Informix DataBlade API Programmer's Manual DataBlade API Function Descriptions

The mi_lo_read() function reads a specified number of bytes of data from an open smart large object.

mi_integer mi_lo_read(conn, LO_fd, buf, nbytes)

MI_CONNECTION *conn;

MI_LO_FD LO_fd;

char *buf;

mi_integer nbytes;

conn	is a pointer to the connection descriptor that a previous call to mi_open(), mi_server_connect(), or mi_server_reconnect() has established.
LO_fd	is an LO file descriptor for the smart large object from which to read the data.
buf	is a pointer to a user-allocated character buffer that contains the data that mi_lo_read() reads from the smart large object.
nbytes	is the maximum number of bytes to read into the buf character buffer. This value cannot exceed two gigabytes.

Valid in Client LIBMI Application?	Valid in User-Defined Routine?
Yes	Yes

The mi_lo_read() function reads nbytes of data from the open smart large object that the LO_fd file descriptor identifies. The read begins at the current LO seek position for LO_fd. You can use the mi_lo_tell() function to obtain the current LO seek position.

The function reads this data into the user-allocated buffer that buf references. The buf buffer must be less than two gigabytes in size. To read smart large objects that are larger than two gigabytes, read them in two-gigabyte chunks.

To perform a seek operation before a read operation, use the function mi_lo_readwithseek().

Tip: The mi_lo_read() function replaces the mi_large_object_read() function, which Informix supports for backward compatibility only. Use mi_lo_read() for all new DataBlade API modules.

Return Values

>=0	is the actual number of bytes that the function has read from the open smart large object to the buf character buffer.
MI_ERROR	indicates that the function was not successful.

See the descriptions of the following functions: mi_lo_readwithseek(), mi_lo_seek(), mi_lo_tell(), and mi_lo_write().

For more information, see Opening a Smart Large Object and Reading Data from a Smart Large Object.