fix realpath builtin’s handling of (source) pathnames with a trailing slash

as per POSIX (if a trailing slash is part of the symlink target it fails as
well, like GNU readlink -f does)

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.386 2010/07/25 11:35:38 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.387 2010/08/24 14:42:00 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -25,7 +25,7 @@
 # http://www.research.att.com/~gsf/public/ifs.sh
 
 expected-stdout:
-	@(#)MIRBSD KSH R39 2010/07/25
+	@(#)MIRBSD KSH R39 2010/08/24
 description:
 	Check version of shell.
 stdin:
@@ -7372,3 +7372,74 @@ stdin:
 expected-stdout:
 	1 .
 ---
+name: realpath-1
+description:
+	Check proper return values for realpath
+stdin:
+	wd=$(realpath .)
+	mkdir dir
+	:>file
+	:>dir/file
+	ln -s dir lndir
+	ln -s file lnfile
+	ln -s nix lnnix
+	ln -s . lnself
+	i=0
+	chk() {
+		typeset x y
+		x=$(realpath "$wd/$1" 2>&1); y=$?
+		print $((++i)) "?$1" =${x##*$wd/} !$y
+	}
+	chk dir
+	chk dir/
+	chk dir/file
+	chk dir/nix
+	chk file
+	chk file/
+	chk file/file
+	chk file/nix
+	chk nix
+	chk nix/
+	chk nix/file
+	chk nix/nix
+	chk lndir
+	chk lndir/
+	chk lndir/file
+	chk lndir/nix
+	chk lnfile
+	chk lnfile/
+	chk lnfile/file
+	chk lnfile/nix
+	chk lnnix
+	chk lnnix/
+	chk lnnix/file
+	chk lnnix/nix
+	chk lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself
+	rm lnself
+expected-stdout:
+	1 ?dir =dir !0
+	2 ?dir/ =dir !0
+	3 ?dir/file =dir/file !0
+	4 ?dir/nix =dir/nix !0
+	5 ?file =file !0
+	6 ?file/ =file/: Not a directory !20
+	7 ?file/file =file/file: Not a directory !20
+	8 ?file/nix =file/nix: Not a directory !20
+	9 ?nix =nix !0
+	10 ?nix/ =nix !0
+	11 ?nix/file =nix/file: No such file or directory !2
+	12 ?nix/nix =nix/nix: No such file or directory !2
+	13 ?lndir =dir !0
+	14 ?lndir/ =dir !0
+	15 ?lndir/file =dir/file !0
+	16 ?lndir/nix =dir/nix !0
+	17 ?lnfile =file !0
+	18 ?lnfile/ =lnfile/: Not a directory !20
+	19 ?lnfile/file =lnfile/file: Not a directory !20
+	20 ?lnfile/nix =lnfile/nix: Not a directory !20
+	21 ?lnnix =nix !0
+	22 ?lnnix/ =nix !0
+	23 ?lnnix/file =lnnix/file: No such file or directory !2
+	24 ?lnnix/nix =lnnix/nix: No such file or directory !2
+	25 ?lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself =lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself/lnself: Too many levels of symbolic links !62
+---

funcs.c

@@ -25,7 +25,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/funcs.c,v 1.156 2010/07/17 22:09:34 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/funcs.c,v 1.157 2010/08/24 14:42:01 tg Exp $");
 
 #if HAVE_KILLPG
 /*
@@ -290,7 +290,7 @@ do_realpath(const char *upath)
 			 */
 			xp = (ldest[0] == '/') ? Xstring(xs, xp) :
 			    Xrestpos(xs, xp, pos);
-			tp = shf_smprintf("%s/%s", ldest, ip);
+			tp = shf_smprintf("%s%s%s", ldest, *ip ? "/" : "", ip);
 			afree(ipath, ATEMP);
 			ip = ipath = tp;
 		}
@@ -309,6 +309,22 @@ do_realpath(const char *upath)
 		Xput(xs, xp, '/');
 	Xput(xs, xp, '\0');
 
+	/*
+	 * if source path had a trailing slash, check if target path
+	 * is not a non-directory existing file
+	 */
+	if (ip > ipath && ip[-1] == '/') {
+		if (stat(Xstring(xs, xp), &sb)) {
+			if (errno != ENOENT)
+				goto notfound;
+		} else if (!S_ISDIR(sb.st_mode)) {
+			errno = ENOTDIR;
+			goto notfound;
+		}
+		/* target now either does not exist or is a directory */
+	}
+
+	/* return target path */
 	if (ldest != NULL)
 		afree(ldest, ATEMP);
 	afree(ipath, ATEMP);

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.234 2010/08/14 20:13:10 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.235 2010/08/24 14:42:03 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.136 2010/07/15 20:04:35 schwarze Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
@@ -71,7 +71,7 @@
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
-.Dd $Mdocdate: August 14 2010 $
+.Dd $Mdocdate: August 24 2010 $
 .\"
 .\" Check which macro package we use
 .\"
@@ -3629,6 +3629,14 @@ printed.
 .Xc
 Prints the resolved absolute pathname corresponding to
 .Ar name .
+If
+.Ar name
+ends with a slash
+.Pq Sq / ,
+it's also checked for existence and whether it is a directory; otherwise,
+.Ic realpath
+returns 0 if the pathname either exists or can be created immediately,
+i.e. all but the last component exist and are directories.
 .Pp
 .It Ic rename Ar from to
 Renames the file

sh.h

@@ -150,9 +150,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.403 2010/08/14 21:35:13 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.404 2010/08/24 14:42:04 tg Exp $");
 #endif
-#define MKSH_VERSION "R39 2010/07/25"
+#define MKSH_VERSION "R39 2010/08/24"
 
 #ifndef MKSH_INCLUDES_ONLY