is supposed to point directly to struct mbuf or struct sockaddr in kernel
space as appropriate, rather than being a pointer to memory in userland.
This is to be used by compat/* when emulation needs to wrap
send{to|msg}(2)/recv{from|msg}(2) and modify the passed struct
sockaddr.
between creation of a file descriptor and close(2) when using kernel
assisted threads. What we do is stick descriptors in the table, but
mark them as "larval". This causes essentially everything to treat
it as a non-existent descriptor, except for fdalloc(), which sees a
filled slot so that it won't (incorrectly) allocate it again. When
a descriptor is fully constructed, the code that has constructed it
marks it as "mature" (which actually clears the "larval" flag), and
things continue to work as normal.
While here, gather all the code that gets a descriptor from the table
into a fd_getfile() function, and call it, rather than having the
same (sometimes incorrect) code copied all over the place.
christos