For the benefit of linux emulation create a new minor device '2'
which is a ptmx with linux semantics. Linux changes the permissions
of the slave pty upon creation, not when grantpt(3) is called. The
glibc linux grantpt(3) checks that the pty is on ptyfs, and if it is,
it does nothing. To make use of this fix:
mknod /emul/linux/dev/ptmx c 165 2
chmod 666 /emul/linux/dev/ptmx
This is a lot simpler than copying a bunch of code and creating a
ptmx device just for the benefit of linux emulation.
1. make fileops const
2. add 2 new negative errno's to `officially' support the cloning hack:
- EDUPFD (used to overload ENODEV)
- EMOVEFD (used to overload ENXIO)
3. Created an fdclone() function to encapsulate the operations needed for
EMOVEFD, and made all cloners use it.
4. Centralize the local noop/badop fileops functions to:
fnullop_fcntl, fnullop_poll, fnullop_kqfilter, fbadop_stat
the code that `knows' about /dev/[pt]tyXX names (the BSD ptys) into a separate
file. Make an interface to be used by the tty creating provider. The code
to enable old PTY searching via ptm is enabled via COMPAT_BSDPTY, and it
is turned on by default on all kernels that have compatibility options enabled.
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