1  #include <dlfcn.h>
       2  #include <elf.h>
       3  #include <errno.h>
       4  #include <error.h>
       5  #include <link.h>
       6  #include <stdio.h>
       7  #include <stdlib.h>
       8  
       9  #define MAPS ((struct link_map *) _r_debug.r_map)
      10  
      11  #define OUT \
      12    for (map = MAPS; map != NULL; map = map->l_next)			      \
      13      if (map->l_type == lt_loaded)					      \
      14        printf ("name = \"%s\", direct_opencount = %d\n",			      \
      15  	      map->l_name, (int) map->l_direct_opencount);		      \
      16    fflush (stdout)
      17  
      18  int
      19  main (void)
      20  {
      21    void *h[3];
      22    struct link_map *map;
      23    void (*fp) (void);
      24  
      25    h[0] = dlopen ("unload2mod.so", RTLD_LAZY);
      26    h[1] = dlopen ("unload2mod.so", RTLD_LAZY);
      27    if (h[0] == NULL || h[1] == NULL)
      28      error (EXIT_FAILURE, errno, "cannot load \"unload2mod.so\"");
      29    h[2] = dlopen ("unload2dep.so", RTLD_LAZY);
      30    if (h[2] == NULL)
      31      error (EXIT_FAILURE, errno, "cannot load \"unload2dep.so\"");
      32  
      33    puts ("\nAfter loading everything:");
      34    OUT;
      35  
      36    dlclose (h[0]);
      37  
      38    puts ("\nAfter unloading \"unload2mod.so\" once:");
      39    OUT;
      40  
      41    dlclose (h[1]);
      42  
      43    puts ("\nAfter unloading \"unload2mod.so\" twice:");
      44    OUT;
      45  
      46    fp = dlsym (h[2], "foo");
      47    puts ("\nnow calling `foo'");
      48    fflush (stdout);
      49    fp ();
      50    puts ("managed to call `foo'");
      51    fflush (stdout);
      52  
      53    dlclose (h[2]);
      54  
      55    puts ("\nAfter unloading \"unload2dep.so\":");
      56    OUT;
      57  
      58    return 0;
      59  }