Accessing Files Programmer's Guide (32650-90885)
Chapter 2 29
Creating A File
The HPFOPEN Intrinsic
length
parameter of the read or write request) exceeds the size of the
physical record (that is, a block) that is referenced, the remaining half
words or bytes are taken from subsequent successive records until the
number specified by
length
has been transferred. For message (MSG) files
not accessed with
itemnum
=17 enabled, the file system sets this option to
zero. This option is available only if
itemnum
=46 is set to 1.
(ASC) This option is not used for printers.
16/I32 Nowait I/O:
Allows the accessor to initiate an I/O request and to have control returned
before the completion of the I/O. This option implies the inhibit buffering
option; if NOBUF is not specified, the file system does it. Multirecord access
is not available. This option is not available if the file is located on a
remote computer. When opening nonmessage files, the process must be
running in PM (execution level 2) to specify this option. Set
itemnum
=29 to
3 if the file is to be accessed while in user mode (execution level 3).
The following values are valid:
0 Nowait I/O not in effect
1 Nowait I/O in effect
Default: 0
Directories may not be opened using Nowait I/O (1).
17/I32 Copy mode:
Passes a value that determines if any file should be treated as a standard
sequential file so it can be copied by logical record or physical block to
another file.
Byte stream files and directories are accessed using normal access (0)
regardless of the value specified for this
itemnum
.
The following values are valid:
0 The file is accessed as its own file type (for example, a
message file is treated as a message file).
1 The file is to be treated as a standard (STD) file with
variable-length records. For message files, this allows
nondestructive reading of an old message file at either the
logical record or physical block record level. Only
block-level access is permitted if the file is opened with
write access. This prevents incorrectly formatted data
from being written to the message file while it is
unprotected. To access a message file in copy mode, a
process must have exclusive access to the file.
(KSAM) only allowed for read access for KSAM XL or
KSAM64 files.
Default: 0