xapian-applications/omega/portability/mkdtemp.cc

   1 /* $Progeny: mkdtemp.c 3839 2003-11-17 04:25:01Z dsp $ */
   2 /*      $NetBSD: gettemp.c,v 1.5 1999/09/20 04:39:30 lukem Exp $        */
   3
   4 /*
   5  * Copyright (c) 1987, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34 #include "mkdtemp.h"
  35
  36 #include <sys/types.h>
  37
  38 #include "safesysstat.h"
  39 #include "safeunistd.h"
  40
  41 #include <cerrno>
  42
  43 static int
  44 do_mkdtemp(char *path)
  45 {
  46         char *start, *trv;
  47         struct stat sbuf;
  48         pid_t pid;
  49
  50         /* To guarantee multiple calls generate unique names even if
  51            the file is not created. 676 different possibilities with 7
  52            or more X's, 26 with 6 or less. */
  53         static char xtra[2] = { 'a', 'a' };
  54         int xcnt = 0;
  55
  56         pid = getpid();
  57
  58         /* Move to end of path and count trailing X's. */
  59         for (trv = path; *trv; ++trv)
  60                 if (*trv == 'X')
  61                         xcnt++;
  62                 else
  63                         xcnt = 0;
  64
  65         /* Use at least one from xtra.  Use 2 if more than 6 X's. */
  66         if (*(trv-1) == 'X')
  67                 *--trv = xtra[0];
  68         if (xcnt > 6 && *(trv-1) == 'X')
  69                 *--trv = xtra[1];
  70
  71         /* Set remaining X's to pid digits with 0's to the left. */
  72         while (*--trv == 'X') {
  73                 *trv = (pid % 10) + '0';
  74                 pid /= 10;
  75         }
  76
  77         /* update xtra for next call. */
  78         if (xtra[0] != 'z')
  79                 xtra[0]++;
  80         else {
  81                 xtra[0] = 'a';
  82                 if (xtra[1] != 'z')
  83                         xtra[1]++;
  84                 else
  85                         xtra[1] = 'a';
  86         }
  87
  88         /*
  89          * check the target directory; if you have six X's and it
  90          * doesn't exist this runs for a *very* long time.
  91          */
  92         for (start = trv + 1;; --trv) {
  93                 if (trv <= path)
  94                         break;
  95                 if (*trv == '/') {
  96                         *trv = '\0';
  97                         if (stat(path, &sbuf))
  98                                 return (0);
  99                         if (!S_ISDIR(sbuf.st_mode)) {
 100                                 errno = ENOTDIR;
 101                                 return (0);
 102                         }
 103                         *trv = '/';
 104                         break;
 105                 }
 106         }
 107
 108         for (;;) {
 109                 if (mkdir(path, 0700) >= 0)
 110                         return (1);
 111                 if (errno != EEXIST)
 112                         return (0);
 113
 114                 /* tricky little algorithm for backward compatibility */
 115                 for (trv = start;;) {
 116                         if (!*trv)
 117                                 return (0);
 118                         if (*trv == 'z')
 119                                 *trv++ = 'a';
 120                         else {
 121                                 if (*trv >= '0' && *trv <= '9')
 122                                         *trv = 'a';
 123                                 else
 124                                         ++*trv;
 125                                 break;
 126                         }
 127                 }
 128         }
 129         /*NOTREACHED*/
 130 }
 131
 132 char *
 133 mkdtemp(char *path)
 134 {
 135         return (do_mkdtemp(path) ? path : (char *)0);
 136 }