Guardian Procedure Calls Reference Manual

NOTE: The system stores the tag value until the I/O operation completes. It then returns the
tag information to the program in either the tag parameter of the call to FILE_AWAITIO64_
or the tag field of the completion-info parameter of the call to FILE_COMPLETEL_, thus
indicating that the operation finished.
Returned Value
INT
A file-system error code that indicates the outcome of the call.
FEOK0
Successful operation.
FESYSMESSAGE6
Successful operation that reads a system message. Valid only if filenum is $RECEIVE.
FEBOUNDSERR22
• The address of a parameter is extended, but either the extended data segment is invalid or the address is
for a selectable segment that is not in use at the time of the call.
• The address of a parameter is extended, but it is an absolute address and the caller is not privileged.
Considerations
• EpTAL callers must set toggle
EpTAL callers must set the toggle _64BIT_CALLS before sourcing the FILE_READUPDATE64_
procedure section from EXTDECS.
• Familiar semantics
Unless otherwise described, the semantic behavior of FILE_READUPDATE64_ is the same as
that of READUPDATEXL.
• Random processing and positioning
A call to FILE_READUPDATE64_ returns the record from the current position in the file. Because
FILE_READUPDATE64_ is designed for random processing, it cannot be used for successive
positioning through a subset of records as the FILE_READ64_ procedure does. Rather,
FILE_READUPDATE64_ reads a record after a call to FILE_SETPOSITION_ (or POSITION) or
FILE_SETKEY_ (or KEYPOSITION[X]), possibly in anticipation of a subsequent update through
a call to the FILE_WRITEUPDATE64_ procedure.
• Calling FILE_READUPDATE64_ after FILE_READ64_
A call to FILE_READUPDATE64_ after a call to FILE_READ64_, without intermediate positioning,
returns the same record as the call to FILE_READ64_.
• Waited FILE_READUPDATE64_
If a waited FILE_READUPDATE64_ is executed, the count-read parameter indicates the
number of bytes actually read.
• Nowait I/O and FILE_READUPDATE64_
If a nowait FILE_READUPDATE64_ is executed, count-read has no meaning and can be
omitted. The count of the number of bytes read is obtained through the count-transferred
parameter of the FILE_AWAITIO64_ procedure or the count-transferred field of the
completion-info parameter of the call to FILE_COMPLETEL_ when the I/O operation
completes.
488 Guardian Procedure Calls (F)