io/tst-closefrom.c

   1 /* Smoke test for the closefrom.
   2    Copyright (C) 2021 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
  28 #include <array_length.h>
  29
  30 #define NFDS 100
  31
  32 static int
  33 open_multiple_temp_files (void)
  34 {
  35   /* Check if the temporary file descriptor has no no gaps.  */
  36   int lowfd = xopen ("/dev/null", O_RDONLY, 0600);
  37   for (int i = 1; i <= NFDS; i++)
  38     TEST_COMPARE (xopen ("/dev/null", O_RDONLY, 0600), lowfd + i);
  39   return lowfd;
  40 }
  41
  42 static int
  43 closefrom_test (void)
  44 {
  45   struct support_descriptors *descrs = support_descriptors_list ();
  46
  47   int lowfd = open_multiple_temp_files ();
  48
  49   const int maximum_fd = lowfd + NFDS;
  50   const int half_fd = lowfd + NFDS / 2;
  51   const int gap = maximum_fd / 4;
  52
  53   /* Close half of the descriptors and check result.  */
  54   closefrom (half_fd);
  55
  56   for (int i = half_fd; i <= maximum_fd; i++)
  57     {
  58       TEST_COMPARE (fcntl (i, F_GETFL), -1);
  59       TEST_COMPARE (errno, EBADF);
  60     }
  61   for (int i = 0; i < half_fd; i++)
  62     TEST_VERIFY (fcntl (i, F_GETFL) > -1);
  63
  64   /* Create some gaps, close up to a threshold, and check result.  */
  65   xclose (lowfd + 35);
  66   xclose (lowfd + 38);
  67   xclose (lowfd + 42);
  68   xclose (lowfd + 46);
  69
  70   /* Close half of the descriptors and check result.  */
  71   closefrom (gap);
  72   for (int i = gap + 1; i < maximum_fd; i++)
  73     {
  74       TEST_COMPARE (fcntl (i, F_GETFL), -1);
  75       TEST_COMPARE (errno, EBADF);
  76     }
  77   for (int i = 0; i < gap; i++)
  78     TEST_VERIFY (fcntl (i, F_GETFL) > -1);
  79
  80   /* Close the remmaining but the last one.  */
  81   closefrom (lowfd + 1);
  82   for (int i = lowfd + 1; i <= maximum_fd; i++)
  83     {
  84       TEST_COMPARE (fcntl (i, F_GETFL), -1);
  85       TEST_COMPARE (errno, EBADF);
  86     }
  87   TEST_VERIFY (fcntl (lowfd, F_GETFL) > -1);
  88
  89   /* Close the last one.  */
  90   closefrom (lowfd);
  91   TEST_COMPARE (fcntl (lowfd, F_GETFL), -1);
  92   TEST_COMPARE (errno, EBADF);
  93
  94   /* Double check by check the /proc.  */
  95   support_descriptors_check (descrs);
  96   support_descriptors_free (descrs);
  97
  98   return 0;
  99 }
 100
 101 /* Check if closefrom works even when no new file descriptors can be
 102    created.  */
 103 static int
 104 closefrom_test_file_desc_limit (void)
 105 {
 106   int max_fd = NFDS;
 107   {
 108     struct rlimit rl;
 109     if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
 110       FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
 111
 112     max_fd = (rl.rlim_cur < max_fd ? rl.rlim_cur : max_fd);
 113     rl.rlim_cur = max_fd;
 114
 115     if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
 116       FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
 117   }
 118
 119   /* Exhauste the file descriptor limit.  */
 120   int lowfd = xopen ("/dev/null", O_RDONLY, 0600);
 121   for (;;)
 122     {
 123       int fd = open ("/dev/null", O_RDONLY, 0600);
 124       if (fd == -1)
 125         {
 126           if (errno != EMFILE)
 127             FAIL_EXIT1 ("open: %m");
 128           break;
 129         }
 130       TEST_VERIFY_EXIT (fd < max_fd);
 131     }
 132
 133   closefrom (lowfd);
 134   for (int i = lowfd; i < NFDS; i++)
 135     {
 136       TEST_COMPARE (fcntl (i, F_GETFL), -1);
 137       TEST_COMPARE (errno, EBADF);
 138     }
 139
 140   return 0;
 141 }
 142
 143 static int
 144 do_test (void)
 145 {
 146   closefrom_test ();
 147   closefrom_test_file_desc_limit ();
 148
 149   return 0;
 150 }
 151
 152 #include <support/test-driver.c>