Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (F)
Guardian Procedure Calls Reference Manual—522629-013
5-121
FILE_OPEN_ Procedure
A named process can be represented with or without a sequence number.
FILE_OPEN_ treats the two name forms differently.
•
If you supply a process file name that includes a sequence number, the
process must have a matching sequence number or the open fails with error
14. When retrying I/O on a process opened under such a name, the file
system does not attempt to send messages to a possible backup process of
the same name unless it has a matching sequence number. This is to assure
that it is a true backup.
•
If you supply a process file name that does not include a sequence number,
any process with a matching name can be opened and can be sent I/O retries.
A newly created process that receives an I/O retry intended for another
process of the same name will usually reject it with an error 60, but this is
under the control of the application.
•
Partitioned files
A separate FCB exists for each partition of a partitioned file. There is one ACB per
accessor (as for single-volume files), but this ACB requires more main memory
since it contains the information necessary to access all of the partitions, including
the location and partial-key value for each partition.
•
Disk file open—security check
When a disk file open is attempted, the system performs a security check. The
accessor’s (that is, the caller’s) security level is checked against the file security
level for the requested access mode, as follows:
for read access: read security level is checked.
for write access: write security level is checked.
for read-write access: read and write security levels are checked.
A file has one of seven levels of security for each access mode. (The owner of the
file can set the security level for each access mode by using SETMODE function 1
or by using the File Utility Program SECURE command.) Table 5-5
shows the
seven levels of security.