elf/tst-ldconfig-ld_so_conf-update.c

   1 /* Test ldconfig after /etc/ld.so.conf update and verify that a running process
   2    observes changes to /etc/ld.so.cache.
   3
   4    Copyright (C) 2019-2024 Free Software Foundation, Inc.
   5    This file is part of the GNU C Library.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public License as
   9    published by the Free Software Foundation; either version 2.1 of the
  10    License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; see the file COPYING.LIB.  If
  19    not, see <https://www.gnu.org/licenses/>.  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <errno.h>
  25
  26 #include <support/capture_subprocess.h>
  27 #include <support/check.h>
  28 #include <support/support.h>
  29 #include <support/xdlfcn.h>
  30 #include <support/xstdio.h>
  31 #include <support/xunistd.h>
  32
  33
  34 #define DSO "libldconfig-ld-mod.so"
  35 #define DSO_DIR "/tmp/tst-ldconfig"
  36
  37
  38 static void
  39 run_ldconfig (void *x __attribute__((unused)))
  40 {
  41   char *prog = xasprintf ("%s/ldconfig", support_install_rootsbindir);
  42   char *args[] = { prog, NULL };
  43
  44   execv (args[0], args);
  45   FAIL_EXIT1 ("execv: %m");
  46 }
  47
  48
  49 /* Create a new directory.
  50    Copy a test shared object there.
  51    Try to dlopen it by soname.  This should fail.
  52    (Directory is not searched.)
  53    Run ldconfig.
  54    Try to dlopen it again.  It should still fail.
  55    (Directory is still not searched.)
  56    Add the directory to /etc/ld.so.conf.
  57    Try to dlopen it again.  It should still fail.
  58    (The loader does not read /etc/ld.so.conf, only /etc/ld.so.cache.)
  59    Run ldconfig.
  60    Try to dlopen it again.  This should finally succeed.  */
  61 static int
  62 do_test (void)
  63 {
  64   struct support_capture_subprocess result;
  65
  66   char *conf_path = xasprintf ("%s/ld.so.conf", support_sysconfdir_prefix);
  67
  68   /* Create the needed directories.  */
  69   xmkdirp ("/var/cache/ldconfig", 0777);
  70   xmkdirp (DSO_DIR, 0777);
  71
  72   /* Rename the DSO to start with "lib" because there's an undocumented
  73      filter in ldconfig where it ignores any file that doesn't start with
  74      "lib" (for regular shared libraries) or "ld-" (for ld-linux-*).  */
  75   char *mod_src_path = xasprintf ("%s/tst-ldconfig-ld-mod.so",
  76                                   support_libdir_prefix);
  77   if (rename (mod_src_path, "/tmp/tst-ldconfig/libldconfig-ld-mod.so"))
  78     FAIL_EXIT1 ("Renaming/moving the DSO failed: %m");
  79   free (mod_src_path);
  80
  81
  82   /* Open the DSO.  We expect this to fail - tst-ldconfig directory
  83      is not searched.  */
  84   TEST_VERIFY_EXIT (dlopen (DSO, RTLD_NOW | RTLD_GLOBAL) == NULL);
  85
  86   FILE *fp = xfopen (conf_path, "a+");
  87   if (!fp)
  88     FAIL_EXIT1 ("creating %s failed: %m", conf_path);
  89   xfclose (fp);
  90
  91   /* Run ldconfig.  */
  92   result = support_capture_subprocess (run_ldconfig, NULL);
  93   support_capture_subprocess_check (&result, "execv", 0, sc_allow_none);
  94
  95   /* Try to dlopen the same DSO again, we expect this to fail again.  */
  96   TEST_VERIFY_EXIT (dlopen (DSO, RTLD_NOW | RTLD_GLOBAL) == NULL);
  97
  98   /* Add tst-ldconfig directory to /etc/ld.so.conf.  */
  99   fp = xfopen (conf_path, "w");
 100   if (!(fwrite (DSO_DIR, 1, sizeof (DSO_DIR), fp)))
 101     FAIL_EXIT1 ("updating %s failed: %m", conf_path);
 102   xfclose (fp);
 103
 104   /* Try to dlopen the same DSO again, we expect this to still fail.  */
 105   TEST_VERIFY_EXIT (dlopen (DSO, RTLD_NOW | RTLD_GLOBAL) == NULL);
 106
 107   /* Run ldconfig again.  */
 108   result = support_capture_subprocess (run_ldconfig, NULL);
 109   support_capture_subprocess_check (&result, "execv", 0, sc_allow_none);
 110   support_capture_subprocess_free (&result);
 111
 112   /* Finally, we expect dlopen to pass now.  */
 113   TEST_VERIFY_EXIT (dlopen (DSO, RTLD_NOW | RTLD_GLOBAL) != NULL);
 114
 115   free (conf_path);
 116
 117   return 0;
 118 }
 119
 120 #include <support/test-driver.c>