/*      $OpenBSD: basename.c,v 1.17 2020/10/20 19:30:14 naddy Exp $     */

/*
 * Copyright (c) 1997, 2004 Todd C. Miller <millert@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <errno.h>
#include <libgen.h>
#include <limits.h>
#include <string.h>

char *
basename(char *path)
{
        static char bname[PATH_MAX];
        size_t len;
        const char *endp, *startp;

        /* Empty or NULL string gets treated as "." */
        if (path == NULL || *path == '\0') {
                bname[0] = '.';
                bname[1] = '\0';
                return (bname);
        }

        /* Strip any trailing slashes */
        endp = path + strlen(path) - 1;
        while (endp > path && *endp == '/')
                endp--;

        /* All slashes becomes "/" */
        if (endp == path && *endp == '/') {
                bname[0] = '/';
                bname[1] = '\0';
                return (bname);
        }

        /* Find the start of the base */
        startp = endp;
        while (startp > path && *(startp - 1) != '/')
                startp--;

        len = endp - startp + 1;
        if (len >= sizeof(bname)) {
                errno = ENAMETOOLONG;
                return (NULL);
        }
        memcpy(bname, startp, len);
        bname[len] = '\0';
        return (bname);
}