compat_mkdtemp.c

   1 /* $Id: compat_mkdtemp.c,v 1.3 2020/06/15 01:37:15 schwarze Exp $ */
   2 /*
   3  * Copyright (c) 2015 Ingo Schwarze <schwarze@openbsd.org>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  *
  17  * The algorithm of this function is inspired by OpenBSD mkdtemp(3)
  18  * by Theo de Raadt and Todd Miller, but the code differs.
  19  */
  20 #include "config.h"
  21
  22 #include <sys/stat.h>
  23 #include <errno.h>
  24 #include <limits.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 char *
  29 mkdtemp(char *path)
  30 {
  31         char            *start, *cp;
  32         unsigned         int tries;
  33
  34         start = strchr(path, '\0');
  35         while (start > path && start[-1] == 'X')
  36                 start--;
  37
  38         for (tries = INT_MAX; tries; tries--) {
  39                 if (mktemp(path) == NULL) {
  40                         errno = EEXIST;
  41                         return NULL;
  42                 }
  43                 if (mkdir(path, S_IRUSR | S_IWUSR | S_IXUSR) == 0)
  44                         return path;
  45                 if (errno != EEXIST)
  46                         return NULL;
  47                 for (cp = start; *cp != '\0'; cp++)
  48                         *cp = 'X';
  49         }
  50         errno = EEXIST;
  51         return NULL;
  52 }