274 lines
7.2 KiB
C
274 lines
7.2 KiB
C
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/*++
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Copyright (c) 1992 Microsoft Corporation
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Module Name:
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io.c
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Abstract:
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This module contains IRP building routines.
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Author:
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Manny Weiser (mannyw) 13-Jan-1992
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Revision History:
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--*/
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#include "mup.h"
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text( PAGE, MupBuildIoControlRequest )
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#endif
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PIRP
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MupBuildIoControlRequest (
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IN OUT PIRP Irp OPTIONAL,
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IN PFILE_OBJECT FileObject OPTIONAL,
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IN PVOID Context,
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IN UCHAR MajorFunction,
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IN ULONG IoControlCode,
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IN PVOID MainBuffer,
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IN ULONG InputBufferLength,
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IN PVOID AuxiliaryBuffer OPTIONAL,
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IN ULONG OutputBufferLength,
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IN PIO_COMPLETION_ROUTINE CompletionRoutine
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)
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/*++
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Routine Description:
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This function builds an I/O request packet for a device or
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file system I/O control request.
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Arguments:
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Irp - Supplies a pointer to an IRP. If NULL, this routine allocates
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an IRP and returns its address. Otherwise, it supplies the
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address of an IRP allocated by the caller.
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FileObject - Supplies a pointer the file object to which this
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request is directed. This pointer is copied into the IRP, so
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that the called driver can find its file-based context. NOTE
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THAT THIS IS NOT A REFERENCED POINTER. The caller must ensure
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that the file object is not deleted while the I/O operation is
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in progress. The server accomplishes this by incrementing a
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reference count in a local block to account for the I/O; the
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local block in turn references the file object.
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Context - Supplies a PVOID value that is passed to the completion
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routine.
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MajorFunction - The major function that we are calling. Currently
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this most be one of IRP_MJ_FILE_SYSTEM_CONTROL or
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IRP_MJ_DEVICE_IO_CONTROL.
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IoControlCode - Supplies the control code for the operation.
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MainBuffer - Supplies the address of the main buffer. This must
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be a system virtual address, and the buffer must be locked in
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memory. If ControlCode specifies a method 0 request, the actual
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length of the buffer must be the greater of InputBufferLength
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and OutputBufferLength.
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InputBufferLength - Supplies the length of the input buffer.
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AuxiliaryBuffer - Supplies the address of the auxiliary buffer. If the
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control code method is 0, this is a buffered I/O buffer, but the
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data returned by the called driver in the system buffer is not
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automatically copied into the auxiliary buffer. Instead, the
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auxiliary data ends up in MainBuffer. If the caller wishes the
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data to be in AuxiliaryBuffer, it must copy the data at some point
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after the completion routine runs.
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If the control code method is 1 or 2, this parameter is ignored;
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instead, the Mdl parameter is used to obtain the starting
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virtual address of the buffer.
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CompletionRoutine - The IO completion routine.
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Return Value:
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PIRP - Returns a pointer to the constructed IRP. If the Irp
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parameter was not NULL on input, the function return value will
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be the same value (so it is safe to discard the return value in
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this case). It is the responsibility of the calling program to
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deallocate the IRP after the I/O request is complete.
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--*/
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{
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CLONG method;
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PDEVICE_OBJECT deviceObject;
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PIO_STACK_LOCATION irpSp;
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PMDL pMdl;
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ASSERT( MajorFunction == IRP_MJ_DEVICE_CONTROL );
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PAGED_CODE();
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if (MainBuffer == NULL) {
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return (NULL);
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}
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//
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// Get the method with which the buffers are being passed.
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//
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method = IoControlCode & 3;
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//
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// Allocate an IRP. The stack size is one higher
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// than that of the target device, to allow for the caller's
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// completion routine.
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//
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deviceObject = IoGetRelatedDeviceObject( FileObject );
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//
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// Get the address of the target device object.
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//
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Irp = IoAllocateIrp( (CCHAR)(deviceObject->StackSize + 1), FALSE );
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if ( Irp == NULL ) {
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//
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// Unable to allocate an IRP. Inform the caller.
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//
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return NULL;
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}
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IoSetNextIrpStackLocation( Irp );
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Irp->Tail.Overlay.OriginalFileObject = FileObject;
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Irp->Tail.Overlay.Thread = PsGetCurrentThread();
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//
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// Get a pointer to the current stack location and fill in the
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// device object pointer.
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//
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irpSp = IoGetCurrentIrpStackLocation( Irp );
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irpSp->DeviceObject = deviceObject;
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//
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// Set up the completion routine.
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//
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IoSetCompletionRoutine(
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Irp,
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CompletionRoutine,
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Context,
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TRUE,
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TRUE,
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TRUE
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);
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//
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// Get a pointer to the next stack location. This one is used to
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// hold the parameters for the device I/O control request.
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//
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irpSp = IoGetNextIrpStackLocation( Irp );
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irpSp->MajorFunction = MajorFunction;
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irpSp->MinorFunction = 0;
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irpSp->FileObject = FileObject;
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irpSp->DeviceObject = deviceObject;
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//
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// Copy the caller's parameters to the service-specific portion of the
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// IRP for those parameters that are the same for all three methods.
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//
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irpSp->Parameters.DeviceIoControl.OutputBufferLength = OutputBufferLength;
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irpSp->Parameters.DeviceIoControl.InputBufferLength = InputBufferLength;
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irpSp->Parameters.DeviceIoControl.IoControlCode = IoControlCode;
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//
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// Based on the method by which the buffers are being passed,
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// describe a system buffer and optionally build an MDL.
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//
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switch ( method ) {
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case 0:
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//
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// For this case, InputBuffer must be large enough to contain
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// both the input and the output buffers.
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//
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Irp->MdlAddress = NULL;
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Irp->AssociatedIrp.SystemBuffer = MainBuffer;
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Irp->UserBuffer = AuxiliaryBuffer;
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Irp->Flags = (ULONG)IRP_BUFFERED_IO;
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if ( ARGUMENT_PRESENT(AuxiliaryBuffer) ) {
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Irp->Flags |= IRP_INPUT_OPERATION;
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}
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break;
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case 1:
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case 2:
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//
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// For these two cases, MainBuffer is the buffered I/O "system
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// buffer". Build an MDL for either read or write access,
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// depending on the method, for the output buffer.
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//
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pMdl = IoAllocateMdl( MainBuffer, InputBufferLength, FALSE, FALSE, Irp );
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if (pMdl == NULL) {
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IoFreeIrp(Irp);
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return NULL;
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}
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Irp->AssociatedIrp.SystemBuffer = MainBuffer;
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Irp->Flags = (ULONG)IRP_BUFFERED_IO;
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//
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// An MDL to describe the buffer has not been built. Build
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// it now.
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//
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MmProbeAndLockPages(
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Irp->MdlAddress,
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KernelMode,
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IoReadAccess
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);
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break;
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case 3:
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//
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// For this case, do nothing. Everything is up to the driver.
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// Simply give the driver a copy of the caller's parameters and
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// let the driver do everything itself.
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//
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Irp->MdlAddress = NULL;
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Irp->AssociatedIrp.SystemBuffer = NULL;
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Irp->UserBuffer = AuxiliaryBuffer;
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irpSp->Parameters.DeviceIoControl.Type3InputBuffer = MainBuffer;
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break;
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}
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return Irp;
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} // MupBuildIoControlRequest
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