Add counting of temporary references to a struct file (as opposed to references

from fd tables and other long-lived objects). This is to avoid races between
using a file descriptor and having another process (with shared fd table)
close it. We use a separate refence count so that error values from close(2)
will be correctly returned to the caller of close(2).

The macros for those reference counts are FILE_USE(fp) and FILE_UNUSE(fp).

Make sure that the cases where closef can be called "incorrectly" (most notably
dup2(2)) are handled.

Right now only callers of closef (and {,p}read) use FILE_{,UN}USE correctly,
more fixes incoming soon.

1 files changed, 4 insertions, 3 deletions

diff --git a/sys/nfs/nfs_syscalls.c b/sys/nfs/nfs_syscalls.c
index ae14c56ca07..1843336d880 100644
--- a/sys/nfs/nfs_syscalls.c
+++ b/sys/nfs/nfs_syscalls.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: nfs_syscalls.c,v 1.25 2002/01/20 23:51:29 hugh Exp $	*/
+/*	$OpenBSD: nfs_syscalls.c,v 1.26 2002/02/05 16:02:27 art Exp $	*/
 /*	$NetBSD: nfs_syscalls.c,v 1.19 1996/02/18 11:53:52 fvdl Exp $	*/
 
 /*
@@ -781,11 +781,12 @@ nfsrv_zapsock(slp)
 	slp->ns_flag &= ~SLP_ALLFLAGS;
 	fp = slp->ns_fp;
 	if (fp) {
-		slp->ns_fp = (struct file *)0;
+		FILE_USE(fp);
+		slp->ns_fp = NULL;
 		so = slp->ns_so;
 		so->so_upcall = NULL;
 		soshutdown(so, 2);
-		closef(fp, (struct proc *)0);
+		closef(fp, NULL);
 		if (slp->ns_nam)
 			MFREE(slp->ns_nam, m);
 		m_freem(slp->ns_raw);