lib/mkstemp.c

/* Adapted from NetBSB libc by Dieter Baron */

/*	NetBSD: gettemp.c,v 1.13 2003/12/05 00:57:36 uebayasi 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.
 */

#include <sys/stat.h>
#include <sys/types.h>

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#ifdef _WIN32
#include <io.h>
#include <process.h>
#else
#include <unistd.h>
#endif
#include <stdio.h>
#include <stdlib.h>

#ifndef O_BINARY
#define O_BINARY 0
#endif


int
_zip_mkstemp(char *path) {
#ifdef _WIN32
    int ret;
    ret = _creat(_mktemp(path), _S_IREAD | _S_IWRITE);
    if (ret == -1) {
	return 0;
    }
    else {
	return ret;
    }
#else
    int fd;
    char *start, *trv;
    struct stat sbuf;
    pid_t 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;

    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 (*(trv - 1) == 'X')
	*--trv = xtra[0];
    if (xcnt > 6 && *(trv - 1) == 'X')
	*--trv = xtra[1];

    /* Set remaining X's to pid digits with 0's to the left. */
    while (*--trv == 'X') {
	*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 == '/') {
	    *trv = '\0';
	    if (stat(path, &sbuf))
		return (0);
	    if (!S_ISDIR(sbuf.st_mode)) {
		errno = ENOTDIR;
		return (0);
	    }
	    *trv = '/';
	    break;
	}
    }

    for (;;) {
	if ((fd = open(path, O_CREAT | O_EXCL | O_RDWR | O_BINARY, 0600)) >= 0)
	    return (fd);
	if (errno != EEXIST)
	    return (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
}