Enscribe Programmer's Guide

ManualsBrandsHP ManualsServerHP NonStop G-Series

File Access

The following paragraphs describe different ways to access Enscribe files.

Opening and Closing Files

You use the FILE_OPEN_ procedure to establish communication with a permanent disk file:

LITERAL name^length = 23,

syncdpth = 1;

LITERAL usebigkeys = 1D;

INT error;

INT filenum;

STRING .filename [0:22] := "$VOL1.MYSUBVOL.DATAFILE";

error := FILE_OPEN_(filename:name^length,

filenum,,,,syncdpth, ! read-write access,

,,,,usebigkeys); ! shared access,

! waited I/O,

! syncdepth = 1

! use 64-bit primary key

NOTE: With the release of D46, users may now use 64-bit primary keys instead of 32-bit values

for unstructured, relative or entry-sequenced disk files. If the default 32-bit keys are used, only files

up to 4 GB can be opened. If the 64-bit selection is used, access to any size file is allowed, but

32-bit interfaces such as POSITION must be avoided.

Once the file is open, use the file number (FILENUM) returned by the FILE_OPEN_ procedure to

identify the file to other file-system procedures.

Use the FILE_CLOSE_ procedure to terminate access to a disk file:

error := FILE_CLOSE_(filenum);

If you do not explicitly close the file, the file remains open until the process stops, at which point

all files are automatically closed.

To establish communication with a temporary file, use the temporary file name returned by the

FILE_CREATE_ procedure:

LITERAL temp^name^len = 256;

INT namelen;

INT error;

INT temp^filenum;

STRING .temp^filename [0:temp^name^len-1];

temp^filename ':=' "$VOL";

namelen := 4;

error := FILE_CREATE_ (temp^filename:temp^name^len, namelen);

error := FILE_OPEN_ (temp^filename:namelen,

temp^filenum);

FILE_CREATE_ returns a file name that you can use when you call FILE_OPEN_.

Temporary files are purged when you close them. If you do not want a temporary file to be purged,

call FILE_RENAME_ using the file number returned from FILE_OPEN_ to make the file permanent.

Opening Partitioned Files

When you open the primary (first) partition of a partitioned file, all of the associated secondary

partitions are also opened automatically. If a secondary partition cannot be opened, access to the

file is still granted but the FILE_OPEN_ procedure returns a code 3 warning indication and some

operations might not work. You can call the FILE_GETINFOLIST_ procedure to identify the highest

numbered partition that did not open.

Individual partitions cannot be opened separately unless you specify unstructured access in the

FILE_OPEN_ call.

File Access 51