Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

PUT_FILE_OPEN_(2) OSS System Calls Reference Manual
• 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 pro-
cess of the same name unless it has a matching sequence number. This
behavior ensures that the named process is a true backup of the primary
process.
• 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 behavior 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 because it contains the information necessary to access all of the parti-
tions, 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 Guardian 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 SET-
MODE function 1 or by using the File Utility Program (FUP) SECURE com-
mand. The following table shows the seven levels of security:
Table 5−1. Levels of Guardian File Security
FUP Code Program Value Access Permitted
_________________________________________________
_________________________________________________
- 7 Local super ID only
U 6 Owner (local or remote),
that is, any user with
owner’s ID
C 5 Member of owner’s group
(local or remote), that is,
any member of owner’s
community
N 4 Any user (local or remote)
O 2 Owner only (local)
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