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vfat.c
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// FsLib project
//
// module: vfat.c
// $Revision: 67 $
// $Date: 2012-05-29 22:20:56 +0400 (Вт, 29 май 2012) $
// description:
// Virtual FAT partition driver.
#include <ntifs.h>
#include <ntddk.h>
#include "version.h"
#include "ntddkex.h"
#include "kdbg.h"
#include "bklib.h"
#include "..\bklib\fssup.h"
#include "vfat.h"
#include "fslib.h"
#include "rc6.h"
#ifdef _BK_FILTER
#include "..\bkfilter\bkfilter.h"
#endif
VFAT_VOLUME g_VfatVolume = {0};
UCHAR g_VfatRc6Key[RC6_KEY_CHARS];
// ---- Low level disk IO -------------------------------------------------------------------------------------------------
//
// Encrypts/Decrypts sectors data
//
VOID VfatRc6CryptSectors(
PCHAR InBuffer, // Source buffer
PCHAR OutBuffer, // Destination buffer
ULONG Count, // Number of sectors
ULONG SubKey, // Sub key value
BOOL Encrypt // TRUE to encrypt, FALSE to decrypt data
)
{
ULONG i, c, k;
ULONG CryptBlock[RC6_BLOCK_SIZE/sizeof(ULONG)];
RC6CONTEXT CryptCtx;
for (i=0; i<Count; i++)
{
RC6KeySetup(&CryptCtx, (PUCHAR)&g_VfatRc6Key);
for (c=0; c<(VFAT_SECTOR_SIZE / RC6_BLOCK_SIZE); c++)
{
if (Encrypt)
{
for (k=0; k<(RC6_BLOCK_SIZE/sizeof(ULONG)); k++)
CryptBlock[k] = _rotl(((PULONG)InBuffer)[k] ^ (SubKey + i), c);
MainRC6Encrypt(&CryptCtx, (PULONG)&CryptBlock, (PULONG)OutBuffer);
}
else
{
MainRC6Decrypt(&CryptCtx, (PULONG)InBuffer, (PULONG)&CryptBlock);
for (k=0; k<(RC6_BLOCK_SIZE/sizeof(ULONG)); k++)
((PULONG)InBuffer)[k] = _rotr(CryptBlock[k], c) ^ (SubKey + i);
}
InBuffer += RC6_BLOCK_SIZE;
OutBuffer += RC6_BLOCK_SIZE;
} // for (c=0;
} // for (i=0; i<Count; i++)
}
//
// Writes sectors to a disk. Performs encryption if needed.
//
NTSTATUS VfatWriteSectors(
PUNICODE_STRING uDriveName,
PCHAR pBuffer,
ULONG Length,
ULONGLONG StartSector,
ULONG Count,
BOOL Encrypt
)
{
NTSTATUS ntStatus;
PCHAR NewBuffer;
ASSERT((Length / VFAT_SECTOR_SIZE) >= Count);
if (Encrypt)
{
if (NewBuffer = MyAllocatePool(PagedPool, Length))
{
VfatRc6CryptSectors(pBuffer, NewBuffer, Count, (ULONG)StartSector, TRUE);
#ifdef _BK_FILTER
ntStatus = FltWriteSectors(NewBuffer, (ULONG)StartSector, Count);
#else
ntStatus = BkWriteSectors(uDriveName, NewBuffer, Length, StartSector, Count);
#endif
MyFreePool(NewBuffer);
}
else
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
} // if (Encrypt)
else
#ifdef _BK_FILTER
ntStatus = FltWriteSectors(pBuffer, (ULONG)StartSector, Count);
#else
ntStatus = BkWriteSectors(uDriveName, pBuffer, Length, StartSector, Count);
#endif
return(ntStatus);
}
//
// Writes VBR sector to disk and saves RC6 key into it.
//
NTSTATUS VfatWriteVbr(
PUNICODE_STRING uDriveName,
PVBR pVbr,
ULONGLONG StartSector
)
{
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
PCHAR NewBuffer;
if (NewBuffer = MyAllocatePool(PagedPool, VFAT_SECTOR_SIZE))
{
// Encrypting whole VBR
VfatRc6CryptSectors((PCHAR)pVbr, NewBuffer, 1, (ULONG)StartSector, TRUE);
// Storing encryption key within the VBR
memcpy(NewBuffer + VFAT_SECTOR_SIZE - RC6_KEY_CHARS, &g_VfatRc6Key, RC6_KEY_CHARS);
// Writing encrypted VBR with the encryption key to disk
ntStatus = VfatWriteSectors(uDriveName, NewBuffer, VFAT_SECTOR_SIZE, StartSector, 1, FALSE);
MyFreePool(NewBuffer);
} // if (NewBuffer = MyAllocatePool(PagedPool, VFAT_SECTOR_SIZE))
return(ntStatus);
}
//
// Reads sectors from a disk. Performs decryption if needed.
//
NTSTATUS VfatReadSectors(
PUNICODE_STRING uDriveName,
PCHAR pBuffer,
ULONG Length,
ULONGLONG StartSector,
ULONG Count,
BOOL Decrypt
)
{
NTSTATUS ntStatus;
ASSERT((Length / VFAT_SECTOR_SIZE) >= Count);
#ifdef _BK_FILTER
ntStatus = FltReadSectors(pBuffer, (ULONG)StartSector, Count);
#else
ntStatus = BkReadSectors(uDriveName, pBuffer, Length, StartSector, Count);
#endif
if (NT_SUCCESS(ntStatus) && Decrypt)
VfatRc6CryptSectors(pBuffer, pBuffer, Count, (ULONG)StartSector, FALSE);
return(ntStatus);
}
VOID VfatGenerateKey(PCHAR pKey)
{
ASSERT(RC6_KEY_CHARS == (2 * sizeof(LARGE_INTEGER)));
*((PLARGE_INTEGER)pKey) = KeQueryPerformanceCounter((PLARGE_INTEGER)(pKey + sizeof(LARGE_INTEGER)));
}
// ---- File Control Block ------------------------------------------------------------------------------------------------
static PVFAT_FCB VfatAllocateFcb(VOID)
{
PVFAT_FCB pFcb = NULL;
if (pFcb = MyAllocatePool(PagedPool, sizeof(VFAT_FCB)))
{
memset(pFcb, 0, sizeof(VFAT_FCB));
InitializeListHead(&pFcb->FcbListHead);
InitializeListHead(&pFcb->FcbListEntry);
KeInitializeMutex(&pFcb->Lock, 0);
#if DBG
pFcb->Magic = VFAT_FCB_MAGIC;
#endif
}
return(pFcb);
}
static VOID VfatReleaseFcb(PVFAT_FCB pFcb)
{
ASSERT_FCB(pFcb);
ASSERT(pFcb->ReferenceCount == 0);
ASSERT(IsListEmpty(&pFcb->FcbListHead));
if (!IsListEmpty(&pFcb->FcbListEntry))
RemoveEntryList(&pFcb->FcbListEntry);
MyFreePool(pFcb);
}
static VOID VfatLockFcb(PVFAT_FCB pFcb)
{
VfatLockObject(pFcb);
ASSERT((pFcb->Flags & FCB_FLAG_DIRTY) == 0);
}
static VOID VfatGetSystemTime(PTIME_FIELDS Times)
{
LARGE_INTEGER SystemTime;
KeQuerySystemTime(&SystemTime);
RtlTimeToTimeFields(&SystemTime, Times);
}
static VOID VfatTimeFieldsToFatTime(PTIME_FIELDS pTimes, PFAT_DATE pDate, PFAT_TIME pTime)
{
pDate->Day = pTimes->Day;
pDate->Month = pTimes->Month;
pDate->Year = pTimes->Year - 1980;
pTime->Hour = pTimes->Hour;
pTime->Minutes = pTimes->Minute;
pTime->Seconds = pTimes->Second / 2;
}
static VOID VfatGetDateTime(PFAT_DATE pDate, PFAT_TIME pTime)
{
TIME_FIELDS TimeFields;
VfatGetSystemTime(&TimeFields);
VfatTimeFieldsToFatTime(&TimeFields, pDate, pTime);
}
static VOID VfatDateTimeToSysTime(PLARGE_INTEGER pSysTime, PFAT_DATE pDate, PFAT_TIME pTime)
{
TIME_FIELDS TimeFields = {0};
TimeFields.Day = pDate->Day;
TimeFields.Month = pDate->Month;
TimeFields.Year = pDate->Year + 1980;
TimeFields.Hour = pTime->Hour;
TimeFields.Minute = pTime->Minutes;
TimeFields.Second = pTime->Seconds * 2;
RtlTimeFieldsToTime(&TimeFields, pSysTime);
}
static NTSTATUS VfatSaveVolumeData(PVFAT_VOLUME pVolume)
{
NTSTATUS ntStatus = STATUS_SUCCESS;
ULONG i, FatSize = pVolume->pVbr->Bpb.SectorsPerFat * VFAT_SECTOR_SIZE;
ULONGLONG StartSector;
PCHAR Sector;
// Writing FAT(s)
for (i=0; (NT_SUCCESS(ntStatus) && i<(ULONG)(pVolume->pVbr->Bpb.NumberOfFats)); i++)
{
StartSector = pVolume->StartSector + pVolume->pVbr->Bpb.RecervedSectors + (i * pVolume->pVbr->Bpb.SectorsPerFat);
ntStatus = VfatWriteSectors(pVolume->pDeviceName, (PCHAR)pVolume->Fat0, FatSize, StartSector, pVolume->pVbr->Bpb.SectorsPerFat, TRUE);
}
if (NT_SUCCESS(ntStatus))
// Writing VBR
ntStatus = VfatWriteVbr(pVolume->pDeviceName, pVolume->pVbr, pVolume->StartSector);
return(ntStatus);
}
static NTSTATUS VfatFormatPartition(PBK_FS_AREA pFsArea)
{
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
PVBR pVbr = NULL;
PFAT Fat0 = NULL;
ULONG EntriesPerSector = pFsArea->BytesPerSector / sizeof(FAT_DIR_ENTRY);
ULONG FatsPerSector = pFsArea->BytesPerSector / sizeof(FAT);
ULONG i, FatSize, FatRecords, RootDirSize;
ULONGLONG StartSector;
do
{
// Initializing VBR
if (!(pVbr = MyAllocatePool(PagedPool, pFsArea->BytesPerSector)))
break;
memset(pVbr, 0, pFsArea->BytesPerSector);
memcpy(&pVbr->VolumeOemId, VFAT_OEM_ID, sizeof(VFAT_OEM_ID));
pVbr->Bpb.SectorSize = (USHORT)pFsArea->BytesPerSector;
pVbr->Bpb.SectorsPerCluster = 1;
pVbr->Bpb.RecervedSectors = 1;
pVbr->Bpb.NumberOfFats = 1;
// Calculating FAT size (sectors)
i = (pFsArea->NumberOfSectors - pVbr->Bpb.RecervedSectors - pVbr->Bpb.NumberOfFats);
i = (i + FatsPerSector - 1) / FatsPerSector;
pVbr->Bpb.SectorsPerFat = (USHORT)i;
// Total number of reserved sectors between volume start and partition
pVbr->Bpb.SmallSectorsCount = (USHORT)(pVbr->Bpb.RecervedSectors + (pVbr->Bpb.NumberOfFats * pVbr->Bpb.SectorsPerFat));
// Total number of sectors within the partition
pVbr->Bpb.FatTotalSectors = pFsArea->NumberOfSectors - pVbr->Bpb.SmallSectorsCount;
// Initializing file allocation tables
FatSize = pVbr->Bpb.SectorsPerFat * pFsArea->BytesPerSector; // bytes
if (!(Fat0 = MyAllocatePool(PagedPool, FatSize)))
break;
// Initializng Root Directory first sector
pVbr->Bpb.FirstRDSector = 2;
memset(Fat0, 0, FatSize);
Fat0[0] = FAT_EOC;
Fat0[1] = FAT_EOC;
Fat0[2] = FAT_EOC; // will be the first sector of the root directory
i = pVbr->Bpb.FatTotalSectors;
FatRecords = FatSize / sizeof(FAT); // number of FAT records
while((i + 2) < FatRecords)
{
Fat0[i + 2] = FAT_BAD;
i += 1;
}
ntStatus = STATUS_SUCCESS;
VfatGenerateKey((PCHAR)&g_VfatRc6Key);
// Writing FAT(s)
for (i=0; (NT_SUCCESS(ntStatus) && i<(ULONG)(pVbr->Bpb.NumberOfFats)); i++)
{
StartSector = pFsArea->StartSector + pVbr->Bpb.RecervedSectors + (i * pVbr->Bpb.SectorsPerFat);
ntStatus = VfatWriteSectors(pFsArea->pDeviceName, (PCHAR)Fat0, FatSize, StartSector, pVbr->Bpb.SectorsPerFat, TRUE);
}
if (!NT_SUCCESS(ntStatus))
break;
// Writing VBR
ntStatus = VfatWriteVbr(pFsArea->pDeviceName, pVbr, pFsArea->StartSector);
} while(FALSE);
if (pVbr)
MyFreePool(pVbr);
if (Fat0)
MyFreePool(Fat0);
return(ntStatus);
}
static NTSTATUS VfatLoadVolume(PBK_FS_AREA pFsArea, PVFAT_VOLUME pVolume)
{
ULONG bSize;
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
ULONGLONG StartSector;
KeInitializeMutex(&pVolume->Lock, 0);
do // not a loop
{
if (!(pVolume->pVbr = MyAllocatePool(PagedPool, pFsArea->BytesPerSector)))
break;
// Reading VBR sector as it is (without decryption)
ntStatus = VfatReadSectors(pFsArea->pDeviceName, (PCHAR)pVolume->pVbr, pFsArea->BytesPerSector, pFsArea->StartSector, 1, FALSE);
if (!NT_SUCCESS(ntStatus))
break;
// Copying RC6 key from the VBR sector
memcpy(&g_VfatRc6Key, (PCHAR)pVolume->pVbr + pFsArea->BytesPerSector - RC6_KEY_CHARS, RC6_KEY_CHARS);
// Reloading VBR and decrypting it
ntStatus = VfatReadSectors(pFsArea->pDeviceName, (PCHAR)pVolume->pVbr, pFsArea->BytesPerSector, pFsArea->StartSector, 1, TRUE);
if (!NT_SUCCESS(ntStatus))
break;
ntStatus = STATUS_INVALID_IMAGE_FORMAT;
if (memcmp(&pVolume->pVbr->VolumeOemId, VFAT_OEM_ID, sizeof(VFAT_OEM_ID)) != 0)
break;
if (pVolume->pVbr->Bpb.SectorSize != pFsArea->BytesPerSector)
break;
if (pVolume->pVbr->Bpb.SectorsPerFat == 0 || pVolume->pVbr->Bpb.SectorsPerFat > FAT_SIZE_MAX)
break;
// Reading FAT
bSize = pVolume->pVbr->Bpb.SectorsPerFat * pFsArea->BytesPerSector;
if (!(pVolume->Fat0 = MyAllocatePool(PagedPool, bSize)))
{
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
break;
}
StartSector = pFsArea->StartSector + pVolume->pVbr->Bpb.RecervedSectors;
ntStatus = VfatReadSectors(pFsArea->pDeviceName, (PCHAR)pVolume->Fat0, bSize, StartSector, pVolume->pVbr->Bpb.SectorsPerFat, TRUE);
if (!NT_SUCCESS(ntStatus) || pVolume->Fat0[0] != FAT_EOC || pVolume->Fat0[1] != FAT_EOC)
{
ntStatus = STATUS_INVALID_IMAGE_FORMAT;
break;
}
pVolume->StartSector = pFsArea->StartSector;
pVolume->pDeviceName = pFsArea->pDeviceName;
pVolume->Flags |= VF_ACTIVE;
// Initializing Root Directory
if (!(pVolume->RootFcb = VfatAllocateFcb()))
{
ntStatus = STATUS_INSUFFICIENT_RESOURCES;
break;
}
pVolume->RootFcb->pVolume = pVolume;
pVolume->RootFcb->ReferenceCount = 1;
pVolume->RootFcb->DirEntry.Cluster = pVolume->pVbr->Bpb.FirstRDSector;
pVolume->RootFcb->DirEntry.FileSize = pVolume->pVbr->Bpb.RDSize;
} while(FALSE);
if (!NT_SUCCESS(ntStatus))
{
if (pVolume->Fat0)
MyFreePool(pVolume->Fat0);
if (pVolume->pVbr)
MyFreePool(pVolume->pVbr);
}
return(ntStatus);
}
NTSTATUS VfatInitialize(PBK_FS_AREA pFsArea)
{
NTSTATUS ntStatus;
memset(&g_VfatVolume, 0, sizeof(VFAT_VOLUME));
ntStatus = VfatLoadVolume(pFsArea, &g_VfatVolume);
if (ntStatus == STATUS_INVALID_IMAGE_FORMAT)
{
if (NT_SUCCESS(ntStatus = VfatFormatPartition(pFsArea)))
{
memset(&g_VfatVolume, 0, sizeof(VFAT_VOLUME));
ntStatus = VfatLoadVolume(pFsArea, &g_VfatVolume);
}
} // if (ntStatus == STATUS_INVALID_IMAGE_FORMAT)
return(ntStatus);
}
static VOID VfatCleanupVolume(PVFAT_VOLUME pVolume)
{
if (pVolume->Flags & VF_ACTIVE)
{
VfatLockVolume(pVolume);
InterlockedAnd(&pVolume->Flags, ~VF_ACTIVE);
if (pVolume->Fat0)
MyFreePool(pVolume->Fat0);
if (pVolume->pVbr)
MyFreePool(pVolume->pVbr);
VfatUnlockVolume(pVolume);
}
}
VOID VfatCleanup(VOID)
{
VfatCleanupVolume(&g_VfatVolume);
}
LONG AnsiStrRChr(PANSI_STRING aStr, UCHAR uChar)
{
LONG i = aStr->Length;
while((i -= 1) >= 0)
{
if (aStr->Buffer[i] == uChar)
break;
}
return(i);
}
LONG AnsiStrChr(PANSI_STRING aStr, UCHAR uChar)
{
ULONG i = 0;
while((i < aStr->Length) && (aStr->Buffer[i] != uChar))
i += 1;
return(i);
}
static NTSTATUS VfatTruncateChain(
PVFAT_VOLUME pVolume,
USHORT FirstSector, // File first sector number
LONG Index // Sector to truncate from
)
{
NTSTATUS ntStatus = STATUS_SUCCESS;
FAT Next, Current = (FAT)FirstSector;
VfatLockVolume(pVolume);
do
{
Index -= 1;
Next = pVolume->Fat0[Current];
if (Next == FAT_RESERVED || Next == FAT_AVALIABLE || Next == FAT_BAD)
{
ntStatus = STATUS_NO_SUCH_FILE;
break;
}
if (Index < 0)
pVolume->Fat0[Current] = FAT_AVALIABLE;
else if (Index == 0)
pVolume->Fat0[Current] = FAT_EOC;
Current = Next;
} while (Next != FAT_EOC);
VfatUnlockVolume(pVolume);
return(ntStatus);
}
//
// Scans FAT for the next free sector starting from the specified one.
// In case of no free sectors avaliable returns 0.
//
static FAT VfatFindFreeSector(PVFAT_VOLUME pVolume, FAT Start)
{
// Searching from Start index
FAT Index = Start;
do
{
if ((Index += 1) >= pVolume->pVbr->Bpb.FatTotalSectors)
{
// No more free space
Index = 0;
break;
}
} while(pVolume->Fat0[Index] != FAT_AVALIABLE);
if (Index == 0 && Start != 0)
// Searching from the beginning of FAT
Index = VfatFindFreeSector(pVolume, 0);
return(Index);
}
//
// Scans FAT chain starting from the FirstSector for the Index sector.
// If Index sector is not present and Ind
//
NTSTATUS VfatGetFileSector(PVFAT_VOLUME pVolume, ULONG FirstSector, ULONG Index, PULONG pCurrent)
{
NTSTATUS ntStatus = STATUS_INVALID_PARAMETER;
FAT Next, Current = (FAT)FirstSector;
if (Current == 0)
{
Index = 0;
ntStatus = STATUS_DISK_FULL;
if (Current = VfatFindFreeSector(pVolume, 0))
pVolume->Fat0[Current] = FAT_EOC;
} // if (Current == 0)
if (Current > 1)
{
ntStatus = STATUS_SUCCESS;
// Walking the FAT chain to obtain current sector index
while(Index)
{
Next = pVolume->Fat0[Current];
if (Next == FAT_AVALIABLE || Next == FAT_BAD)
{
ntStatus = STATUS_NO_SUCH_FILE;
break;
}
if (Next == FAT_EOC)
{
// Trying to write beyond the sector chain?
if (Index > 1)
{
ntStatus = STATUS_NO_SUCH_FILE;
break;
}
// Adding new sector to chain
if (!(Next = VfatFindFreeSector(pVolume, Current)))
{
ntStatus = STATUS_DISK_FULL;
break;
}
pVolume->Fat0[Next] = FAT_EOC;
pVolume->Fat0[Current] = Next;
} // if (Next == FAT_EOC)
Current = Next;
Index -= 1;
} // while(Index)
*pCurrent = Current;
} // if (Current > 1)
return(ntStatus);
}
static NTSTATUS VfatAppendChain(
PVFAT_VOLUME pVolume,
PUSHORT pFirstSector, // pointer to the file first sector number
LONG Index // Sector to append to
)
{
NTSTATUS ntStatus = STATUS_SUCCESS;
ULONG FileFirst = (ULONG)*pFirstSector;
ASSERT(Index > 0);
VfatLockVolume(pVolume);
ntStatus = VfatGetFileSector(pVolume, FileFirst, 1, &FileFirst);
if (*pFirstSector == 0)
*pFirstSector = (USHORT)FileFirst;
while((Index -= 1) && NT_SUCCESS(ntStatus))
ntStatus = VfatGetFileSector(pVolume, FileFirst, 1, &FileFirst);
VfatUnlockVolume(pVolume);
return(ntStatus);
}
static NTSTATUS VfatDeleteFile(PVFAT_FCB Fcb)
{
NTSTATUS ntStatus = STATUS_SUCCESS;
FAT Next, Current = Fcb->DirEntry.Cluster;
if (Current > 1)
{
ASSERT(Fcb->DirEntry.FileSize);
ntStatus = VfatTruncateChain(Fcb->pVolume, Current, 0);
} // if (Current > 1)
Fcb->DirEntry.FileName.Name[0] = 0;
return(ntStatus);
}
static NTSTATUS VfatReadFileSector(PVFAT_VOLUME pVolume, ULONG FirstSector, ULONG Index, PCHAR pSector)
{
NTSTATUS ntStatus = STATUS_INVALID_PARAMETER;
FAT Current = (FAT)FirstSector;
ASSERT(KeGetCurrentIrql() == PASSIVE_LEVEL);
VfatLockVolume(pVolume);
if (Current > 1)
{
ntStatus = STATUS_SUCCESS;
// Walking the FAT chain to obtain current sector index
while(Index)
{
Current = pVolume->Fat0[Current];
if (Current == FAT_AVALIABLE || Current >= FAT_RESERVED)
{
// Current sector is the last one or is corrupt
ntStatus = STATUS_NO_SUCH_FILE;
break;
}
Index -= 1;
} // while(Index)
if (NT_SUCCESS(ntStatus))
{
ULONGLONG StartSector = pVolume->StartSector + pVolume->pVbr->Bpb.SmallSectorsCount + Current - 2;
ntStatus = VfatReadSectors(pVolume->pDeviceName, pSector, VFAT_SECTOR_SIZE, StartSector, 1, TRUE);
} // if (NT_SUCCESS(ntStatus))
} // if (Current > 1)
VfatUnlockVolume(pVolume);
return(ntStatus);
}
static NTSTATUS VfatWriteFileSector(PVFAT_VOLUME pVolume, ULONG FirstSector, ULONG Index, PCHAR pSector, PULONG pCurrent)
{
NTSTATUS ntStatus = STATUS_INVALID_PARAMETER;
ULONG Current;
ASSERT(KeGetCurrentIrql() == PASSIVE_LEVEL);
VfatLockVolume(pVolume);
ntStatus = VfatGetFileSector(pVolume, FirstSector, Index, &Current);
if (FirstSector == 0)
*pCurrent = Current;
if (NT_SUCCESS(ntStatus))
{
ULONGLONG StartSector = pVolume->StartSector + pVolume->pVbr->Bpb.SmallSectorsCount + Current - 2;
ntStatus = VfatWriteSectors(pVolume->pDeviceName, pSector, VFAT_SECTOR_SIZE, StartSector, 1, TRUE);
}
VfatUnlockVolume(pVolume);
return(ntStatus);
}
static NTSTATUS VfatReadFileInternal(PVFAT_FILE_CONTEXT FileCtx, PVOID Buffer, PULONG bRead)
{
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
PVFAT_FCB Fcb = FileCtx->Fcb;
ULONG i, StartSector, NumberSectors, FirstOffset;
PCHAR ReadBuffer, Current;
if (Fcb->DirEntry.Cluster == 0 || Fcb->DirEntry.FileSize == 0 || *bRead == 0)
{
// Trying to read 0 bytes or read from zero-sized file
*bRead = 0;
return(STATUS_SUCCESS);
}
FirstOffset = FileCtx->pPosition->LowPart % VFAT_SECTOR_SIZE;
StartSector = FileCtx->pPosition->LowPart / VFAT_SECTOR_SIZE;
NumberSectors = (FirstOffset + *bRead + VFAT_SECTOR_SIZE - 1) / VFAT_SECTOR_SIZE;
StartSector += Fcb->DirEntry.Cluster;
if (ReadBuffer = MyAllocatePool(PagedPool, NumberSectors * VFAT_SECTOR_SIZE))
{
Current = ReadBuffer;
for (i=0; i<NumberSectors; i++)
{
ntStatus = VfatReadFileSector(Fcb->pVolume, StartSector, i, Current);
if (!NT_SUCCESS(ntStatus))
break;
Current += VFAT_SECTOR_SIZE;
} // for (i=0; i<NumberSectors; i++)
if (i != 0)
{
// Calculating bytes read
i = i*VFAT_SECTOR_SIZE - FirstOffset;
if (i > *bRead)
i = *bRead;
FileCtx->pPosition->LowPart += i;
memcpy(Buffer, ReadBuffer + FirstOffset, i);
*bRead = i;
ntStatus = STATUS_SUCCESS;
}
MyFreePool(ReadBuffer);
} // if (ReadBuffer = MyAllocatePool(PagedPool, NumberSectors * VFAT_SECTOR_SIZE))
return(ntStatus);
}
static NTSTATUS VfatWriteFileInternal(PVFAT_FILE_CONTEXT FileCtx, PVOID Buffer, PULONG bWrite)
{
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
PVFAT_FCB Fcb = FileCtx->Fcb;
ULONG i, StartSector, NumberSectors, FirstOffset;
PCHAR WriteBuffer, Current;
FirstOffset = FileCtx->pPosition->LowPart % VFAT_SECTOR_SIZE;
StartSector = FileCtx->pPosition->LowPart / VFAT_SECTOR_SIZE;
NumberSectors = (FirstOffset + *bWrite + VFAT_SECTOR_SIZE - 1) / VFAT_SECTOR_SIZE;
StartSector += Fcb->DirEntry.Cluster;
if (WriteBuffer = MyAllocatePool(PagedPool, NumberSectors * VFAT_SECTOR_SIZE))
{
Current = WriteBuffer;
memset(WriteBuffer, 0, NumberSectors * VFAT_SECTOR_SIZE);
if (FirstOffset || (Fcb->DirEntry.FileSize > *bWrite))
// Reading StartSector data
ntStatus = VfatReadFileSector(Fcb->pVolume, StartSector, 0, WriteBuffer);
if (Fcb->DirEntry.FileSize > (FileCtx->pPosition->LowPart + *bWrite) && NumberSectors > 1)
// Reading last sector data
ntStatus = VfatReadFileSector(Fcb->pVolume, StartSector, NumberSectors - 1, WriteBuffer + (NumberSectors - 1)* VFAT_SECTOR_SIZE);
memcpy(WriteBuffer + FirstOffset, Buffer, *bWrite);
for (i=0; i<NumberSectors; i++)
{
ntStatus = VfatWriteFileSector(Fcb->pVolume, StartSector, i, Current, &StartSector);
if (!NT_SUCCESS(ntStatus))
break;
Current += VFAT_SECTOR_SIZE;
}
if (Fcb->DirEntry.Cluster == 0)
Fcb->DirEntry.Cluster = (USHORT)StartSector;
if (NT_SUCCESS(ntStatus))
{
FileCtx->pPosition->LowPart += *bWrite;
if (Fcb->DirEntry.FileSize < FileCtx->pPosition->LowPart)
// File size increased by write
Fcb->DirEntry.FileSize = FileCtx->pPosition->LowPart;
ntStatus = STATUS_SUCCESS;
}
MyFreePool(WriteBuffer);
} // if (WriteBuffer = MyAllocatePool(PagedPool, NumberSectors * VFAT_SECTOR_SIZE))
return(ntStatus);
}
static NTSTATUS VfatGetDirectoryEntry(PVFAT_FCB DirFcb, PFAT_NAME FatName, DWORD CreateOptions, PFAT_DIR_ENTRY DirEntry)
{
ULONG i, NumberEntries, DirSize, bRead = 0;
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
PFAT_DIR_ENTRY Entries = NULL, Matching = NULL, EmptyOne = NULL;
VFAT_FILE_CONTEXT FileCtx;
ULONG CreationDisposition = (CreateOptions >> 24);
VfatLockObject(DirFcb);
DirSize = DirFcb->DirEntry.FileSize;
FileCtx.Fcb = DirFcb;
FileCtx.pPosition = &FileCtx.FilePosition;
FileCtx.FilePosition.QuadPart = 0;
// Allocating memory for the directory
// Adding one extra sector to be able to inrease directory size if needed
while (Entries = MyAllocatePool(PagedPool, DirSize + VFAT_SECTOR_SIZE)) // not a loop
{
ntStatus = STATUS_SUCCESS;
if (DirSize)
{
// The directory is not empty
ASSERT(DirFcb->DirEntry.Cluster > 1);
ASSERT(DirSize == sizeof(FAT_DIR_ENTRY) * (DirSize / sizeof(FAT_DIR_ENTRY)));
bRead = DirSize;
// Reading directory content
ntStatus = VfatReadFileInternal(&FileCtx, (PCHAR)Entries, &bRead);
if (!NT_SUCCESS(ntStatus))
break;
if (bRead != DirSize)
{
// Possibly corrupt directory structure, trying to truncate it
ASSERT(bRead < DirSize);
DirSize = ((bRead + sizeof(FAT_DIR_ENTRY) - 1) / sizeof(FAT_DIR_ENTRY)) * sizeof(FAT_DIR_ENTRY);
}
NumberEntries = bRead / sizeof(FAT_DIR_ENTRY);
for (i=0; i<NumberEntries; i++)
{
if (Entries[i].FileName.Name[0] != 0)
{
if (memcmp(&Entries[i].FileName, FatName, sizeof(FAT_NAME)) == 0)
{
// Matching entry found
Matching = &Entries[i];
break;
}
} // if (Entries[i].FileName[0] != 0)
else
{
// Saving an empty record for future use
if (EmptyOne == NULL)
EmptyOne = &Entries[i];
}
} // for (i=0; i<NumberEntries; i++)
} // if (DirSize)
if (!Matching)
{
// No entry found
if (!(CreationDisposition & FILE_CREATE || CreationDisposition == FILE_OVERWRITE_IF))
{
ntStatus = STATUS_OBJECT_NAME_NOT_FOUND;
break;
}
// Creating new file record
if (!EmptyOne)
{
// No empty records: increasing directory size for one sector
EmptyOne = (PFAT_DIR_ENTRY)((PCHAR)Entries + DirSize);
memset(EmptyOne, 0, VFAT_SECTOR_SIZE);
DirFcb->DirEntry.FileSize = (DirSize += sizeof(FAT_DIR_ENTRY));
DirFcb->Flags |= FCB_FLAG_DIRTY;
}
memcpy(&EmptyOne->FileName, FatName, sizeof(FAT_NAME));
EmptyOne->Cluster = 0;
EmptyOne->FileSize = 0;
EmptyOne->Index = (UCHAR)(EmptyOne - Entries);
VfatGetDateTime((PFAT_DATE)&EmptyOne->CreateDate, (PFAT_TIME)&EmptyOne->CreateTime);
Matching = EmptyOne;
}
else
{
// Directory entry was found
if (!(CreationDisposition & FILE_OPEN))
ntStatus = STATUS_OBJECT_NAME_COLLISION;
}
memcpy(DirEntry, Matching, sizeof(FAT_DIR_ENTRY));
break;
} // while (Entries = MyAllocatePool(PagedPool, DirSize + VFAT_SECTOR_SIZE))
VfatUnlockObject(DirFcb);
if (Entries)
MyFreePool(Entries);
return(ntStatus);
}
static BOOL VfatStringToFileName(PANSI_STRING String, PFAT_NAME FileName)
{
BOOL Ret = FALSE;
LONG NameLen, ExtLen = 0;
NameLen = AnsiStrRChr(String, '.');
if (NameLen < 0)
NameLen = String->Length;
if (NameLen < String->Length)
ExtLen = String->Length - NameLen - 1;
if (NameLen > 0 && NameLen <= VFAT_NAME_LENGTH && ExtLen <= VFAT_EXTENSION_LENGTH)
{
ASSERT(String->Length == (NameLen + ExtLen + 1));
memset(FileName, 0, sizeof(FAT_NAME));
memcpy(&FileName->Name, String->Buffer, NameLen);
if (ExtLen)
memcpy(&FileName->Extension, String->Buffer + NameLen + 1, ExtLen);
Ret = TRUE;
}
return(Ret);
}
static VOID VfatFileNameToString(PFAT_NAME FileName, PANSI_STRING String)
{
ULONG Length;
ASSERT(String->MaximumLength >= (sizeof(FAT_NAME) + 2));
memset(String->Buffer, 0, (sizeof(FAT_NAME) + 2));
memcpy(String->Buffer, FileName->Name, VFAT_NAME_LENGTH);
String->Length = VFAT_NAME_LENGTH;
Length = AnsiStrChr(String, 0);
if (FileName->Extension[0])
{
String->Buffer[Length] = '.';
memcpy(String->Buffer + Length + 1, FileName->Extension, VFAT_EXTENSION_LENGTH);
String->Length += (VFAT_EXTENSION_LENGTH + 1);
Length = AnsiStrChr(String, 0);