OpenVMS I/O User's Reference Manual
If a nonzero directory ID is specified in FIB$W_DID, a lookupsubfunction is performed (see Section 1.3.1). The file name located isremoved from the directory.
If the function modifier IO$M_DELETE is specified, the file is markedfor deletion. If the file is not currently open, it is deletedimmediately. If the file is open, it is deleted when the last accessorcloses it.
1.6.6 Movefile Subfunction
The movefile subfunction permits you to move the contents of a file, orpart of the contents of a file, to a new disk location. Thissubfunction can, for example, form the basis of a disk defragmentationapplication.
You can disable movefile operations on specific user files by specifying the /NOMOVE qualifier on the SET FILE command. Use the DIRECTORY/FULL and the DUMP/HEADER commands to find out if movefile operations are disabled on a file.
220.127.116.11 Calling the Movefile Subfunction
A program can invoke a movefile subfunction by issuing a QIO requestusing the function code IO$_MODIFY and the function modifierIO$M_MOVEFILE. This section describes the various input parameters thatcontrol the processing of movefile operations together with anoperational description.
18.104.22.168 Input Parameters
Table 1-13 lists the FIB fields that control the processing of amovefile subfunction.
Table 1-13 FIB Fields (Movefile)
|Field ||Subfields ||Meaning |
| FIB$L_ACCTL || || Movefile control flag. The following flags are applicable: |
| || FIB$V_NOVERIFY || Inhibits comparison of the moved blocks. If this flag is clear, the movefile operation verifies that the operation was carried out correctly by comparing the moved blocks to the original blocks. |
| || FIB$V_CHANGE_VOL || Enables the movefile operation to move blocks from one volume to another within a volume set. |
The movefile operation clears this flag if the specified file is a directory.
| FIB$W_FID || || Specifies the file identification of the file to be moved. |
| FIB$W_EXCTL || || Movefile control flags. The following flags apply to the movefile operation. All other FIB$W_EXCTL flags must be clear. |
| || FIB$V_ALCON || Specifies that the movefile operation must allocate contiguous disk space to the moved blocks. If the necessary contiguous space is not available, the movefile operation fails. |
The movefile operation sets this flag if the file was previously marked as contiguous.
| || FIB$V_ALCONB || Specifies that the movefile operation should attempt to allocate contiguous disk space to the moved blocks. That is, if the movefile operation cannot allocate contiguous space to all the moved blocks, it allocates contiguous space to as many of the blocks as possible. |
The movefile operation sets this flag if the file was previously marked as contiguous best try.
| || FIB$V_FILCON || Specifies that the entire file must be made contiguous. Do not set this flag without also setting the FIB$V_ALCON flag. |
If the FIB$V_FILCON flag is set, and either the FIB$V_ALCON flag is clear or the file would not be made contiguous by moving the specified virtual blocks, the movefile operation fails.
The movefile operation sets this flag if the file was previously marked as contiguous.
| || FIB$V_NOPLACE || Specifies that placement information will not be recorded in the file header. |
If this flag is clear and you specify exact placement for the moved blocks, placement information for those blocks will be recorded in the file header. If this flag is set, the placement information will not be recorded.
You specify exact placement through the FIB$V_EXACT, FIB$C_LBN, and FIB$L_LOC_ADDR fields.
| FIB$B_ALOPTS || || Flags that control the placement of the allocated blocks. Currently, only the FIB$V_EXACT flag applies to the movefile operation. All other FIB$B_ALOPTS flags must be clear. The following flags are applicable: |
| || FIB$V_EXACT || Set to require exact placement. If this flag is set and the specified blocks are not available, the movefile operation fails. |
| FIB$B_ALALIGN || || Contains the interpretation mode of the allocation field (FIB$W_ALLOC). You can specify a field value of 0 or you can specify the symbolic value FIB$C_LBN. If you specify zero, the allocation field is ignored. |
| FIB$W_ALLOC || || Contains the desired location of the blocks being allocated. Interpretation of the field is controlled by the FIB$B_ALALIGN field. The following subfields are defined: |
| || FIB$B_LOC_RVN || Specifies the relative volume number (RVN) of the volume to which the blocks are moved. Do not specify a value for this field unless you have set the FIB$V_CHANGE_VOL flag. |
| || FIB$L_LOC_ADDR || If the FIB$C_LBN and FIB$V_EXACT flags are set, specifies the starting logical address to which the blocks are moved. |
| FIB$L_MOV_SVBN || || Specifies the virtual block number (VBN) of the first block to be moved. |
The starting VBN must correspond to the first block of a disk cluster. The value must be greater than 0 and it must not exceed the number of virtual blocks allocated to the file. If you specify an invalid value, the movefile operation fails.
| FIB$L_MOV_VBNCNT || || Specifies the number of consecutive virtual blocks to be moved. |
This value must be a multiple of the disk cluster size, and it must not exceed the difference between the greatest VBN allocated to the file and the FIB$L_MOV_SVBN value. If you specify a value of 0, the movefile operation moves all the virtual blocks between the FIB$L_MOV_SVBN value and the greatest VBN.
If you specify an invalid value, the movefile operation fails.
A program can perform a movefile operation on a file if the followingconditions are met:
- The program has write and control access to the file.
- The file is closed.
- Movefile operations are not disabled on the file.
Movefile operations are automatically disabled on critical system files. You can disable movefile operations on specific user files by specifying the /NOMOVE qualifier with the SET FILE command.
- The operation is not interrupted.
If the movefile operation is interrupted by any other operation, such as a read or write operation, the movefile operation aborts and the file remains in its original position.
The movefile operation moves a specified number of consecutive virtualblocks to new logical blocks on disk, beginning with the virtual blockspecified in the FIB$L_SVBN field.
The number of blocks moved is specified in the FIB$L_VBNCNT field. Tomove an entire file, specify FIB$L_VBNCNT as 0 and FIB$L_SVBN as 1.
To specify a starting logical block for the moved blocks, specify thelogical block address in the FIB$L_LOC_ADDR subfield and set theFIB$C_LBN and the FIB$V_EXACT flags.
To move the blocks to another volume, or move blocks that span morethan one volume, set the FIB$V_CHANGE_VOL flag of the FIB$L_ACCTLfield. Use the FIB$B_LOC_RVN subfield of the FIB$W_ALLOC field tospecify the volume to which the blocks are moved. If you do not specifya volume, the blocks are moved to the volume containing the firstvirtual block. Note that you cannot move blocks of a directory file toanother volume.
If the file was previously marked as contiguous, the movefile operationsets the FIB$V_ALCON, FIB$V_ALCONB, and FIB$V_FILCON flags. Thisensures that a contiguous file is not fragmented by a movefileoperation.
For virtual blocks beyond the file's highwater mark, the movefileoperation allocates new logical blocks but does not copy the contents.The position of the file's highwater mark remains unchanged.
On VAX and Alpha systems, mount is a virtual I/O function that informsthe ACP when a disk or magnetic tape volume is mounted. MOUNT privilegeis required.
IO$_MOUNT takes no arguments or function modifiers. This function ispart of the volume mounting operation only, and it is not meant forgeneral use. Most of the actual processing is performed by the MOUNTcommand or the Mount Volume ($MOUNT) system service.
1.6.8 ACP Control
ACP Control is a virtual I/O function that performs miscellaneouscontrol functions, depending on the arguments specified.
The following is the function code:
The following is the function modifier:
- IO$M_DMOUNT---Dismounts a volume.
22.214.171.124 Input Parameters
The following are the device- or function-dependent arguments forIO$_ACPCONTROL:
- P1---The address of the file information block (FIB) descriptor.
- P2---The address of the file name string descriptor (optional).
- P3---The address of the word that is to receive the length of the resultant file name string (optional).
- P4---The address of a descriptor for a buffer that is to receive the resultant file name string (optional).
Table 1-14 lists FIB fields that control the processing of theIO$_ACPCONTROL function.
Table 1-14 IO$_ACPCONTROL and the FIB
|Field ||Subfields ||Meaning |
| FIB$W_CNTRLFUNC || || Specifies the control function to be performed. This field overlays FIB$W_EXCTL. |
| FIB$L_CNTRLVAL 1 || || Specifies additional function-dependent data. This field overlays FIB$L_EXSZ. |
| FIB$L_ACL_STATUS || || Status of the requested ACL attribute operation, if any. The ACL attributes are included in Table 1-7. If no ACL attributes are given, SS$_NORMAL is returned here. For Files-11 C/D, this field is always set to SS$_NORMAL. |
| FIB$L_STATUS 1 || || Alternate access status. The following bits are supported: |
| || FIB$V_ALT_REQ || Set to indicate whether the alternate access bit is required for the current operation. If not set, the alternate access bit is optional. |
| || FIB$V_ALT_GRANTED || If FIB$V_ALT_REQ = 0 and the alternate access check succeeded, the FIB bit returned from the file system is set. |
| FIB$L_ALT_ACCESS 1 || || A 32-bit mask that represents an access mask to check against file protection; for example, to open a file for read and to check whether it can be deleted or not. The mask has the same configuration as the standard protection mask. |
1Not supported or invalid for Files-11 C/D.
126.96.36.199 Magnetic Tape Control Functions
Table 1-15 the lists FIB field applicable to magnetic tapeoperations.
Table 1-15 Magnetic Tape Operations and the FIB
|Field ||Subfields ||Meaning |
| FIB$W_CNTRLFUNC || || Several ACP control functions are used for magnetic tape positioning. These functions are specified by supplying a FIB with P1 containing the FIB descriptor address. Modifiers and parameters P2, P3, and P4 are not allowed. These functions clear serious exceptions in magnetic tape drivers. The following control functions can be specified to control magnetic tape positioning: |
| || FIB$C_REWINDFIL || Rewind to beginning-of-file. |
| || FIB$C_REWINDVOL || Rewind to beginning-of-volume set. |
| || FIB$C_POSEND || Position to end-of-volume set. |
| || FIB$C_NEXTVOL || Force next volume. |
| || FIB$C_SPACE || Space n blocks forward or backward. The FIB$L_CNTRLVAL field specifies the number of magnetic tape blocks to space forward if positive or to space backward if negative. |
| || FIB$C_CLSEREXCP || If set, clears the serious exception in the magnetic tape driver (see FIB$C_USEREOT in Section 1.6.1 and Section 1.6.2). If writing, allows you to write data blocks beyond the EOT marker, which can result in the magnetic tape not conforming to the ANSI standard for magnetic tapes (see ANSI Standard X3.27--1978). If reading, allows you to handle the move to the next volume or to stop reading the tape. Do not attempt to read past EOV. |
188.8.131.52 Miscellaneous Disk Control Functions
Several ACP control functions are available for disk volume control.The following function does not use parameters P2, P3, and P4:
| IO$M_DMOUNT || Specifying the dismount modifier on the IO$_ACPCNTRL function executes a dismount QIO. No parameters in the FIB are used; the FIB can be omitted. This function does not perform a dismount by itself, but is used to synchronize the ACP with the DISMOUNT command and the Dismount Volume ($DISMOUNT) system service. |
The FIB$W_CNTRLFUNC field of the FIB specifies the followingmiscellaneous control functions (with no modifier on the IO$_ACPCONTROLfunction code). These functions use no other parameters.
| FIB$C_REMAP || Remap a file. The file window for the file open on the user's channel is remapped so that it maps the entire file. |
| FIB$C_LOCK_VOL || Allocation lock the volume. Operations that change the file structure, such as file creation, deletion, extension, and deaccess, are not permitted. If such requests are queued to the file system for an allocation-locked volume, they are not processed until the FIB$C_UNLK_VOL function is issued to unlock the volume. |
To issue the FIB$C_LOCK_VOL function, you must have either a system UIC or SYSPRV privilege, or be the owner of the volume.
| FIB$C_UNLK_VOL || Unlock the volume. Cancels FIB$C_LOCK_VOL. To issue this function, you must have either a system UIC or SYSPRV privilege, or be the owner of the volume. |
184.108.40.206 Disk Quotas
Disk quota enforcement is enabled by a quota file on the volume, orrelative volume 1 if the file is on a volume set. The quota fileappears in the volume's master file directory (MFD) under the nameQUOTA.SYS;1. This section describes the control functions that operateon the quota file.
Table 1-16 lists the enable and disable quota control functions.
Table 1-16 Disk Quota Functions (Enable/Disable)
|Value ||Meaning |
| FIB$C_ENA_QUOTA || Enable the disk quota file. If a nonzero directory file ID is specified in FIB$W_DID, a lookup subfunction is performed to locate the quota file (see Section 1.3.1). To issue this function, you must have either a system UIC or SYSPRV privilege, or be the owner of the volume. |
The quota file specified by FIB$W_FID, if present, is accessed by the ACP, and quota enforcement is turned on. By convention, the quota file is named [0,0]QUOTA.SYS;1. Therefore, FIB$W_DID should contain the value 4,4,0 and the name string specified with P2 should be "QUOTA.SYS;1".
| FIB$C_DSA_QUOTA || Disable the disk quota file. The quota file is deaccessed and quota enforcement is turned off. To issue this function, you must have either a system UIC or SYSPRV privilege, or be the owner of the volume. |
Table 1-17 lists the quota control functions that operate onindividual entries in the quota file. Each operation transfers quotafile data to and from the ACP using a quota data block. This block hasthe same format as a record in the quota file. Figure 1-9 shows theformat of this block.
Table 1-17 Disk Quota Functions (Individual Entries)
|Value ||Meaning |
| FIB$C_ADD_QUOTA || Add an entry to the disk quota file, using the UIC and quota specified in the P2 argument block. FIB$C_ADD_QUOTA requires write access to the quota file. |
| FIB$C_EXA_QUOTA || Examine a disk quota file entry. The entry whose UIC is specified in the P2 argument block is returned in the P4 argument block, and its length is returned in the P3 argument word. Using two flags in FIB$L_CNTRLVAL, it is possible to search through the quota file using wildcards. The two flags are: |
| FIB$V_ALL_MEM || Match all UIC members |
| FIB$V_ALL_GRP || Match all UIC groups |
The ACP maintains position context in FIB$L_WCC. On the first examine call, you specify 0 in FIB$L_WCC; the ACP returns a nonzero value so that each succeeding examine call returns the next matching entry.
Read access to the quota file is required to examine all non-user entries.
| FIB$C_MOD_QUOTA || Modify a disk quota file entry. The quota file entry specified by the UIC in the P2 argument block is modified according to the values in the block, as controlled by three flags in FIB$L_CNTRLVAL. |
| FIB$V_MOD_PERM || Change the permanent quota |
| FIB$V_MOD_OVER || Change the overdraft quota |
| FIB$V_MOD_USE || Change the usage data |
The usage data can be changed only if the volume is locked by FIB$C_LOCK_VOL (see Section 220.127.116.11). FIB$C_MOD_QUOTA requires write access to the quota file.
The P3 and P4 arguments return the modified quota entry to you.
By using the flags FIB$V_ALL_MEM and FIB$V_ALL_GRP, you can search through the quota file using wildcards just as you would with the FIB$C_EXA_QUOTA function.
| FIB$C_REM_QUOTA || Remove a disk quota file entry whose UIC is specified in the P2 argument block. FIB$C_REM_QUOTA requires write access to the quota file. |
The P3 and P4 arguments return the removed quota file entry to you.
By using the flags FIB$V_ALL_MEM and FIB$V_ALL_GRP, you can search through the quota file using wildcards just as you would with the FIB$C_EXAQUOTA function.
Figure 1-9 Quota File Transfer Block
IO$_ACPCONTROL functions that transfer quota file data between thecaller and the ACP use the following device- or function-dependentarguments:
- P2---The address of a descriptor for the quota data block being sent to the ACP.
- P3---The address of a word that returns the data length.
- P4---The address of a descriptor for a buffer to receive the quota data block returned from the ACP.
1.7 I/O Status Block
Figure 1-10 shows the I/O status block (IOSB) for ACP--QIO functions.Appendix A lists the status returns for these functions. (TheOpenVMS system messages documentation provides explanations andsuggested user actions for these returns.)
The file ACP returns a completion status in the first longword of theIOSB. In an extend operation, the second longword is used to return thenumber of blocks allocated to the file. If a contiguous extendoperation (FIB$V_ALCON) fails, the second longword is used to returnthe size of the file after truncation.
Values returned in the IOSB are most useful during operations incompatibility mode. When executing programs in the native mode, use thevalues returned in FIB locations.
Figure 1-10 IOSB Contents---ACP-QIO Functions
If an extend operation (including CREATE) was performed, IOSB+4contains the number of blocks allocated, or the largest availablecontiguous space if a contiguous extend operation failed. If a truncateoperation was performed, IOSB+4 contains the number of blocks added tothe file size to reach the next cluster boundary.