elf/reldep.c

   1 #include <dlfcn.h>
   2 #include <mcheck.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5
   6 int
   7 main (void)
   8 {
   9   void *h1;
  10   void *h2;
  11   int (*fp) (void);
  12   int *vp;
  13
  14   mtrace ();
  15
  16   /* Open the two objects.  */
  17   h1 = dlopen ("reldepmod1.so", RTLD_LAZY | RTLD_GLOBAL);
  18   if (h1 == NULL)
  19     {
  20       printf ("cannot open reldepmod1.so: %s\n", dlerror ());
  21       exit (1);
  22     }
  23   h2 = dlopen ("reldepmod2.so", RTLD_LAZY);
  24   if (h2 == NULL)
  25     {
  26       printf ("cannot open reldepmod2.so: %s\n", dlerror ());
  27       exit (1);
  28     }
  29
  30   /* Get the address of the variable in reldepmod1.so.  */
  31   vp = dlsym (h1, "some_var");
  32   if (vp == NULL)
  33     {
  34       printf ("cannot get address of \"some_var\": %s\n", dlerror ());
  35       exit (1);
  36     }
  37
  38   *vp = 42;
  39
  40   /* Get the function `call_me' in the second object.  This has a
  41      dependency which is resolved by a definition in reldepmod1.so.  */
  42   fp = dlsym (h2, "call_me");
  43   if (fp == NULL)
  44     {
  45       printf ("cannot get address of \"call_me\": %s\n", dlerror ());
  46       exit (1);
  47     }
  48
  49   /* Call the function.  */
  50   if (fp () != 0)
  51     {
  52       puts ("function \"call_me\" returned wrong result");
  53       exit (1);
  54     }
  55
  56   /* Now close the first object.  If must still be around since we have
  57      an implicit dependency.  */
  58   if (dlclose (h1) != 0)
  59     {
  60       printf ("closing h1 failed: %s\n", dlerror ());
  61       exit (1);
  62     }
  63
  64   /* Try calling the function again.  This will fail if the first object
  65      got unloaded.  */
  66   if (fp () != 0)
  67     {
  68       puts ("second call of function \"call_me\" returned wrong result");
  69       exit (1);
  70     }
  71
  72   /* Now close the second file as well.  */
  73   if (dlclose (h2) != 0)
  74     {
  75       printf ("closing h2 failed: %s\n", dlerror ());
  76       exit (1);
  77     }
  78
  79   /* Finally, open the first object again.   */
  80   h1 = dlopen ("reldepmod1.so", RTLD_LAZY | RTLD_GLOBAL);
  81   if (h1 == NULL)
  82     {
  83       printf ("cannot open reldepmod1.so the second time: %s\n", dlerror ());
  84       exit (1);
  85     }
  86
  87   /* And get the variable address again.  */
  88   vp = dlsym (h1, "some_var");
  89   if (vp == NULL)
  90     {
  91       printf ("cannot get address of \"some_var\" the second time: %s\n",
  92               dlerror ());
  93       exit (1);
  94     }
  95
  96   /* The variable now must have its original value.  */
  97   if (*vp != 0)
  98     {
  99       puts ("variable \"some_var\" not reset");
 100       exit (1);
 101     }
 102
 103   /* Close the first object again, we are done.  */
 104   if (dlclose (h1) != 0)
 105     {
 106       printf ("closing h1 failed: %s\n", dlerror ());
 107       exit (1);
 108     }
 109
 110   return 0;
 111 }