/*
* FUNCTION: Retrieve the next FAT16 cluster from the FAT table
*/
NTSTATUS
FAT16GetNextCluster(
PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
{
PVOID BaseAddress;
ULONG FATOffset;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FATOffset = CurrentCluster * 2;
Offset.QuadPart = ROUND_DOWN(FATOffset, ChunkSize);
if (!CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, MAP_WAIT, &Context, &BaseAddress))
{
return STATUS_UNSUCCESSFUL;
}
CurrentCluster = *((PUSHORT)((char*)BaseAddress + (FATOffset % ChunkSize)));
if (CurrentCluster >= 0xfff8 && CurrentCluster <= 0xffff)
CurrentCluster = 0xffffffff;
CcUnpinData(Context);
*NextCluster = CurrentCluster;
return STATUS_SUCCESS;
}
NTSTATUS
FAT32FindAndMarkAvailableCluster (PDEVICE_EXTENSION DeviceExt, PULONG Cluster)
/*
* FUNCTION: Finds the first available cluster in a FAT32 table
*/
{
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);
if(!CcPinRead(DeviceExt->FATFileObject, &Offset, ChunkSize, 1, &Context, &BaseAddress))
{
DPRINT1("CcMapData(Offset %x, Length %d) failed\n", (ULONG)Offset.QuadPart, ChunkSize);
return STATUS_UNSUCCESSFUL;
}
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);
}
NTSTATUS
FAT32GetNextCluster(PDEVICE_EXTENSION DeviceExt,
ULONG CurrentCluster,
PULONG NextCluster)
/*
* FUNCTION: Retrieve the next FAT32 cluster from the FAT table via a physical
* disk read
*/
{
PVOID BaseAddress;
ULONG FATOffset;
ULONG ChunkSize;
PVOID Context;
LARGE_INTEGER Offset;
ChunkSize = CACHEPAGESIZE(DeviceExt);
FATOffset = CurrentCluster * sizeof(ULONG);
Offset.QuadPart = ROUND_DOWN(FATOffset, ChunkSize);
if(!CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, 1, &Context, &BaseAddress))
{
return STATUS_UNSUCCESSFUL;
}
CurrentCluster = (*(PULONG)((char*)BaseAddress + (FATOffset % ChunkSize))) & 0x0fffffff;
if (CurrentCluster >= 0xffffff8 && CurrentCluster <= 0xfffffff)
CurrentCluster = 0xffffffff;
CcUnpinData(Context);
*NextCluster = CurrentCluster;
return (STATUS_SUCCESS);
}
static NTSTATUS
FAT32CountAvailableClusters(PDEVICE_EXTENSION DeviceExt)
/*
* FUNCTION: Counts free clusters in a FAT32 table
*/
{
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);
if(!CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, 1, &Context, &BaseAddress))
{
DPRINT1("CcMapData(Offset %x, Length %d) failed\n", (ULONG)Offset.QuadPart, ChunkSize);
return STATUS_UNSUCCESSFUL;
}
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);
}
/*
* 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);
if (!CcMapData(DeviceExt->FATFileObject, &Offset, ChunkSize, 1, &Context, &BaseAddress))
{
return STATUS_UNSUCCESSFUL;
}
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;
}
