lspu is a command-line FreeBSD utility to list running processes currently using given binaries or shared libraries, because this information is not available via fstat.
For example, it might help finding out how many processes will be affected when upgrading a shared library.
Run it with full paths to binaries or shared libraries. For example, lspu /lib/libc.so.7 will list pretty much every non-jailed running user process.
One can also use procstat -va | grep /lib/libc.so.7, but procstat omits process name/path.
Exit codes are
0if no processes found,1on error of some sort,2if one or more processes are found.
Just type make.
Makefile contains few "test" targets, for example
# make test2
./lspu /lib/libcam.so.6
pid jid command
815 0 /usr/local/sbin/smartd
*** Error code 2
make fails, because, on my machine, lspu returns 2, as smartmontools are using /lib/libcam.so.6.
It will omit listing processes if binaries or shared libraries are already deleted or replaced; lsop might help you there.