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