Add support for the -L and -P options.

Based on a patch from Kent R. Spillner (kspillner (at) acm.org)
ok jmc@ millert@

2 files changed, 35 insertions, 16 deletions

diff --git a/bin/ln/ln.1 b/bin/ln/ln.1
index 89a2be0f00a..8e72ac88dff 100644
--- a/bin/ln/ln.1
+++ b/bin/ln/ln.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ln.1,v 1.29 2011/03/02 07:47:21 jmc Exp $
+.\"	$OpenBSD: ln.1,v 1.30 2013/03/12 06:00:05 guenther Exp $
 .\"	$NetBSD: ln.1,v 1.10 1995/07/25 19:37:04 jtc Exp $
 .\"
 .\" Copyright (c) 1980, 1990, 1993
@@ -33,7 +33,7 @@
 .\"
 .\"	@(#)ln.1	8.2 (Berkeley) 12/30/93
 .\"
-.Dd $Mdocdate: March 2 2011 $
+.Dd $Mdocdate: March 12 2013 $
 .Dt LN 1
 .Os
 .Sh NAME
@@ -41,11 +41,11 @@
 .Nd make hard and symbolic links to files
 .Sh SYNOPSIS
 .Nm ln
-.Op Fl fhns
+.Op Fl fhLnPs
 .Ar source
 .Op Ar target
 .Nm ln
-.Op Fl fs
+.Op Fl fLPs
 .Ar source ...\&
 .Op Ar directory
 .Sh DESCRIPTION
@@ -68,10 +68,23 @@ The options are as follows:
 Unlink any already existing file, permitting the link to occur.
 .It Fl h
 If the target is a symlink to a directory, do not descend into it.
+.It Fl L
+When creating a hard link and the source is a symbolic link,
+link to the fully resolved target of the symbolic link.
+This is the default.
+This option cancels the
+.Fl P
+option.
 .It Fl n
 An alias for
 .Fl h
 for compatibility with other operating systems.
+.It Fl P
+When creating a hard link and the source is a symbolic link,
+link to the symbolic link itself.
+This option cancels the
+.Fl L
+option.
 .It Fl s
 Create a symbolic link.
 .El
@@ -183,7 +196,7 @@ create a new symlink
 pointing to itself.
 This results from directory-walking.
 .Sh SEE ALSO
-.Xr link 2 ,
+.Xr linkat 2 ,
 .Xr lstat 2 ,
 .Xr readlink 2 ,
 .Xr stat 2 ,
diff --git a/bin/ln/ln.c b/bin/ln/ln.c
index 0b0be08f7a4..c5c40e7c409 100644
--- a/bin/ln/ln.c
+++ b/bin/ln/ln.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ln.c,v 1.18 2009/10/27 23:59:21 deraadt Exp $	*/
+/*	$OpenBSD: ln.c,v 1.19 2013/03/12 06:00:05 guenther Exp $	*/
 /*	$NetBSD: ln.c,v 1.10 1995/03/21 09:06:10 cgd Exp $	*/
 
 /*
@@ -35,6 +35,7 @@
 
 #include <err.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <libgen.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -44,9 +45,8 @@
 int	dirflag;			/* Undocumented directory flag. */
 int	fflag;				/* Unlink existing files. */
 int	hflag;				/* Check new name for symlink first. */
+int	Pflag;				/* Hard link to symlink. */
 int	sflag;				/* Symbolic, not hard, link. */
-					/* System link call. */
-int (*linkf)(const char *, const char *);
 
 int	linkit(char *, char *, int);
 void	usage(void) __dead;
@@ -58,7 +58,7 @@ main(int argc, char *argv[])
 	int ch, exitval;
 	char *sourcedir;
 
-	while ((ch = getopt(argc, argv, "Ffhns")) != -1)
+	while ((ch = getopt(argc, argv, "FfhLnPs")) != -1)
 		switch (ch) {
 		case 'F':
 			dirflag = 1;	/* XXX: deliberately undocumented. */
@@ -70,6 +70,12 @@ main(int argc, char *argv[])
 		case 'n':
 			hflag = 1;
 			break;
+		case 'L':
+			Pflag = 0;
+			break;
+		case 'P':
+			Pflag = 1;
+			break;
 		case 's':
 			sflag = 1;
 			break;
@@ -80,8 +86,6 @@ main(int argc, char *argv[])
 	argv += optind;
 	argc -= optind;
 
-	linkf = sflag ? symlink : link;
-
 	switch(argc) {
 	case 0:
 		usage();
@@ -118,7 +122,7 @@ linkit(char *target, char *source, int isdir)
 
 	if (!sflag) {
 		/* If target doesn't exist, quit now. */
-		if (stat(target, &sb)) {
+		if ((Pflag ? lstat : stat)(target, &sb)) {
 			warn("%s", target);
 			return (1);
 		}
@@ -157,7 +161,7 @@ linkit(char *target, char *source, int isdir)
 	if (exists && !sflag) {
 		struct stat tsb;
 
-		if (stat(target, &tsb) != 0) {
+		if ((Pflag ? lstat : stat)(target, &tsb)) {
 			warn("%s: disappeared", target);
 			return (1);
 		}
@@ -177,7 +181,9 @@ linkit(char *target, char *source, int isdir)
 	 * Attempt the link.
 	 */
 	if ((fflag && unlink(source) < 0 && errno != ENOENT) ||
-	    (*linkf)(target, source)) {
+	    sflag ? symlink(target, source) :
+	    linkat(AT_FDCWD, target, AT_FDCWD, source,
+	    Pflag ? 0 : AT_SYMLINK_FOLLOW)) {
 		warn("%s", source);
 		return (1);
 	}
@@ -191,8 +197,8 @@ usage(void)
 	extern char *__progname;
 
 	(void)fprintf(stderr,
-	    "usage: %s [-fhns] source [target]\n"
-	    "       %s [-fs] source ... [directory]\n",
+	    "usage: %s [-fhLnPs] source [target]\n"
+	    "       %s [-fLPs] source ... [directory]\n",
 	    __progname, __progname);
 	exit(1);
 }