Open System Services System Calls Reference Manual (G06.28+)

SPT_FILE_OPEN_(2) OSS System Calls Reference Manual
Considerations for Terminals
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 1. Attempting to open $RECEIVE and to specify a value greater
than 1 causes an error 28 to be returned.
When SPT_FILE_OPEN_() completes
When process A attempts to open process B, SPT_FILE_OPEN_() completes
as follows:
• If process B has already opened $RECEIVE with file-management sys-
tem messages disabled, the open call by process A completes immedi-
ately.
• If process B has opened $RECEIVE requesting file-management system
messages enabled, the open call completes when process B reads the
open message from process A by using READX, or if B uses READUP-
DATEX, the open call completes when process B replies to the open
message (by using REPLYX).
If process B has not yet opened $RECEIVE, the open by process A does
not complete until process B opens $RECEIVE. Specifically, the open
by process A completes as follows:
— When process B opens $RECEIVE with file-management sys-
tem messages disabled, a waited open by process A completes
immediately, but a nowait open by process A completes after the
first read of $RECEIVE by process B.
— When process B opens $RECEIVE with file-management sys-
tem messages enabled, the open call by process A completes
when process B reads the open message from A by using
READ[X], or if B uses READUPDATE[X], the open call com-
pletes when process B replies to the open message (by using
REPLY[X]).
Message formats
When $RECEIVE is opened by SPT_FILE_OPEN_(), system messages are
delivered to the caller in D-series format unless messages in C-series format are
requested by setting options bit 14 to 1. (No file-management system messages
are delivered to the caller if options bit 15 is set to 1 when opening $RECEIVE.)
Messages from high-PIN processes
Opening $RECEIVE with SPT_FILE_OPEN_() implies that the caller is capa-
ble of handling messages from processes with PINs greater than 255.
Opening $RECEIVE and being opened by a remote long-named process
If a process uses the SPT_FILE_OPEN_() procedure to open $RECEIVE and
requests that C-series format messages be delivered (or if a process uses the
Guardian OPEN procedure to open $RECEIVE), then a subsequent open of that
process by another process on a remote node that has a process name consisting
of more than five characters will fail with an error 20. Notification of this failure
is not sent to the process reading $RECEIVE.
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