Change kernel-only open flag FNOSYMLINK to userland-visible O_NOFOLLOW;

adapated from FreeBSD.  Also change O_FSYNC to the more standard O_SYNC
and document it.  open(2) needs some real examples for proper usage,
to come later.

1 files changed, 36 insertions, 3 deletions

diff --git a/lib/libc/sys/open.2 b/lib/libc/sys/open.2
index 860340e6b63..062ff002537 100644
--- a/lib/libc/sys/open.2
+++ b/lib/libc/sys/open.2
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: open.2,v 1.14 2000/04/10 19:36:02 deraadt Exp $
+.\"	$OpenBSD: open.2,v 1.15 2000/04/21 15:47:27 millert Exp $
 .\"	$NetBSD: open.2,v 1.8 1995/02/27 12:35:14 cgd Exp $
 .\"
 .\" Copyright (c) 1980, 1991, 1993
@@ -77,8 +77,10 @@ O_APPEND	append on each write
 O_CREAT		create file if it does not exist
 O_TRUNC		truncate size to 0
 O_EXCL		error if create and file exists
+O_SYNC		perform syncronous I/O operations
 O_SHLOCK	atomically obtain a shared lock
 O_EXLOCK	atomically obtain an exclusive lock
+O_NOFOLLOW	if last path element is a symlink, don't follow it
 .Ed
 .Pp
 Opening a file with
@@ -97,9 +99,11 @@ exists,
 .Fn open
 returns an error.  This may be used to
 implement a simple exclusive access locking mechanism.
-If
+If either of
 .Dv O_EXCL
-is set and the last component of the pathname is
+or
+.Dv O_NOFOLLOW
+are set and the last component of the pathname is
 a symbolic link,
 .Fn open
 will fail even if the symbolic
@@ -115,6 +119,9 @@ carrier on a dialup line),
 .Fn open
 returns immediately.
 This flag also has the effect of making all subsequent I/O on the open file non-blocking.
+If the
+.Dv O_SYNC
+flag is set, all I/O operations on the file will be done syncronously.
 .Pp
 When opening a file, a lock with
 .Xr flock 2
@@ -275,6 +282,32 @@ is already locked.
 .Xr umask 2 ,
 .Xr write 2 ,
 .Xr getdtablesize 3
+.Sh STANDARDS
+The
+.Fn open
+function conforms to
+.St -ansiC ,
+.St -p1003.1-90
+and
+.St -xpg4.2 .
+.Pp
+.Dv POSIX
+specifies three different flavors for syncronous I/O:
+.Dv O_SYNC ,
+.Dv O_DSYNC
+and
+.Dv O_RSYNC .
+In
+.Ox ,
+these are all equivalent.
+.Pp
+The
+.Dv O_SHLOCK ,
+.Dv O_EXLOCK
+and
+.Dv O_NOFOLLOW
+flags are non-standard extensions and should not be used if portability
+is of concern.
 .Sh HISTORY
 An
 .Fn open