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
18int
19main (void)
20{
21 void *h[3];
22 struct link_map *map;
23 void (*fp) (void);
24
25 h[0] = dlopen (file: "unload2mod.so", RTLD_LAZY);
26 h[1] = dlopen (file: "unload2mod.so", RTLD_LAZY);
27 if (h[0] == NULL || h[1] == NULL)
28 error (EXIT_FAILURE, errno, format: "cannot load \"unload2mod.so\"");
29 h[2] = dlopen (file: "unload2dep.so", RTLD_LAZY);
30 if (h[2] == NULL)
31 error (EXIT_FAILURE, errno, format: "cannot load \"unload2dep.so\"");
32
33 puts (s: "\nAfter loading everything:");
34 OUT;
35
36 dlclose (handle: h[0]);
37
38 puts (s: "\nAfter unloading \"unload2mod.so\" once:");
39 OUT;
40
41 dlclose (handle: h[1]);
42
43 puts (s: "\nAfter unloading \"unload2mod.so\" twice:");
44 OUT;
45
46 fp = dlsym (handle: h[2], name: "foo");
47 puts (s: "\nnow calling `foo'");
48 fflush (stdout);
49 fp ();
50 puts (s: "managed to call `foo'");
51 fflush (stdout);
52
53 dlclose (handle: h[2]);
54
55 puts (s: "\nAfter unloading \"unload2dep.so\":");
56 OUT;
57
58 return 0;
59}
60

source code of glibc/elf/unload2.c