1// © 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
3/*
4******************************************************************************
5*
6* Copyright (C) 2009-2015, International Business Machines
7* Corporation and others. All Rights Reserved.
8*
9******************************************************************************
10*
11* FILE NAME : icuplug.h
12*
13* Date Name Description
14* 10/29/2009 sl New.
15******************************************************************************
16*/
17
18/**
19 * \file
20 * \brief C API: ICU Plugin API
21 *
22 * <h2>C API: ICU Plugin API</h2>
23 *
24 * <p>C API allowing run-time loadable modules that extend or modify ICU functionality.</p>
25 *
26 * <h3>Loading and Configuration</h3>
27 *
28 * <p>At ICU startup time, the environment variable "ICU_PLUGINS" will be
29 * queried for a directory name. If it is not set, the preprocessor symbol
30 * "DEFAULT_ICU_PLUGINS" will be checked for a default value.</p>
31 *
32 * <p>Within the above-named directory, the file "icuplugins##.txt" will be
33 * opened, if present, where ## is the major+minor number of the currently
34 * running ICU (such as, 44 for ICU 4.4, thus icuplugins44.txt)</p>
35 *
36 * <p>The configuration file has this format:</p>
37 *
38 * <ul>
39 * <li>Hash (#) begins a comment line</li>
40 *
41 * <li>Non-comment lines have two or three components:
42 * LIBRARYNAME ENTRYPOINT [ CONFIGURATION .. ]</li>
43 *
44 * <li>Tabs or spaces separate the three items.</li>
45 *
46 * <li>LIBRARYNAME is the name of a shared library, either a short name if
47 * it is on the loader path, or a full pathname.</li>
48 *
49 * <li>ENTRYPOINT is the short (undecorated) symbol name of the plugin's
50 * entrypoint, as above.</li>
51 *
52 * <li>CONFIGURATION is the entire rest of the line . It's passed as-is to
53 * the plugin.</li>
54 * </ul>
55 *
56 * <p>An example configuration file is, in its entirety:</p>
57 *
58 * \code
59 * # this is icuplugins44.txt
60 * testplug.dll myPlugin hello=world
61 * \endcode
62 * <p>Plugins are categorized as "high" or "low" level. Low level are those
63 * which must be run BEFORE high level plugins, and before any operations
64 * which cause ICU to be 'initialized'. If a plugin is low level but
65 * causes ICU to allocate memory or become initialized, that plugin is said
66 * to cause a 'level change'. </p>
67 *
68 * <p>At load time, ICU first queries all plugins to determine their level,
69 * then loads all 'low' plugins first, and then loads all 'high' plugins.
70 * Plugins are otherwise loaded in the order listed in the configuration file.</p>
71 *
72 * <h3>Implementing a Plugin</h3>
73 * \code
74 * U_CAPI UPlugTokenReturn U_EXPORT2
75 * myPlugin (UPlugData *plug, UPlugReason reason, UErrorCode *status) {
76 * if(reason==UPLUG_REASON_QUERY) {
77 * uplug_setPlugName(plug, "Simple Plugin");
78 * uplug_setPlugLevel(plug, UPLUG_LEVEL_HIGH);
79 * } else if(reason==UPLUG_REASON_LOAD) {
80 * ... Set up some ICU things here....
81 * } else if(reason==UPLUG_REASON_UNLOAD) {
82 * ... unload, clean up ...
83 * }
84 * return UPLUG_TOKEN;
85 * }
86 * \endcode
87 *
88 * <p>The UPlugData* is an opaque pointer to the plugin-specific data, and is
89 * used in all other API calls.</p>
90 *
91 * <p>The API contract is:</p>
92 * <ol><li>The plugin MUST always return UPLUG_TOKEN as a return value- to
93 * indicate that it is a valid plugin.</li>
94 *
95 * <li>When the 'reason' parameter is set to UPLUG_REASON_QUERY, the
96 * plugin MUST call uplug_setPlugLevel() to indicate whether it is a high
97 * level or low level plugin.</li>
98 *
99 * <li>When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin
100 * SHOULD call uplug_setPlugName to indicate a human readable plugin name.</li></ol>
101 *
102 *
103 * \internal ICU 4.4 Technology Preview
104 */
105
106
107#ifndef ICUPLUG_H
108#define ICUPLUG_H
109
110#include "unicode/utypes.h"
111
112
113#if UCONFIG_ENABLE_PLUGINS || defined(U_IN_DOXYGEN)
114
115
116
117/* === Basic types === */
118
119#ifndef U_HIDE_INTERNAL_API
120struct UPlugData;
121/**
122 * @{
123 * Typedef for opaque structure passed to/from a plugin.
124 * Use the APIs to access it.
125 * @internal ICU 4.4 Technology Preview
126 */
127typedef struct UPlugData UPlugData;
128
129/** @} */
130
131/**
132 * Random Token to identify a valid ICU plugin. Plugins must return this
133 * from the entrypoint.
134 * @internal ICU 4.4 Technology Preview
135 */
136#define UPLUG_TOKEN 0x54762486
137
138/**
139 * Max width of names, symbols, and configuration strings
140 * @internal ICU 4.4 Technology Preview
141 */
142#define UPLUG_NAME_MAX 100
143
144
145/**
146 * Return value from a plugin entrypoint.
147 * Must always be set to UPLUG_TOKEN
148 * @see UPLUG_TOKEN
149 * @internal ICU 4.4 Technology Preview
150 */
151typedef uint32_t UPlugTokenReturn;
152
153/**
154 * Reason code for the entrypoint's call
155 * @internal ICU 4.4 Technology Preview
156 */
157typedef enum {
158 UPLUG_REASON_QUERY = 0, /**< The plugin is being queried for info. **/
159 UPLUG_REASON_LOAD = 1, /**< The plugin is being loaded. **/
160 UPLUG_REASON_UNLOAD = 2, /**< The plugin is being unloaded. **/
161 /**
162 * Number of known reasons.
163 * @internal The numeric value may change over time, see ICU ticket #12420.
164 */
165 UPLUG_REASON_COUNT
166} UPlugReason;
167
168
169/**
170 * Level of plugin loading
171 * INITIAL: UNKNOWN
172 * QUERY: INVALID -> { LOW | HIGH }
173 * ERR -> INVALID
174 * @internal ICU 4.4 Technology Preview
175 */
176typedef enum {
177 UPLUG_LEVEL_INVALID = 0, /**< The plugin is invalid, hasn't called uplug_setLevel, or can't load. **/
178 UPLUG_LEVEL_UNKNOWN = 1, /**< The plugin is waiting to be installed. **/
179 UPLUG_LEVEL_LOW = 2, /**< The plugin must be called before u_init completes **/
180 UPLUG_LEVEL_HIGH = 3, /**< The plugin can run at any time. **/
181 /**
182 * Number of known levels.
183 * @internal The numeric value may change over time, see ICU ticket #12420.
184 */
185 UPLUG_LEVEL_COUNT
186} UPlugLevel;
187
188/**
189 * Entrypoint for an ICU plugin.
190 * @param plug the UPlugData handle.
191 * @param reason the reason code for the entrypoint's call.
192 * @param status Standard ICU error code. Its input value must
193 * pass the U_SUCCESS() test, or else the function returns
194 * immediately. Check for U_FAILURE() on output or use with
195 * function chaining. (See User Guide for details.)
196 * @return A valid plugin must return UPLUG_TOKEN
197 * @internal ICU 4.4 Technology Preview
198 */
199typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) (
200 UPlugData *plug,
201 UPlugReason reason,
202 UErrorCode *status);
203
204/* === Needed for Implementing === */
205
206/**
207 * Request that this plugin not be unloaded at cleanup time.
208 * This is appropriate for plugins which cannot be cleaned up.
209 * @see u_cleanup()
210 * @param plug plugin
211 * @param dontUnload set true if this plugin can't be unloaded
212 * @internal ICU 4.4 Technology Preview
213 */
214U_CAPI void U_EXPORT2
215uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload);
216
217/**
218 * Set the level of this plugin.
219 * @param plug plugin data handle
220 * @param level the level of this plugin
221 * @internal ICU 4.4 Technology Preview
222 */
223U_CAPI void U_EXPORT2
224uplug_setPlugLevel(UPlugData *plug, UPlugLevel level);
225
226/**
227 * Get the level of this plugin.
228 * @param plug plugin data handle
229 * @return the level of this plugin
230 * @internal ICU 4.4 Technology Preview
231 */
232U_CAPI UPlugLevel U_EXPORT2
233uplug_getPlugLevel(UPlugData *plug);
234
235/**
236 * Get the lowest level of plug which can currently load.
237 * For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load
238 * if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load.
239 * @return the lowest level of plug which can currently load
240 * @internal ICU 4.4 Technology Preview
241 */
242U_CAPI UPlugLevel U_EXPORT2
243uplug_getCurrentLevel(void);
244
245
246/**
247 * Get plug load status
248 * @return The error code of this plugin's load attempt.
249 * @internal ICU 4.4 Technology Preview
250 */
251U_CAPI UErrorCode U_EXPORT2
252uplug_getPlugLoadStatus(UPlugData *plug);
253
254/**
255 * Set the human-readable name of this plugin.
256 * @param plug plugin data handle
257 * @param name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.
258 * @internal ICU 4.4 Technology Preview
259 */
260U_CAPI void U_EXPORT2
261uplug_setPlugName(UPlugData *plug, const char *name);
262
263/**
264 * Get the human-readable name of this plugin.
265 * @param plug plugin data handle
266 * @return the name of this plugin
267 * @internal ICU 4.4 Technology Preview
268 */
269U_CAPI const char * U_EXPORT2
270uplug_getPlugName(UPlugData *plug);
271
272/**
273 * Return the symbol name for this plugin, if known.
274 * @param plug plugin data handle
275 * @return the symbol name, or NULL
276 * @internal ICU 4.4 Technology Preview
277 */
278U_CAPI const char * U_EXPORT2
279uplug_getSymbolName(UPlugData *plug);
280
281/**
282 * Return the library name for this plugin, if known.
283 * @param plug plugin data handle
284 * @param status error code
285 * @return the library name, or NULL
286 * @internal ICU 4.4 Technology Preview
287 */
288U_CAPI const char * U_EXPORT2
289uplug_getLibraryName(UPlugData *plug, UErrorCode *status);
290
291/**
292 * Return the library used for this plugin, if known.
293 * Plugins could use this to load data out of their
294 * @param plug plugin data handle
295 * @return the library, or NULL
296 * @internal ICU 4.4 Technology Preview
297 */
298U_CAPI void * U_EXPORT2
299uplug_getLibrary(UPlugData *plug);
300
301/**
302 * Return the plugin-specific context data.
303 * @param plug plugin data handle
304 * @return the context, or NULL if not set
305 * @internal ICU 4.4 Technology Preview
306 */
307U_CAPI void * U_EXPORT2
308uplug_getContext(UPlugData *plug);
309
310/**
311 * Set the plugin-specific context data.
312 * @param plug plugin data handle
313 * @param context new context to set
314 * @internal ICU 4.4 Technology Preview
315 */
316U_CAPI void U_EXPORT2
317uplug_setContext(UPlugData *plug, void *context);
318
319
320/**
321 * Get the configuration string, if available.
322 * The string is in the platform default codepage.
323 * @param plug plugin data handle
324 * @return configuration string, or else null.
325 * @internal ICU 4.4 Technology Preview
326 */
327U_CAPI const char * U_EXPORT2
328uplug_getConfiguration(UPlugData *plug);
329
330/**
331 * Return all currently installed plugins, from newest to oldest
332 * Usage Example:
333 * \code
334 * UPlugData *plug = NULL;
335 * while(plug=uplug_nextPlug(plug)) {
336 * ... do something with 'plug' ...
337 * }
338 * \endcode
339 * Not thread safe- do not call while plugs are added or removed.
340 * @param prior pass in 'NULL' to get the first (most recent) plug,
341 * otherwise pass the value returned on a prior call to uplug_nextPlug
342 * @return the next oldest plugin, or NULL if no more.
343 * @internal ICU 4.4 Technology Preview
344 */
345U_CAPI UPlugData* U_EXPORT2
346uplug_nextPlug(UPlugData *prior);
347
348/**
349 * Inject a plugin as if it were loaded from a library.
350 * This is useful for testing plugins.
351 * Note that it will have a 'NULL' library pointer associated
352 * with it, and therefore no llibrary will be closed at cleanup time.
353 * Low level plugins may not be able to load, as ordering can't be enforced.
354 * @param entrypoint entrypoint to install
355 * @param config user specified configuration string, if available, or NULL.
356 * @param status error result
357 * @return the new UPlugData associated with this plugin, or NULL if error.
358 * @internal ICU 4.4 Technology Preview
359 */
360U_CAPI UPlugData* U_EXPORT2
361uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status);
362
363
364/**
365 * Inject a plugin from a library, as if the information came from a config file.
366 * Low level plugins may not be able to load, and ordering can't be enforced.
367 * @param libName DLL name to load
368 * @param sym symbol of plugin (UPlugEntrypoint function)
369 * @param config configuration string, or NULL
370 * @param status error result
371 * @return the new UPlugData associated with this plugin, or NULL if error.
372 * @internal ICU 4.4 Technology Preview
373 */
374U_CAPI UPlugData* U_EXPORT2
375uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *config, UErrorCode *status);
376
377/**
378 * Remove a plugin.
379 * Will request the plugin to be unloaded, and close the library if needed
380 * @param plug plugin handle to close
381 * @param status error result
382 * @internal ICU 4.4 Technology Preview
383 */
384U_CAPI void U_EXPORT2
385uplug_removePlug(UPlugData *plug, UErrorCode *status);
386#endif /* U_HIDE_INTERNAL_API */
387
388#endif /* UCONFIG_ENABLE_PLUGINS */
389
390#endif /* _ICUPLUG */
391
392