1  /* Test the xreadlink function.
       2     Copyright (C) 2017-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <errno.h>
      20  #include <fcntl.h>
      21  #include <stdio.h>
      22  #include <stdlib.h>
      23  #include <string.h>
      24  #include <support/check.h>
      25  #include <support/support.h>
      26  #include <support/temp_file.h>
      27  #include <support/xunistd.h>
      28  
      29  static int
      30  do_test (void)
      31  {
      32    char *dir = support_create_temp_directory ("tst-xreadlink-");
      33    char *symlink_name = xasprintf ("%s/symlink", dir);
      34    add_temp_file (symlink_name);
      35  
      36    /* The limit 10000 is arbitrary and simply there to prevent an
      37       attempt to exhaust all available disk space.  */
      38    for (int size = 1; size < 10000; ++size)
      39      {
      40        char *contents = xmalloc (size + 1);
      41        for (int i = 0; i < size; ++i)
      42          contents[i] = 'a' + (rand () % 26);
      43        contents[size] = '\0';
      44        if (symlink (contents, symlink_name) != 0)
      45          {
      46            if (errno == ENAMETOOLONG)
      47              {
      48                printf ("info: ENAMETOOLONG failure at %d bytes\n", size);
      49                free (contents);
      50                break;
      51              }
      52            FAIL_EXIT1 ("symlink (%d bytes): %m", size);
      53          }
      54  
      55        char *readlink_result = xreadlink (symlink_name);
      56        TEST_VERIFY (strcmp (readlink_result, contents) == 0);
      57        free (readlink_result);
      58        xunlink (symlink_name);
      59        free (contents);
      60      }
      61  
      62    /* Create an empty file to suppress the temporary file deletion
      63       warning.  */
      64    xclose (xopen (symlink_name, O_WRONLY | O_CREAT, 0));
      65  
      66    free (symlink_name);
      67    free (dir);
      68  
      69    return 0;
      70  }
      71  
      72  #include <support/test-driver.c>