support/tst-support-open-dev-null-range.c

   1 /* Tests for support_open_dev_null_range.
   2    Copyright (C) 2021-2022 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 <dirent.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <support/check.h>
  24 #include <support/support.h>
  25 #include <support/xunistd.h>
  26 #include <sys/resource.h>
  27 #include <stdlib.h>
  28
  29 #ifndef PATH_MAX
  30 # define PATH_MAX 1024
  31 #endif
  32
  33 #include <stdio.h>
  34
  35 static void
  36 check_path (int fd)
  37 {
  38   char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
  39   char file_path[PATH_MAX];
  40   ssize_t file_path_length
  41     = readlink (proc_fd_path, file_path, sizeof (file_path));
  42   free (proc_fd_path);
  43   if (file_path_length < 0)
  44     FAIL_EXIT1 ("readlink (%s, %p, %zu)", proc_fd_path, file_path,
  45                 sizeof (file_path));
  46   file_path[file_path_length] = '\0';
  47   TEST_COMPARE_STRING (file_path, "/dev/null");
  48 }
  49
  50 static int
  51 number_of_opened_files (void)
  52 {
  53   DIR *fds = opendir ("/proc/self/fd");
  54   if (fds == NULL)
  55     FAIL_EXIT1 ("opendir (\"/proc/self/fd\"): %m");
  56
  57   int r = 0;
  58   while (true)
  59     {
  60       errno = 0;
  61       struct dirent64 *e = readdir64 (fds);
  62       if (e == NULL)
  63         {
  64           if (errno != 0)
  65             FAIL_EXIT1 ("readdir: %m");
  66           break;
  67         }
  68
  69       if (e->d_name[0] == '.')
  70         continue;
  71
  72       char *endptr;
  73       long int fd = strtol (e->d_name, &endptr, 10);
  74       if (*endptr != '\0' || fd < 0 || fd > INT_MAX)
  75         FAIL_EXIT1 ("readdir: invalid file descriptor name: /proc/self/fd/%s",
  76                     e->d_name);
  77
  78       /* Skip the descriptor which is used to enumerate the
  79          descriptors.  */
  80       if (fd == dirfd (fds))
  81         continue;
  82
  83       r = r + 1;
  84     }
  85
  86   closedir (fds);
  87
  88   return r;
  89 }
  90
  91 static int
  92 do_test (void)
  93 {
  94   const int nfds1 = 8;
  95   int lowfd = support_open_dev_null_range (nfds1, O_RDONLY, 0600);
  96   for (int i = 0; i < nfds1; i++)
  97     {
  98       TEST_VERIFY (fcntl (lowfd + i, F_GETFL) > -1);
  99       check_path (lowfd + i);
 100     }
 101
 102   /* create some gaps.  */
 103   xclose (lowfd + 1);
 104   xclose (lowfd + 5);
 105   xclose (lowfd + 6);
 106
 107   const int nfds2 = 16;
 108   int lowfd2 = support_open_dev_null_range (nfds2, O_RDONLY, 0600);
 109   for (int i = 0; i < nfds2; i++)
 110     {
 111       TEST_VERIFY (fcntl (lowfd2 + i, F_GETFL) > -1);
 112       check_path (lowfd2 + i);
 113     }
 114
 115   /* Decrease the maximum number of files.  */
 116   {
 117     struct rlimit rl;
 118     if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
 119       FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
 120
 121     rl.rlim_cur = number_of_opened_files ();
 122
 123     if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
 124       FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
 125   }
 126
 127   const int nfds3 = 16;
 128   int lowfd3 = support_open_dev_null_range (nfds3, O_RDONLY, 0600);
 129   for (int i = 0; i < nfds3; i++)
 130     {
 131       TEST_VERIFY (fcntl (lowfd3 + i, F_GETFL) > -1);
 132       check_path (lowfd3 + i);
 133     }
 134
 135   /* create a lot of gaps to trigger the range extension.  */
 136   xclose (lowfd3 + 1);
 137   xclose (lowfd3 + 3);
 138   xclose (lowfd3 + 5);
 139   xclose (lowfd3 + 7);
 140   xclose (lowfd3 + 9);
 141   xclose (lowfd3 + 11);
 142   xclose (lowfd3 + 13);
 143
 144   const int nfds4 = 16;
 145   int lowfd4 = support_open_dev_null_range (nfds4, O_RDONLY, 0600);
 146   for (int i = 0; i < nfds4; i++)
 147     {
 148       TEST_VERIFY (fcntl (lowfd4 + i, F_GETFL) > -1);
 149       check_path (lowfd4 + i);
 150     }
 151
 152   return 0;
 153 }
 154
 155 #include <support/test-driver.c>