94 lines
4.2 KiB
HTML
94 lines
4.2 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>i5/OS PASE Signal Handling</title><!-- Begin Header Records -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- Created by V2DCIJB on 23 Nov 1999 -->
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<!-- Edited by Kersten Jan 02 -->
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<!-- End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>i5/OS PASE Signal Handling</h2>
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<h3>i5/OS PASE Signals and ILE Signals</h3>
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<p>OS/PASE signals and POSIX/ILE signals are independent, so it is not possible
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to directly call a handler for one signal type by raising the other type of
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signal. However, the <a href="qp2signalpase.htm">Post an i5/OS PASE Signal</a>
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(Qp2SignalPase) API can be used as the handler for any ILE signal to post a
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corresponding i5/OS PASE signal. An i5/OS PASE program can also define
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handlers for i5/OS PASE signals that call ILE procedures to post equivalent
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ILE signals. Program <strong>QP2SHELL</strong> and the i5/OS PASE
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<strong>fork</strong> function always setup handlers to map every ILE signal to
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a corresponding i5/OS PASE signal.</p>
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<br>
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<h3>i5/OS Messages and i5/OS PASE Programs</h3>
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<p>Many i5/OS applications and system functions report errors with exception
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messages sent to program call message queues. See <a href="term.htm">Message
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Handling Terms and Concepts</a> for information about exception messages and
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program call message queues.</p>
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<p>The system only creates program call message queues for ILE procedures and
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OMI programs. Any machine exception caused by an operation inside an i5/OS
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PASE program (such as MCH0601 for a storage reference error) is sent to the
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program call message queue for an (internal) ILE procedure in service program
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QP2USER. This ILE procedure is also the apparent caller of any ILE procedure
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the i5/OS PASE program calls directly (using _ILECALLX or _ILECALL), so any
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i5/OS message the called procedure sends to its caller goes to the same
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message queue used for machine exceptions.</p>
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<br>
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<h3>i5/OS Exceptions and i5/OS PASE Signals</h3>
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<p>The ILE procedure in service program QP2USER that runs i5/OS PASE programs
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handles any exception and converts it to an i5/OS PASE signal, the same way
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POSIX/ILE C runtime converts exceptions to ILE signals. The specific signal
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used depends on the i5/OS message identifier for the exception. i5/OS PASE
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and ILE use different signal numbers, but both map any specific message
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identifier to the same signal name (such as SIGSEGV). See the
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<a href="../books/sc092712.pdf" target="_blank">WebSphere Development
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Studio: ILE C/C++ Programmer's Guide</a><IMG SRC="wbpdf.gif" ALT="Link to PDF">
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for details.</p>
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<p>An i5/OS PASE signal handler
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can determine whether a signal is associated with an exception message by
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inspecting field <em>msgkey</em> in the ucontext_t_os400 structure (declared in
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header file as400_types.h) that is passed as an argument to the handler. A non-zero value is the message
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reference key for the i5/OS message that caused the signal. Zero indicates the
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signal is not associated with an i5/OS message (which is always true for
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asynchronous signals). The i5/OS PASE program can use the message reference
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key to receive the exception message (see <a href="pase_qmhrcvpm.htm">Receive
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Program Message for i5/OS PASE</a>) for more details about the error.</p>
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<br>
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<br>
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"pase1.htm">i5/OS PASE APIs</a> | <a href="aplist.htm">APIs by category</a>
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</td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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