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
|
// Copyright (C) 2013-2022 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef HOOKS_H
#define HOOKS_H
#include <hooks/callout_handle.h>
#include <hooks/library_handle.h>
namespace {
// Version 20200 of the hooks framework, set for Kea 2.2.0
const int KEA_HOOKS_VERSION = 20200;
// Names of the framework functions.
const char* const LOAD_FUNCTION_NAME = "load";
const char* const UNLOAD_FUNCTION_NAME = "unload";
const char* const VERSION_FUNCTION_NAME = "version";
const char* const MULTI_THREADING_COMPATIBLE_FUNCTION_NAME =
"multi_threading_compatible";
// Typedefs for pointers to the framework functions.
typedef int (*version_function_ptr)();
typedef int (*load_function_ptr)(isc::hooks::LibraryHandle&);
typedef int (*unload_function_ptr)();
typedef int (*multi_threading_compatible_function_ptr)();
} // Anonymous namespace
namespace isc {
namespace hooks {
/// @brief User-Library Initialization for Statically-Linked Kea
///
/// If Kea is statically-linked, a user-created hooks library will not be
/// able to access symbols in it. In particular, it will not be able to access
/// singleton objects.
///
/// The hooks framework handles some of this. For example, although there is
/// a singleton ServerHooks object, hooks framework objects store a reference
/// to it when they are created. When the user library needs to register a
/// callout (which requires access to the ServerHooks information), it accesses
/// the ServerHooks object through a pointer passed from the Kea image.
///
/// The logging framework is more problematical. Here the code is partly
/// statically linked (the Kea logging library) and partly shared (the
/// log4cplus). The state of the former is not accessible to the user library,
/// but the state of the latter is. So within the user library, we need to
/// initialize the Kea logging library but not initialize the log4cplus
/// code. Some of the initialization is done when the library is loaded, but
/// other parts are done at run-time.
///
/// This function - to be called by the user library code in its load() function
/// when running against a statically linked Kea - initializes the Kea
/// logging library. In particular, it loads the message dictionary with the
/// text of the Kea messages.
///
/// @note This means that the virtual address space is loaded with two copies
/// of the message dictionary. Depending on how the user libraries are linked,
/// loading multiple user libraries may involve loading one message dictionary
/// per library.
void hooksStaticLinkInit();
} // namespace hooks
} // namespace isc
#endif // HOOKS_H
|
