Currently the OOB client for Solaris is not built against the Solaris threads library. As a result, if you attempt to link a threaded program with the libesoobclient shared object you will probably get an undefined symbol for h_errno. When a program is built threaded, h_errnop is defined instead of h_errno.
An example where you might see this is if you build unixODBC with threads (the default configuration) and then try and use OOB with it. The solution is to rebuild unixODBC without threads (--enable-threads=no).
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