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, 4 deletions

diff --git a/sys/kern/sys_generic.c b/sys/kern/sys_generic.c
index 575e4fc58c0..fd32b2a9959 100644
--- a/sys/kern/sys_generic.c
+++ b/sys/kern/sys_generic.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sys_generic.c,v 1.32 2002/02/02 16:05:58 art Exp $	*/
+/*	$OpenBSD: sys_generic.c,v 1.33 2002/02/05 16:02:27 art Exp $	*/
 /*	$NetBSD: sys_generic.c,v 1.24 1996/03/29 00:25:32 cgd Exp $	*/
 
 /*
@@ -91,6 +91,8 @@ sys_read(p, v, retval)
 	if ((fp->f_flag & FREAD) == 0)
 		return (EBADF);
 
+	FILE_USE(fp);
+
 	/* dofileread() will unuse the descriptor for us */
 	return (dofileread(p, fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
 	    &fp->f_offset, retval));
@@ -152,9 +154,7 @@ dofileread(p, fd, fp, buf, nbyte, offset, retval)
 #endif
 	*retval = cnt;
  out:
-#if notyet
-	FILE_UNUSE(fp, p);
-#endif
+	FILE_UNUSE(fp);
 	return (error);
 }