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
|
/**
* @file plugins.h
* @author Radek Krejci <rkrejci@cesnet.cz>
* @brief Plugins manipulation.
*
* Copyright (c) 2021 CESNET, z.s.p.o.
*
* This source code is licensed under BSD 3-Clause License (the "License").
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://opensource.org/licenses/BSD-3-Clause
*/
#ifndef LY_PLUGINS_H_
#define LY_PLUGINS_H_
#include "log.h"
struct lyplg_ext_record;
struct lyplg_type_record;
#ifdef __cplusplus
extern "C" {
#endif
/**
* @page howtoPlugins Plugins
*
* libyang supports two types of plugins to better support generic features of YANG that need some specific code for
* their specific instances in YANG modules. This is the case of YANG types, which are derived from YANG built-in types.
* The description of a derived type can specify some additional requirements or restriction that cannot be implemented
* generically and some special code is needed. The second case for libyang plugins are YANG extensions. For YANG extensions,
* most of the specification is hidden in their description (e.g. allowed substatements or place of the extension
* instantiation) and libyang is not able to process such a text in a generic way.
*
* In both cases, libyang provides API to get functionality implementing the specifics of each type or extension.
* Furthermore, there are several internal plugins, implementing built-in data types and selected derived types and YANG
* extensions. These internal plugins uses the same API and can be taken as examples for implementing user plugins. Internal
* plugins are always loaded with the first created [context](@ref howtoContext) and unloaded with destroying the last one.
* The external plugins are in the same phase loaded from the default directories specified at compile time via cmake
* variables `PLUGINS_DIR` (where the `extensions` and `types` subdirectories are added for each plugin type) or separately
* via `PLUGINS_DIR_EXTENSIONS` and `PLUGINS_DIR_TYPES` for each plugin type. The default directories can be replaced runtime
* using environment variables `LIBYANG_TYPES_PLUGINS_DIR` and `LIBYANG_EXTENSIONS_PLUGINS_DIR`.
*
* Order of the plugins determines their priority. libyang searches for the first match with the extension and type, so the
* firstly loaded plugin for the specific item is used. Since the internal plugins are loaded always before the external
* plugins, the internal plugins cannot be replaced.
*
* There is also a separate function ::lyplg_add() to add a plugin anytime later. Note, that such a plugin is being used
* after it is added with the lowest priority among other already loaded plugins. Also note that since all the plugins are
* unloaded with the destruction of the last context, creating a new context after that starts the standard plugins
* initiation and the manually added plugins are not loaded automatically.
*
* The following pages contain description of the API for creating user plugins.
*
* - @subpage howtoPluginsTypes
* - @subpage howtoPluginsExtensions
*/
/**
* @defgroup plugins Plugins
* @{
*
*/
/**
* @brief Identifiers of the plugin type.
*/
enum LYPLG {
LYPLG_TYPE, /**< Specific type (typedef) */
LYPLG_EXTENSION /**< YANG extension */
};
/**
* @brief Manually load a plugin file.
*
* Note, that a plugin can be loaded only if there is at least one context. The loaded plugins are connected with the
* existence of a context. When all the contexts are destroyed, all the plugins are unloaded.
*
* @param[in] pathname Path to the plugin file. It can contain types or extensions plugins, both are accepted and correctly
* loaded.
*
* @return LY_SUCCESS if the file contains valid plugin compatible with the library version.
* @return LY_EDENIED in case there is no context and the plugin cannot be loaded.
* @return LY_EINVAL when pathname is NULL or the plugin contains invalid content for this libyang version.
* @return LY_ESYS when the plugin file cannot be loaded.
*/
LIBYANG_API_DECL LY_ERR lyplg_add(const char *pathname);
/**
* @brief Manually load extension plugins from memory
*
* Note, that a plugin can be loaded only if there is at least one context. The loaded plugins are connected with the
* existence of a context. When all the contexts are destroyed, all the plugins are unloaded.
*
* @param[in] ctx The context to which the plugin should be associated with. If NULL, the plugin is considered to be shared
* between all existing contexts.
* @param[in] version The version of plugin records.
* @param[in] recs An array of plugin records provided by the plugin implementation. The array must be terminated by a zeroed
* record.
*
* @return LY_SUCCESS if the plugins with compatible version were successfully loaded.
* @return LY_EDENIED in case there is no context and the plugin cannot be loaded.
* @return LY_EINVAL when recs is NULL or the plugin contains invalid content for this libyang version.
*/
LIBYANG_API_DECL LY_ERR lyplg_add_extension_plugin(struct ly_ctx *ctx, uint32_t version, const struct lyplg_ext_record *recs);
/**
* @brief Manually load type plugins from memory
*
* Note, that a plugin can be loaded only if there is at least one context. The loaded plugins are connected with the
* existence of a context. When all the contexts are destroyed, all the plugins are unloaded.
*
* @param[in] ctx The context to which the plugin should be associated with. If NULL, the plugin is considered to be shared
* between all existing contexts.
* @param[in] version The version of plugin records.
* @param[in] recs An array of plugin records provided by the plugin implementation. The array must be terminated by a zeroed
* record.
*
* @return LY_SUCCESS if the plugins with compatible version were successfully loaded.
* @return LY_EDENIED in case there is no context and the plugin cannot be loaded.
* @return LY_EINVAL when recs is NULL or the plugin contains invalid content for this libyang version.
*/
LIBYANG_API_DECL LY_ERR lyplg_add_type_plugin(struct ly_ctx *ctx, uint32_t version, const struct lyplg_type_record *recs);
/** @} plugins */
#ifdef __cplusplus
}
#endif
#endif /* LY_PLUGINS_H_ */
|
