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Change basename(3) and dirname(3) to return a pointer to static
storage, rather than modifying their input arguments.  While not
reentrant, this is explcitly allowed by IEEE Std 1003.1-2001 (which
allows either behavior, stating that it is implementation-dependent).

The new semantics are considered less hostile/more useful by most programs
which use basename(3) and/or dirname(3) (several programs in the NetBSD
tree reimplement basename()/dirname() themselves to avoid modification
of the input argument).

This new implementation truncates results to PATH_MAX.  The Std does
not address this in the static storage case.  However since PATH_MAX
is the maximum pathname length in the Std, this should not be a problem
in practice.  Nontheless, it is noted in the BUGS section.

See the basename(3)/dirname(3) regression tests in src/regress/lib/libc.

Inspired by discussion with Niels Provos, related to PR 18647.

/*	$NetBSD: basename.c,v 1.5 2002/10/17 02:06:04 thorpej Exp $	*/

/*-
 * Copyright (c) 1997, 2002 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Klaus Klein and Jason R. Thorpe.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *        This product includes software developed by the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``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 FOUNDATION OR CONTRIBUTORS
 * 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: basename.c,v 1.5 2002/10/17 02:06:04 thorpej Exp $");
#endif /* !LIBC_SCCS && !lint */

#include "namespace.h"
#include <libgen.h>
#include <limits.h>
#include <string.h>

#ifdef __weak_alias
__weak_alias(basename,_basename)
#endif

#if !HAVE_BASENAME
char *
basename(path)
	char *path;
{
	static char singledot[] = ".";
	static char result[PATH_MAX];
	char *p, *lastp;
	size_t len;

	/*
	 * If `path' is a null pointer or points to an empty string,
	 * return a pointer to the string ".".
	 */
	if ((path == NULL) || (*path == '\0'))
		return (singledot);

	/* Strip trailing slashes, if any. */
	lastp = path + strlen(path) - 1;
	while (lastp != path && *lastp == '/')
		lastp--;

	/* Now find the beginning of this (final) component. */
	p = lastp;
	while (p != path && *(p - 1) != '/')
		p--;

	/* ...and copy the result into the result buffer. */
	len = (lastp - p) + 1 /* last char */;
	if (len > (PATH_MAX - 1))
		len = PATH_MAX - 1;

	memcpy(result, p, len);
	result[len] = '\0';

	return (result);
}
#endif