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

PUT_FILE_OPEN_(2) OSS System Calls Reference Manual
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 PUT_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
its structured form. (HP reserves the right to change this block
format at any time.) For information about Enscribe block for-
mats, see the Enscribe Programmer’s Guide.
For a file opened using the unstructured access option, a data
transfer occurs to the position in the file specified by an RBA
(instead of to the position indicated by a key address field or
record number); the number of bytes transferred is that specified
in the file-system procedure call (instead of the number of bytes
indicated by the record format).
If a partitioned file, either structured or unstructured, is opened
using the unstructured access option, only the first partition is
opened. You must open the remaining partitions individually
with separate calls to PUT_FILE_OPEN_() (each call specify-
ing unstructured access).
Accessing audited structured files as unstructured files is not
allowed.
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