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mkstemp.c

/* $NiH: mkstemp.c,v 1.3 2006/04/23 14:51:45 wiz Exp $ */

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

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>

#ifndef O_BINARY
#define O_BINARY 0
#endif



int
_zip_mkstemp(char *path)
{
      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*/
}

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