io/tst-closefrom.c

   1 /* Smoke test for the closefrom.
   2    Copyright (C) 2021-2023 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 <sys/resource.h>
  22 #include <unistd.h>
  23
  24 #include <support/check.h>
  25 #include <support/descriptors.h>
  26 #include <support/xunistd.h>
  27 #include <support/support.h>
  28
  29 #include <array_length.h>
  30
  31 #define NFDS 100
  32
  33 static int
  34 closefrom_test (void)
  35 {
  36   struct support_descriptors *descrs = support_descriptors_list ();
  37
  38   int lowfd = support_open_dev_null_range (NFDS, O_RDONLY, 0600);
  39
  40   const int maximum_fd = lowfd + NFDS - 1;
  41   const int half_fd = lowfd + NFDS / 2;
  42   const int gap = lowfd + NFDS / 4;
  43
  44   /* Close half of the descriptors and check result.  */
  45   closefrom (half_fd);
  46
  47   for (int i = half_fd; i <= maximum_fd; i++)
  48     {
  49       TEST_COMPARE (fcntl (i, F_GETFL), -1);
  50       TEST_COMPARE (errno, EBADF);
  51     }
  52   for (int i = lowfd; i < half_fd; i++)
  53     TEST_VERIFY (fcntl (i, F_GETFL) > -1);
  54
  55   /* Create some gaps, close up to a threshold, and check result.  */
  56   xclose (lowfd + 35);
  57   xclose (lowfd + 38);
  58   xclose (lowfd + 42);
  59   xclose (lowfd + 46);
  60
  61   /* Close half of the descriptors and check result.  */
  62   closefrom (gap);
  63   for (int i = gap + 1; i < maximum_fd; i++)
  64     {
  65       TEST_COMPARE (fcntl (i, F_GETFL), -1);
  66       TEST_COMPARE (errno, EBADF);
  67     }
  68   for (int i = lowfd; i < gap; i++)
  69     TEST_VERIFY (fcntl (i, F_GETFL) > -1);
  70
  71   /* Close the remmaining but the last one.  */
  72   closefrom (lowfd + 1);
  73   for (int i = lowfd + 1; i <= maximum_fd; i++)
  74     {
  75       TEST_COMPARE (fcntl (i, F_GETFL), -1);
  76       TEST_COMPARE (errno, EBADF);
  77     }
  78   TEST_VERIFY (fcntl (lowfd, F_GETFL) > -1);
  79
  80   /* Close the last one.  */
  81   closefrom (lowfd);
  82   TEST_COMPARE (fcntl (lowfd, F_GETFL), -1);
  83   TEST_COMPARE (errno, EBADF);
  84
  85   /* Double check by check the /proc.  */
  86   support_descriptors_check (descrs);
  87   support_descriptors_free (descrs);
  88
  89   return 0;
  90 }
  91
  92 /* Check if closefrom works even when no new file descriptors can be
  93    created.  */
  94 static int
  95 closefrom_test_file_desc_limit (void)
  96 {
  97   int max_fd = NFDS;
  98   {
  99     struct rlimit rl;
 100     if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
 101       FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
 102
 103     max_fd = (rl.rlim_cur < max_fd ? rl.rlim_cur : max_fd);
 104     rl.rlim_cur = max_fd;
 105
 106     if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
 107       FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
 108   }
 109
 110   /* Exhauste the file descriptor limit.  */
 111   int lowfd = xopen ("/dev/null", O_RDONLY, 0600);
 112   for (;;)
 113     {
 114       int fd = open ("/dev/null", O_RDONLY, 0600);
 115       if (fd == -1)
 116         {
 117           if (errno != EMFILE)
 118             FAIL_EXIT1 ("open: %m");
 119           break;
 120         }
 121       TEST_VERIFY_EXIT (fd < max_fd);
 122     }
 123
 124   closefrom (lowfd);
 125   for (int i = lowfd; i < NFDS; i++)
 126     {
 127       TEST_COMPARE (fcntl (i, F_GETFL), -1);
 128       TEST_COMPARE (errno, EBADF);
 129     }
 130
 131   return 0;
 132 }
 133
 134 static int
 135 do_test (void)
 136 {
 137   closefrom_test ();
 138   closefrom_test_file_desc_limit ();
 139
 140   return 0;
 141 }
 142
 143 #include <support/test-driver.c>