elf/tst-libc_dlvsym.h

   1 /* Compare dlvsym and __libc_dlvsym results.  Common code.
   2    Copyright (C) 2017-2020 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 /* compare_vsyms is the main entry point for these tests.
  20
  21    Indirectly, It calls __libc_dlvsym (from libc.so; internal
  22    interface) and dlvsym (from libdl.so; public interface) to compare
  23    the results for a selected set of symbols in libc.so which
  24    typically have more than one symbol version.  The two functions are
  25    implemented by somewhat different code, and this test checks that
  26    their results are the same.
  27
  28    The versions are generated to range from GLIBC_2.0 to GLIBC_2.Y,
  29    with Y being the current __GLIBC_MINOR__ version plus two.  In
  30    addition, there is a list of special symbol versions of the form
  31    GLIBC_2.Y.Z, which were used for some releases.
  32
  33    Comparing the two dlvsym results at versions which do not actually
  34    exist does not test much, but it will not contribute to false test
  35    failures, either.  */
  36
  37 #include <array_length.h>
  38 #include <gnu/lib-names.h>
  39 #include <stdbool.h>
  40 #include <stdio.h>
  41 #include <support/check.h>
  42 #include <support/xdlfcn.h>
  43
  44 /* Run consistency check for versioned symbol NAME@VERSION.  NB: We
  45    may execute in a shared object, so exit on error for proper error
  46    reporting.  */
  47 static void
  48 compare_vsyms_0 (void *libc_handle, const char *name, const char *version,
  49                  bool *pfound)
  50 {
  51   void *dlvsym_address = dlvsym (libc_handle, name, version);
  52   void *libc_dlvsym_address
  53     = __libc_dlvsym (libc_handle, name, version);
  54   if (dlvsym_address != libc_dlvsym_address)
  55     FAIL_EXIT1 ("%s@%s mismatch: %p != %p",
  56                 name, version, dlvsym_address, libc_dlvsym_address);
  57   if (dlvsym_address != NULL)
  58     *pfound = true;
  59 }
  60
  61
  62 /* Run consistency check for versioned symbol NAME at multiple symbol
  63    version.  */
  64 static void
  65 compare_vsyms_1 (void *libc_handle, const char *name)
  66 {
  67   bool found = false;
  68
  69   /* Historic versions which do not follow the usual GLIBC_2.Y
  70      pattern, to increase test coverage.  Not all architectures have
  71      those, but probing additional versions does not hurt.  */
  72   static const char special_versions[][12] =
  73     {
  74       "GLIBC_2.1.1",
  75       "GLIBC_2.1.2",
  76       "GLIBC_2.1.3",
  77       "GLIBC_2.1.4",
  78       "GLIBC_2.2.1",
  79       "GLIBC_2.2.2",
  80       "GLIBC_2.2.3",
  81       "GLIBC_2.2.4",
  82       "GLIBC_2.2.5",
  83       "GLIBC_2.2.6",
  84       "GLIBC_2.3.2",
  85       "GLIBC_2.3.3",
  86       "GLIBC_2.3.4",
  87     };
  88   for (int i = 0; i < array_length (special_versions); ++i)
  89     compare_vsyms_0 (libc_handle, name, special_versions[i], &found);
  90
  91   /* Iterate to an out-of-range version, to cover some unused symbols
  92      as well.  */
  93   for (int minor_version = 0; minor_version <= __GLIBC_MINOR__ + 2;
  94        ++minor_version)
  95     {
  96       char version[30];
  97       snprintf (version, sizeof (version), "GLIBC_%d.%d",
  98                 __GLIBC__, minor_version);
  99       compare_vsyms_0 (libc_handle, name, version, &found);
 100     }
 101
 102   if (!found)
 103     FAIL_EXIT1 ("symbol %s not found at any version", name);
 104 }
 105
 106 /* Run consistency checks for various symbols which usually have
 107    multiple versions.  */
 108 static void
 109 compare_vsyms (void)
 110 {
 111   /* The minor version loop in compare_vsyms_1 needs updating in case
 112      we ever switch to glibc 3.0.  */
 113   if (__GLIBC__ != 2)
 114     FAIL_EXIT1 ("unexpected glibc major version: %d", __GLIBC__);
 115
 116   /* __libc_dlvsym does not recognize the special RTLD_* handles, so
 117      obtain an explicit handle for libc.so.  */
 118   void *libc_handle = xdlopen (LIBC_SO, RTLD_LAZY | RTLD_NOLOAD);
 119
 120   compare_vsyms_1 (libc_handle, "_sys_errlist");
 121   compare_vsyms_1 (libc_handle, "_sys_siglist");
 122   compare_vsyms_1 (libc_handle, "quick_exit");
 123
 124   xdlclose (libc_handle);
 125 }