readlink.c

/*
 * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
 * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
 * Copyright (c) 1993-1996 Rick Sladkey <jrs@world.std.com>
 * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
 * Copyright (c) 2006 Ulrich Drepper <drepper@redhat.com>
 * Copyright (c) 2006 Bernhard Kaindl <bk@suse.de>
 * Copyright (c) 2006-2015 Dmitry V. Levin <ldv@altlinux.org>
 * Copyright (c) 2014-2017 The strace developers.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "defs.h"

static int
decode_readlink(struct tcb *tcp, int offset)
{
	if (entering(tcp)) {
		printpath(tcp, tcp->u_arg[offset]);
		tprints(", ");
	} else {
		if (syserror(tcp))
			printaddr(tcp->u_arg[offset + 1]);
		else
			/* Used to use printpathn(), but readlink
			 * neither includes NUL in the returned count,
			 * nor actually writes it into memory.
			 * printpathn() would decide on printing
			 * "..." continuation based on garbage
			 * past return buffer's end.
			 */
			printstrn(tcp, tcp->u_arg[offset + 1], tcp->u_rval);
		tprintf(", %" PRI_klu, tcp->u_arg[offset + 2]);
	}
	return 0;
}

SYS_FUNC(readlink)
{
	return decode_readlink(tcp, 0);
}

SYS_FUNC(readlinkat)
{
	if (entering(tcp))
		print_dirfd(tcp, tcp->u_arg[0]);
	return decode_readlink(tcp, 1);
}