MFC r260336,r260355: find: Fix -lname and -ilname:

* Take into account that readlink() does not add a terminating '\0'.

* Do not match symlinks that are followed because of -H or -L. This is
  explicitly documented in GNU find's info file and is like -type l.

* Fix matching symlinks in subdirectories when fts changes directories.

As before, symlinks of length PATH_MAX or more are not handled correctly.
(These can only be created on other operating systems.)

Also, avoid some readlink() calls on files that are obviously not symlinks
(because of fts(3) restrictions, not all of them).

PR:		bin/185393
Submitted by:	Ben Reser (parts, original version)

2 files changed, 18 insertions, 3 deletions

diff --git a/usr.bin/find/find.1 b/usr.bin/find/find.1
index cffeacf..1abe825 100644
--- a/usr.bin/find/find.1
+++ b/usr.bin/find/find.1
@@ -31,7 +31,7 @@
 .\"	@(#)find.1	8.7 (Berkeley) 5/9/95
 .\" $FreeBSD$
 .\"
-.Dd November 18, 2012
+.Dd January 5, 2014
 .Dt FIND 1
 .Os
 .Sh NAME
@@ -520,6 +520,8 @@ Like
 .Ic -name ,
 but the contents of the symbolic link are matched instead of the file
 name.
+Note that this only matches broken symbolic links
+if symbolic links are being followed.
 This is a GNU find extension.
 .It Ic -ls
 This primary always evaluates to true.
diff --git a/usr.bin/find/function.c b/usr.bin/find/function.c
index 56d361c..9f15675 100644
--- a/usr.bin/find/function.c
+++ b/usr.bin/find/function.c
@@ -1122,11 +1122,24 @@ f_name(PLAN *plan, FTSENT *entry)
 {
 	char fn[PATH_MAX];
 	const char *name;
+	ssize_t len;
 
 	if (plan->flags & F_LINK) {
-		name = fn;
-		if (readlink(entry->fts_path, fn, sizeof(fn)) == -1)
+		/*
+		 * The below test both avoids obviously useless readlink()
+		 * calls and ensures that symlinks with existent target do
+		 * not match if symlinks are being followed.
+		 * Assumption: fts will stat all symlinks that are to be
+		 * followed and will return the stat information.
+		 */
+		if (entry->fts_info != FTS_NSOK && entry->fts_info != FTS_SL &&
+		    entry->fts_info != FTS_SLNONE)
 			return 0;
+		len = readlink(entry->fts_accpath, fn, sizeof(fn) - 1);
+		if (len == -1)
+			return 0;
+		fn[len] = '\0';
+		name = fn;
 	} else
 		name = entry->fts_name;
 	return !fnmatch(plan->c_data, name,