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.
callers and appropriate routines to cope. This makes fo_stat more
consistent with rest of fileops routines and also makes the fo_stat
match FreeBSD as an added bonus.
Discussed with Luke Mewburn on tech-kern@.
count is 0, wait for use count to drain before finishing the close.
This is necessary in order for multiple processes to safely share file
descriptor tables.
- Created compat_util.c and compat_util.h to be used by the compatibility
modules, so they don't duplicate the same code.
- Added prototypes to the stackgap allocation routines.
lukem