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AIX Version 4.3 Communications Technical Reference, Volume 2
mi_open_comm Utility
Purpose
Performs housekeeping during STREAMS driver or module open operations.
Syntax
#include <pse/mi.h>
#include <sys/stream.h>
int mi_open_comm (StaticPointer, Size, Queue, Device, Flag, SFlag, credp)
caddr_t *StaticPointer;
uint Size;
queue_t *Queue;
dev_t *Device;
int Flag;
int SFlag;
cred_t *credp;
Description
The mi_open_comm subroutine performs housekeeping during STREAMS driver or module open operations. It is intended to be called by the driver or module open routine. It assigns a minor device number to the stream (as specified by the SFlag parameter), allocates the requested per-stream data, and sets the q_ptr fields of the stream being opened.
Notes:
- Each call to the mi_open_comm subroutine must have a corresponding call to the mi_close_comm subroutine. Executing one of these utilities without making a corresponding call to the other will lead to unpredictable results.
- The stream.h header file must be the last included header file of each source file using the stream library.
Parameters
StaticPointer |
Specifies the address of a static pointer which will be used internally by the mi_open_comm and related utilities to store the address of the module's list of open streams. This pointer should be initialized to NULL. |
Size |
Specifies the amount of memory the module needs for its per-stream data. It is usually the size of the local structure which contains the module's instance data. |
Queue |
Specifies the address of a queue_t structure. The q_ptr field of the of this structure, and of the corresponding read queue structure (if Queue points to a write queue) or write queue structure (if Queue points to a read queue), are filled in with the address of the queue_t structure being initialized. |
Device |
Specifies the address of a dev_t structure. The use of this parameter depends on the value of the SFlag parameter. |
Flag |
Unused. |
SFlag |
Specifies how the Device parameter is to be used. The SFlag parameter may take one of the following values:
DEVOPEN |
The minor device number specified by the Device argument is used. |
MODOPEN |
The Device parameter is NULL. This value should be used if the mi_open_com subroutine is called from the open routine of a STREAMS module rather than a STREAMS driver. |
CLONEOPEN |
A unique minor device number above 5 is assigned (minor numbers 0-5 are reserved as special access codes). |
|
credp |
Unused |
Return Values
On successful completion, the mi_open_comm subroutine returns a value of zero, otherwise one of the following codes is returned:
ENXIO |
Indicates an invalid parameter. |
EAGAIN |
Indicates that an internal structure could not be allocated, and that the call should be retried. |
Implementation Specifics
The mi_open_comm subroutine is part of STREAMS kernel extensions.
Related Information
List of Streams Programming References
in AIX Version 4.3 Communications Programming Concepts
.
STREAMS Overview
in AIX Version 4.3 Communications Programming Concepts
.
The mi_close_comm subroutine, mi_next_ptr subroutine, mi_bufcall subroutine.
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