Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (C)
Guardian Procedure Calls Reference Manual—522629-013
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CHECKOPEN Procedure
(Superseded by FILE_OPEN_CHKPT_ Procedure )
Parameters
With the exception of filenum, all of the input parameters to this procedure are
ignored; the values that were specified when the primary process called OPEN or
FILE_OPEN_ are used instead. The ignored parameters are described under the
OPEN procedure.
filenum output
INT:ref:1
is the number that identifies the file that was opened by the primary process and
that is now to be opened by the backup process.
backerror output
INT:ref:1
returns one of the following values:
Š0 is the file-system error number reflecting the call to FILE_OPEN_ in the
backup process.
-1 indicates that the backup process is not running or that the checkpoint
facility could not communicate with the backup process.
Condition Code Settings
The following settings are obtained from the FILE_OPEN_ procedure in the backup
process:
< (CCL) indicates that the open failed. The file-system error number returns in
backerror.
= (CCE) indicates that the open was successful.
> (CCG) indicates that the open was successful, but an exceptional condition was
detected. The file-system error number returns in
backerror.
Considerations
•
Identification of the backup process
The system identifies the process to be affected by CHECKOPEN from the
process’s mom field in the process control block (PCB). For named process pairs,
this field is automatically set up during the creation of a backup process.
•
Nowait opens with CHECKOPEN
If a process file is opened nowait (
flag.<8> = 1 with OPEN, options.<1> = 1
with FILE_OPEN_ ), that file is CHECKOPEN nowait. CHECKOPEN returns errors
detected in parameter specification and system data-space allocation in
backerror and the operation is considered complete.