The mi_lo_from_file_by_lofd() function

The mi_lo_from_file_by_lofd() function copies the contents of an operating-system file on the server or client computer to an open smart large object.

Syntax

mi_integer mi_lo_from_file_by_lofd(conn, LO_fd, fname_spec, open_mode,
   offset, amount)
   MI_CONNECTION *conn;
   MI_LO_FD LO_fd;
   const char *fname_spec;
   mi_integer open_mode;
   mi_integer offset;
   mi_integer amount;
conn
This is one of the following connection values:

A pointer to a connection descriptor established by a previous call to mi_open(), mi_server_connect(), or mi_server_reconnect().

A NULL-valued pointer (database server only)

LO_fd
A file descriptor for an existing smart large object
fname_spec
The path to the operating-system file to copy into a smart large object.
open_mode
An integer bitmask to indicate how to open the operating-system file and where this file is located. For a list of valid file-mode constants, see the following “Usage” section.
offset
The point to begin reading in the file. The offset value is the number of bytes from the beginning of the file, starting at 0.
amount
The amount of data to read, starting at the offset. An amount value of -1 means read to the end of the file.
Valid in client LIBMI application? Valid in user-defined routine?
No Yes

Usage

The mi_lo_from_file_by_lofd() function enables you to write to a smart large object that is already open. This function provides more flexibility than mi_lo_from_file() in the following ways:
  • You can position the LO file descriptor anywhere before the operation.
  • You can copy multiple files to a single smart large object.
To include environment variables in the fname_spec path, use the following syntax: 
$ENV_VAR

You must set these environment variables in the database server environment, before the database server starts.

The mi_lo_from_file_by_lofd() function can create the target files on either the server or the client computer. The file-mode flag values for the open_mode argument indicate the location of the file to copy and the access mode of the source file. Valid values include the following file-mode constants.
MI_O_EXCL
Open the file only if fname_spec does not exist.
MI_O_TRUNC
Zero out the input file before reading it.
MI_O_APPEND
Allow appending to the end of the file. (This function does not write to the source file.)
MI_O_RDWR
Open the file in read/write mode. (This function does not write to the source file.)
MI_O_RDONLY
Open the file in read-only mode.
MI_O_TEXT
Process the file as text (not binary). (Binary is used if you do not specify MI_O_TEXT.)
MI_O_SERVER_FILE
The fname_spec file is on the server computer.
MI_O_CLIENT_FILE
The fname_spec file is on the client computer.
Important: The MI_O_TRUNC flag is valid but is not often useful in a DataBlade® API module.
The default open_mode value is:
MI_O_RDONLY | MI_O_CLIENT_FILE
Server only: The mi_lo_from_file_by_lofd() function does not need a connection descriptor to execute. If your UDR does not need a valid connection for other operations, you can specify a NULL-valued pointer for the conn parameter to establish a NULL connection. For information about the advantages of a NULL connection, see the HCL OneDB™ DataBlade API Programmer's Guide.

Return values

MI_OK
The function was successful.
MI_ERROR
The function was not successful.