheckEntryClusterL(entry,vfatPos);
+ if(err==KErrNone)
+ {
+ --iRecursiveDepth;
+ return(err);
+ }
+ if(IsEndOfRootDir(entryPos))
+ break;
+ MoveToNextEntryL(entryPos);
+ }
+ --iRecursiveDepth;
+ return(KErrNotFound);
+ }
+
+/**
+Procces aEntry to find matching start cluster
+
+@param aEntry Directory entry to check
+@param aEntryPos Position of directory to check
+@return System wide error value
+@leave
+*/
+TInt CScanDrive::CheckEntryClusterL(const TFatDirEntry& aEntry, const TEntryPos& aEntryPos)
+ {
+ __PRINT(_L("CScanDrive::CheckEntryClusterL"));
+ if(iMount->StartCluster(aEntry)==iMatching.iStartCluster)
+ {
+ TBool complete=AddMatchingEntryL(aEntryPos);
+ if(complete)
+ return(KErrNone);
+ }
+ else if(aEntry.Attributes()&KEntryAttDir)
+ return(FindStartClusterL(iMount->StartCluster(aEntry)));
+ return(KErrNotFound);
+ }
+
+/**
+Checks directory strucutre for errors, can be considered the start point of the scan.
+Handles recursion depth to avoid stack overflow.
+
+@leave System wide error code
+*/
+void CScanDrive::CheckDirStructureL()
+ {
+ CheckDirL(iMount->RootIndicator());
+ // Due to recursive nature of CheckDirL when a depth of
+ // KMaxScanDepth is reached clusters are stored in a list
+ // and passed into CheckDirL afresh
+ for(TInt i=0;i<KMaxArrayDepth && iClusterListArray[i]!=NULL;++i)
+ {
+ RArray<TInt>* clusterList=iClusterListArray[i];
+ ++iListArrayIndex;
+ for(TInt j=0;j<clusterList->Count();++j)
+ {
+ iRecursiveDepth=0;
+ CheckDirL((*clusterList)[j]);
+ }
+ }
+ }
+
+
+/**
+Function is called recursively with Process entry untill the whole volume has been scanned.
+Each directory entry is scanned for errors, these are recorded for later fixing.
+
+@param aCluster Directory cluster to start checking
+@leave System wide error codes
+*/
+void CScanDrive::CheckDirL(TInt aCluster)
+ {
+ __PRINT1(_L("CScanDrive::CheckDirL aCluster=%d"),aCluster);
+ __ASSERT_ALWAYS(aCluster>=0,User::Leave(KErrCorrupt));
+ // check depth of recursion
+ if(++iRecursiveDepth==KMaxScanDepth)
+ {
+ AddToClusterListL(aCluster);
+ --iRecursiveDepth;
+ return;
+ }
+#if defined(DEBUG_SCANDRIVE)
+ ++iDirsChecked;
+#endif
+ TEntryPos entryPos(aCluster,0);
+ TInt dirEntries=0;
+ FOREVER
+ {
+ TFatDirEntry entry;
+ ReadDirEntryL(entryPos,entry);
+ if(!iMount->IsEndOfClusterCh(entryPos.iCluster))
+ ++dirEntries;
+ if(entry.IsParentDirectory()||entry.IsCurrentDirectory()||entry.IsErased())
+ {
+ if(IsEndOfRootDir(entryPos))
+ break;
+ MoveToNextEntryL(entryPos);
+ continue;
+ }
+ if(entry.IsEndOfDirectory())
+ {
+ if(aCluster)
+ WriteClusterChainL(aCluster,dirEntries<<KSizeOfFatDirEntryLog2);
+ break;
+ }
+ TEntryPos origPos=entryPos;
+ TFatDirEntry origEntry=entry;
+ TInt origDirEntries=dirEntries;
+ TBool isComplete;
+ isComplete=MoveToVFatEndL(entryPos,entry,dirEntries);
+ // Only assume that this is a corrupted VFAT entry if the VFAT attributes are set;
+ // assuming a non-VFAT corrupted entry is a VFAT entry is dangerous as we then assume that the
+ // first byte is a count of entries to skip, thus completely invalidating the next <n> directories.
+ if (!isComplete && origEntry.IsVFatEntry())
+ {
+ AddPartialVFatL(origPos,origEntry);
+ if(entryPos.iCluster!=KEndOfDirectory)
+ {
+ TInt toMove=origEntry.NumFollowing()-(dirEntries-origDirEntries);
+ if(toMove)
+ MovePastEntriesL(entryPos,entry,toMove,dirEntries);
+ }
+ else
+ {
+ // we fell off the end of the directory file, so just strip this
+ // incomplete long file name entry
+ dirEntries = origDirEntries;
+ }
+ }
+ else
+ ProcessEntryL(entry);
+ if(IsEndOfRootDir(entryPos))
+ break;
+ MoveToNextEntryL(entryPos);
+ }
+ --iRecursiveDepth;
+ }
+
+
+/**
+Process non trivial entries, such as files, if they are correct by filling out their
+cluster allocation in the bit packed Fat table. If it comes accross a directory
+CheckDirL will be called.
+
+@param aEntry Directory entry to check
+@leave System wide error code
+*/
+void CScanDrive::ProcessEntryL(const TFatDirEntry& aEntry)
+ {
+ __PRINT(_L("CScanDrive::ProcessEntryL"));
+ TInt entryAtt=aEntry.Attributes();
+
+ __ASSERT_ALWAYS(!(entryAtt&~KEntryAttMaskSupported)&&!aEntry.IsErased(),User::Leave(KErrCorrupt));
+ if(!(entryAtt&(KEntryAttDir|KEntryAttVolume)) && iMount->StartCluster(aEntry)>0)
+ WriteClusterChainL(iMount->StartCluster(aEntry),(TUint) aEntry.Size());
+ else if(entryAtt&KEntryAttDir)
+ CheckDirL(iMount->StartCluster(aEntry));
+ }
+
+/**
+Writes out the cluster chain for a correct file or directory, checks that the cluster
+has not already been used and that the correct number of clusters are allocated for the
+size of file. Registers cluster as used if correct
+
+@param aCluster Cluster chain start point
+@param aSizeInBytes Size of the file or directory in bytes
+@leave System wide error values
+*/
+void CScanDrive::WriteClusterChainL(TInt aCluster,TUint aSizeInBytes)
+//
+// Mark off in the new fat the clusters used by entry with start cluster of aCluster
+//
+ {
+ __PRINT1(_L("CScanDrive::WriteClusterChainL starting at %d"),aCluster);
+ __ASSERT_ALWAYS(aCluster>0,User::Leave(KErrCorrupt));
+ TInt clusterCount;
+ if(aSizeInBytes==0)
+ clusterCount=1;
+ else
+ clusterCount = (TInt) (( TInt64(aSizeInBytes) + TInt64((1<<iMount->ClusterSizeLog2())-1) ) >> iMount->ClusterSizeLog2());
+ TInt startCluster=aCluster;
+ while(clusterCount)
+ {
+ if(AlreadyUsedL(aCluster))
+ {
+ __ASSERT_ALWAYS(!IsDirError()&&iMatching.iStartCluster==0&&aCluster==startCluster,User::Leave(KErrCorrupt));
+ iMatching.iStartCluster=aCluster;
+ iDirError=EScanMatchingEntry; //ERROR POINT
+ IndicateErrorsFound(); //-- indicate that we have found errors
+ return;
+ }
+ if(clusterCount==1)
+ {
+ if(!iMount->IsEndOfClusterCh(ReadFatL(aCluster)))
+ {
+ //This is a genuine truncation
+ iTruncationCluster = aCluster;
+ }
+ SetUsedL(aCluster);
+ return;
+ }
+ else
+ {
+ TInt clusterVal=ReadFatL(aCluster);
+ __ASSERT_ALWAYS(!IsEofF(clusterVal) && clusterVal!=0,User::Leave(KErrCorrupt));
+ SetUsedL(aCluster);
+ aCluster=clusterVal;
+ --clusterCount;
+ }
+ }
+ }
+
+/**
+Move to dos entry, checking all vfat entry ID numbers are in sequence.
+Assumes aEntry is not erased
+
+@param aPos Position of the entry to move from, returns with new position
+@param aEntry The Dos entry after the Vfat entries on return
+@param aDirLength Running total of the length of the directory in entries
+@leave System wide error codes
+@return EFalse if not valid vfat entries or dos entry, else returns ETrue
+*/
+TBool CScanDrive::MoveToVFatEndL(TEntryPos& aPos,TFatDirEntry& aEntry,TInt& aDirLength)
+ {
+ __PRINT2(_L("CScanDrive::MoveToVFatEndL cluster=%d,pos=%d"),aPos.iCluster,aPos.iPos);
+ if(!aEntry.IsVFatEntry())
+ return IsDosEntry(aEntry);
+ TInt toFollow=aEntry.NumFollowing();
+ __ASSERT_ALWAYS(toFollow>0&&!aEntry.IsErased(),User::Leave(KErrCorrupt));
+ FOREVER
+ {
+ MoveToNextEntryL(aPos);
+ ReadDirEntryL(aPos,aEntry);
+ ++aDirLength;
+ --toFollow;
+ if(!toFollow)
+ break;
+ if(!IsValidVFatEntry(aEntry,toFollow))
+ return(EFalse);
+ }
+ return(IsDosEntry(aEntry));
+ }
+
+/**
+Check if an entry is valid VFat
+
+@param aEntry Entry to check
+@param aPrevNum Number into VFat entries for a dos entry to ensure in correct position
+@return ETrue if aEntry is a valid vfat entry
+*/
+TBool CScanDrive::IsValidVFatEntry(const TFatDirEntry& aEntry,TInt aPrevNum)const
+ {
+ if(aEntry.IsErased()||!aEntry.IsVFatEntry())
+ return(EFalse);
+ return(aEntry.NumFollowing()==aPrevNum);
+ }
+
+/**
+Check if an entry is a Dos entry
+
+@param aEntry Entry to check
+@return ETrue if aEntry is a dos entry
+*/
+TBool CScanDrive::IsDosEntry(const TFatDirEntry& aEntry)const
+ {
+ TBool res = !(aEntry.Attributes()&~KEntryAttMaskSupported) && !aEntry.IsErased() && !aEntry.IsVFatEntry() && !aEntry.IsEndOfDirectory();
+ return res;
+ }
+
+/**
+Add partial entry to iPartEntry under the error condition of not all Vfat entries
+being present
+
+@param aStartPos Position of the Dos entry associated with the VFat entries
+@param aEntry Directory Entry of the Dos entry associated with the VFat entries
+@leave KErrCorrupt Occurs if the entry is not valid
+*/
+void CScanDrive::AddPartialVFatL(const TEntryPos& aStartPos, const TFatDirEntry& aEntry)
+ {
+ __PRINT2(_L("CScanDrive::AddPartialVFatL cluster=%d pos=%d"),aStartPos.iCluster,aStartPos.iPos);
+ __ASSERT_ALWAYS(!IsDirError(),User::Leave(KErrCorrupt));
+ iPartEntry.iEntryPos=aStartPos;
+ iPartEntry.iEntry=aEntry;
+ iDirError=EScanPartEntry;
+ }
+
+/**
+Add entry position to iMatching
+
+@param aEntryPos Position of the entry with the matching entry
+@leave KErrCorrupt if the start cluster is 0 or more that two matching entries occurs
+@return
+*/
+TBool CScanDrive::AddMatchingEntryL(const TEntryPos& aEntryPos)
+ {
+ __PRINT2(_L("CScanDrive::AddMatchingEntryL cluster=%d pos=%d"),aEntryPos.iCluster,aEntryPos.iPos);
+ __ASSERT_ALWAYS(iMatching.iStartCluster>0 && iMatching.iCount<KMaxMatchingEntries,User::Leave(KErrCorrupt));
+ iMatching.iEntries[iMatching.iCount++]=aEntryPos;
+ return iMatching.iCount==KMaxMatchingEntries;
+ }
+
+
+static inline TBool BoolXOR(TBool a1, TBool a2)
+ {
+ if(!a1 && !a2)
+ return EFalse;
+ else if(a1 && a2)
+ return EFalse;
+ else
+ return ETrue;
+ }
+
+
+/**
+Scan for differnces in the new and old FAT table writing them to media if discovered
+
+@leave System wide error codes
+*/
+void CScanDrive::WriteNewFatsL()
+ {
+
+ __PRINT1(_L("CScanDrive::WriteNewFatsL() drv:%d"),iMount->DriveNumber());
+
+ TUint32 nClustersFixed = 0; //-- fixed clusters count
+ TUint32 nBadClusters = 0; //-- bad cluster count
+ TUint32 dirtyFatSector = 0; //-- FAT table media sector with not-flushed data
+
+ const TUint32 KSectorSzLog2 = iMount->SectorSizeLog2(); //-- Log2(media Sector Size)
+
+ TUint32 diffPos;
+ if(iMediaFatBits.Diff(iScanFatBits, diffPos))
+ {//-- there is a difference between FATs' bit representation
+
+ ASSERT(diffPos >= KFatFirstSearchCluster);
+
+ const TUint32 maxClusters = iScanFatBits.Size();
+
+ for(TUint32 i=diffPos; i<maxClusters; ++i)
+ {
+ if(BoolXOR(iMediaFatBits[i], iScanFatBits[i]))
+ {//-- difference in the cluster "i" between a real FAT and what ScanDrive restored.
+
+ //-- indicate that there are some problems in FAT. and we probably wrote something there.
+ IndicateErrorsFound();
+
+ //-- skip BAD cluster, can't mark it as unused.
+ if(iMount->IsBadCluster(ReadFatL(i)))
+ {
+ ++nBadClusters;
+ continue;
+ }
+
+ //-- here we found a lost cluster. Its FAT entry will be replaced with KSpareCluster. In the case of multiple lost clusters FAT table will
+ //-- be flushed on media sector basis. It is much faster than flushing FAT after every write and will
+ //-- guarantee that FAT won't be corrupted if the media driver provides atomic sector write.
+ if(nClustersFixed == 0)
+ {//-- this is the first lost cluster entry we found
+
+ //-- relative FAT media sector for the 'i' entry. The real value doesn't matter,
+ //-- we will just be flushing FAT before writing to the different FAT media sector.
+ dirtyFatSector = iMount->FAT().PosInBytes(i) >> KSectorSzLog2;
+
+ iMount->FAT().WriteL(i, KSpareCluster); //-- fix lost cluster
+ }
+ else
+ {
+ const TUint32 fatSec = iMount->FAT().PosInBytes(i) >> KSectorSzLog2;
+
+ if(fatSec != dirtyFatSector)
+ {//-- we are going to write to a differrent media sector
+ iMount->FAT().FlushL();
+ iMount->FAT().WriteL(i, KSpareCluster); //-- fix lost cluster
+ dirtyFatSector = fatSec;
+ }
+ else
+ {//-- write to the same FAT media sector without flushing
+ iMount->FAT().WriteL(i, KSpareCluster); //-- fix lost cluster
+ }
+
+ }
+
+ ++nClustersFixed;
+
+ }//if(BoolXOR(iMediaFatBits[i], iScanFatBits[i])
+
+ }//for(TInt i=KFatFirstSearchCluster; i<maxClusters; ++i)
+
+ }//if(iMediaFatBits.Diff(iScanFatBits, diffPos))
+
+
+ if(nClustersFixed)
+ iMount->FAT().FlushL();
+
+ //------
+
+ if(iTruncationCluster != 0)
+ {
+ iMount->FAT().WriteFatEntryEofL(iTruncationCluster);
+ iMount->FAT().FlushL();
+
+ //-- indicate that there are some problems in FAT. and we probably wrote something there.
+ IndicateErrorsFound(); //-- indicate that we have found errors
+
+ ++nClustersFixed;
+ }
+
+ __PRINT2(_L("CScanDrive::WriteNewFatsL() fixed:%d, bad:%d"), nClustersFixed, nBadClusters);
+ }
+
+/**
+Read the ID stored in reserved2 in the Dos entry or associated with the Dos entry of the
+Entry at the position passed in. This is used to find which version of two matching entries
+should be kept.
+
+@param aVFatPos Position of an entry to read ID from
+@leave System wide error codes
+@return The ID found in reserved2 field of dos entry
+*/
+TInt CScanDrive::GetReservedidL(TEntryPos aVFatPos)
+ {
+ __PRINT(_L("CScanDrive::GetReservedidL"));
+ TFatDirEntry entry;
+ ReadDirEntryL(aVFatPos,entry);
+ if(!IsDosEntry(entry))
+ {
+ TInt toMove=entry.NumFollowing();
+ while(toMove--)
+ MoveToNextEntryL(aVFatPos);
+ ReadDirEntryL(aVFatPos,entry);
+ }
+ return(entry.RuggedFatEntryId());
+ }
+
+/**
+Erase part entry found in iPartEntry
+
+@leave System wide error code
+*/
+void CScanDrive::FixPartEntryL()
+ {
+ __PRINT2(_L("CScanDrive::FixPartEntryL cluster=%d,pos=%d"),iPartEntry.iEntryPos.iCluster,iPartEntry.iEntryPos.iPos);
+ iMount->EraseDirEntryL(iPartEntry.iEntryPos,iPartEntry.iEntry);
+ IndicateErrorsFound(); //-- indicate that we have found errors
+ }
+
+/**
+Delete entry with largest value in the reserved2 section(bytes 20 and 21) of dos entry
+
+@leave System wide error code
+*/
+void CScanDrive::FixMatchingEntryL()
+ {
+ __PRINT1(_L("CScanDrive::FixMatchingEntryL() start cluster=%d"),iMatching.iStartCluster);
+ __ASSERT_ALWAYS(iMatching.iCount==KMaxMatchingEntries,User::Leave(KErrCorrupt));
+ TInt idOne=GetReservedidL(iMatching.iEntries[0]);
+ TInt idTwo=GetReservedidL(iMatching.iEntries[1]);
+ TFatDirEntry entry;
+ TInt num=idOne>idTwo?0:1;
+ ReadDirEntryL(iMatching.iEntries[num],entry);
+ iMount->EraseDirEntryL(iMatching.iEntries[num],entry);
+ IndicateErrorsFound(); //-- indicate that we have found errors
+ }
+/**
+Move past specified number of entries
+
+@param aEntryPos Start position to move from, updated as move takes place
+@param aEntry Directory entry moved to
+@param aToMove Number of entries to move through
+@param aDirEntries Number of entries moved, updated as move takes place
+@leave System wide error code
+*/
+void CScanDrive::MovePastEntriesL(TEntryPos& aEntryPos,TFatDirEntry& aEntry,TInt aToMove,TInt& aDirEntries)
+ {
+ while(aToMove-- && aEntryPos.iCluster!=KEndOfDirectory)
+ {
+ MoveToNextEntryL(aEntryPos);
+ ++aDirEntries;
+ }
+ ReadDirEntryL(aEntryPos,aEntry);
+ }
+
+/**
+Adds aCluster to cluster list array so that it may be revisited later, avoids stack
+over flow
+
+@param aCluster Directory cluster number to add to the list
+@leave KErrNoMemory If allocation fails
+*/
+void CScanDrive::AddToClusterListL(TInt aCluster)
+ {
+ if(iListArrayIndex>=KMaxArrayDepth)
+ return;
+ if(iClusterListArray[iListArrayIndex]==NULL)
+ iClusterListArray[iListArrayIndex]=new(ELeave) RArray<TInt>(KClusterListGranularity);
+ iClusterListArray[iListArrayIndex]->Append(aCluster);
+ }
+
+
+#if defined(DEBUG_SCANDRIVE)
+/**
+Used for debug purposes only, compares new Fat and first Fat table, displays any differences
+and there meaning
+
+@leave System wide error codes
+*/
+void CScanDrive::CompareFatsL() const
+ {
+ __PRINT(_L("CScanDrive::CompareFatsL()"));
+
+
+ TUint32 diffPos;
+ if(!iMediaFatBits.Diff(iScanFatBits, diffPos))
+ return; //-- FATs are identical
+
+ //-- there is a difference between the real FAT and reconstructed one. Find the mismaching bit and fix FAT.
+ const TInt clusters = iMount->UsableClusters();
+ ASSERT(diffPos < (TUint32)clusters);
+
+ TInt scanusedcnt=0;
+ TInt mediausedcnt=0;
+
+ for(TInt i=diffPos; i<clusters; ++i)
+ {
+ const TBool bRealFatEntry = iMediaFatBits[i];
+ const TBool bNewFatEntry = iScanFatBits[i];
+
+ if(BoolXOR(bRealFatEntry, bNewFatEntry))
+ {
+ if(bRealFatEntry && !bNewFatEntry)
+ {
+ __PRINT1(_L("Lost cluster=%d\n"),i);
+ }
+ else if((bRealFatEntry && !IsEofF(ReadFatL(i))) && (i==iTruncationCluster))
+ {
+ __PRINT1(_L("Hanging cluster = %d\n"),i);
+ }
+ else if(!bRealFatEntry && bNewFatEntry)
+ {
+ __PRINT1(_L("Unflushed cluster = %d\n"),i);
+ }
+ else
+ User::Leave(KErrCorrupt);
+ }
+
+ if(bRealFatEntry)
+ mediausedcnt++;
+
+ if(bNewFatEntry)
+ scanusedcnt++;
+ }
+
+ __PRINT2(_L("Scan Fat Used=%d, Media Fat Used=%d \n"),scanusedcnt,mediausedcnt);
+ }
+
+/**
+For debug purposes, print errors found as debug output
+*/
+void CScanDrive::PrintErrors()
+ {
+ __PRINT1(_L("Directories visisted = %d\n"),iDirsChecked);
+
+ if(iDirError==EScanPartEntry)
+ {
+ __PRINT2(_L("Part entry-dir cluster=%d,dir pos=%d,\n"),iPartEntry.iEntryPos.iCluster,iPartEntry.iEntryPos.iPos);
+ }
+ else if(iDirError==EScanMatchingEntry)
+ {
+ __PRINT1(_L("Matching cluster - cluster no=%d\n"),iMatching.iStartCluster);
+ __PRINT2(_L("\tcluster 1 - dir cluster=%d,dir pos=%d\n"),iMatching.iEntries[0].iCluster,iMatching.iEntries[0].iPos);
+ __PRINT2(_L("\tcluster 2 - dir cluster=%d,dir pos=%d\n"),iMatching.iEntries[1].iCluster,iMatching.iEntries[1].iPos);
+ }
+ }
+#endif
+
+/**
+Read a FAT directory entry from disk, either reads directly from the main cache or
+from the cluster buffer if scan drive is running in a seperate thread.
+
+@param aPos Media position of entry to read
+@param aDirEntry Contents of directory entry read
+@leave System wide error code
+*/
+void CScanDrive::ReadDirEntryL(const TEntryPos& aPos,TFatDirEntry& aDirEntry)
+ {
+ __PRINT(_L("CScanDrive::ReadDirEntryL"));
+ if (iMount->IsEndOfClusterCh(aPos.iCluster))
+ {
+ Mem::FillZ(&aDirEntry,sizeof(TFatDirEntry));
+ return;
+ }
+
+ iMount->ReadDirEntryL(aPos, aDirEntry);
+ }
+
+
+/**
+Move to next directory entry, if anEntry is at the end of the cluster, and we are not
+the root dir, move it to the next cluster in the chain.
+
+@param aPos Current directory position up dated to position of next entry.
+@leave System wide error codes
+
+*/
+void CScanDrive::MoveToNextEntryL(TEntryPos& aPos)
+ {
+ //__PRINT(_L("CScanDrive::MoveToNextEntryL"));
+ iMount->MoveToNextEntryL(aPos);
+ }
+
+/**
+Read a cluster from the Media Fat if scan run in a seperate thread read from scan fat table
+otherwise read from mount owned Fat table
+
+@param aClusterNum Cluster to read
+@leave System wide error code
+@return Value of cluster read from Fat
+*/
+TUint32 CScanDrive::ReadFatL(TInt aClusterNum) const
+ {
+ return iMount->FAT().ReadL(aClusterNum);
+ }
+
+
+
+
+
+
+
+
+
+
+