Make ftruncate a 'struct file' operation rather than a vnode operation.

This makes it possible to support ftruncate() on non-vnode file types in
the future.
- 'struct fileops' grows a 'fo_truncate' method to handle an ftruncate() on
  a given file descriptor.
- ftruncate() moves to kern/sys_generic.c and now just fetches a file
  object and invokes fo_truncate().
- The vnode-specific portions of ftruncate() move to vn_truncate() in
  vfs_vnops.c which implements fo_truncate() for vnode file types.
- Non-vnode file types return EINVAL in their fo_truncate() method.

Submitted by:	rwatson

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/dev/streams/streams.c b/sys/dev/streams/streams.c
index 55df9e5..5b97f85 100644
--- a/sys/dev/streams/streams.c
+++ b/sys/dev/streams/streams.c
@@ -90,6 +90,7 @@ static struct cdev *dt_ptm, *dt_arp, *dt_icmp, *dt_ip, *dt_tcp, *dt_udp,
 static struct fileops svr4_netops = {
 	.fo_read = soo_read,
 	.fo_write = soo_write,
+	.fo_truncate = soo_truncate,
 	.fo_ioctl = soo_ioctl,
 	.fo_poll = soo_poll,
 	.fo_kqfilter = soo_kqfilter,