SVR5 and SCO OpenServer 5

iocblk(D4str)

iocblk -- STREAMS ioctl structure

Synopsis

   #include <sys/stream.h>
   #include <sys/ddi.h>

Description

The iocblk structure describes a user's M_IOCTL(D7str) request.

Usage

The iocblk structure is used in M_IOCTL(D7str), M_IOCACK(D7str), and M_IOCNAK(D7str) message types Modules and drivers usually convert M_IOCTL messages into M_IOCACK or M_IOCNAK messages by changing the type and updating the relevant members in the iocblk structure.

Data cannot be copied to the user's buffer with an M_IOCACK message if the ioctl is transparent in HDK Technical Reference.

No data can be copied to the user's buffer with an M_IOCNAK message.

When processing a transparent ioctl, the iocblk structure is usually overlaid with a copyreq(D4str) structure. The stream head guarantees that the message is large enough to contain either structure.

DDI structure definitions

The DDI iocblk structure contains the following members:

   int	ioc_cmd;
   cred_t	*ioc_cr;
   uint_t	ioc_id;
   uint_t	ioc_count;
   int	ioc_error;
   int	ioc_rval;

ODDI structure definitions

The ODDI iocblk structure contains the following members:

   int ioc_cmd;
   ushort ioc_uid;
   ushort ioc_gid;
   uint ioc_id;	
   uint ioc_count;	
   int ioc_error;
   int ioc_rval;

Structure members

ioc_cmd: the ioctl command request specified by the user.
ioc_cr: contains a pointer to the user credentials. (DDI only)
ioc_uid: effective UID for the user sending the ioctl. (ODDI only).
ioc_uid: effective GID for the user sending the ioctl. (ODDI only).
The ODDI ioc_uid and ioc_gid structure members correspond to the DDI ioc_cr member in the SVR5 structure. In SVR5, these values are #defined for accessing the same information from within the ioc_cr member. Note that these members can be tested to determine if the user issuing the ioctl call can be authorized to do so, and should not be modified.
ioc_id: ioctl ID, used to uniquely identify the ioctl request in the stream.
ioc_count: specifies the amount of user data contained in the M_IOCTL message. User data appears in M_DATA message blocks linked to the M_IOCTL message block. If ioc_countis set to the special value TRANSPARENT, then the ioctl request is ``transparent.'' This means that the user did not use the I_STR format of STREAMS ioctls and the module or driver will have to obtain any user data with M_COPYIN messages, and change any user data with M_COPYOUT messages. In this case, the M_DATA message block linked to the M_IOCTL message block contains the value of the arg parameter in the ioctl system call. For an M_IOCACK message, the ioc_count member specifies the amount of data to copy back to the user's buffer.
ioc_error: can be used to set an error for either an M_IOCACK or an M_IOCNAK message.
ioc_rval: can be used to set the return value in an M_IOCACK message. This will be returned to the user as the return value for the ioctl system call that generated the request.

Hardware applicability

All

Version applicability

ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 8, 8mp
oddi: 1, 2, 2mp, 3, 3mp, 4, 4mp, 5, 5mp

References

copyreq(D4str), copyresp(D4str), datab(D4str), Intro(D7str), M_COPYIN(D7str), M_COPYOUT(D7str), M_IOCTL(D7str), M_IOCACK(D7str), M_IOCNAK(D7str), msgb(D4str)

``STREAMS ioctls'' in HDK Technical Reference