dlfcn/tst-rec-dlopen.c

   1 /* Test recursive dlopen using malloc hooks.
   2    Copyright (C) 2015-2023 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 <stdio.h>
  20 #include <stdlib.h>
  21 #include <dlfcn.h>
  22 #include <stdbool.h>
  23 #include <stdalign.h>
  24 #include <sys/mman.h>
  25 #include <unistd.h>
  26 #include <string.h>
  27
  28 #define DSO "moddummy1.so"
  29 #define FUNC "dummy1"
  30
  31 #define DSO1 "moddummy2.so"
  32 #define FUNC1 "dummy2"
  33
  34 /* Result of the called function.  */
  35 int func_result;
  36
  37 /* Call function func_name in DSO dso_name via dlopen.  */
  38 void
  39 call_func (const char *dso_name, const char *func_name)
  40 {
  41   int ret;
  42   void *dso;
  43   int (*func) (void);
  44   char *err;
  45
  46   /* Open the DSO.  */
  47   dso = dlopen (dso_name, RTLD_NOW|RTLD_GLOBAL);
  48   if (dso == NULL)
  49     {
  50       err = dlerror ();
  51       fprintf (stderr, "%s\n", err);
  52       exit (1);
  53     }
  54   /* Clear any errors.  */
  55   dlerror ();
  56
  57   /* Lookup func.  */
  58   func = (int (*) (void)) dlsym (dso, func_name);
  59   if (func == NULL)
  60     {
  61       err = dlerror ();
  62       if (err != NULL)
  63         {
  64           fprintf (stderr, "%s\n", err);
  65           exit (1);
  66         }
  67     }
  68   /* Call func.  */
  69   func_result = (*func) ();
  70
  71   /* Close the library and look for errors too.  */
  72   ret = dlclose (dso);
  73   if (ret != 0)
  74     {
  75       err = dlerror ();
  76       fprintf (stderr, "%s\n", err);
  77       exit (1);
  78     }
  79
  80 }
  81
  82 /* If true, call another function from malloc.  */
  83 static bool call_function;
  84
  85 /* Set to true to indicate that the interposed malloc was called.  */
  86 static bool interposed_malloc_called;
  87
  88 /* Interposed malloc which optionally calls another function.  */
  89 void *
  90 malloc (size_t size)
  91 {
  92   interposed_malloc_called = true;
  93   static void *(*original_malloc) (size_t);
  94
  95   if (original_malloc == NULL)
  96     {
  97       static bool in_initialization;
  98       if (in_initialization)
  99         {
 100           const char *message
 101             = "error: malloc called recursively during initialization\n";
 102           (void) write (STDOUT_FILENO, message, strlen (message));
 103           _exit (2);
 104         }
 105       in_initialization = true;
 106
 107       original_malloc
 108         = (__typeof (original_malloc)) dlsym (RTLD_NEXT, "malloc");
 109       if (original_malloc == NULL)
 110         {
 111           const char *message
 112             = "error: dlsym for malloc failed\n";
 113           (void) write (STDOUT_FILENO, message, strlen (message));
 114           _exit (2);
 115         }
 116     }
 117
 118   if (call_function)
 119     {
 120       call_function = false;
 121       call_func (DSO1, FUNC1);
 122       call_function = true;
 123     }
 124   return original_malloc (size);
 125 }
 126
 127 static int
 128 do_test (void)
 129 {
 130   /* Ensure initialization.  */
 131   {
 132     void *volatile ptr = malloc (1);
 133     free (ptr);
 134   }
 135
 136   if (!interposed_malloc_called)
 137     {
 138       printf ("error: interposed malloc not called during initialization\n");
 139       return 1;
 140     }
 141
 142   call_function = true;
 143
 144   /* Bug 17702 fixes two things:
 145        * A recursive dlopen unmapping the ld.so.cache.
 146        * An assertion that _r_debug is RT_CONSISTENT at entry to dlopen.
 147      We can only test the latter. Testing the former requires modifying
 148      ld.so.conf to cache the dummy libraries, then running ldconfig,
 149      then run the test. If you do all of that (and glibc's test
 150      infrastructure doesn't support that yet) then the test will
 151      SEGFAULT without the fix. If you don't do that, then the test
 152      will abort because of the assert described in detail below.  */
 153   call_func (DSO, FUNC);
 154
 155   call_function = false;
 156
 157   /* The function dummy2() is called by the malloc hook. Check to
 158      see that it was called. This ensures the second recursive
 159      dlopen happened and we called the function in that library.
 160      Before the fix you either get a SIGSEGV when accessing mmap'd
 161      ld.so.cache data or an assertion failure about _r_debug not
 162      beint RT_CONSISTENT.  We don't test for the SIGSEGV since it
 163      would require finding moddummy1 or moddummy2 in the cache and
 164      we don't have any infrastructure to test that, but the _r_debug
 165      assertion triggers.  */
 166   printf ("Returned result is %d\n", func_result);
 167   if (func_result <= 0)
 168     {
 169       printf ("FAIL: Function call_func() not called.\n");
 170       exit (1);
 171     }
 172
 173   printf ("PASS: Function call_func() called more than once.\n");
 174   return 0;
 175 }
 176
 177 #define TEST_FUNCTION do_test ()
 178 #include "../test-skeleton.c"