Guardian Procedure Calls Reference Manual

NOTE: The CONTROL 2 operation is valid only for unstructured files or structured files
opened for unstructured access. For XP-based files, using the CONTROL 2 operation to
move the EOF will involve more CPU cycles. Writing the application data to the file and
letting the disk process move the EOF as the data is written to the file, and removing the
CONTROL 2 operations from the application code will improve the performance.
◦ File is locked
If a CONTROL operation is attempted for a file locked through a filenum other than
that specified in the call to FILE_CONTROL64_, the call is rejected with a "file is locked"
error 73.
If any record is locked in a file, a call to FILE_CONTROL64_ to write EOF (operation 2)
to that same file will be rejected with a "file is locked" error 73.
• Magnetic tapes
When device is not ready
If a magnetic tape rewind is performed concurrently with application program execution
(that is, rewind operation <> 6), any attempt to perform a read, write, or control operation
to the rewinding tape unit while rewind is taking place results in an error 100 indication.
◦
◦ Wait for rewind to complete
If a magnetic tape rewind operation = 6 (wait for completion) is performed as a nowait
operation, the application waits at the call to FILE_AWAITIO64_ for the rewind to
complete.
• Interprocess communication
Nonstandard operation and parameter values
Any value can be specified for the operation and parameter parameters. An
application-defined protocol should be established for interpreting nonstandard parameter
values.
◦
◦ Process not accepting system messages
If the object of the control operation is not accepting process CONTROL messages, the
call to FILE_CONTROL64_ completes with an error code of 7.
◦ Process control
The server process can obtain the process identifier of the caller to FILE_CONTROL64_
in a subsequent call to FILE_GETRECEIVEINFO_.
Related Programming Manuals
For programming information about the FILE_CONTROL64_ procedure, see the Guardian
Programmer's Guide, the Enscribe Programmer's Guide, and the data communications manuals.
FILE_CONTROL64_ Procedure 381