mkdtemp.c

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/*-------------------------------------------------------------------------
 *
 * mkdtemp.c
 *    create a mode-0700 temporary directory
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/port/mkdtemp.c
 *
 * This code was taken from NetBSD to provide an implementation for platforms
 * that lack it.  (Among compatibly-licensed implementations, the OpenBSD
 * version better resists denial-of-service attacks.  However, it has a
 * cryptographic dependency.)  The NetBSD copyright terms follow.
 *-------------------------------------------------------------------------
 */
 
#include "c.h"
 
#define _DIAGASSERT(x) do {} while (0)
 
 
/*  $NetBSD: gettemp.c,v 1.17 2014/01/21 19:09:48 seanb Exp $   */
 
/*
 * 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. 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 HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
 
#if !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP || !HAVE_MKDTEMP
 
#ifdef NOT_POSTGRESQL
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)mktemp.c    8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: gettemp.c,v 1.17 2014/01/21 19:09:48 seanb Exp $");
#endif
#endif                          /* LIBC_SCCS and not lint */
#endif
 
#include <sys/types.h>
#include <sys/stat.h>
 
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
 
#ifdef NOT_POSTGRESQL
#if HAVE_NBTOOL_CONFIG_H
#define GETTEMP     __nbcompat_gettemp
#else
#include "reentrant.h"
#include "local.h"
#define GETTEMP     __gettemp
#endif
#endif
 
static int
GETTEMP(char *path, int *doopen, int domkdir)
{
    char       *start,
               *trv;
    struct stat sbuf;
    u_int       pid;
 
    /*
     * To guarantee multiple calls generate unique names even if the file is
     * not created. 676 different possibilities with 7 or more X's, 26 with 6
     * or less.
     */
    static char xtra[2] = "aa";
    int         xcnt = 0;
 
    _DIAGASSERT(path != NULL);
    /* doopen may be NULL */
 
    pid = getpid();
 
    /* Move to end of path and count trailing X's. */
    for (trv = path; *trv; ++trv)
        if (*trv == 'X')
            xcnt++;
        else
            xcnt = 0;
 
    /* Use at least one from xtra.  Use 2 if more than 6 X's. */
    if (xcnt > 0)
    {
        *--trv = xtra[0];
        xcnt--;
    }
    if (xcnt > 5)
    {
        *--trv = xtra[1];
        xcnt--;
    }
 
    /* Set remaining X's to pid digits with 0's to the left. */
    for (; xcnt > 0; xcnt--)
    {
        *--trv = (pid % 10) + '0';
        pid /= 10;
    }
 
    /* update xtra for next call. */
    if (xtra[0] != 'z')
        xtra[0]++;
    else
    {
        xtra[0] = 'a';
        if (xtra[1] != 'z')
            xtra[1]++;
        else
            xtra[1] = 'a';
    }
 
    /*
     * 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 == '/')
        {
            int         e;
 
            *trv = '\0';
            e = stat(path, &sbuf);
            *trv = '/';
            if (e == -1)
                return doopen == NULL && !domkdir;
            if (!S_ISDIR(sbuf.st_mode))
            {
                errno = ENOTDIR;
                return doopen == NULL && !domkdir;
            }
            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 ? 1 : 0;
 
        /* tricky little algorithm for backward compatibility */
        for (trv = start;;)
        {
            if (!*trv)
                return 0;
            if (*trv == 'z')
                *trv++ = 'a';
            else
            {
                if (isdigit((unsigned char) *trv))
                    *trv = 'a';
                else
                    ++*trv;
                break;
            }
        }
    }
    /* NOTREACHED */
}
 
#endif                          /* !HAVE_NBTOOL_CONFIG_H || !HAVE_MKSTEMP ||
                                 * !HAVE_MKDTEMP */
 
 
/*  $NetBSD: mkdtemp.c,v 1.11 2012/03/15 18:22:30 christos Exp $    */
 
/*
 * 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. 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 HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
 
#if !HAVE_NBTOOL_CONFIG_H || !HAVE_MKDTEMP
 
#ifdef NOT_POSTGRESQL
 
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)mktemp.c    8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: mkdtemp.c,v 1.11 2012/03/15 18:22:30 christos Exp $");
#endif
#endif                          /* LIBC_SCCS and not lint */
 
#if HAVE_NBTOOL_CONFIG_H
#define GETTEMP     __nbcompat_gettemp
#else
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "reentrant.h"
#include "local.h"
#define GETTEMP     __gettemp
#endif
 
#endif
 
char *
mkdtemp(char *path)
{
    _DIAGASSERT(path != NULL);
 
    return GETTEMP(path, NULL, 1) ? path : NULL;
}
 
#endif                          /* !HAVE_NBTOOL_CONFIG_H || !HAVE_MKDTEMP */