OpenVMS System Services Reference Manual

Document revision date: 30 March 2001

OpenVMS System Services Reference Manual

Contents

Index

Setting the prmflg argument to nonzero changes privilege bits in both the CURPRIV mask and the PROCPRIV mask.

prvprv

OpenVMS usage:	mask_privileges
type:	quadword (unsigned)
access:	write only
mechanism:	by reference

Privileges previously possessed by the calling process. The prvprv argument is the address of a quadword bit vector wherein each bit corresponds to a privilege that was previously either enabled or disabled. If you do not specify prvprv or assign it the value 0, the previous privilege mask is not returned.

Description

The Set Privileges service enables or disables specified privileges for the calling process.
The operating system maintains four separate privilege masks for each process:

AUTHPRIV---Privileges that the process is authorized to enable, as designated by the system manager or the process creator. The AUTHPRIV mask never changes during the life of the process.
PROCPRIV---Privileges that are designated as permanently enabled for the process. The PROCPRIV mask can be modified by $SETPRV.
IMAGPRIV---Privileges with which the current image is installed.
CURPRIV---Privileges that are currently enabled. The CURPRIV mask can be modified by $SETPRV.

When a process is created, its AUTHPRIV, PROCPRIV, and CURPRIV masks have the same contents. Whenever a system service (other than $SETPRV) must check the process privileges, that service checks the CURPRIV mask.
When a process runs an installed image, the privileges with which that image was installed are enabled in the CURPRIV mask. When the installed image exits, the PROCPRIV mask is copied to the CURPRIV mask.
The $SETPRV service can set bits only in the CURPRIV and PROCPRIV mask, but $SETPRV checks the AUTHPRIV mask to see whether a process can set specified privilege bits in the CURPRIV or PROCPRIV masks. Consequently, a process can give itself the SETPRV privilege only if this privilege is enabled in the AUTHPRIV mask.
You can obtain each of a process's four privilege masks by calling the $GETJPI (Get Job/Process Information) service and specifying the desired privilege mask or masks as item codes in the itmlst argument. You construct the item code for a privilege mask by prefixing the name of the privilege mask with the characters JPI$_ (for example, JPI$_CURPRIV is the item code for the current privilege mask).
The DCL command SET PROCESS/PRIVILEGES also enables or disables specified privileges; refer to the OpenVMS DCL Dictionary for details.
Required Access or Privileges

To set a privilege permanently, the calling process must be authorized to set the specified privilege, or the process must be executing in kernel or executive mode.
To set a privilege temporarily, one of the following three conditions must be true:

The calling process must be authorized to set the specified privilege.
The calling process must be executing in kernel or executive mode.
The image currently executing must be one that was installed with the specified privilege.

Required Quota

None
Related Services

$CANEXH, $CMKRNL, $CREPRC, $DCLEXH, $DELPRC, $EXIT, $FORCEX, $GETJPI, $GETJPIW, $HIBER, $PROCESS_SCAN, $RESUME, $SETPRI, $SETPRN, $SETRWM, $SUSPND, $WAKE

Condition Values Returned

SS$_NORMAL The service completed successfully. All privileges were enabled or disabled as specified.

SS$_NOTALLPRIV The service completed successfully. Not all specified privileges were enabled; see the Description section for details.

SS$_ACCVIO The privilege mask cannot be read or the previous privilege mask cannot be written by the caller.

SS$_IVSTSFLG You specified a value other than 1 or 0 in either the prmflg argument or the enblfg argument.

$SETRWM

Allows a process to specify what action system services should take when system resources required for their execution are unavailable.

Caution
Disabling resource waiting should be performed with caution, as doing so can have unexpected effects on constituent sharable images and runtime libraries.

Format

SYS$SETRWM [watflg]

C Prototype

int sys$setrwm ( char watflg);

Argument

watflg

OpenVMS usage: longword_unsigned

type: longword (unsigned)

access: read only

mechanism: by value

Indicator specifying whether system services should wait for required resources. The watflg argument is a longword value. The value 0 (the default) specifies that system services should wait until resources needed for their execution become available. The value 1 specifies that system services should return failure status immediately when resources needed for their execution are unavailable.
The operating system enables resource wait mode for all processes. You can disable resource wait mode only by calling $SETRWM.
If resource wait mode is disabled, it remains disabled until it is explicitly reenabled or until the process is deleted.

Description

The Set Resource Wait Mode service allows a process to specify what action system services should take when system resources required for their execution are unavailable.
When resource wait mode is enabled, system services wait for the required system resources to become available and then continue execution. When resource wait mode is disabled, system services return to the caller when required system resources are unavailable. The condition value returned by $SETRWM indicates whether resource wait mode was previously enabled or previously disabled.
The following system resources and process quotas are affected by resource wait mode:

System dynamic memory
UNIBUS adapter map registers
Direct I/O limit (DIOLM) quota
Buffered I/O limit (BIOLM) quota
Buffered I/O byte count limit (BYTLM) quota

Caution
Due to the process-wide implications of resource waiting, disabling resource waiting should be performed with caution.
Disabling resource wait mode can have unexpected effects on libraries or shareable images upon which your application may be directly or indirectly dependent. If resource waiting is disabled, these constituent libraries or shareable images may not perform as expected. It is possible that these constituent components are coded to assume resource waiting is enabled; therefore, they may not be coded to receive various quota-related errors such as SS$_EXQUOTA.
Note that you should have full control over the entire program context down to the system calls before disabling resource wait mode.

Required Access or Privileges

None
Required Quota

None
Related Services

$CANEXH, $CREPRC, $DCLEXH, $DELPRC, $EXIT, $FORCEX, $GETJPI, $GETJPIW, $HIBER, $PROCESS_SCAN, $RESUME, $SETPRI, $SETPRN, $SETPRV, $SUSPND, $WAKE

Condition Values Returned

SS$_WASCLR The service completed successfully. Resource wait mode was previously enabled.

SS$_WASSET The service completed successfully. Resource wait mode was previously disabled.

$SETSHLV

Controls whether a process automatically unshelves files.

Format

SYS$SETSHLV [pidadr] ,[prcnam] ,[shlvflg]

C Prototype

int sys$setshlv (unsigned int *pidadr, void *prcnam, unsigned int shlvflg);

Arguments

pidadr

OpenVMS usage: process_id

type: longword (unsigned)

access: modify

mechanism: by reference

Process identification (PID) of the process. The pidadr argument is the address of the PID. The pidadr argument can only refer to a process running on the local node. You cannot modify a process on a remote node.
You must specify the pidadr argument to modify a process whose UIC group number is different from that of the calling process.
prcnam

OpenVMS usage: process_name

type: character--coded text string

access: read only

mechanism: by descriptor--fixed-length string descriptor

Process name of the process. The prcnam argument is the address of a character string descriptor pointing to the process name. You identify a process with a 1- to 15-character string.
You can only use the prcnam argument to modify a process in the same UIC group as the calling process. To modify a process in another UIC group, you must specify the pidadr argument.
shlvflg

OpenVMS usage: longword_unsigned

type: longword (unsigned)

access: read only

mechanism: by value

Value specifying whether automatic unshelving is to be turned on or off. The shlvflg argument is a longword containing this value. The value 0 turns automatic unshelving on. The value 1 turns automatic unshelving off.

Description

The Set Automatic Unshelving service controls whether a process automatically unshelves files.
The pidadr and prcnam default to the current process. If the longword at address pidadr is 0, the PID of the target process is returned.
The setting for automatic unshelving is inherited by subprocesses.
The DCL command SET PROCESS/[NO]AUTOUNSHELVE also controls automatic unshelving for a process; refer to the OpenVMS DCL Dictionary for details.
Required Access or Privileges

Depending on the operation, the calling process might need one of the following privileges to use $SETSHLV:

GROUP privilege to modify a process in the same group, unless the target process has the same UIC as the calling process.
WORLD privilege to modify any process in the system.

Required Quota

None
Related Services

$GETJPI

Condition Values Returned

SS$_WASCLR The service completed successfully. Automatic unshelving was previously on.

SS$_WASSET The service completed successfully. Automatic unshelving was previously off.

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

SS$_BADPARAM The shlvflg argument was invalid.

SS$_IVLOGNAM The prcnam argument was invalid. The process name string had either 0 characters or more than 15 characters.

SS$_NONEXPR The specified process did not exist, or the specified process identification was invalid.

SS$_NOPRIV The caller did not have the privilege to modify other processes.

SS$_REMOTE_PROC The specified process was not on the local node. The service cannot modify a process on a remote node.

$SETSTK

Allows a process to change the size of its supervisor, executive, and kernel stacks by altering the values in the stack limit and base arrays held in P1 (per-process) space.

Format

SYS$SETSTK inadr ,[retadr] ,[acmode]

C Prototype

int sys$setstk (struct _va_range *inadr, struct _va_range *retadr, unsigned int acmode);

Arguments

inadr

OpenVMS usage: address_range

type: longword (unsigned)

access: read only

mechanism: by reference

Range of addresses that express the stack's new limits. The inadr argument is the address of a 2-longword array containing, in order, the address of the top of the stack and the address of the base of the stack. Because stacks in P1 space expand from high to low addresses, the address of the base of the stack must be greater than the address of the top of the stack.
retadr

OpenVMS usage: address_range

type: longword (unsigned)

access: write only

mechanism: by reference

Range of addresses that express the stack's previous limits. The retadr argument is the address of a 2-longword array into which $SETSTK writes, in the first longword, the previous address of the top of the stack and, in the second longword, the previous address of the base of the stack.
acmode

OpenVMS usage: access_mode

type: longword (unsigned)

access: read only

mechanism: by value

Access mode of the stack to be altered. The acmode argument is a longword containing the access mode. The $PSLDEF macro defines symbols for the four access modes. The most privileged access mode used is the access mode of the caller.
If acmode specifies user mode, $SETSTK performs no operation and returns the SS$_NORMAL condition value.

Description

The Set Stack Limits service allows a process to change the size of its supervisor, executive, and kernel stacks by altering the values in the stack limit and base arrays held in P1 (per-process) space.
Required Access or Privileges

The calling process can adjust the size of stacks only for access modes that are equal to or less privileged than the access mode of the calling process.
Required Quota

None
Related Services

$ADJSTK, $ADJWSL, $CRETVA, $CRMPSC, $DELTVA, $DGBLSC, $EXPREG, $LCKPAG, $LKWSET, $MGBLSC, $PURGWS, $SETPRT, $SETSWM, $ULKPAG, $ULWSET, $UPDSEC, $UPDSECW

Condition Values Returned

SS$_NORMAL The service completed successfully.

SS$_ACCVIO The input address array cannot be read by the caller; the input range is invalid; or the return address array cannot be written by the caller.

$SETSWM

Allows a process to control whether it can be swapped out of the balance set.

Format

SYS$SETSWM [swpflg]

C Prototype

int sys$setswm (char swpflg);

Argument

swpflg

OpenVMS usage: longword_unsigned

type: longword (unsigned)

access: read only

mechanism: by value

Indicator specifying whether the process can be swapped. The swpflg argument is a longword value. The value 0 (the default) enables process swap mode, meaning the process can be swapped. The value 1 disables process swap mode, meaning the process cannot be swapped.

Description

The Set Process Swap Mode service allows a process to control whether it can be swapped out of the balance set.
When the process swap mode is enabled, the process can be swapped out; when disabled, the process remains in the balance set until (1) process swap mode is reenabled or (2) the process is deleted.
The $SETSWM service returns a condition value indicating whether process swap mode was enabled or disabled prior to the call to $SETSWM.
Required Access or Privileges

To change its process swap mode, the calling process must have PSWAPM privilege.
Required Quota

None
Related Services

$ADJSTK, $ADJWSL, $CRETVA, $CRMPSC, $DELTVA, $DGBLSC, $EXPREG, $LCKPAG, $LKWSET, $MGBLSC, $PURGWS, $SETPRT, $SETSTK, $ULKPAG, $ULWSET, $UPDSEC, $UPDSECW
To lock some but not necessarily all process pages into the balance set, use the Lock Pages in Memory ($LCKPAG) service.
For more information, refer to the chapter on memory management in the OpenVMS Programming Concepts Manual.

Condition Values Returned

SS$_WASCLR The service completed successfully. The process was not previously locked in the balance set.

SS$_WASSET The service completed successfully. The process was previously locked in the balance set.

SS$_NOPRIV The process does not have the necessary PSWAPM privilege.

$SETUAI

Modifies the user authorization file (UAF) record for a specified user.

Format

SYS$SETUAI [nullarg] ,[contxt] ,usrnam ,itmlst ,[nullarg] ,[nullarg] ,[nullarg]

C Prototype

int sys$setuai (unsigned int efn, unsigned int *contxt, void *usrnam, void *itmlst, struct _iosb *iosb, void (*astadr)(__unknown_params), int astprm);

Arguments

nullarg

OpenVMS usage: null_arg

type: longword (unsigned)

access: read only

mechanism: by value

Placeholding argument reserved to Compaq.
contxt

OpenVMS usage: longword

type: longword (unsigned)

access: modify

mechanism: by reference

A longword used to maintain authorization file context. The contxt argument is the address of a longword to receive a $SETUAI context value. On the initial call, this longword should contain the value --1. On subsequent calls, the value of the contxt argument from the previous call should be passed back in.
usrnam

OpenVMS usage: char_string

type: character-coded text string

access: read only

mechanism: by descriptor--fixed-length string descriptor

Name of the user whose UAF record is modified. The usrnam argument is the address of a descriptor pointing to a character text string containing the user name. The user name string can contain a maximum of 32 alphanumeric characters.
itmlst

OpenVMS usage: item_list_3

type: longword (unsigned)

access: read only

mechanism: by reference

Item list specifying which information from the specified UAF record is to be modified. The itmlst argument is the address of a list of one or more item descriptors, each of which specifies an item code. The item list is terminated by the item code 0 or by the longword 0.
The following diagram depicts the format of a single item descriptor:

The following table defines the item descriptor fields:

Descriptor Field Definition

Buffer length A word specifying the length (in bytes) of the buffer in which $SETUAI is to write the information. The length of the buffer varies, depending on the item code specified in the item code field of the item descriptor, and is given in the description of each item code. If the value of the buffer length field is too small, $SETUAI truncates the data.

Item code A word containing a user-supplied symbolic code specifying the item of information that $SETUAI is to set. The $UAIDEF macro defines these codes.

Buffer address A longword address of the buffer that specifies the information to be set by $SETUAI.

Return length address A longword containing the user-supplied address of a word in which $SETUAI writes the length in bytes of the information it actually set.

Descriptor Field	Definition
Buffer length	A word specifying the length (in bytes) of the buffer in which $SETUAI is to write the information. The length of the buffer varies, depending on the item code specified in the item code field of the item descriptor, and is given in the description of each item code. If the value of the buffer length field is too small, $SETUAI truncates the data.
Item code	A word containing a user-supplied symbolic code specifying the item of information that $SETUAI is to set. The $UAIDEF macro defines these codes.
Buffer address	A longword address of the buffer that specifies the information to be set by $SETUAI.
Return length address	A longword containing the user-supplied address of a word in which $SETUAI writes the length in bytes of the information it actually set.

The symbolic codes have the following format:

UAI$_code

Item Codes

UAI$_ACCOUNT
Sets, as a blank-padded 32-character string, the account name of the user.
An account name can include up to 8 characters. Because the account name is a blank-filled string, however, the buffer length field of the item descriptor should specify 32 (bytes).
UAI$_ASTLM
Sets the AST queue limit.
Because this decimal number is a word in length, the buffer length field in the item descriptor should specify 2 (bytes).
UAI$_BATCH_ACCESS_P
Sets, as a 3-byte value, the range of times during which batch access is permitted for primary days. Each bit set represents a 1-hour period, from bit 0 as midnight to 1 a.m., to bit 23 as 11 p.m. to midnight.
The buffer length field in the item descriptor should specify 3 (bytes).
UAI$_BATCH_ACCESS_S
Sets, as a 3-byte value, the range of times during which batch access is permitted for secondary days. Each bit set represents a 1-hour period, from bit 0 as midnight to 1 a.m., to bit 23 as 11 p.m. to midnight.
The buffer length field in the item descriptor should specify 3 (bytes).
UAI$_BIOLM
Sets the buffered I/O count limit.
Because this decimal number is a word in length, the buffer length field in the item descriptor should specify 2 (bytes).
UAI$_BYTLM
Sets the buffered I/O byte limit.
Because the buffered I/O count limit is a longword decimal number, the buffer length field in the item descriptor should specify 4 (bytes).
UAI$_CLITABLES
Sets, as a character string, the name of the user-defined CLI table for the account, if any.
Because the CLI table name can include up to 31 characters plus a size-byte prefix, the buffer length field of the item descriptor should specify 32 (bytes).
UAI$_CPUTIM
Sets the maximum CPU time limit (per session) for the process in 10-millisecond units.
Because the maximum CPU time limit is a longword decimal number, the buffer length field in the item descriptor should specify 4 (bytes).
UAI$_DEFCLI
Sets, as an OpenVMS RMS file name component, the name of the command language interpreter used to execute the specified batch job. The file specification set assumes the device name and directory SYS$SYSTEM and the file type .EXE.
Because a file name can include up to 31 characters plus a size-byte prefix, the buffer length field in the item descriptor should specify 32 (bytes).
UAI$_DEFDEV
Sets, as a 1- to 31-character string, the name of the default device.
Because the device name string can include up to 31 characters plus a size-byte prefix, the buffer length field in the item descriptor should specify 32 (bytes).
UAI$_DEFDIR
Sets, as a 1- to 63-character string, the name of the default directory.
Because the directory name string can include up to 63 characters plus a size-byte prefix, the buffer length field in the item descriptor should specify 64 (bytes).
UAI$_DEF_PRIV
Sets, as a quadword value, the default privileges for the user.
Because the default privileges are set as a quadword value, the buffer length field in the item descriptor should specify 8 (bytes).
UAI$_DFWSCNT
Sets, in pages (on VAX systems) or pagelets (on Alpha systems), the default working set size.
Because the default working set size is a longword decimal number, the buffer length field in the item descriptor should specify 4 (bytes).
UAI$_DIALUP_ACCESS_P
Sets, as a 3-byte value, the range of times during which dialup access is permitted for primary days. Each bit set represents a 1-hour period, from bit 0 as midnight to 1 a.m., to bit 23 as 11 p.m. to midnight.

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SS$_NORMAL	The service completed successfully. All privileges were enabled or disabled as specified.
SS$_NOTALLPRIV	The service completed successfully. Not all specified privileges were enabled; see the Description section for details.
SS$_ACCVIO	The privilege mask cannot be read or the previous privilege mask cannot be written by the caller.
SS$_IVSTSFLG	You specified a value other than 1 or 0 in either the prmflg argument or the enblfg argument.

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

SS$_WASCLR	The service completed successfully. Resource wait mode was previously enabled.
SS$_WASSET	The service completed successfully. Resource wait mode was previously disabled.

OpenVMS usage:	process_id
type:	longword (unsigned)
access:	modify
mechanism:	by reference

OpenVMS usage:	process_name
type:	character--coded text string
access:	read only
mechanism:	by descriptor--fixed-length string descriptor

SS$_WASCLR	The service completed successfully. Automatic unshelving was previously on.
SS$_WASSET	The service completed successfully. Automatic unshelving was previously off.
SS$_ACCVIO	An argument was not accessible by the caller.
SS$_BADPARAM	The shlvflg argument was invalid.
SS$_IVLOGNAM	The prcnam argument was invalid. The process name string had either 0 characters or more than 15 characters.
SS$_NONEXPR	The specified process did not exist, or the specified process identification was invalid.
SS$_NOPRIV	The caller did not have the privilege to modify other processes.
SS$_REMOTE_PROC	The specified process was not on the local node. The service cannot modify a process on a remote node.

OpenVMS usage:	address_range
type:	longword (unsigned)
access:	read only
mechanism:	by reference

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

SS$_NORMAL	The service completed successfully.
SS$_ACCVIO	The input address array cannot be read by the caller; the input range is invalid; or the return address array cannot be written by the caller.

SS$_WASCLR	The service completed successfully. The process was not previously locked in the balance set.
SS$_WASSET	The service completed successfully. The process was previously locked in the balance set.
SS$_NOPRIV	The process does not have the necessary PSWAPM privilege.

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

OpenVMS usage:	longword
type:	longword (unsigned)
access:	modify
mechanism:	by reference

OpenVMS usage:	char_string
type:	character-coded text string
access:	read only
mechanism:	by descriptor--fixed-length string descriptor

OpenVMS usage:	item_list_3
type:	longword (unsigned)
access:	read only
mechanism:	by reference