559 lines
14 KiB
C
559 lines
14 KiB
C
/*++
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Copyright (c) 1989-2000 Microsoft Corporation
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Module Name:
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Read.c
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Abstract:
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This module implements the File Read routine for Read called by the
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Fsd/Fsp dispatch drivers.
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// @@BEGIN_DDKSPLIT
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Author:
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Brian Andrew [BrianAn] 01-July-1995
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Revision History:
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// @@END_DDKSPLIT
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--*/
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#include "CdProcs.h"
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//
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// The Bug check file id for this module
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//
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#define BugCheckFileId (CDFS_BUG_CHECK_READ)
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//
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// VOID
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// SafeZeroMemory (
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// IN PUCHAR At,
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// IN ULONG ByteCount
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// );
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//
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//
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// This macro just puts a nice little try-except around RtlZeroMemory
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//
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#define SafeZeroMemory(IC,AT,BYTE_COUNT) { \
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try { \
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RtlZeroMemory( (AT), (BYTE_COUNT) ); \
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} except( EXCEPTION_EXECUTE_HANDLER ) { \
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CdRaiseStatus( IC, STATUS_INVALID_USER_BUFFER ); \
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} \
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}
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//
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// Read ahead amount used for normal data files
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//
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#define READ_AHEAD_GRANULARITY (0x10000)
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGE, CdCommonRead)
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#endif
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NTSTATUS
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CdCommonRead (
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IN PIRP_CONTEXT IrpContext,
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IN PIRP Irp
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)
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/*++
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Routine Description:
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This is the common entry point for NtReadFile calls. For synchronous requests,
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CommonRead will complete the request in the current thread. If not
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synchronous the request will be passed to the Fsp if there is a need to
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block.
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Arguments:
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Irp - Supplies the Irp to process
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Return Value:
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NTSTATUS - The result of this operation.
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--*/
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{
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NTSTATUS Status;
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PIO_STACK_LOCATION IrpSp = IoGetCurrentIrpStackLocation( Irp );
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TYPE_OF_OPEN TypeOfOpen;
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PFCB Fcb;
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PCCB Ccb;
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BOOLEAN Wait;
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ULONG PagingIo;
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ULONG SynchronousIo;
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ULONG NonCachedIo;
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PVOID UserBuffer;
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LONGLONG StartingOffset;
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LONGLONG ByteRange;
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ULONG ByteCount;
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ULONG ReadByteCount;
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ULONG OriginalByteCount;
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PVOID SystemBuffer;
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BOOLEAN ReleaseFile = TRUE;
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CD_IO_CONTEXT LocalIoContext;
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PAGED_CODE();
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//
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// If this is a zero length read then return SUCCESS immediately.
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//
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if (IrpSp->Parameters.Read.Length == 0) {
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CdCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
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return STATUS_SUCCESS;
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}
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//
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// Decode the file object and verify we support read on this. It
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// must be a user file, stream file or volume file (for a data disk).
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//
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TypeOfOpen = CdDecodeFileObject( IrpContext, IrpSp->FileObject, &Fcb, &Ccb );
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if ((TypeOfOpen == UnopenedFileObject) ||
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(TypeOfOpen == UserDirectoryOpen)) {
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CdCompleteRequest( IrpContext, Irp, STATUS_INVALID_DEVICE_REQUEST );
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return STATUS_INVALID_DEVICE_REQUEST;
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}
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//
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// Examine our input parameters to determine if this is noncached and/or
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// a paging io operation.
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//
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Wait = BooleanFlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT );
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PagingIo = FlagOn( Irp->Flags, IRP_PAGING_IO );
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NonCachedIo = FlagOn( Irp->Flags, IRP_NOCACHE );
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SynchronousIo = FlagOn( IrpSp->FileObject->Flags, FO_SYNCHRONOUS_IO );
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//
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// Extract the range of the Io.
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//
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StartingOffset = IrpSp->Parameters.Read.ByteOffset.QuadPart;
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OriginalByteCount = ByteCount = IrpSp->Parameters.Read.Length;
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ByteRange = StartingOffset + ByteCount;
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//
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// Make sure that Dasd access is always non-cached.
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//
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if (TypeOfOpen == UserVolumeOpen) {
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NonCachedIo = TRUE;
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}
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//
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// Acquire the file shared to perform the read. If we are doing paging IO,
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// it may be the case that we would have a deadlock imminent because we may
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// block on shared access, so starve out any exclusive waiters. This requires
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// a degree of caution - we believe that any paging IO bursts will recede and
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// allow the exclusive waiter in.
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//
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if (PagingIo) {
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CdAcquireFileSharedStarveExclusive( IrpContext, Fcb );
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} else {
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CdAcquireFileShared( IrpContext, Fcb );
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}
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//
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// Use a try-finally to facilitate cleanup.
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//
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try {
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//
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// Verify the Fcb. Allow reads if this is a DASD handle that is
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// dismounting the volume.
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//
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if ((TypeOfOpen != UserVolumeOpen) || (NULL == Ccb) ||
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!FlagOn( Ccb->Flags, CCB_FLAG_DISMOUNT_ON_CLOSE)) {
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CdVerifyFcbOperation( IrpContext, Fcb );
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}
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//
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// If this is a non-cached then check whether we need to post this
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// request if this thread can't block.
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//
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if (!Wait && NonCachedIo) {
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//
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// XA requests must always be waitable.
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//
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if (FlagOn( Fcb->FcbState, FCB_STATE_RAWSECTOR_MASK )) {
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SetFlag( IrpContext->Flags, IRP_CONTEXT_FLAG_FORCE_POST );
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try_return( Status = STATUS_CANT_WAIT );
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}
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}
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//
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// If this is a user request then verify the oplock and filelock state.
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//
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if (TypeOfOpen == UserFileOpen) {
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//
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// We check whether we can proceed
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// based on the state of the file oplocks.
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//
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Status = FsRtlCheckOplock( &Fcb->Oplock,
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Irp,
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IrpContext,
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CdOplockComplete,
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CdPrePostIrp );
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//
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// If the result is not STATUS_SUCCESS then the Irp was completed
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// elsewhere.
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//
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if (Status != STATUS_SUCCESS) {
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Irp = NULL;
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IrpContext = NULL;
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try_return( NOTHING );
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}
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if (!PagingIo &&
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(Fcb->FileLock != NULL) &&
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!FsRtlCheckLockForReadAccess( Fcb->FileLock, Irp )) {
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try_return( Status = STATUS_FILE_LOCK_CONFLICT );
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}
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}
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//
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// Complete the request if it begins beyond the end of file.
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//
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if (StartingOffset >= Fcb->FileSize.QuadPart) {
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try_return( Status = STATUS_END_OF_FILE );
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}
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//
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// Truncate the read if it extends beyond the end of the file.
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//
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if (ByteRange > Fcb->FileSize.QuadPart) {
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ByteCount = (ULONG) (Fcb->FileSize.QuadPart - StartingOffset);
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ByteRange = Fcb->FileSize.QuadPart;
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}
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//
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// Handle the non-cached read first.
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//
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if (NonCachedIo) {
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//
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// If we have an unaligned transfer then post this request if
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// we can't wait. Unaligned means that the starting offset
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// is not on a sector boundary or the read is not integral
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// sectors.
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//
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ReadByteCount = BlockAlign( Fcb->Vcb, ByteCount );
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if (SectorOffset( StartingOffset ) ||
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SectorOffset( ReadByteCount ) ||
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(ReadByteCount > OriginalByteCount)) {
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if (!Wait) {
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CdRaiseStatus( IrpContext, STATUS_CANT_WAIT );
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}
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//
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// Make sure we don't overwrite the buffer.
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//
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ReadByteCount = ByteCount;
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}
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//
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// Initialize the IoContext for the read.
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// If there is a context pointer, we need to make sure it was
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// allocated and not a stale stack pointer.
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//
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if (IrpContext->IoContext == NULL ||
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!FlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO )) {
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//
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// If we can wait, use the context on the stack. Otherwise
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// we need to allocate one.
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//
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if (Wait) {
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IrpContext->IoContext = &LocalIoContext;
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ClearFlag( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO );
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} else {
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IrpContext->IoContext = CdAllocateIoContext();
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SetFlag( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO );
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}
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}
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RtlZeroMemory( IrpContext->IoContext, sizeof( CD_IO_CONTEXT ));
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//
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// Store whether we allocated this context structure in the structure
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// itself.
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//
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IrpContext->IoContext->AllocatedContext =
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BooleanFlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO );
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if (Wait) {
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KeInitializeEvent( &IrpContext->IoContext->SyncEvent,
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NotificationEvent,
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FALSE );
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} else {
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IrpContext->IoContext->ResourceThreadId = ExGetCurrentResourceThread();
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IrpContext->IoContext->Resource = Fcb->Resource;
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IrpContext->IoContext->RequestedByteCount = ByteCount;
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}
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Irp->IoStatus.Information = ReadByteCount;
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//
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// Call one of the NonCacheIo routines to perform the actual
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// read.
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//
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if (FlagOn( Fcb->FcbState, FCB_STATE_RAWSECTOR_MASK )) {
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Status = CdNonCachedXARead( IrpContext, Fcb, StartingOffset, ReadByteCount );
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} else {
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Status = CdNonCachedRead( IrpContext, Fcb, StartingOffset, ReadByteCount );
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}
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//
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// Don't complete this request now if STATUS_PENDING was returned.
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//
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if (Status == STATUS_PENDING) {
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Irp = NULL;
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ReleaseFile = FALSE;
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//
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// Test is we should zero part of the buffer or update the
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// synchronous file position.
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//
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} else {
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//
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// Convert any unknown error code to IO_ERROR.
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//
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if (!NT_SUCCESS( Status )) {
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//
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// Set the information field to zero.
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//
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Irp->IoStatus.Information = 0;
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//
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// Raise if this is a user induced error.
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//
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if (IoIsErrorUserInduced( Status )) {
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CdRaiseStatus( IrpContext, Status );
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}
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Status = FsRtlNormalizeNtstatus( Status, STATUS_UNEXPECTED_IO_ERROR );
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//
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// Check if there is any portion of the user's buffer to zero.
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//
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} else if (ReadByteCount != ByteCount) {
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CdMapUserBuffer( IrpContext, &UserBuffer);
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SafeZeroMemory( IrpContext,
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Add2Ptr( UserBuffer,
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ByteCount,
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PVOID ),
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ReadByteCount - ByteCount );
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Irp->IoStatus.Information = ByteCount;
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}
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//
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// Update the file position if this is a synchronous request.
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//
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if (SynchronousIo && !PagingIo && NT_SUCCESS( Status )) {
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IrpSp->FileObject->CurrentByteOffset.QuadPart = ByteRange;
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}
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}
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try_return( NOTHING );
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}
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//
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// Handle the cached case. Start by initializing the private
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// cache map.
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//
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if (IrpSp->FileObject->PrivateCacheMap == NULL) {
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//
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// Now initialize the cache map.
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//
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CcInitializeCacheMap( IrpSp->FileObject,
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(PCC_FILE_SIZES) &Fcb->AllocationSize,
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FALSE,
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&CdData.CacheManagerCallbacks,
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Fcb );
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CcSetReadAheadGranularity( IrpSp->FileObject, READ_AHEAD_GRANULARITY );
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}
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//
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// Read from the cache if this is not an Mdl read.
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//
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if (!FlagOn( IrpContext->MinorFunction, IRP_MN_MDL )) {
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//
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// If we are in the Fsp now because we had to wait earlier,
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// we must map the user buffer, otherwise we can use the
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// user's buffer directly.
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//
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CdMapUserBuffer( IrpContext, &SystemBuffer );
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//
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// Now try to do the copy.
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//
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if (!CcCopyRead( IrpSp->FileObject,
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(PLARGE_INTEGER) &StartingOffset,
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ByteCount,
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Wait,
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SystemBuffer,
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&Irp->IoStatus )) {
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try_return( Status = STATUS_CANT_WAIT );
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}
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//
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// If the call didn't succeed, raise the error status
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//
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if (!NT_SUCCESS( Irp->IoStatus.Status )) {
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CdNormalizeAndRaiseStatus( IrpContext, Irp->IoStatus.Status );
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}
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//
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// Otherwise perform the MdlRead operation.
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//
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} else {
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CcMdlRead( IrpSp->FileObject,
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(PLARGE_INTEGER) &StartingOffset,
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ByteCount,
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&Irp->MdlAddress,
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&Irp->IoStatus );
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Status = Irp->IoStatus.Status;
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}
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//
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// Update the current file position in the user file object.
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//
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if (SynchronousIo && !PagingIo && NT_SUCCESS( Status )) {
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IrpSp->FileObject->CurrentByteOffset.QuadPart = ByteRange;
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}
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try_exit: NOTHING;
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} finally {
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//
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// Release the Fcb.
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//
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if (ReleaseFile) {
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CdReleaseFile( IrpContext, Fcb );
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}
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}
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//
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// Post the request if we got CANT_WAIT.
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//
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if (Status == STATUS_CANT_WAIT) {
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Status = CdFsdPostRequest( IrpContext, Irp );
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//
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// Otherwise complete the request.
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//
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} else {
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CdCompleteRequest( IrpContext, Irp, Status );
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}
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return Status;
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}
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