tests/test-tempname.c

   1 /* Test of creating a temporary file.
   2    Copyright (C) 2022-2025 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2022.  */
  18
  19 #include <config.h>
  20
  21 #include "tempname.h"
  22
  23 #include <string.h>
  24 #include <unistd.h>
  25
  26 #include "macros.h"
  27
  28 int
  29 main ()
  30 {
  31   /* Verify that two consecutive calls to gen_tempname return two different
  32      file names, with a high probability.  */
  33   const char *templ18 = "gl-temp-XXXXXX.xyz";
  34   char filename1[18 + 1];
  35   char filename2[18 + 1];
  36
  37   /* Case 1: The first file still exists while gen_tempname is called a second
  38      time.  */
  39   {
  40     strcpy (filename1, templ18);
  41     int fd1 = gen_tempname (filename1, strlen (".xyz"), 0, GT_FILE);
  42     ASSERT (fd1 >= 0);
  43
  44     strcpy (filename2, templ18);
  45     int fd2 = gen_tempname (filename2, strlen (".xyz"), 0, GT_FILE);
  46     ASSERT (fd2 >= 0);
  47
  48     /* gen_tempname arranges (via O_EXCL) to not return the name of an existing
  49        file.  */
  50     ASSERT (strcmp (filename1, filename2) != 0);
  51
  52     /* Clean up.  */
  53     close (fd1);
  54     close (fd2);
  55     unlink (filename1);
  56     unlink (filename2);
  57   }
  58
  59   /* Case 2: The first file is deleted before gen_tempname is called a second
  60      time.  */
  61   {
  62     strcpy (filename1, templ18);
  63     int fd1 = gen_tempname (filename1, strlen (".xyz"), 0, GT_FILE);
  64     ASSERT (fd1 >= 0);
  65
  66     /* Clean up.  */
  67     close (fd1);
  68     unlink (filename1);
  69
  70     strcpy (filename2, templ18);
  71     int fd2 = gen_tempname (filename2, strlen (".xyz"), 0, GT_FILE);
  72     ASSERT (fd2 >= 0);
  73
  74     /* With 6 'X' and a good pseudo-random number generator behind the scenes,
  75        the probability of getting the same file name twice in a row should be
  76        1/62^6 < 1/10^10.
  77        But on 64-bit native Windows, this probability is ca. 0.1% to 0.3%.  */
  78     ASSERT (strcmp (filename1, filename2) != 0);
  79
  80     /* Clean up.  */
  81     close (fd2);
  82     unlink (filename2);
  83   }
  84
  85   return test_exit_status;
  86 }