reactos/drivers/filesystems/fastfat/fat.c

822 lines
22 KiB
C

/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* FILE: drivers/fs/vfat/fat.c
* PURPOSE: VFAT Filesystem
* PROGRAMMER: Jason Filby (jasonfilby@yahoo.com)
*
*/
/* INCLUDES *****************************************************************/
#include "vfat.h"
#define NDEBUG
#include <debug.h>
/* GLOBALS ******************************************************************/
#define CACHEPAGESIZE(pDeviceExt) ((pDeviceExt)->FatInfo.BytesPerCluster > PAGE_SIZE ? \
(pDeviceExt)->FatInfo.BytesPerCluster : PAGE_SIZE)
/* FUNCTIONS ****************************************************************/
/*
* FUNCTION: Retrieve the next FAT32 cluster from the FAT table via a physical
* disk read
*/
NTSTATUS
FAT32GetNextCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
{
NTSTATUS Status = STATUS_SUCCESS;
PVOID BaseAddress;
ULONG FATOffset;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FATOffset = CurrentCluster * sizeof(ULONG);
Offset.QuadPart = ROUND_DOWN(FATOffset, ChunkSize);
_SEH2_TRY
{
CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, MAP_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
CurrentCluster = (*(PULONG)((char*)BaseAddress + (FATOffset % ChunkSize))) & 0x0fffffff;
if (CurrentCluster >= 0xffffff8 && CurrentCluster <= 0xfffffff)
CurrentCluster = 0xffffffff;
if (CurrentCluster == 0)
{
DPRINT1("WARNING: File system corruption detected. You may need to run a disk repair utility.\n");
Status = STATUS_FILE_CORRUPT_ERROR;
if (VfatGlobalData->Flags & VFAT_BREAK_ON_CORRUPTION)
ASSERT(CurrentCluster != 0);
}
CcUnpinData(Context);
*NextCluster = CurrentCluster;
return Status;
}
/*
* FUNCTION: Retrieve the next FAT16 cluster from the FAT table
*/
NTSTATUS
FAT16GetNextCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
{
NTSTATUS Status = STATUS_SUCCESS;
PVOID BaseAddress;
ULONG FATOffset;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FATOffset = CurrentCluster * 2;
Offset.QuadPart = ROUND_DOWN(FATOffset, ChunkSize);
_SEH2_TRY
{
CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, MAP_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
CurrentCluster = *((PUSHORT)((char*)BaseAddress + (FATOffset % ChunkSize)));
if (CurrentCluster >= 0xfff8 && CurrentCluster <= 0xffff)
CurrentCluster = 0xffffffff;
if (CurrentCluster == 0)
{
DPRINT1("WARNING: File system corruption detected. You may need to run a disk repair utility.\n");
Status = STATUS_FILE_CORRUPT_ERROR;
if (VfatGlobalData->Flags & VFAT_BREAK_ON_CORRUPTION)
ASSERT(CurrentCluster != 0);
}
CcUnpinData(Context);
*NextCluster = CurrentCluster;
return Status;
}
/*
* FUNCTION: Retrieve the next FAT12 cluster from the FAT table
*/
NTSTATUS
FAT12GetNextCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
{
PUSHORT CBlock;
ULONG Entry;
PVOID BaseAddress;
PVOID Context;
LARGE_INTEGER Offset;
*NextCluster = 0;
Offset.QuadPart = 0;
_SEH2_TRY
{
CcMapData(DeviceExt->FATFileObject, &Offset, DeviceExt->FatInfo.FATSectors * DeviceExt->FatInfo.BytesPerSector, MAP_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
CBlock = (PUSHORT)((char*)BaseAddress + (CurrentCluster * 12) / 8);
if ((CurrentCluster % 2) == 0)
{
Entry = *CBlock & 0x0fff;
}
else
{
Entry = *CBlock >> 4;
}
// DPRINT("Entry %x\n",Entry);
if (Entry >= 0xff8 && Entry <= 0xfff)
Entry = 0xffffffff;
// DPRINT("Returning %x\n",Entry);
ASSERT(Entry != 0);
*NextCluster = Entry;
CcUnpinData(Context);
// return Entry == 0xffffffff ? STATUS_END_OF_FILE : STATUS_SUCCESS;
return STATUS_SUCCESS;
}
/*
* FUNCTION: Finds the first available cluster in a FAT16 table
*/
NTSTATUS
FAT16FindAndMarkAvailableCluster(
PDEVICE_EXTENSION DeviceExt,
PULONG Cluster)
{
ULONG FatLength;
ULONG StartCluster;
ULONG i, j;
PVOID BaseAddress;
ULONG ChunkSize;
PVOID Context = 0;
LARGE_INTEGER Offset;
PUSHORT Block;
PUSHORT BlockEnd;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FatLength = (DeviceExt->FatInfo.NumberOfClusters + 2);
*Cluster = 0;
StartCluster = DeviceExt->LastAvailableCluster;
for (j = 0; j < 2; j++)
{
for (i = StartCluster; i < FatLength;)
{
Offset.QuadPart = ROUND_DOWN(i * 2, ChunkSize);
_SEH2_TRY
{
CcPinRead(DeviceExt->FATFileObject, &Offset, ChunkSize, PIN_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
DPRINT1("CcPinRead(Offset %x, Length %u) failed\n", (ULONG)Offset.QuadPart, ChunkSize);
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
Block = (PUSHORT)((ULONG_PTR)BaseAddress + (i * 2) % ChunkSize);
BlockEnd = (PUSHORT)((ULONG_PTR)BaseAddress + ChunkSize);
/* Now process the whole block */
while (Block < BlockEnd && i < FatLength)
{
if (*Block == 0)
{
DPRINT("Found available cluster 0x%x\n", i);
DeviceExt->LastAvailableCluster = *Cluster = i;
*Block = 0xffff;
CcSetDirtyPinnedData(Context, NULL);
CcUnpinData(Context);
if (DeviceExt->AvailableClustersValid)
InterlockedDecrement((PLONG)&DeviceExt->AvailableClusters);
return STATUS_SUCCESS;
}
Block++;
i++;
}
CcUnpinData(Context);
}
FatLength = StartCluster;
StartCluster = 2;
}
return STATUS_DISK_FULL;
}
/*
* FUNCTION: Finds the first available cluster in a FAT12 table
*/
NTSTATUS
FAT12FindAndMarkAvailableCluster(
PDEVICE_EXTENSION DeviceExt,
PULONG Cluster)
{
ULONG FatLength;
ULONG StartCluster;
ULONG Entry;
PUSHORT CBlock;
ULONG i, j;
PVOID BaseAddress;
PVOID Context;
LARGE_INTEGER Offset;
FatLength = DeviceExt->FatInfo.NumberOfClusters + 2;
*Cluster = 0;
StartCluster = DeviceExt->LastAvailableCluster;
Offset.QuadPart = 0;
_SEH2_TRY
{
CcPinRead(DeviceExt->FATFileObject, &Offset, DeviceExt->FatInfo.FATSectors * DeviceExt->FatInfo.BytesPerSector, PIN_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
DPRINT1("CcPinRead(Offset %x, Length %u) failed\n", (ULONG)Offset.QuadPart, DeviceExt->FatInfo.FATSectors * DeviceExt->FatInfo.BytesPerSector);
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
for (j = 0; j < 2; j++)
{
for (i = StartCluster; i < FatLength; i++)
{
CBlock = (PUSHORT)((char*)BaseAddress + (i * 12) / 8);
if ((i % 2) == 0)
{
Entry = *CBlock & 0xfff;
}
else
{
Entry = *CBlock >> 4;
}
if (Entry == 0)
{
DPRINT("Found available cluster 0x%x\n", i);
DeviceExt->LastAvailableCluster = *Cluster = i;
if ((i % 2) == 0)
*CBlock = (*CBlock & 0xf000) | 0xfff;
else
*CBlock = (*CBlock & 0xf) | 0xfff0;
CcSetDirtyPinnedData(Context, NULL);
CcUnpinData(Context);
if (DeviceExt->AvailableClustersValid)
InterlockedDecrement((PLONG)&DeviceExt->AvailableClusters);
return STATUS_SUCCESS;
}
}
FatLength = StartCluster;
StartCluster = 2;
}
CcUnpinData(Context);
return STATUS_DISK_FULL;
}
/*
* FUNCTION: Finds the first available cluster in a FAT32 table
*/
NTSTATUS
FAT32FindAndMarkAvailableCluster(
PDEVICE_EXTENSION DeviceExt,
PULONG Cluster)
{
ULONG FatLength;
ULONG StartCluster;
ULONG i, j;
PVOID BaseAddress;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
PULONG Block;
PULONG BlockEnd;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FatLength = (DeviceExt->FatInfo.NumberOfClusters + 2);
*Cluster = 0;
StartCluster = DeviceExt->LastAvailableCluster;
for (j = 0; j < 2; j++)
{
for (i = StartCluster; i < FatLength;)
{
Offset.QuadPart = ROUND_DOWN(i * 4, ChunkSize);
_SEH2_TRY
{
CcPinRead(DeviceExt->FATFileObject, &Offset, ChunkSize, PIN_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
DPRINT1("CcPinRead(Offset %x, Length %u) failed\n", (ULONG)Offset.QuadPart, ChunkSize);
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
Block = (PULONG)((ULONG_PTR)BaseAddress + (i * 4) % ChunkSize);
BlockEnd = (PULONG)((ULONG_PTR)BaseAddress + ChunkSize);
/* Now process the whole block */
while (Block < BlockEnd && i < FatLength)
{
if ((*Block & 0x0fffffff) == 0)
{
DPRINT("Found available cluster 0x%x\n", i);
DeviceExt->LastAvailableCluster = *Cluster = i;
*Block = 0x0fffffff;
CcSetDirtyPinnedData(Context, NULL);
CcUnpinData(Context);
if (DeviceExt->AvailableClustersValid)
InterlockedDecrement((PLONG)&DeviceExt->AvailableClusters);
return STATUS_SUCCESS;
}
Block++;
i++;
}
CcUnpinData(Context);
}
FatLength = StartCluster;
StartCluster = 2;
}
return STATUS_DISK_FULL;
}
/*
* FUNCTION: Counts free cluster in a FAT12 table
*/
static
NTSTATUS
FAT12CountAvailableClusters(
PDEVICE_EXTENSION DeviceExt)
{
ULONG Entry;
PVOID BaseAddress;
ULONG ulCount = 0;
ULONG i;
ULONG numberofclusters;
LARGE_INTEGER Offset;
PVOID Context;
PUSHORT CBlock;
Offset.QuadPart = 0;
_SEH2_TRY
{
CcMapData(DeviceExt->FATFileObject, &Offset, DeviceExt->FatInfo.FATSectors * DeviceExt->FatInfo.BytesPerSector, MAP_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
numberofclusters = DeviceExt->FatInfo.NumberOfClusters + 2;
for (i = 2; i < numberofclusters; i++)
{
CBlock = (PUSHORT)((char*)BaseAddress + (i * 12) / 8);
if ((i % 2) == 0)
{
Entry = *CBlock & 0x0fff;
}
else
{
Entry = *CBlock >> 4;
}
if (Entry == 0)
ulCount++;
}
CcUnpinData(Context);
DeviceExt->AvailableClusters = ulCount;
DeviceExt->AvailableClustersValid = TRUE;
return STATUS_SUCCESS;
}
/*
* FUNCTION: Counts free clusters in a FAT16 table
*/
static
NTSTATUS
FAT16CountAvailableClusters(
PDEVICE_EXTENSION DeviceExt)
{
PUSHORT Block;
PUSHORT BlockEnd;
PVOID BaseAddress = NULL;
ULONG ulCount = 0;
ULONG i;
ULONG ChunkSize;
PVOID Context = NULL;
LARGE_INTEGER Offset;
ULONG FatLength;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FatLength = (DeviceExt->FatInfo.NumberOfClusters + 2);
for (i = 2; i < FatLength; )
{
Offset.QuadPart = ROUND_DOWN(i * 2, ChunkSize);
_SEH2_TRY
{
CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, MAP_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
Block = (PUSHORT)((ULONG_PTR)BaseAddress + (i * 2) % ChunkSize);
BlockEnd = (PUSHORT)((ULONG_PTR)BaseAddress + ChunkSize);
/* Now process the whole block */
while (Block < BlockEnd && i < FatLength)
{
if (*Block == 0)
ulCount++;
Block++;
i++;
}
CcUnpinData(Context);
}
DeviceExt->AvailableClusters = ulCount;
DeviceExt->AvailableClustersValid = TRUE;
return STATUS_SUCCESS;
}
/*
* FUNCTION: Counts free clusters in a FAT32 table
*/
static
NTSTATUS
FAT32CountAvailableClusters(
PDEVICE_EXTENSION DeviceExt)
{
PULONG Block;
PULONG BlockEnd;
PVOID BaseAddress = NULL;
ULONG ulCount = 0;
ULONG i;
ULONG ChunkSize;
PVOID Context = NULL;
LARGE_INTEGER Offset;
ULONG FatLength;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FatLength = (DeviceExt->FatInfo.NumberOfClusters + 2);
for (i = 2; i < FatLength; )
{
Offset.QuadPart = ROUND_DOWN(i * 4, ChunkSize);
_SEH2_TRY
{
CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, MAP_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
DPRINT1("CcMapData(Offset %x, Length %u) failed\n", (ULONG)Offset.QuadPart, ChunkSize);
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
Block = (PULONG)((ULONG_PTR)BaseAddress + (i * 4) % ChunkSize);
BlockEnd = (PULONG)((ULONG_PTR)BaseAddress + ChunkSize);
/* Now process the whole block */
while (Block < BlockEnd && i < FatLength)
{
if ((*Block & 0x0fffffff) == 0)
ulCount++;
Block++;
i++;
}
CcUnpinData(Context);
}
DeviceExt->AvailableClusters = ulCount;
DeviceExt->AvailableClustersValid = TRUE;
return STATUS_SUCCESS;
}
NTSTATUS
CountAvailableClusters(
PDEVICE_EXTENSION DeviceExt,
PLARGE_INTEGER Clusters)
{
NTSTATUS Status = STATUS_SUCCESS;
ExAcquireResourceExclusiveLite (&DeviceExt->FatResource, TRUE);
if (!DeviceExt->AvailableClustersValid)
{
if (DeviceExt->FatInfo.FatType == FAT12)
Status = FAT12CountAvailableClusters(DeviceExt);
else if (DeviceExt->FatInfo.FatType == FAT16 || DeviceExt->FatInfo.FatType == FATX16)
Status = FAT16CountAvailableClusters(DeviceExt);
else
Status = FAT32CountAvailableClusters(DeviceExt);
}
Clusters->QuadPart = DeviceExt->AvailableClusters;
ExReleaseResourceLite (&DeviceExt->FatResource);
return Status;
}
/*
* FUNCTION: Writes a cluster to the FAT12 physical and in-memory tables
*/
NTSTATUS
FAT12WriteCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG ClusterToWrite,
ULONG NewValue,
PULONG OldValue)
{
ULONG FATOffset;
PUCHAR CBlock;
PVOID BaseAddress;
PVOID Context;
LARGE_INTEGER Offset;
Offset.QuadPart = 0;
_SEH2_TRY
{
CcPinRead(DeviceExt->FATFileObject, &Offset, DeviceExt->FatInfo.FATSectors * DeviceExt->FatInfo.BytesPerSector, PIN_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
CBlock = (PUCHAR)BaseAddress;
FATOffset = (ClusterToWrite * 12) / 8;
DPRINT("Writing 0x%x for 0x%x at 0x%x\n",
NewValue, ClusterToWrite, FATOffset);
if ((ClusterToWrite % 2) == 0)
{
*OldValue = CBlock[FATOffset] + ((CBlock[FATOffset + 1] & 0x0f) << 8);
CBlock[FATOffset] = (UCHAR)NewValue;
CBlock[FATOffset + 1] &= 0xf0;
CBlock[FATOffset + 1] |= (NewValue & 0xf00) >> 8;
}
else
{
*OldValue = (CBlock[FATOffset] >> 4) + (CBlock[FATOffset + 1] << 4);
CBlock[FATOffset] &= 0x0f;
CBlock[FATOffset] |= (NewValue & 0xf) << 4;
CBlock[FATOffset + 1] = (UCHAR)(NewValue >> 4);
}
/* Write the changed FAT sector(s) to disk */
CcSetDirtyPinnedData(Context, NULL);
CcUnpinData(Context);
return STATUS_SUCCESS;
}
/*
* FUNCTION: Writes a cluster to the FAT16 physical and in-memory tables
*/
NTSTATUS
FAT16WriteCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG ClusterToWrite,
ULONG NewValue,
PULONG OldValue)
{
PVOID BaseAddress;
ULONG FATOffset;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
PUSHORT Cluster;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FATOffset = ClusterToWrite * 2;
Offset.QuadPart = ROUND_DOWN(FATOffset, ChunkSize);
_SEH2_TRY
{
CcPinRead(DeviceExt->FATFileObject, &Offset, ChunkSize, PIN_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
DPRINT("Writing 0x%x for offset 0x%x 0x%x\n", NewValue, FATOffset,
ClusterToWrite);
Cluster = ((PUSHORT)((char*)BaseAddress + (FATOffset % ChunkSize)));
*OldValue = *Cluster;
*Cluster = (USHORT)NewValue;
CcSetDirtyPinnedData(Context, NULL);
CcUnpinData(Context);
return STATUS_SUCCESS;
}
/*
* FUNCTION: Writes a cluster to the FAT32 physical tables
*/
NTSTATUS
FAT32WriteCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG ClusterToWrite,
ULONG NewValue,
PULONG OldValue)
{
PVOID BaseAddress;
ULONG FATOffset;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
PULONG Cluster;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FATOffset = (ClusterToWrite * 4);
Offset.QuadPart = ROUND_DOWN(FATOffset, ChunkSize);
_SEH2_TRY
{
CcPinRead(DeviceExt->FATFileObject, &Offset, ChunkSize, PIN_WAIT, &Context, &BaseAddress);
}
_SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
{
_SEH2_YIELD(return _SEH2_GetExceptionCode());
}
_SEH2_END;
DPRINT("Writing 0x%x for offset 0x%x 0x%x\n", NewValue, FATOffset,
ClusterToWrite);
Cluster = ((PULONG)((char*)BaseAddress + (FATOffset % ChunkSize)));
*OldValue = *Cluster & 0x0fffffff;
*Cluster = (*Cluster & 0xf0000000) | (NewValue & 0x0fffffff);
CcSetDirtyPinnedData(Context, NULL);
CcUnpinData(Context);
return STATUS_SUCCESS;
}
/*
* FUNCTION: Write a changed FAT entry
*/
NTSTATUS
WriteCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG ClusterToWrite,
ULONG NewValue)
{
NTSTATUS Status;
ULONG OldValue;
ExAcquireResourceExclusiveLite (&DeviceExt->FatResource, TRUE);
Status = DeviceExt->WriteCluster(DeviceExt, ClusterToWrite, NewValue, &OldValue);
if (DeviceExt->AvailableClustersValid)
{
if (OldValue && NewValue == 0)
InterlockedIncrement((PLONG)&DeviceExt->AvailableClusters);
else if (OldValue == 0 && NewValue)
InterlockedDecrement((PLONG)&DeviceExt->AvailableClusters);
}
ExReleaseResourceLite(&DeviceExt->FatResource);
return Status;
}
/*
* FUNCTION: Converts the cluster number to a sector number for this physical
* device
*/
ULONGLONG
ClusterToSector(
PDEVICE_EXTENSION DeviceExt,
ULONG Cluster)
{
return DeviceExt->FatInfo.dataStart +
((ULONGLONG)(Cluster - 2) * DeviceExt->FatInfo.SectorsPerCluster);
}
/*
* FUNCTION: Retrieve the next cluster depending on the FAT type
*/
NTSTATUS
GetNextCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
{
NTSTATUS Status;
DPRINT("GetNextCluster(DeviceExt %p, CurrentCluster %x)\n",
DeviceExt, CurrentCluster);
if (CurrentCluster == 0)
{
DPRINT1("WARNING: File system corruption detected. You may need to run a disk repair utility.\n");
if (VfatGlobalData->Flags & VFAT_BREAK_ON_CORRUPTION)
ASSERT(CurrentCluster != 0);
return STATUS_FILE_CORRUPT_ERROR;
}
ExAcquireResourceSharedLite(&DeviceExt->FatResource, TRUE);
Status = DeviceExt->GetNextCluster(DeviceExt, CurrentCluster, NextCluster);
ExReleaseResourceLite(&DeviceExt->FatResource);
return Status;
}
/*
* FUNCTION: Retrieve the next cluster depending on the FAT type
*/
NTSTATUS
GetNextClusterExtend(
PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
{
ULONG NewCluster;
NTSTATUS Status;
DPRINT("GetNextClusterExtend(DeviceExt %p, CurrentCluster %x)\n",
DeviceExt, CurrentCluster);
ExAcquireResourceExclusiveLite(&DeviceExt->FatResource, TRUE);
/*
* If the file hasn't any clusters allocated then we need special
* handling
*/
if (CurrentCluster == 0)
{
Status = DeviceExt->FindAndMarkAvailableCluster(DeviceExt, &NewCluster);
if (!NT_SUCCESS(Status))
{
ExReleaseResourceLite(&DeviceExt->FatResource);
return Status;
}
*NextCluster = NewCluster;
ExReleaseResourceLite(&DeviceExt->FatResource);
return STATUS_SUCCESS;
}
Status = DeviceExt->GetNextCluster(DeviceExt, CurrentCluster, NextCluster);
if ((*NextCluster) == 0xFFFFFFFF)
{
/* We are after last existing cluster, we must add one to file */
/* Firstly, find the next available open allocation unit and
mark it as end of file */
Status = DeviceExt->FindAndMarkAvailableCluster(DeviceExt, &NewCluster);
if (!NT_SUCCESS(Status))
{
ExReleaseResourceLite(&DeviceExt->FatResource);
return Status;
}
/* Now, write the AU of the LastCluster with the value of the newly
found AU */
WriteCluster(DeviceExt, CurrentCluster, NewCluster);
*NextCluster = NewCluster;
}
ExReleaseResourceLite(&DeviceExt->FatResource);
return Status;
}
/* EOF */