IO_STACK_LOCATION

The IO_STACK_LOCATION structure defines an I/O stack location, which is an entry in the I/O stack that is associated with each IRP. Each I/O stack location in an IRP has some common members and some request-type-specific members.

typedef struct _IO_STACK_LOCATION {
  UCHAR  MajorFunction;
  UCHAR  MinorFunction;
  UCHAR  Flags;
  UCHAR  Control;
  union {
        //
        // Parameters for IRP_MJ_CREATE 
        //
        struct {
            PIO_SECURITY_CONTEXT  SecurityContext;
            ULONG  Options;
            USHORT POINTER_ALIGNMENT  FileAttributes;
            USHORT  ShareAccess;
            ULONG POINTER_ALIGNMENT  EaLength;
        } Create;
        //
        // Parameters for IRP_MJ_READ 
        //
        struct {
            ULONG  Length;
            ULONG POINTER_ALIGNMENT  Key;
            LARGE_INTEGER  ByteOffset;
        } Read;
        //
        // Parameters for IRP_MJ_WRITE 
        //
        struct {
            ULONG  Length;
            ULONG POINTER_ALIGNMENT  Key;
            LARGE_INTEGER  ByteOffset;
        } Write;
        //
        // Parameters for IRP_MJ_QUERY_INFORMATION 
        //
        struct {
            ULONG  Length;
            FILE_INFORMATION_CLASS POINTER_ALIGNMENT  FileInformationClass;
        } QueryFile;
        //
        // Parameters for IRP_MJ_SET_INFORMATION 
        //
        struct {
            ULONG  Length;
            FILE_INFORMATION_CLASS POINTER_ALIGNMENT  FileInformationClass;
            PFILE_OBJECT  FileObject;
            union {
                struct {
                    BOOLEAN  ReplaceIfExists;
                    BOOLEAN  AdvanceOnly;
                };
                ULONG  ClusterCount;
                HANDLE  DeleteHandle;
            };
        } SetFile;
        //
        // Parameters for IRP_MJ_QUERY_VOLUME_INFORMATION 
        //
        struct {
            ULONG  Length;
            FS_INFORMATION_CLASS POINTER_ALIGNMENT  FsInformationClass;
        } QueryVolume;
        //
        // Parameters for IRP_MJ_DEVICE_CONTROL and IRP_MJ_INTERNAL_DEVICE_CONTROL 
        //
        struct {
            ULONG  OutputBufferLength;
            ULONG POINTER_ALIGNMENT  InputBufferLength;
            ULONG POINTER_ALIGNMENT  IoControlCode;
            PVOID  Type3InputBuffer;
        } DeviceIoControl;
        //
        // Nonsystem service parameters.
        //
        // Parameters for IRP_MN_MOUNT_VOLUME 
        //
        struct {
            PVOID  DoNotUse1;
            PDEVICE_OBJECT  DeviceObject;
        } MountVolume;
        //
        // Parameters for IRP_MN_VERIFY_VOLUME 
        //
        struct {
            PVOID  DoNotUse1;
            PDEVICE_OBJECT  DeviceObject;
        } VerifyVolume;
        //
        // Parameters for Scsi using IRP_MJ_INTERNAL_DEVICE_CONTROL 
        //
        struct {
            struct _SCSI_REQUEST_BLOCK  *Srb;
        } Scsi;
        //
        // Parameters for IRP_MN_QUERY_DEVICE_RELATIONS 
        //
        struct {
            DEVICE_RELATION_TYPE  Type;
        } QueryDeviceRelations;
        //
        // Parameters for IRP_MN_QUERY_INTERFACE 
        //
        struct {
            CONST GUID  *InterfaceType;
            USHORT  Size;
            USHORT  Version;
            PINTERFACE  Interface;
            PVOID  InterfaceSpecificData;
        } QueryInterface;
        //
        // Parameters for IRP_MN_QUERY_CAPABILITIES 
        //
        struct {
            PDEVICE_CAPABILITIES  Capabilities;
        } DeviceCapabilities;
        //
        // Parameters for IRP_MN_FILTER_RESOURCE_REQUIREMENTS 
        //
        struct {
            PIO_RESOURCE_REQUIREMENTS_LIST  IoResourceRequirementList;
        } FilterResourceRequirements;
        //
        // Parameters for IRP_MN_READ_CONFIG and IRP_MN_WRITE_CONFIG 
        //
        struct {
            ULONG  WhichSpace;
            PVOID  Buffer;
            ULONG  Offset;
            ULONG  POINTER_ALIGNMENT Length;
        } ReadWriteConfig;
        //
        // Parameters for IRP_MN_SET_LOCK 
        //
        struct {
            BOOLEAN  Lock;
        } SetLock;
        //
        // Parameters for IRP_MN_QUERY_ID 
        //
        struct {
            BUS_QUERY_ID_TYPE  IdType;
        } QueryId;
        //
        // Parameters for IRP_MN_QUERY_DEVICE_TEXT 
        //
        struct {
            DEVICE_TEXT_TYPE  DeviceTextType;
            LCID POINTER_ALIGNMENT  LocaleId;
        } QueryDeviceText;
        //
        // Parameters for IRP_MN_DEVICE_USAGE_NOTIFICATION 
        //
        struct {
            BOOLEAN  InPath;
            BOOLEAN  Reserved[3];
            DEVICE_USAGE_NOTIFICATION_TYPE POINTER_ALIGNMENT Type;
        } UsageNotification;
        //
        // Parameters for IRP_MN_WAIT_WAKE 
        //
        struct {
            SYSTEM_POWER_STATE  PowerState;
        } WaitWake;
        //
        // Parameter for IRP_MN_POWER_SEQUENCE 
        //
        struct {
            PPOWER_SEQUENCE  PowerSequence;
        } PowerSequence;
        //
        // Parameters for IRP_MN_SET_POWER and IRP_MN_QUERY_POWER 
        //
#if (NTDDI_VERSION >= NTDDI_VISTA)
        struct {
            union {
                ULONG  SystemContext;
                SYSTEM_POWER_STATE_CONTEXT  SystemPowerStateContext;
            };
            POWER_STATE_TYPE POINTER_ALIGNMENT  Type;
            POWER_STATE POINTER_ALIGNMENT  State;
            POWER_ACTION POINTER_ALIGNMENT  ShutdownType;
        } Power;
#else
        struct {
            ULONG  SystemContext;
            POWER_STATE_TYPE POINTER_ALIGNMENT  Type;
            POWER_STATE POINTER_ALIGNMENT  State;
            POWER_ACTION POINTER_ALIGNMENT  ShutdownType;
        } Power;
#endif
        //
        // Parameters for IRP_MN_START_DEVICE 
        //
        struct {
            PCM_RESOURCE_LIST  AllocatedResources;
            PCM_RESOURCE_LIST  AllocatedResourcesTranslated;
        } StartDevice;
        //
        // Parameters for WMI Minor IRPs 
        //
        struct {
            ULONG_PTR  ProviderId;
            PVOID  DataPath;
            ULONG  BufferSize;
            PVOID  Buffer;
        } WMI;
        //
        // Others - driver-specific
        //
        struct {
            PVOID  Argument1;
            PVOID  Argument2;
            PVOID  Argument3;
            PVOID  Argument4;
        } Others;
    } Parameters;
  PDEVICE_OBJECT  DeviceObject;
  PFILE_OBJECT  FileObject;
  .
  .
  .
} IO_STACK_LOCATION, *PIO_STACK_LOCATION;

Members

MajorFunction

The IRP major function code indicating the type of I/O operation to be performed.

MinorFunction

A subfunction code for MajorFunction. The PnP manager, the power manager, file system drivers, and SCSI class drivers set this member for some requests.

Flags

Request-type-specific values used almost exclusively by file system drivers. Removable-media device drivers check whether this member is set with SL_OVERRIDE_VERIFY_VOLUME for read requests to determine whether to continue the read operation even if the device object's Flags is set with DO_VERIFY_VOLUME. Intermediate drivers layered over a removable-media device driver must copy this member into the I/O stack location of the next-lower driver in all incoming IRP_MJ_READ requests.

Control

Drivers can check this member to determine whether it is set with SL_PENDING_RETURNED. Drivers have read-only access to this member.

Parameters

A union that depends on the major and minor IRP function code values contained in MajorFunction and MinorFunction. The following table shows which IRPs use the individual members of the Parameters union.

Member name	IRPs that use this member
Create	IRP_MJ_CREATE
Read	IRP_MJ_READ
Write	IRP_MJ_WRITE
QueryFile	IRP_MJ_QUERY_INFORMATION
SetFile	IRP_MJ_SET_INFORMATION
QueryVolume	IRP_MJ_QUERY_VOLUME_INFORMATION
DeviceIoControl	IRP_MJ_DEVICE_CONTROL and IRP_MJ_INTERNAL_DEVICE_CONTROL
MountVolume	IRP_MN_MOUNT_VOLUME
VerifyVolume	IRP_MN_VERIFY_VOLUME
Scsi	IRP_MJ_INTERNAL_DEVICE_CONTROL (SCSI)
QueryDeviceRelations	IRP_MN_QUERY_DEVICE_RELATIONS
QueryInterface	IRP_MN_QUERY_INTERFACE
DeviceCapabilities	IRP_MN_QUERY_CAPABILITIES
FilterResourceRequirements	IRP_MN_FILTER_RESOURCE_REQUIREMENTS
ReadWriteConfig	IRP_MN_READ_CONFIG and IRP_MN_WRITE_CONFIG
SetLock	IRP_MN_SET_LOCK
QueryId	IRP_MN_QUERY_ID
QueryDeviceText	IRP_MN_QUERY_DEVICE_TEXT
UsageNotification	IRP_MN_DEVICE_USAGE_NOTIFICATION
WaitWake	IRP_MN_WAIT_WAKE
PowerSequence	IRP_MN_POWER_SEQUENCE
Power	IRP_MN_SET_POWER and IRP_MN_QUERY_POWER
StartDevice	IRP_MN_START_DEVICE
WMI	WMI minor IRPs
Others	Driver-specific IRPs

For more information, see IRP Major Function Codes.

DeviceObject

A pointer to the driver-created DEVICE_OBJECT structure representing the target physical, logical, or virtual device for which this driver is to handle the IRP.

FileObject

A pointer to a FILE_OBJECT structure that represents the file object, if any, that is associated with DeviceObject pointer.

Remarks

For each IRP, there is one IO_STACK_LOCATION structure for each driver in a driver stack. Each IRP's set of I/O stack locations is appended to the IRP, following the IRP structure.

Every higher-level driver is responsible for setting up the I/O stack location for the next-lower driver in each IRP. A driver must call IoGetCurrentIrpStackLocation to get a pointer to its own stack location for each IRP. Higher-level drivers can call IoGetNextIrpStackLocation to get a pointer to the next-lower driver's stack location.

The higher-level driver must set up the stack location contents before calling IoCallDriver to pass an IRP to the lower-level driver. If the driver will pass the input IRP on to the next lower-level driver, the dispatch routine should call IoSkipCurrentIrpStackLocation or IoCopyCurrentIrpStackLocationToNext to set up the I/O stack location of the next-lower driver.

A higher-level driver's call to IoCallDriver sets the DeviceObject member to the next-lower-level driver's target device object, in the I/O stack location of the lower driver. The I/O manager passes each higher-level driver's IoCompletion routine a pointer to its own device object when the IoCompletion routine is called on completion of the IRP.

If a higher-level driver allocates IRPs to make requests of its own, its IoCompletion routine is passed a NULL DeviceObject pointer if that driver neither allocates a stack location for itself nor sets up the DeviceObject pointer in its own stack location of the newly allocated IRP.

In some cases, a higher-level driver layered over a mass-storage device driver is responsible for splitting up large transfer requests for the underlying device driver. In particular, SCSI class drivers must check the Parameters.Read.Length and Parameters.Write.Length, determine whether the size of the requested transfer exceeds the underlying HBA's transfer capabilities, and, if so, split the Length of the original request into a sequence of partial transfers to satisfy the original IRP.

Requirements

Header	Wdm.h (include Wdm.h, Ntddk.h, or Ntifs.h)

IO_STACK_LOCATION

Members

Remarks

Requirements

See also