HP OpenVMS Systems Documentation

HP OpenVMS System Services Reference Manual

January 2005

This manual describes a set of routines that the HP OpenVMS operating system uses to control resources, to allow process communication, to control I/O, and to perform other such operating system functions.

Revision/Update Information: This manual supersedes the
HP OpenVMS System Services Reference Manual, Version 7.3-2

Software Version: OpenVMS I64 Version 8.2 OpenVMS Alpha Version 8.2

Hewlett-Packard Company
Palo Alto, California

Confidential computer software. Valid license from HP required for possession, use or copying. Consistent with FAR 12.211 and 12.212, Commercial Computer Software, Computer Software Documentation, and Technical Data for Commercial Items are licensed to the U.S. Government under vendor's standard commercial license.

The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.

Intel and Itanium are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries.

Printed in the US

ZK4527

The HP OpenVMS documentation set is available on CD-ROM.

Contents

Index

Preface

Intended Audience

This manual is intended for system and application programmers who want to call system services.

System Services Support for HP OpenVMS Alpha and I64 64-bit Addressing

As of Version 7.0, the HP OpenVMS Alpha operating system provides support for 64-bit virtual memory addresses. This support makes the 64-bit virtual address space defined by the Alpha and I64 architectures available to the OpenVMS Alpha and I64 operating systems and to application programs. In the 64-bit virtual address space, both process-private and system virtual address space extend beyond 2 GB. By using 64-bit address features, programmers can create images that map and access data beyond the previous limits of 32-bit virtual addresses.

New OpenVMS system services are available, and many existing services have been enhanced to manage 64-bit address space. The system services descriptions in this manual indicate the services that accept 64-bit addresses. A list of the OpenVMS system services that accept 64-bit addresses is available in the OpenVMS Programming Concepts Manual.

The following section briefly describes how 64-bit addressing support affects OpenVMS system services. For complete information about OpenVMS Alpha and I64 64-bit addressing features, refer to the OpenVMS Programming Concepts Manual.

64-Bit System Services Terminology

32-Bit System Service
A 32-bit system service only supports 32-bit addresses on any of its arguments that specify addresses. If passed by value on OpenVMS Alpha or I64, a 32-bit virtual address is actually a 64-bit address that is sign-extended from 32 bits.
64-Bit Friendly Interface
A 64-bit friendly interface can be called with all 64-bit addresses. A 32-bit system service interface is 64-bit friendly if, without a change in the interface, it needs no modification to handle 64-bit addresses. The internal code that implements the system service might need modification, but the system service interface will not.
64-Bit System Service
A 64-bit system service is defined to accept all address arguments as 64-bit addresses (not necessarily 32-bit sign-extended values). A 64-bit system service also uses the entire 64 bits of all virtual addresses passed to it.

Use of the _64 Suffix

The 64-bit system services include the _64 suffix for services that accept 64-bit addresses by reference. For promoted services, this suffix distinguishes the 64-bit capable version from its 32-bit counterpart. For new services, it is a visible reminder that a 64-bit-wide address cell will be read/written.

Sign-Extension Checking

The OpenVMS system services that do not support 64-bit addresses and all user-written system services that are not explicitly enhanced to accept 64-bit addresses receive sign-extension checking. Any argument passed to these services that is not properly sign-extended causes the error status SS$_ARG_GTR_32_BITS to be returned.

Reader's Comments

HP welcomes your comments on this manual. Please send comments to either of the following addresses:

Internet	openvmsdoc@hp.com
Postal Mail	Hewlett-Packard Company OSSG Documentation Group, ZKO3-4/U08 110 Spit Brook Rd. Nashua, NH 03062-2698

How To Order Additional Documentation

For information about how to order additional documentation, visit the following World Wide Web address:

http://www.hp.com/go/openvms/doc/order

Conventions

The following conventions are used in this manual:

Ctrl/ x	A sequence such as Ctrl/ x indicates that you must hold down the key labeled Ctrl while you press another key or a pointing device button.
PF1 x	A sequence such as PF1 x indicates that you must first press and release the key labeled PF1 and then press and release another key or a pointing device button.
`[Return]`	In examples, a key name enclosed in a box indicates that you press a key on the keyboard. (In text, a key name is not enclosed in a box.) In the HTML version of this document, this convention appears as brackets, rather than a box.
...	A horizontal ellipsis in examples indicates one of the following possibilities: Additional optional arguments in a statement have been omitted. The preceding item or items can be repeated one or more times. Additional parameters, values, or other information can be entered.
. . .	A vertical ellipsis indicates the omission of items from a code example or command format; the items are omitted because they are not important to the topic being discussed.
( )	In command format descriptions, parentheses indicate that you must enclose choices in parentheses if you specify more than one.
[ ]	In the HP OpenVMS System Services Reference Manual, brackets generally indicate default arguments. If an argument is optional, it is specified as such in the argument text.
\|	In command format descriptions, vertical bars separate choices within brackets or braces. Within brackets, the choices are optional; within braces, at least one choice is required. Do not type the vertical bars on the command line.
{ }	In command format descriptions, braces indicate required choices; you must choose at least one of the items listed. Do not type the braces on the command line.
bold type	Bold type represents the introduction of a new term. It also represents the name of an argument, an attribute, or a reason.
italic type	Italic type indicates important information, complete titles of manuals, or variables. Variables include information that varies in system output (Internal error number), in command lines (/PRODUCER= name), and in command parameters in text (where dd represents the predefined code for the device type).
UPPERCASE TYPE	Uppercase type indicates a command, the name of a routine, the name of a file, or the abbreviation for a system privilege.
`Example`	This typeface indicates code examples, command examples, and interactive screen displays. In text, this type also identifies URLs, UNIX commands and pathnames, PC-based commands and folders, and certain elements of the C programming language.
-	A hyphen at the end of a command format description, command line, or code line indicates that the command or statement continues on the following line.
numbers	All numbers in text are assumed to be decimal unless otherwise noted. Nondecimal radixes---binary, octal, or hexadecimal---are explicitly indicated.

System Service Descriptions

System services provide basic operating system functions, interprocess communication, and various control resources.

Condition values returned by system services not only indicate whether the service completed successfully, but can also provide other information. While the usual condition value indicating success is SS$_NORMAL, other values are also defined. For example, the condition value SS$_BUFFEROVERF, which is returned when a character string returned by a service is longer than the buffer provided to receive it, is a success code, but it also provides additional information.

Warning returns and some error returns indicate that the service may have performed some, but not all, of the requested function.

The particular condition values that each service can return are described in the Condition Values Returned section of each individual service description.

Returns

OpenVMS usage:
type:
access:
mechanism:

cond_value
longword (unsigned)
write only
by value

Longword condition value. All system services (except $EXIT) return by immediate value a condition value in R0.

$ABORT_TRANS

Ends a transaction by aborting it.

Format

SYS$ABORT_TRANS [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[reason] ,[bid]]

C Prototype

int sys$abort_trans (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);

Arguments

efn

OpenVMS usage: ef_number

type: longword (unsigned)

access: read only

mechanism: by value

Number of the event flag that is set when the service completes. If this argument is omitted, event flag 0 is used.
flags

OpenVMS usage: mask_longword

type: longword (unsigned)

access: read only

mechanism: by value

Flags specifying options for the service. The flags argument is a longword bit mask in which each bit corresponds to an option flag. The $DDTMDEF macro defines symbolic names for these option flags, described in Table SYS-1. All undefined bits must be 0. If this argument is omitted, no flags are used.

Table SYS-1 $ABORT_TRANS Option Flags
Flag Description

DDTM$M_NOWAIT Set this flag to indicate that the service should return to the caller without waiting for final cleanup. Note that $ABORT_TRANSW with the DDTM$M_NOWAIT flag set is not equivalent to $ABORT_TRANS. $ABORT_TRANS returns when the operation has been queued. The former does not return until the operation has been initiated. The latter returns as soon as the operation has been queued. The full range of status values may be returned from a nowait call.

DDTM$M_SYNC Set this flag to specify that successful synchronous completion is to be indicated by returning SS$_SYNCH. When SS$_SYNCH is returned, the AST routine is not called, the event flag is not set, and the I/O status block is not filled in.

iosb

OpenVMS usage: io_status_block

type: quadword (unsigned)

access: write only

mechanism: by reference

I/O status block in which the following information is returned:

The completion status of the service, returned as a condition value. See the Condition Values Returned section.
An abort reason code that gives one reason why the transaction aborted, if the completion status of the service is SS$_NORMAL.
Note that, if there are multiple reasons why the transaction aborted, the abort reason code returned in the I/O status block might not be the same as the abort reason code passed in the reason argument. The DECdtm transaction manager returns one of the reasons in the I/O status block. It may return different reasons to different branches of the transaction.
For example, if the call to $ABORT_TRANS gives DDTM$_ABORTED as the reason and the transaction timeout expires at about the same time as the call to $ABORT_TRANS, then either the DDTM$_TIMEOUT or DDTM$_ABORTED reason code can be returned in the I/O status block.

The $DDTMMSGDEF macro defines symbolic names for abort reason codes, which are defined in Table SYS-2:

Table SYS-2 Abort Reason Codes
Symbolic Name Description

DDTM$_ABORTED The application aborted the transaction without giving a reason.

DDTM$_COMM_FAIL A communications link failed.

DDTM$_INTEGRITY A resource manager integrity constraint check failed.

DDTM$_LOG_FAIL A write operation to the transaction log failed.

DDTM$_ORPHAN_BRANCH An unauthorized branch caused failure.

DDTM$_PART_SERIAL A resource manager serialization check failed.

DDTM$_PART_TIMEOUT The timeout specified by a resource manager expired.

DDTM$_SEG_FAIL A process or image terminated.

DDTM$_SERIALIZATION A DECdtm transaction manager serialization check failed.

DDTM$_SYNC_FAIL The transaction was not globally synchronized; an authorized branch was not added to the transaction.

DDTM$_TIMEOUT The timeout specified on $START_TRANS expired.

DDTM$_UNKNOWN The reason is unknown.

DDTM$_VETOED A resource manager was unable to commit the transaction.

The following diagram shows the structure of the I/O status block:

astadr

OpenVMS usage:	ast_procedure
type:	procedure value
access:	call without stack unwinding
mechanism:	by reference

AST routine that is executed when the service completes, if SS$_NORMAL is returned in R0. The astadr argument is the address of the entry mask of this routine. The routine is executed in the access mode of the caller.

astprm

OpenVMS usage:	user_arg
type:	longword (unsigned)
access:	read only
mechanism:	by value

AST parameter that is passed to the AST routine specified by the astadr argument.

tid

OpenVMS usage:	trans_id
type:	octaword (unsigned)
access:	read only
mechanism:	by reference

Identifier of the transaction to be aborted.

If this argument is omitted, $ABORT_TRANS aborts the default transaction of the calling process.

reason

OpenVMS usage:	cond_value
type:	longword (unsigned)
access:	read only
mechanism:	by value

Code that gives the reason why the application is aborting the transaction. The $DDTMMSGDEF macro defines symbolic names for abort reason codes. The codes currently defined are listed in Table SYS-2.

The default value for this argument is DDTM$_ABORTED.

bid

OpenVMS usage:	branch_id
type:	octaword (unsigned)
access:	read only
mechanism:	by reference

The identifier (BID) of the branch that is aborting the transaction.

The default value of this argument is zero, which is the BID of the branch that started the transaction.

Description

The Abort Transaction service ends a transaction by aborting it.
The $ABORT_TRANS system service:

Initiates abort processing for the specified transaction, if it has not already been initiated.
If abort processing has not already been initiated, the DECdtm transaction manager instructs the resource managers to abort (roll back) the transaction operations so that none of those operations ever take effect. It delivers an abort event to each RM participant in the transaction that is associated with an RMI that requested abort events.
Removes the specified branch from the specified transaction in this process.

Preconditions for the successful completion of $ABORT_TRANS include:

If the BID is zero, the calling process must have started the transaction.
If the BID is nonzero, the calling process must contain the specified branch of the specified transaction.
If the BID is nonzero, the tid argument must not be omitted. If you explicitly pass the BID, you must also explicitly pass the TID.

$ABORT_TRANS may fail for various reasons, including:

The preconditions were not met.
There has already been a call to $ABORT_TRANS, $END_TRANS, or $END_BRANCH for the specified branch.

Postconditions on successful completion of $ABORT_TRANS are listed in Table SYS-3:

Table SYS-3 Postconditions When$ABORT_TRANS Completes Successfully
Postcondition Meaning

The transaction is ended. If DDTM$M_NOWAIT is clear:

The TID of the transaction is invalid; calls to any DECdtm system services except $GETDTI and $SETDTI that pass the TID will fail, and calls to resource managers that pass the TID will fail.
The transaction no longer has any application or RM participants on the local node.
All communications about the transaction between the local DECdtm transaction manager and other DECdtm transaction managers are finished (including the final "cleanup" acknowledgment).

The outcome of the transaction is abort. None of the operations of the transaction will ever take effect.

DECdtm quotas are returned. If DDTM$M_NOWAIT is clear, all quotas allocated for the transaction by calls on the local node to DECdtm services are now returned.

The transaction is not the default transaction of the calling process. If DDTM$M_NOWAIT is clear, then, if the transaction was the default transaction of the calling process, it is now no longer the default.

$ABORT_TRANS will not complete successfully (that is, the event flag will not be set, the AST routine will not be called, and the I/O status block will not be filled in) until all branches on the local node have been removed from the transaction. Thus this call to $ABORT_TRANS cannot complete successfully until every authorized and synchronized branch on the local node has initiated a call to $END_TRANS, $END_BRANCH, or $ABORT_TRANS.
$ABORT_TRANS must deliver notification ASTs to resource managers participating in the transaction. Therefore it will not complete successfully while the calling process is either:

In an access mode that is more privileged than the DECdtm calls made by any resource manager participating in the transaction. RMS journaling calls DECdtm in executive mode. Oracle Rdb and Oracle CODASYL DBMS call DECdtm in user mode.
At AST level in the same access mode as the least privileged DECdtm calls made by any resource manager participating in the transaction.

For example, if Oracle Rdb is a participant in the transaction, $ABORT_TRANS will not complete successfully while the calling process is in supervisor, executive, or kernel mode, or while the calling process is at AST level.
Note that successful completion of $ABORT_TRANS is not indefinitely postponed by network failure.

Required Access or Privileges

None

Required Quotas

ASTLM

Related Services

$ABORT_TRANSW, $ACK_EVENT, $ADD_BRANCH, $ADD_BRANCHW, $CREATE_UID, $DECLARE_RM, $DECLARE_RMW, $END_BRANCH, $END_BRANCHW, $END_TRANS, $END_TRANSW, $FORGET_RM, $FORGET_RMW, $GETDTI, $GETDTIW, $GET_DEFAULT_TRANS, $JOIN_RM, $JOIN_RMW, $SETDTI, $SETDTIW, $SET_DEFAULT_TRANS, $SET_DEFAULT_TRANSW, $START_BRANCH, $START_BRANCHW, $START_TRANS, $START_TRANSW, $TRANS_EVENT, $TRANS_EVENTW

Condition Values Returned

SS$_NORMAL If this was returned in R0, the request was successfully queued. If it was returned in the I/O status block, the service completed successfully.

SS$_SYNCH The service completed successfully and synchronously (returned only if the DDTM$M_SYNC flag is set).

SS$_ACCVIO An argument was not accessible by the caller.

SS$_BADPARAM The options flags were invalid or the tid argument was omitted and the bid argument was not zero.

SS$_BADREASON The abort reason code was invalid.

SS$_CURTIDCHANGE The tid argument was omitted and a call to change the default transaction of the calling process was in progress.

SS$_EXASTLM The process AST limit (ASTLM) was exceeded.

SS$_ILLEFC The event flag number was invalid.

SS$_INSFARGS A required argument was missing.

SS$_INSFMEM There was insufficient system dynamic memory for the operation.

SS$_NOCURTID An attempt was made to abort the default transaction (the tid argument was omitted), but the calling process did not have a default transaction.

SS$_NOLOG The local node did not have a transaction log.

SS$_NOSUCHBID The calling process did not contain the branch identified by the BID passed in the bid argument (possibly because there has already been a call to $ABORT_TRANS, $END_TRANS, or $END_BRANCH for that branch).
This error is returned only if the bid argument is not zero.

SS$_NOSUCHTID A transaction with the specified transaction identifier does not exist.

SS$_NOTORIGIN A bid of zero was specified and the calling process did not start the transaction.

SS$_TPDISABLED The TP_SERVER process was not running on the local node.

SS$_WRONGSTATE Commit processing for the transaction had already started. This can occur if bid is zero or the specified branch was unsynchronized.