VMS Help EDT Routines, FILEIO  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The user-supplied FILEIO routine performs file I/O functions.
    Call it by specifying it as an argument in the EDT$EDIT routine.
    It cannot be called independently.

    Format

      FILEIO  code ,stream ,record ,rhb

1 - Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

    A status code that your FILEIO routine returns to EDT$EDIT. The
    fileio argument is a longword containing the status code. The
    only failure code that is normally returned is RMS$_EOF from
    a GET call. All other OpenVMS RMS errors are signaled, not
    returned. The RMS signal should include the file name and both
    longwords of the RMS status. Any errors detected with the FILEIO
    routine can be indicated by setting status to an error code.
    That special error code will be returned to the program by the
    EDT$EDIT routine. There is a special status value EDT$_NONSTDFIL
    for nonstandard file opening.

    Condition values are returned in R0.

2 - Arguments

 code

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    A code from EDT that specifies what function the FILEIO routine
    is to perform. The code argument is the address of a longword
    integer containing this code. Following are the valid function
    codes:

    Function Code          Description

    EDT$K_OPEN_INPUT       The record argument names a file to be
                           opened for input. The rhb argument is the
                           default file name.
    EDT$K_OPEN_OUTPUT_SEQ  The record argument names a file to be
                           opened for output as a sequenced file. The
                           rhb argument is the default file name.
    EDT$K_OPEN_OUTPUT_     The record argument names a file to be
    NOSEQ                  opened for output. The rhb argument is the
                           default file name.
    EDT$K_OPEN_IN_OUT      The record argument names a file to be
                           opened for both input and output. The rhb
                           argument is the default file name.
    EDT$K_GET              The record argument is to be filled with
                           data from the next record of the file.
                           If the file has record prefixes, rhb is
                           filled with the record prefix. If the
                           file has no record prefixes, rhb is not
                           written. When you attempt to read past the
                           end of file, status is set to RMS$_EOF.
    EDT$K_PUT              The data in the record argument is to be
                           written to the file as its next record. If
                           the file has record prefixes, the record
                           prefix is taken from the rhb argument. For
                           a file opened for both input and output,
                           EDT$K_PUT is valid only at the end of the
                           file, indicating that the record is to be
                           appended to the file.
    EDT$K_CLOSE_DEL        The file is to be closed and then deleted.
                           The record and rhb arguments are not used
                           in the call.
    EDT$K_CLOSE            The file is to be closed. The record and
                           rhb arguments are not used in the call.

 stream

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    A code from EDT that indicates which file is being used. The
    stream argument is the address of a longword integer containing
    the code. Following are the valid codes:

    Function Code      Description

    EDT$K_COMMAND_     The command file.
    FILE
    EDT$K_INPUT_FILE   The primary input file.
    EDT$K_INCLUDE_     The secondary input file. Such a file is
    FILE               opened in response to an INCLUDE command. It
                       is closed when the INCLUDE command is complete
                       and will be reused for subsequent INCLUDE
                       commands.
    EDT$K_JOURNAL_     The journal file. If bit 0 of the options is
    FILE               set, it is opened for both input and output
                       and is read completely. Otherwise, it is
                       opened for output only. After it is read
                       or opened for output only, it is used for
                       writing. On a successful termination of the
                       editing session, the journal file is closed
                       and deleted. EXIT/SAVE and QUIT/SAVE close the
                       journal file without deleting it.
    EDT$K_OUTPUT_FILE  The primary output file. It is not opened
                       until you enter the EXIT command.
    EDT$K_WRITE_FILE   The secondary output file. Such a file is
                       opened in response to a WRITE or PRINT
                       command. It is closed when the command is
                       complete and will be reused for subsequent
                       WRITE or PRINT commands.

 record

    OpenVMS usage:char_string
    type:         character-coded text string
    access:       modify
    mechanism:    by descriptor
    Text record passed by descriptor from EDT to the user-supplied
    FILEIO routine; the code argument determines how the record
    argument is used. The record argument is the address of a
    descriptor pointing to this argument. When the code argument
    starts with EDT$K_OPEN, the record is a file name. When the code
    argument is EDT$K_GET, the record is a place to store the record
    that was read from the file. For code argument EDT$K_PUT, the
    record is a place to find the record to be written to the file.
    This argument is not used if the code argument starts with EDT$K_
    CLOSE.

    Note that for EDT$K_GET, EDT uses a dynamic or varying string
    descriptor; otherwise, EDT has no way of knowing the length of
    the record being read. EDT uses only string descriptors that can
    be handled by the Run-Time Library routine STR$COPY_DX.

 rhb

    OpenVMS usage:char_string
    type:         character-coded text string
    access:       modify
    mechanism:    by descriptor
    Text record passed by descriptor from EDT to the user-supplied
    FILEIO routine; the code argument determines how the rhb argument
    is used. When the code argument starts with EDT$K_OPEN, the rhb
    argument is the default file name. When the code is EDT$K_GET
    and the file has record prefixes, the prefixes are put in this
    argument. When the code is EDT$K_PUT and the file has record
    prefixes, the prefixes are taken from this argument. Like the
    record argument, EDT uses a dynamic or varying string descriptor
    for EDT$K_GET and uses only string descriptors that can be
    handled by the Run-Time Library routine STR$COPY_DX.

3 - Description

    If you do not need to intercept any file I/O, you can use the
    entry point EDT$FILEIO for this argument or you can omit it. If
    you need to intercept only some file I/O, call the EDT$FILEIO
    routine for the other cases.

    When you use EDT$FILEIO as a value for the fileio argument, files
    are opened as follows:

    o  The record argument is always the RMS file name.

    o  The rhb argument is always the RMS default file name.

    o  There is no related name for the input file.

    o  The related name for the output file is the input file with
       OFP (output file parse). EDT passes the input file name, the
       output file name, or the name from the EXIT command in the
       record argument.

    o  The related name for the journal file is the input file name
       with the OFP RMS bit set.

    o  The related name for the INCLUDE file is the input file name
       with the OFP set. This is unusual because the file is being
       opened for input.

    EDT contains support for VFC files. Normally, EDT will zero the
    length of the RHB field if the file is not a VFC file. However,
    when the user supplies the FILEIO routines, they are responsible
    for performing this operation.

    EDT checks for a VFC file with the following algorithm:

    IF FAB$B_RFM = FAB$C_VFC
    AND FAB$B_RAT <> FAB$M_PRN
    THEN
            VFC file
    ELSE
            not VFC file, zero out RHB descriptor length field.

4 - Condition Values Returned

    SS$_NORMAL         Normal successful completion.
    EDT$_NONSTDFIL     File is not in standard text format.
    RMS$_EOF           End of file on a GET.