UMSEX1 - UM Security Exit

UMSEX1 is a user-written routine called by UM:

  • during UM initialization;

  • after input from the main menu;

  • before actually scheduling a message switching request.

UMSEX1 can be used to impose security restrictions on the use of certain UM functions or destinations.

The UMSEX1 module is loaded during UM initialization; therefore, internal switches can be set and referenced later on.

A dummy UMSEX1 module is distributed with the Com-plete system as a member of the source and load libraries.

Note:
No security exists for UM functions unless established by you.

This document covers the following topics:

How to use UMSEX1

Upon entry to UMSEX1, a set of parameters is received in the form of 5 fullword addresses. For the meaning of the words see the parameters in the table below.

Upon return from UMSEX1 to UM, the return code area is checked. If the return code is not zero, the requested operation is aborted and an error message is displayed on the main menu screen.

UMSEX1 Conventions

The following table summarizes the UMSEX1 linkage conventions:

Feature Convention
Attributes Reentrant if in resident area
Type Thread
Siz Restricted to the UM thread region size
Registers at entry
Register 1 Address of the parameter list
Register 13 Address of an 18-fullword save area
Register 14 Return address in the calling module
Register 15 Entry address of UMSEX1
Registers at return All registers except R15 must be unchanged.
Parameters
Word 1 Address of a return code halfword
Word 2 Address of a four byte function code
Word 3 Address of the UM00 map area
Word 4 Address of the destination list (100 entries, 10 bytes per entry)
Word 5 Address of a halfword showing the number of already selected destinations
Return Codes
0 Allow the request
4 Disallow the request

Function codes passed via word 2:

F'0' Initialization
F'4' After main menu input
F'8' About to schedule the message

Data area passed via word 3:

UM00D DSECT LAYOUT OF MAP UM00
UM00FUNC DS CL2FUNCTION CODE (SM,SG,...)
UM00MSGS DS CL132 MESSAGE TEXT
UM00MSGM DS CL1 'MORE TEXT' INDICATOR
UM00DEST DS 7CL8 7 DESTINATIONS
UM00CLAS DS CL20 CLASS CODES
UM00DL EQU*-UM00D LENGTH OF THIS DSECT