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The operating system sends an IRP_MJ_QUERY_INFORMATION request to obtain metadata about a file or file handle. For example, when a driver calls ZwQueryInformationFile, the operating system sends an IRP_MJ_QUERY_INFORMATION request.
The Parameters.QueryFile.FileInformationClass member is a FILE_INFORMATION_CLASS constant that specifies the type of metadata to provide. For more information about the types of metadata, see the FileInformationClass parameter of the ZwQueryInformationFile routine.
The Parameters.QueryFile.Length member specifies the length of the buffer that the AssociatedIrp.SystemBuffer member points to.
The AssociatedIrp.SystemBuffer member points to the buffer where the driver supplies the requested information. The value of Parameters.QueryFile.FileInformationClass determines the format of the metadata (a FILE_XXX_INFORMATION structure) to return. For more information about the formats of metadata, see the FILE_INFORMATION_CLASS enumeration.
Drivers are not required to handle this request, and drivers that do are not required to handle every possible value of Parameters.QueryFile.FileInformationClass. The driver's dispatch routine should return an error code such as STATUS_INVALID_DEVICE_REQUEST for any values that it does not handle.