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/*
 * Copyright (c) 1987, 1993
 *      The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)mktemp.c    8.1 (Berkeley) 6/4/93";
#endif
static const char rcsid[] =
                "$\Id: mktemp.c,v 1.4.2.1 1997/04/07 18:03:25 guido Exp $";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
#include <unistd.h>

static int _gettemp(char *, int *);

int
mkstemp(path)
        char *path;
{
        int fd;

        return (_gettemp(path, &fd) ? fd : -1);
}

char *
mktemp(path)
        char *path;
{
        return(_gettemp(path, (int *)NULL) ? path : (char *)NULL);
}

static int
_gettemp(path, doopen)
        char *path;
        register int *doopen;
{
        register char *start, *trv;
        struct stat sbuf;
        pid_t pid;

        pid = getpid();
        for (trv = path; *trv; ++trv);          /* extra X's get set to 0's */
        while (*--trv == 'X') {
                *trv = (pid % 10) + '0';
                pid /= 10;
        }

        /*
         * check the target directory; if you have six X's and it
         * doesn't exist this runs for a *very* long time.
         */
        for (start = trv + 1;; --trv) {
                if (trv <= path)
                        break;
                if (*trv == '/') {
                        *trv = '\0';
                        if (stat(path, &sbuf))
                                return(0);
                        if (!S_ISDIR(sbuf.st_mode)) {
                                errno = ENOTDIR;
                                return(0);
                        }
                        *trv = '/';
                        break;
                }
        }

        for (;;) {
                if (doopen) {
                        if ((*doopen =
                            open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
                                return(1);
                        if (errno != EEXIST)
                                return(0);
                }
                else if (lstat(path, &sbuf))
                        return(errno == ENOENT ? 1 : 0);

                /* tricky little algorithm for backward compatibility */
                for (trv = start;;) {
                        if (!*trv)
                                return(0);
                        if (*trv == 'z')
                                *trv++ = 'a';
                        else {
                                if (isdigit(*trv))
                                        *trv = 'a';
                                else
                                        ++*trv;
                                break;
                        }
                }
        }
        /*NOTREACHED*/
}