source: vendor/FreeBSD-libc/current/stdio/mktemp.c

/*
 * 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)
static char sccsid[] = "@(#)mktemp.c    8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/stdio/mktemp.c,v 1.28 2003/02/16 17:29:10 nectar Exp $");

#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include "un-namespace.h"

char *_mktemp(char *);

static int _gettemp(char *, int *, int, int);

static const unsigned char padchar[] =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

int
mkstemps(path, slen)
        char *path;
        int slen;
{
        int fd;

        return (_gettemp(path, &fd, 0, slen) ? fd : -1);
}

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

        return (_gettemp(path, &fd, 0, 0) ? fd : -1);
}

char *
mkdtemp(path)
        char *path;
{
        return (_gettemp(path, (int *)NULL, 1, 0) ? path : (char *)NULL);
}

char *
_mktemp(path)
        char *path;
{
        return (_gettemp(path, (int *)NULL, 0, 0) ? path : (char *)NULL);
}

__warn_references(mktemp,
    "warning: mktemp() possibly used unsafely; consider using mkstemp()");

char *
mktemp(path)
        char *path;
{
        return (_mktemp(path));
}

static int
_gettemp(path, doopen, domkdir, slen)
        char *path;
        int *doopen;
        int domkdir;
        int slen;
{
        char *start, *trv, *suffp;
        char *pad;
        struct stat sbuf;
        int rval;
        uint32_t rand;

        if (doopen != NULL && domkdir) {
                errno = EINVAL;
                return (0);
        }

        for (trv = path; *trv != '\0'; ++trv)
                ;
        trv -= slen;
        suffp = trv;
        --trv;
        if (trv < path) {
                errno = EINVAL;
                return (0);
        }

        /* Fill space with random characters */
        while (trv >= path && *trv == 'X') {
                rand = arc4random() % (sizeof(padchar) - 1);
                *trv-- = padchar[rand];
        }
        start = trv + 1;

        /*
         * check the target directory.
         */
        if (doopen != NULL || domkdir) {
                for (; trv > path; --trv) {
                        if (*trv == '/') {
                                *trv = '\0';
                                rval = stat(path, &sbuf);
                                *trv = '/';
                                if (rval != 0)
                                        return (0);
                                if (!S_ISDIR(sbuf.st_mode)) {
                                        errno = ENOTDIR;
                                        return (0);
                                }
                                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 (domkdir) {
                        if (mkdir(path, 0700) == 0)
                                return (1);
                        if (errno != EEXIST)
                                return (0);
                } else if (lstat(path, &sbuf))
                        return (errno == ENOENT);

                /* If we have a collision, cycle through the space of filenames */
                for (trv = start;;) {
                        if (*trv == '\0' || trv == suffp)
                                return (0);
                        pad = strchr(padchar, *trv);
                        if (pad == NULL || *++pad == '\0')
                                *trv++ = padchar[0];
                        else {
                                *trv++ = *pad;
                                break;
                        }
                }
        }
        /*NOTREACHED*/
}