Guardian Procedure Calls Reference Manual

Condition Code Settings
indicates that an error occurred (call FILE_GETINFO_ or FILEINFO with filenum of 0).< (CCL)
is also returned following a successful read with an insertion-ordered alternate key path if the alternate
key value of the current record is equal to the alternate key value in this record along that path. A call
< (CCL)
to FILE_GETINFO_ or FILEINFO shows that an error 551 occurred; this error is advisory only and does
not indicate an unsuccessful read operation.
indicates that the READLOCK[X] is successful.= (CCE)
indicates that a system message is received through $RECEIVE. (CCG is not returned by READUPDATE[X]
for disk files.).
> (CCG)
Returned Value
(for READUPDATEXL)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.
Considerations
• Random processing and positioning
A call to READUPDATE[X|XL] returns the record from the current position in the file. Because
READUPDATE[X|XL] is designed for random processing, it cannot be used for successive
positioning through a subset of records as the READ[X] procedure does. Rather,
READUPDATE[X|XL] reads a record after a call to POSITION or KEYPOSITION, possibly in
anticipation of a subsequent update through a call to the WRITEUPDATE[X] procedure.
• Calling READUPDATE[X|XL] after READ[X]
A call to READUPDATE[X|XL] after a call to READ[X], without intermediate positioning, returns
the same record as the call to READ[X].
• Waited READUPDATE[X|XL]
If a waited READUPDATE[X|XL] is executed, the count-read parameter indicates the number
of bytes actually read.
• Nowait I/O and READUPDATE[X|XL]
If a nowait READUPDATE[X|XL] is executed, count-read has no meaning and can be
omitted. The count of the number of bytes read is obtained when the I/O operation completes
through the count-transferred parameter of the AWAITIO[X|XL] procedure.
The READUPDATE[X|XL] procedure call must complete with a corresponding call to the
AWAITIO[X|XL] procedure when used with a file that is OPENed nowait. If READUPDATEXL
is used, you must call AWAITIOXL to complete the I/O. If READUPDATEX is used, you must
call AWAITIOX or AWAITIOXL to complete the I/O. If READUPDATE is used, you may use
AWAITIO or AWAITIOX or AWAITIOXL to complete the I/O.
WARNING! When using nowait file I/O, data corruption might occur if the READ buffer is
modified before the AWAITIOX that completes the call. The buffer space must not be freed or
reused while the I/O is in progress.
1216 Guardian Procedure Calls (R)