[NTFS] - Add support for changing a file's size via SetEndOfFile():

-Handle IRP_MJ_SET_INFORMATION IRP requests.
+NtfsSetEndOfFile() - Sets the end of file (file size) for a given file.
+NtfsSetInformation() - Sets the specified file information. At this point, only FileEndOfFileInformation is fully implemented. FileAllocationInformation is handled the same way and not truly implemented, but this works well enough for SetEndOfFile().
Overwriting a file in NTFS should now work in the majority of use cases.

svn path=/branches/GSoC_2016/NTFS/; revision=74675

drivers/filesystems/ntfs/dispatch.c

@@ -81,6 +81,10 @@ NtfsDispatch(PNTFS_IRP_CONTEXT IrpContext)
             Status = NtfsQueryInformation(IrpContext);
             break;
 
+        case IRP_MJ_SET_INFORMATION:
+            Status = NtfsSetInformation(IrpContext);
+            break;
+
         case IRP_MJ_DIRECTORY_CONTROL:
             Status = NtfsDirectoryControl(IrpContext);
             break;

drivers/filesystems/ntfs/finfo.c

@@ -396,4 +396,248 @@ NtfsQueryInformation(PNTFS_IRP_CONTEXT IrpContext)
     return Status;
 }
 
+/**
+* @name NtfsSetEndOfFile
+* @implemented
+*
+* Sets the end of file (file size) for a given file.
+*
+* @param Fcb
+* Pointer to an NTFS_FCB which describes the target file. Fcb->MainResource should have been
+* acquired with ExAcquireResourceSharedLite().
+*
+* @param FileObject
+* Pointer to a FILE_OBJECT describing the target file.
+*
+* @param DeviceExt
+* Points to the target disk's DEVICE_EXTENSION
+*
+* @param IrpFlags
+* ULONG describing the flags of the original IRP request (Irp->Flags).
+*
+* @param NewFileSize
+* Pointer to a LARGE_INTEGER which indicates the new end of file (file size).
+*
+* @return
+* STATUS_SUCCESS if successful,
+* STATUS_USER_MAPPED_FILE if trying to truncate a file but MmCanFileBeTruncated() returned false,
+* STATUS_OBJECT_NAME_NOT_FOUND if there was no $DATA attribute associated with the target file,
+* STATUS_INVALID_PARAMETER if there was no $FILENAME attribute associated with the target file,
+* STATUS_INSUFFICIENT_RESOURCES if an allocation failed,
+* STATUS_ACCESS_DENIED if target file is a volume or if paging is involved.
+*
+* @remarks As this function sets the size of a file at the file-level 
+* (and not at the attribute level) it's not recommended to use this 
+* function alongside functions that operate on the data attribute directly.
+*
+*/
+NTSTATUS
+NtfsSetEndOfFile(PNTFS_FCB Fcb,
+                 PFILE_OBJECT FileObject,
+                 PDEVICE_EXTENSION DeviceExt,
+                 ULONG IrpFlags,
+                 PLARGE_INTEGER NewFileSize)
+{
+    LARGE_INTEGER CurrentFileSize;
+    PFILE_RECORD_HEADER FileRecord;
+    PNTFS_ATTR_CONTEXT DataContext;
+    ULONG AttributeOffset;
+    NTSTATUS Status = STATUS_SUCCESS;
+    ULONGLONG AllocationSize;
+    PFILENAME_ATTRIBUTE fileNameAttribute;
+    ULONGLONG ParentMFTId;
+    UNICODE_STRING filename;
+
+
+    // Allocate non-paged memory for the file record
+    FileRecord = ExAllocatePoolWithTag(NonPagedPool, DeviceExt->NtfsInfo.BytesPerFileRecord, TAG_NTFS);
+    if (FileRecord == NULL)
+    {
+        DPRINT1("Couldn't allocate memory for file record!");
+        return STATUS_INSUFFICIENT_RESOURCES;
+    }
+
+    // read the file record
+    DPRINT("Reading file record...\n");
+    Status = ReadFileRecord(DeviceExt, Fcb->MFTIndex, FileRecord);
+    if (!NT_SUCCESS(Status))
+    {
+        // We couldn't get the file's record. Free the memory and return the error
+        DPRINT1("Can't find record for %wS!\n", Fcb->ObjectName);
+        ExFreePoolWithTag(FileRecord, TAG_NTFS);
+        return Status;
+    }
+
+    DPRINT("Found record for %wS\n", Fcb->ObjectName);
+
+    CurrentFileSize.QuadPart = NtfsGetFileSize(DeviceExt, FileRecord, L"", 0, (PULONGLONG)&CurrentFileSize);
+
+    // Are we trying to decrease the file size?
+    if (NewFileSize->QuadPart < CurrentFileSize.QuadPart)
+    {
+        // Is the file mapped?
+        if (!MmCanFileBeTruncated(FileObject->SectionObjectPointer,
+                                  NewFileSize))
+        {
+            DPRINT1("Couldn't decrease file size!\n");
+            return STATUS_USER_MAPPED_FILE;
+        }
+    }
+
+    // Find the attribute with the data stream for our file
+    DPRINT("Finding Data Attribute...\n");
+    Status = FindAttribute(DeviceExt,
+                           FileRecord,
+                           AttributeData,
+                           Fcb->Stream,
+                           wcslen(Fcb->Stream),
+                           &DataContext,
+                           &AttributeOffset);
+
+    // Did we fail to find the attribute?
+    if (!NT_SUCCESS(Status))
+    {
+        DPRINT1("No '%S' data stream associated with file!\n", Fcb->Stream);
+        ExFreePoolWithTag(FileRecord, TAG_NTFS);
+        return Status;
+    }
+
+    // Get the size of the data attribute
+    CurrentFileSize.QuadPart = AttributeDataLength(&DataContext->Record);
+
+    // Are we enlarging the attribute?
+    if (NewFileSize->QuadPart > CurrentFileSize.QuadPart)
+    {
+        // is increasing the stream size not allowed?
+        if ((Fcb->Flags & FCB_IS_VOLUME) ||
+            (IrpFlags & IRP_PAGING_IO))
+        {
+            // TODO - just fail for now
+            ReleaseAttributeContext(DataContext);
+            ExFreePoolWithTag(FileRecord, TAG_NTFS);
+            return STATUS_ACCESS_DENIED;
+        }
+    }
+
+    // set the attribute data length
+    Status = SetAttributeDataLength(FileObject, Fcb, DataContext, AttributeOffset, FileRecord, NewFileSize);
+    if (!NT_SUCCESS(Status))
+    {
+        ReleaseAttributeContext(DataContext);
+        ExFreePoolWithTag(FileRecord, TAG_NTFS);
+        return Status;
+    }
+
+    // now we need to update this file's size in every directory index entry that references it
+    // TODO: expand to work with every filename / hardlink stored in the file record.
+    fileNameAttribute = GetBestFileNameFromRecord(Fcb->Vcb, FileRecord);
+    if (fileNameAttribute == NULL)
+    {
+        DPRINT1("Unable to find FileName attribute associated with file!\n");
+        return STATUS_INVALID_PARAMETER;
+    }
+
+    ParentMFTId = fileNameAttribute->DirectoryFileReferenceNumber & NTFS_MFT_MASK;
+
+    filename.Buffer = fileNameAttribute->Name;
+    filename.Length = fileNameAttribute->NameLength * sizeof(WCHAR);
+    filename.MaximumLength = filename.Length;
+
+    AllocationSize = ROUND_UP(NewFileSize->QuadPart, Fcb->Vcb->NtfsInfo.BytesPerCluster);
+
+    Status = UpdateFileNameRecord(Fcb->Vcb, ParentMFTId, &filename, FALSE, NewFileSize->QuadPart, AllocationSize);
+
+    ReleaseAttributeContext(DataContext);
+    ExFreePoolWithTag(FileRecord, TAG_NTFS);
+
+    return Status;
+}
+
+/**
+* @name NtfsSetInformation
+* @implemented
+*
+* Sets the specified file information.
+*
+* @param IrpContext
+* Points to an NTFS_IRP_CONTEXT which describes the set operation
+*
+* @return
+* STATUS_SUCCESS if successful,
+* STATUS_NOT_IMPLEMENTED if trying to set an unimplemented information class,
+* STATUS_USER_MAPPED_FILE if trying to truncate a file but MmCanFileBeTruncated() returned false,
+* STATUS_OBJECT_NAME_NOT_FOUND if there was no $DATA attribute associated with the target file,
+* STATUS_INVALID_PARAMETER if there was no $FILENAME attribute associated with the target file,
+* STATUS_INSUFFICIENT_RESOURCES if an allocation failed,
+* STATUS_ACCESS_DENIED if target file is a volume or if paging is involved.
+*
+* @remarks Called by NtfsDispatch() in response to an IRP_MJ_SET_INFORMATION request.
+* Only the FileEndOfFileInformation InformationClass is fully implemented. FileAllocationInformation
+* is a hack and not a true implementation, but it's enough to make SetEndOfFile() work. 
+* All other information classes are TODO.
+*
+*/
+NTSTATUS
+NtfsSetInformation(PNTFS_IRP_CONTEXT IrpContext)
+{
+    FILE_INFORMATION_CLASS FileInformationClass;
+    PIO_STACK_LOCATION Stack;
+    PDEVICE_EXTENSION DeviceExt;
+    PFILE_OBJECT FileObject;
+    PNTFS_FCB Fcb;
+    PVOID SystemBuffer;
+    ULONG BufferLength;
+    PIRP Irp;
+    PDEVICE_OBJECT DeviceObject;
+    NTSTATUS Status = STATUS_NOT_IMPLEMENTED;
+
+    DPRINT1("NtfsSetInformation(%p)\n", IrpContext);
+
+    Irp = IrpContext->Irp;
+    Stack = IrpContext->Stack;
+    DeviceObject = IrpContext->DeviceObject;
+    DeviceExt = DeviceObject->DeviceExtension;
+    FileInformationClass = Stack->Parameters.QueryFile.FileInformationClass;
+    FileObject = IrpContext->FileObject;
+    Fcb = FileObject->FsContext;
+
+    SystemBuffer = Irp->AssociatedIrp.SystemBuffer;
+    BufferLength = Stack->Parameters.QueryFile.Length;
+
+    if (!ExAcquireResourceSharedLite(&Fcb->MainResource,
+                                     BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT)))
+    {
+        return NtfsMarkIrpContextForQueue(IrpContext);
+    }
+
+    switch (FileInformationClass)
+    {
+        PFILE_END_OF_FILE_INFORMATION EndOfFileInfo;
+
+        /* TODO: Allocation size is not actually the same as file end for NTFS, 
+           however, few applications are likely to make the distinction. */
+        case FileAllocationInformation: 
+            DPRINT1("FIXME: Using hacky method of setting FileAllocationInformation.\n");
+        case FileEndOfFileInformation:
+            EndOfFileInfo = (PFILE_END_OF_FILE_INFORMATION)SystemBuffer;
+            Status = NtfsSetEndOfFile(Fcb, FileObject, DeviceExt, Irp->Flags, &EndOfFileInfo->EndOfFile);
+            break;
+            
+        // TODO: all other information classes
+
+        default:
+            DPRINT1("FIXME: Unimplemented information class %u\n", FileInformationClass);
+            Status = STATUS_NOT_IMPLEMENTED;
+    }
+
+    ExReleaseResourceLite(&Fcb->MainResource);
+
+    if (NT_SUCCESS(Status))
+        Irp->IoStatus.Information =
+        Stack->Parameters.QueryFile.Length - BufferLength;
+    else
+        Irp->IoStatus.Information = 0;
+
+    return Status;
+}
 /* EOF */

drivers/filesystems/ntfs/ntfs.c

@@ -139,6 +139,7 @@ NtfsInitializeFunctionPointers(PDRIVER_OBJECT DriverObject)
     DriverObject->MajorFunction[IRP_MJ_READ]                     = NtfsFsdDispatch;
     DriverObject->MajorFunction[IRP_MJ_WRITE]                    = NtfsFsdDispatch;
     DriverObject->MajorFunction[IRP_MJ_QUERY_INFORMATION]        = NtfsFsdDispatch;
+    DriverObject->MajorFunction[IRP_MJ_SET_INFORMATION]          = NtfsFsdDispatch;
     DriverObject->MajorFunction[IRP_MJ_QUERY_VOLUME_INFORMATION] = NtfsFsdDispatch;
     DriverObject->MajorFunction[IRP_MJ_SET_VOLUME_INFORMATION]   = NtfsFsdDispatch;
     DriverObject->MajorFunction[IRP_MJ_DIRECTORY_CONTROL]        = NtfsFsdDispatch;

drivers/filesystems/ntfs/ntfs.h

@@ -796,6 +796,15 @@ NtfsMakeFCBFromDirEntry(PNTFS_VCB Vcb,
 NTSTATUS
 NtfsQueryInformation(PNTFS_IRP_CONTEXT IrpContext);
 
+NTSTATUS
+NtfsSetEndOfFile(PNTFS_FCB Fcb,
+                 PFILE_OBJECT FileObject,
+                 PDEVICE_EXTENSION DeviceExt,
+                 ULONG IrpFlags,
+                 PLARGE_INTEGER NewFileSize);
+
+NTSTATUS
+NtfsSetInformation(PNTFS_IRP_CONTEXT IrpContext);
 
 /* fsctl.c */