Subject:  LanLink Incompatibility with MicroSoft C
    
    
    While trying to use a program developed using MicroSoft-C(3.0) to 
access files across the LanLink network, we found that the file handles
returned by the LanLink software were incompatibile with the C runtime
functions.  The program most frequently failed to print properly but at
other times the system would lock up requiring it to be rebooted.

    Programs developed with MicroSoft-C (v3.0) should not be used with
LanLink since the results will be unpredictable.  We do not know if 
programs developed using other MicroSoft languages will have similiar 
problems.

    The Software Link, Inc. support/development people said that the file
handle values are intended to be extra large to distinguish which files have
been opened by the server system and which were opened by satellite systems.
They indicated that it would be too costly to change LanLink to return values
within the limits expected by MicroSoft-C.   

    The MicroSoft-C runtime functions for opening and closing files use the
the file handle values as index values into an area beginning with the label
__osfiles in the program link map.  The DOS 2.x documentation indicates that
the file handles are 16 bit values; however, the documentation also says that
the maximum number of open files that a process can have concurrently open is
20.  The LanLink modification of the file handle values may have serious and
unpredictable effects with many MicroSoft products since MicroSoft is 
apparently assuming file handle values less than 20 for any single process.