misc/tst-gethostid.c

   1 /* Basic test for gethostid.
   2    Copyright (C) 2018-2023 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 <gnu/lib-names.h>
  20 #include <nss.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <support/namespace.h>
  25 #include <support/support.h>
  26 #include <support/temp_file.h>
  27 #include <support/xdlfcn.h>
  28 #include <support/xstdio.h>
  29 #include <support/xunistd.h>
  30 #include <unistd.h>
  31
  32 /* Initial test is run outside a chroot, to increase the likelihood of
  33    success.  */
  34 static void
  35 outside_chroot (void *closure)
  36 {
  37   long id = gethostid ();
  38   printf ("info: host ID outside chroot: 0x%lx\n", id);
  39 }
  40
  41 /* The same, but this time perform a chroot operation.  */
  42 static void
  43 in_chroot (void *closure)
  44 {
  45   const char *chroot_path = closure;
  46   xchroot (chroot_path);
  47   long id = gethostid ();
  48   printf ("info: host ID in chroot: 0x%lx\n", id);
  49 }
  50
  51 static int
  52 do_test (void)
  53 {
  54   support_isolate_in_subprocess (outside_chroot, NULL);
  55
  56   /* Now run the test inside a chroot.  */
  57   support_become_root ();
  58   if (!support_can_chroot ())
  59     /* Cannot perform further tests.  */
  60     return 0;
  61
  62   /* Only use nss_files.  */
  63   __nss_configure_lookup ("hosts", "files");
  64
  65   /* Load the DSO outside of the chroot.  */
  66   xdlopen (LIBNSS_FILES_SO, RTLD_LAZY);
  67
  68   char *chroot_dir = support_create_temp_directory ("tst-gethostid-");
  69   support_isolate_in_subprocess (in_chroot, chroot_dir);
  70
  71   /* Tests with /etc/hosts in the chroot.  */
  72   {
  73     char *path = xasprintf ("%s/etc", chroot_dir);
  74     add_temp_file (path);
  75     xmkdir (path, 0777);
  76     free (path);
  77     path = xasprintf ("%s/etc/hosts", chroot_dir);
  78     add_temp_file (path);
  79
  80     FILE *fp = xfopen (path, "w");
  81     xfclose (fp);
  82     printf ("info: chroot test with an empty /etc/hosts file\n");
  83     support_isolate_in_subprocess (in_chroot, chroot_dir);
  84
  85     char hostname[1024];
  86     int ret = gethostname (hostname, sizeof (hostname));
  87     if (ret < 0)
  88       printf ("warning: invalid result from gethostname: %d\n", ret);
  89     else if (strlen (hostname) == 0)
  90       puts ("warning: gethostname returned empty string");
  91     else
  92       {
  93         printf ("info: chroot test with IPv6 address in /etc/hosts for: %s\n",
  94                 hostname);
  95         fp = xfopen (path, "w");
  96         /* Use an IPv6 address to induce another lookup failure.  */
  97         fprintf (fp, "2001:db8::1 %s\n", hostname);
  98         xfclose (fp);
  99         support_isolate_in_subprocess (in_chroot, chroot_dir);
 100       }
 101     free (path);
 102   }
 103   free (chroot_dir);
 104
 105   return 0;
 106 }
 107
 108 #include <support/test-driver.c>