svn commit: r200274 - head/lib/libc/gen

[Andrew Gallatin]

John Baldwin wrote:

> The fact that we don't fail attempts to use pshared outright is probably 
> dubious.  They cannot possibly work as currently implemented aside from fork() 
> since the structure embeds a file descriptor and file descriptor indices are a 
> per-process namespace, not a global namespace.

FWIW, this is what confused me.  It tends to be kind of a land-mine,
since programs can be ported from Linux, and appear to work at first
for casual use.  If we don't support pshared, we should return an error
from sem_init() to make it obvious.

Also, perhaps the sem_init() man page should mention sem_open(), since
that seems to be the only way to really share a semaphore between
processes on FreeBSD.

Drew