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.

4 files changed, 60 insertions, 26 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
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 41c7badf86f..de148e69821 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sig.c,v 1.36 2000/03/03 11:31:43 art Exp $	*/
+/*	$OpenBSD: kern_sig.c,v 1.37 2000/04/21 15:47:27 millert Exp $	*/
 /*	$NetBSD: kern_sig.c,v 1.54 1996/04/22 01:38:32 christos Exp $	*/
 
 /*
@@ -1199,7 +1199,7 @@ coredump(p)
 	sprintf(name, "%s.core", p->p_comm);
 	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, name, p);
 
-	error = vn_open(&nd, O_CREAT | FWRITE | FNOSYMLINK, S_IRUSR | S_IWUSR);
+	error = vn_open(&nd, O_CREAT | FWRITE | O_NOFOLLOW, S_IRUSR | S_IWUSR);
 
 	if (error) {
 		crfree(cred);
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index e6ca0a79df3..e45b3d30c30 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_vnops.c,v 1.24 2000/04/19 08:34:53 csapuntz Exp $	*/
+/*	$OpenBSD: vfs_vnops.c,v 1.25 2000/04/21 15:47:28 millert Exp $	*/
 /*	$NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $	*/
 
 /*
@@ -95,8 +95,7 @@ vn_open(ndp, fmode, cmode)
 	if (fmode & O_CREAT) {
 		ndp->ni_cnd.cn_nameiop = CREATE;
 		ndp->ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF;
-		if (((fmode & O_EXCL) == 0) &&
-		    ((fmode & FNOSYMLINK) == 0))
+		if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
 			ndp->ni_cnd.cn_flags |= FOLLOW;
 		if ((error = namei(ndp)) != 0)
 			return (error);
@@ -124,17 +123,11 @@ vn_open(ndp, fmode, cmode)
 				error = EEXIST;
 				goto bad;
 			}
-			if ((ndp->ni_vp->v_type == VLNK) &&
-			    ((fmode & FNOSYMLINK) != 0)) {
-				error = EFTYPE;
-				goto bad;
-			}
-
-			fmode &= ~O_CREAT;
 		}
 	} else {
 		ndp->ni_cnd.cn_nameiop = LOOKUP;
-		ndp->ni_cnd.cn_flags = FOLLOW | LOCKLEAF;
+		ndp->ni_cnd.cn_flags =
+		    ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
 		if ((error = namei(ndp)) != 0)
 			return (error);
 		vp = ndp->ni_vp;
@@ -143,6 +136,10 @@ vn_open(ndp, fmode, cmode)
 		error = EOPNOTSUPP;
 		goto bad;
 	}
+	if (vp->v_type == VLNK) {
+		error = EMLINK;
+		goto bad;
+	}
 	if ((fmode & O_CREAT) == 0) {
 		if (fmode & FREAD) {
 			if ((error = VOP_ACCESS(vp, VREAD, cred, p)) != 0)
@@ -326,7 +323,7 @@ vn_write(fp, poff, uio, cred)
 		ioflag |= IO_APPEND;
 	if (fp->f_flag & FNONBLOCK)
 		ioflag |= IO_NDELAY;
-	if ((fp->f_flag & O_FSYNC) ||
+	if ((fp->f_flag & FFSYNC) ||
 	    (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
 		ioflag |= IO_SYNC;
 	VOP_LEASE(vp, uio->uio_procp, cred, LEASE_WRITE);
diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
index 1acb5a2bb8e..99e18695481 100644
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fcntl.h,v 1.5 1998/01/09 16:33:47 csapuntz Exp $	*/
+/*	$OpenBSD: fcntl.h,v 1.6 2000/04/21 15:47:27 millert Exp $	*/
 /*	$NetBSD: fcntl.h,v 1.8 1995/03/26 20:24:12 jtc Exp $	*/
 
 /*-
@@ -85,8 +85,10 @@
 #define	O_SHLOCK	0x0010		/* open with shared file lock */
 #define	O_EXLOCK	0x0020		/* open with exclusive file lock */
 #define	O_ASYNC		0x0040		/* signal pgrp when data ready */
-#define	O_FSYNC		0x0080		/* synchronous writes */
+#define	O_FSYNC		O_SYNC		/* backwards compatibility */
+#define	O_NOFOLLOW	0x0100		/* if path is a symlink, don't follow */
 #endif
+#define	O_SYNC		0x0080		/* synchronous writes */
 #define	O_CREAT		0x0200		/* create if nonexistant */
 #define	O_TRUNC		0x0400		/* truncate to zero length */
 #define	O_EXCL		0x0800		/* error if already exists */
@@ -94,14 +96,16 @@
 #define	FMARK		0x1000		/* mark during gc() */
 #define	FDEFER		0x2000		/* defer for next gc pass */
 #define	FHASLOCK	0x4000		/* descriptor holds advisory lock */
-
-/* Note: The below is not a flag that can be used in the struct file. 
-   It's an option that can be passed to vn_open to make sure it doesn't
-   follow a symlink on the last lookup */
-#define FNOSYMLINK     0x10000          /* Don't follow symlink for last
-					   component */
 #endif
 
+/*
+ * POSIX 1003.1 specifies a higher granularity for syncronous operations
+ * than we support.  Since synchronicity is all or nothing in OpenBSD
+ * we just define these to be the same as O_SYNC.
+ */
+#define	O_DSYNC		O_SYNC		/* synchronous data writes */
+#define	O_RSYNC		O_SYNC		/* synchronous reads */
+
 /* defined by POSIX 1003.1; BSD default, this bit is not required */
 #define	O_NOCTTY	0x8000		/* don't assign controlling terminal */
 
@@ -127,7 +131,7 @@
 #ifndef _POSIX_SOURCE
 #define	FAPPEND		O_APPEND	/* kernel/compat */
 #define	FASYNC		O_ASYNC		/* kernel/compat */
-#define	FFSYNC		O_FSYNC		/* kernel */
+#define	FFSYNC		O_SYNC		/* kernel */
 #define	FNONBLOCK	O_NONBLOCK	/* kernel */
 #define	FNDELAY		O_NONBLOCK	/* compat */
 #define	O_NDELAY	O_NONBLOCK	/* compat */