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

System Functions (s and S) SPT_FILE_OPEN_(2)
Any other user, local access XXXYXXY
If the caller to SPT_FILE_OPEN_() fails the security check, the open fails with
an error 48. You can obtain the security level of a file by a call to the Guardian
FILE_GETINFOLIST[BYNAME]_ procedure, the FILEINFO procedure, or by
the File Utility Program (FUP) INFO command.
If you are using the Safeguard product, this security information might not apply.
Tape file open access mode
The file system does not enforce read-only or write-only access for unlabeled
tape, even though no error is returned if you specify one of these access modes
when opening a tape file.
File open exclusion and access mode checking
When a file open is attempted, the requested access and exclusion modes are
compared with those of any opens already granted for the file. If the attempted
open is in conflict with other opens, the open fails with error 12. For a table that
lists the possible current modes and requested modes, indicating whether an
open succeeds or fails, see the description of the FILE_OPEN_ procedure in the
Guardian Procedure Calls Reference Manual. For the Optical Storage Facility
only, the "process exclusive" exclusion mode is also supported. Process
exclusive is the same as exclusive for opens by other processes, but the same as
shared for opens by the same process.
Protected exclusion mode
Protected exclusion mode has meaning only for disk files. For other files, speci-
fying protected exclusion mode is equivalent to specifying shared exclusion
mode.
Disk File Considerations
Maximum number of concurrent nowait operations
The maximum number of concurrent nowait operations permitted for an open of
a disk file is 1. Attempting to open a disk file and specify a nowait_depth value
greater than 1 causes SPT_FILE_OPEN_() to fail with an error 28.
Unstructured files
File pointers after an open
After a disk file is opened, the current-record and next-record
pointers begin at a relative byte address (RBA) of 0, and the first
data transfer (unless positioning is performed) is from that loca-
tion. After a successful open, the pointers are:
current-record pointer = 0D
next-record pointer = 0D
Sharing the same EOF pointer
If a given disk file is opened more than once by the same pro-
cess, separate current-record and next-record pointers are pro-
vided for each open, but all opens share the same EOF pointer.
Structured files
Accessing structured files as unstructured files
The unstructured access option (options bit 0 = 1) permits a file
to be accessed as an unstructured file. You must maintain the
block format used by Enscribe if the file is be accessed again in
527186-023 Hewlett-Packard Company 7−199