1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
/* Close a shared object opened by `_dl_open'.
Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <assert.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>
#include <bits/libc-lock.h>
#include <elf/ldsodefs.h>
#include <sys/types.h>
#include <sys/mman.h>
/* During the program run we must not modify the global data of
loaded shared object simultanously in two threads. Therefore we
protect `dlopen' and `dlclose' in dlclose.c. */
__libc_lock_define (extern, _dl_load_lock)
#define LOSE(s) _dl_signal_error (0, map->l_name, s)
void
internal_function
_dl_close (struct link_map *map)
{
struct link_map **list;
unsigned nsearchlist;
unsigned int i;
if (map->l_opencount == 0)
LOSE ("shared object not open");
/* Acquire the lock. */
__libc_lock_lock (_dl_load_lock);
/* Decrement the reference count. */
if (map->l_opencount > 1 || map->l_type != lt_loaded)
{
/* There are still references to this object. Do nothing more. */
--map->l_opencount;
__libc_lock_unlock (_dl_load_lock);
return;
}
list = map->l_searchlist;
nsearchlist = map->l_nsearchlist;
/* Call all termination functions at once. */
for (i = 0; i < nsearchlist; ++i)
{
struct link_map *imap = list[i];
if (imap->l_opencount == 1 && imap->l_type == lt_loaded
&& imap->l_info[DT_FINI]
/* Skip any half-cooked objects that were never initialized. */
&& imap->l_init_called)
{
/* When debugging print a message first. */
if (_dl_debug_impcalls)
_dl_debug_message (1, "\ncalling fini: ", imap->l_name,
"\n\n", NULL);
/* Call its termination function. */
(*(void (*) (void)) ((void *) imap->l_addr
+ imap->l_info[DT_FINI]->d_un.d_ptr)) ();
}
}
/* Notify the debugger we are about to remove some loaded objects. */
_r_debug.r_state = RT_DELETE;
_dl_debug_state ();
/* The search list contains a counted reference to each object it
points to, the 0th elt being MAP itself. Decrement the reference
counts on all the objects MAP depends on. */
for (i = 0; i < nsearchlist; ++i)
--list[i]->l_opencount;
if (map->l_origin != NULL)
free ((char *) map->l_origin);
/* The name always is allocated. */
free (map->l_name);
/* Check each element of the search list to see if all references to
it are gone. */
for (i = 0; i < nsearchlist; ++i)
{
struct link_map *imap = list[i];
if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
{
/* That was the last reference, and this was a dlopen-loaded
object. We can unmap it. */
const ElfW(Phdr) *ph;
const ElfW(Phdr) *first, *last;
ElfW(Addr) mapstart, mapend;
if (imap->l_global)
{
/* This object is in the global scope list. Remove it. */
struct link_map **tail = _dl_global_scope_end;
do
--tail;
while (*tail != imap);
while (tail < _dl_global_scope_end)
{
tail[0] = tail[1];
++tail;
}
--_dl_global_scope_end;
}
/* We can unmap all the maps at once. We just have to determine
the length and the `munmap' call does the rest. */
first = last = NULL;
for (ph = imap->l_phdr; ph < imap->l_phdr + imap->l_phnum; ++ph)
if (ph->p_type == PT_LOAD)
{
if (first == NULL)
first = ph;
last = ph;
}
/* Now we have all the information we need for the unmapping.
See the method used in `_dl_map_object_from_fd'. */
mapstart = first->p_vaddr & ~(first->p_align - 1);
mapend = last->p_vaddr + last->p_memsz;
__munmap ((caddr_t) (imap->l_addr + mapstart), mapend - mapstart);
/* Finally, unlink the data structure and free it. */
#ifdef PIC
/* We will unlink the first object only if this is a statically
linked program. */
assert (imap->l_prev != NULL);
imap->l_prev->l_next = imap->l_next;
#else
if (imap->l_prev != NULL)
imap->l_prev->l_next = imap->l_next;
else
_dl_loaded = imap->l_next;
#endif
if (imap->l_next)
imap->l_next->l_prev = imap->l_prev;
if (imap->l_searchlist && imap->l_searchlist != list)
free (imap->l_searchlist);
free (imap);
}
}
free (list);
/* Notify the debugger those objects are finalized and gone. */
_r_debug.r_state = RT_CONSISTENT;
_dl_debug_state ();
/* Release the lock. */
__libc_lock_unlock (_dl_load_lock);
}
|
