Guardian Procedure Calls Reference Manual

• Queue files
If the READUPDATELOCK[X] operation is to be used, the sync-or-receive-depth
parameter must be 0. A separate open may be used for operations with
sync-or-receive-depth >0.
Sequential block buffering cannot be used.
• Format 2 key-sequenced files with increased limits not supported on legacy 514-byte sector
disks
OPEN does not support the open of format 2 key-sequenced files with increased limits (in
H06.28/J06.17 RVUs with specific SPRs and later RVUs) on legacy 514-byte sector disks.
The open attempt will fail with an FEINVALOP (2) error.
Terminal Considerations
The terminal being used as the operator console should not be opened with exclusive access. If it
is, console messages are not logged.
Interprocess Communication Considerations
• Maximum concurrent nowait operations for an open of $RECEIVE
The maximum number of concurrent nowait operations permitted for an open of $RECEIVE is
one. Attempting to open $RECEIVE and to specify a value greater than 1 returns an error
indication. A subsequent call to FILEINFO or FILE_GETINFO_ shows that an error 28 occurred.
• When open completes
When process A attempts to open process B, open completes as follows:
◦ The open for process A won't complete if process B has not opened its $RECEIVE.
◦ If process B has opened its $RECEIVE, but has not requested system messages, the open
for process A completes immediately.
◦ If process B has opened its $RECEIVE requesting system messages, and with a
receive-depth equal to 0, the open for process A completes when process B does a
read of $RECEIVE to get the open message from A.
◦ If process B has opened its $RECEIVE requesting system messages and with
receive-depth greater than 0, the open for process A completes after process B has
read the open message of process A and replied to it.
• Opening high-PIN processes
The OPEN procedure cannot be used to open a high-PIN unnamed process because the
process ID cannot fit into the process file name; FILE_OPEN_ must be used instead. However
the OPEN procedure can be used on high-PIN named processes, devices, and files on high-PIN
volumes.
• Opening an unconverted (C-series) process from a high-PIN process.
A high-PIN process cannot open an unconverted process unless the unconverted process has
the HIGHREQUESTERS object-file attribute set. If a high-PIN process attempts to open a low-PIN
process that does not have this attribute set, file-system error 560 occurs.
• Opening $RECEIVE and being opened by a remote long-named process
If a process uses the OPEN procedure to open $RECEIVE (or if it uses the FILE_OPEN_
procedure to open $RECEIVE and requests that C-series format messages be delivered), then
a subsequent open of that process (using either OPEN or FILE_OPEN_) by another process
906 Guardian Procedure Calls (O)