142 lines
2.6 KiB
C
142 lines
2.6 KiB
C
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/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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DevIoSup.c
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Abstract:
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This module implements the memory locking routines for Npfs.
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Author:
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Brian Andrew [BrianAn] 03-Apr-1991
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Revision History:
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--*/
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#include "NpProcs.h"
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//
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// Local debug trace level
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//
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#define Dbg (DEBUG_TRACE_DEVIOSUP)
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGE, NpLockUserBuffer)
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#pragma alloc_text(PAGE, NpMapUserBuffer)
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#endif
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PVOID
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NpMapUserBuffer (
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IN OUT PIRP Irp
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)
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/*++
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Routine Description:
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This routine conditionally maps the user buffer for the current I/O
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request in the specified mode. If the buffer is already mapped, it
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just returns its address.
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Arguments:
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Irp - Pointer to the Irp for the request.
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Return Value:
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Mapped address
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--*/
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{
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PAGED_CODE();
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//
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// If there is no Mdl, then we must be in the Fsd, and we can simply
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// return the UserBuffer field from the Irp.
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//
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if (Irp->MdlAddress == NULL) {
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return Irp->UserBuffer;
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} else {
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return MmGetSystemAddressForMdl( Irp->MdlAddress );
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}
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}
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VOID
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NpLockUserBuffer (
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IN OUT PIRP Irp,
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IN LOCK_OPERATION Operation,
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IN ULONG BufferLength
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)
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/*++
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Routine Description:
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This routine locks the specified buffer for the specified type of
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access. The file system requires this routine since it does not
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ask the I/O system to lock its buffers for direct I/O. This routine
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may only be called from the Fsd while still in the user context.
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Arguments:
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Irp - Pointer to the Irp for which the buffer is to be locked.
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Operation - IoWriteAccess for read operations, or IoReadAccess for
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write operations.
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BufferLength - Length of user buffer.
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Return Value:
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None
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--*/
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{
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PMDL Mdl;
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PAGED_CODE();
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if (Irp->MdlAddress == NULL) {
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//
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// This read is bound for the current process. Perform the
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// same functions as above, only do not switch processes.
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//
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Mdl = IoAllocateMdl( Irp->UserBuffer, BufferLength, FALSE, TRUE, Irp );
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if (Mdl == NULL) {
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ExRaiseStatus( STATUS_INSUFFICIENT_RESOURCES );
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}
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try {
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MmProbeAndLockPages( Mdl,
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Irp->RequestorMode,
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Operation );
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} except(EXCEPTION_EXECUTE_HANDLER) {
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IoFreeMdl( Mdl );
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Irp->MdlAddress = NULL;
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ExRaiseStatus( FsRtlNormalizeNtstatus( GetExceptionCode(),
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STATUS_INVALID_USER_BUFFER ));
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}
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}
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}
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