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date Tue, 18 Mar 2025 17:55:14 -0400
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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
120 /**
121 * @{
122 * Opaque structure passed to/from a plugin.
123 * use the APIs to access it.
124 * @internal ICU 4.4 Technology Preview
125 */
126
127 struct UPlugData;
128 typedef struct UPlugData UPlugData;
129
130 /** @} */
131
132 /**
133 * Random Token to identify a valid ICU plugin. Plugins must return this
134 * from the entrypoint.
135 * @internal ICU 4.4 Technology Preview
136 */
137 #define UPLUG_TOKEN 0x54762486
138
139 /**
140 * Max width of names, symbols, and configuration strings
141 * @internal ICU 4.4 Technology Preview
142 */
143 #define UPLUG_NAME_MAX 100
144
145
146 /**
147 * Return value from a plugin entrypoint.
148 * Must always be set to UPLUG_TOKEN
149 * @see UPLUG_TOKEN
150 * @internal ICU 4.4 Technology Preview
151 */
152 typedef uint32_t UPlugTokenReturn;
153
154 /**
155 * Reason code for the entrypoint's call
156 * @internal ICU 4.4 Technology Preview
157 */
158 typedef enum {
159 UPLUG_REASON_QUERY = 0, /**< The plugin is being queried for info. **/
160 UPLUG_REASON_LOAD = 1, /**< The plugin is being loaded. **/
161 UPLUG_REASON_UNLOAD = 2, /**< The plugin is being unloaded. **/
162 /**
163 * Number of known reasons.
164 * @internal The numeric value may change over time, see ICU ticket #12420.
165 */
166 UPLUG_REASON_COUNT
167 } UPlugReason;
168
169
170 /**
171 * Level of plugin loading
172 * INITIAL: UNKNOWN
173 * QUERY: INVALID -> { LOW | HIGH }
174 * ERR -> INVALID
175 * @internal ICU 4.4 Technology Preview
176 */
177 typedef enum {
178 UPLUG_LEVEL_INVALID = 0, /**< The plugin is invalid, hasn't called uplug_setLevel, or can't load. **/
179 UPLUG_LEVEL_UNKNOWN = 1, /**< The plugin is waiting to be installed. **/
180 UPLUG_LEVEL_LOW = 2, /**< The plugin must be called before u_init completes **/
181 UPLUG_LEVEL_HIGH = 3, /**< The plugin can run at any time. **/
182 /**
183 * Number of known levels.
184 * @internal The numeric value may change over time, see ICU ticket #12420.
185 */
186 UPLUG_LEVEL_COUNT
187 } UPlugLevel;
188
189 /**
190 * Entrypoint for an ICU plugin.
191 * @param plug the UPlugData handle.
192 * @param status the plugin's extended status code.
193 * @return A valid plugin must return UPLUG_TOKEN
194 * @internal ICU 4.4 Technology Preview
195 */
196 typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) (
197 UPlugData *plug,
198 UPlugReason reason,
199 UErrorCode *status);
200
201 /* === Needed for Implementing === */
202
203 /**
204 * Request that this plugin not be unloaded at cleanup time.
205 * This is appropriate for plugins which cannot be cleaned up.
206 * @see u_cleanup()
207 * @param plug plugin
208 * @param dontUnload set true if this plugin can't be unloaded
209 * @internal ICU 4.4 Technology Preview
210 */
211 U_INTERNAL void U_EXPORT2
212 uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload);
213
214 /**
215 * Set the level of this plugin.
216 * @param plug plugin data handle
217 * @param level the level of this plugin
218 * @internal ICU 4.4 Technology Preview
219 */
220 U_INTERNAL void U_EXPORT2
221 uplug_setPlugLevel(UPlugData *plug, UPlugLevel level);
222
223 /**
224 * Get the level of this plugin.
225 * @param plug plugin data handle
226 * @return the level of this plugin
227 * @internal ICU 4.4 Technology Preview
228 */
229 U_INTERNAL UPlugLevel U_EXPORT2
230 uplug_getPlugLevel(UPlugData *plug);
231
232 /**
233 * Get the lowest level of plug which can currently load.
234 * For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load
235 * if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load.
236 * @return the lowest level of plug which can currently load
237 * @internal ICU 4.4 Technology Preview
238 */
239 U_INTERNAL UPlugLevel U_EXPORT2
240 uplug_getCurrentLevel(void);
241
242
243 /**
244 * Get plug load status
245 * @return The error code of this plugin's load attempt.
246 * @internal ICU 4.4 Technology Preview
247 */
248 U_INTERNAL UErrorCode U_EXPORT2
249 uplug_getPlugLoadStatus(UPlugData *plug);
250
251 /**
252 * Set the human-readable name of this plugin.
253 * @param plug plugin data handle
254 * @param name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.
255 * @internal ICU 4.4 Technology Preview
256 */
257 U_INTERNAL void U_EXPORT2
258 uplug_setPlugName(UPlugData *plug, const char *name);
259
260 /**
261 * Get the human-readable name of this plugin.
262 * @param plug plugin data handle
263 * @return the name of this plugin
264 * @internal ICU 4.4 Technology Preview
265 */
266 U_INTERNAL const char * U_EXPORT2
267 uplug_getPlugName(UPlugData *plug);
268
269 /**
270 * Return the symbol name for this plugin, if known.
271 * @param plug plugin data handle
272 * @return the symbol name, or NULL
273 * @internal ICU 4.4 Technology Preview
274 */
275 U_INTERNAL const char * U_EXPORT2
276 uplug_getSymbolName(UPlugData *plug);
277
278 /**
279 * Return the library name for this plugin, if known.
280 * @param plug plugin data handle
281 * @param status error code
282 * @return the library name, or NULL
283 * @internal ICU 4.4 Technology Preview
284 */
285 U_INTERNAL const char * U_EXPORT2
286 uplug_getLibraryName(UPlugData *plug, UErrorCode *status);
287
288 /**
289 * Return the library used for this plugin, if known.
290 * Plugins could use this to load data out of their
291 * @param plug plugin data handle
292 * @return the library, or NULL
293 * @internal ICU 4.4 Technology Preview
294 */
295 U_INTERNAL void * U_EXPORT2
296 uplug_getLibrary(UPlugData *plug);
297
298 /**
299 * Return the plugin-specific context data.
300 * @param plug plugin data handle
301 * @return the context, or NULL if not set
302 * @internal ICU 4.4 Technology Preview
303 */
304 U_INTERNAL void * U_EXPORT2
305 uplug_getContext(UPlugData *plug);
306
307 /**
308 * Set the plugin-specific context data.
309 * @param plug plugin data handle
310 * @param context new context to set
311 * @internal ICU 4.4 Technology Preview
312 */
313 U_INTERNAL void U_EXPORT2
314 uplug_setContext(UPlugData *plug, void *context);
315
316
317 /**
318 * Get the configuration string, if available.
319 * The string is in the platform default codepage.
320 * @param plug plugin data handle
321 * @return configuration string, or else null.
322 * @internal ICU 4.4 Technology Preview
323 */
324 U_INTERNAL const char * U_EXPORT2
325 uplug_getConfiguration(UPlugData *plug);
326
327 /**
328 * Return all currently installed plugins, from newest to oldest
329 * Usage Example:
330 * \code
331 * UPlugData *plug = NULL;
332 * while(plug=uplug_nextPlug(plug)) {
333 * ... do something with 'plug' ...
334 * }
335 * \endcode
336 * Not thread safe- do not call while plugs are added or removed.
337 * @param prior pass in 'NULL' to get the first (most recent) plug,
338 * otherwise pass the value returned on a prior call to uplug_nextPlug
339 * @return the next oldest plugin, or NULL if no more.
340 * @internal ICU 4.4 Technology Preview
341 */
342 U_INTERNAL UPlugData* U_EXPORT2
343 uplug_nextPlug(UPlugData *prior);
344
345 /**
346 * Inject a plugin as if it were loaded from a library.
347 * This is useful for testing plugins.
348 * Note that it will have a 'NULL' library pointer associated
349 * with it, and therefore no llibrary will be closed at cleanup time.
350 * Low level plugins may not be able to load, as ordering can't be enforced.
351 * @param entrypoint entrypoint to install
352 * @param config user specified configuration string, if available, or NULL.
353 * @param status error result
354 * @return the new UPlugData associated with this plugin, or NULL if error.
355 * @internal ICU 4.4 Technology Preview
356 */
357 U_INTERNAL UPlugData* U_EXPORT2
358 uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status);
359
360
361 /**
362 * Inject a plugin from a library, as if the information came from a config file.
363 * Low level plugins may not be able to load, and ordering can't be enforced.
364 * @param libName DLL name to load
365 * @param sym symbol of plugin (UPlugEntrypoint function)
366 * @param config configuration string, or NULL
367 * @param status error result
368 * @return the new UPlugData associated with this plugin, or NULL if error.
369 * @internal ICU 4.4 Technology Preview
370 */
371 U_INTERNAL UPlugData* U_EXPORT2
372 uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *config, UErrorCode *status);
373
374 /**
375 * Remove a plugin.
376 * Will request the plugin to be unloaded, and close the library if needed
377 * @param plug plugin handle to close
378 * @param status error result
379 * @internal ICU 4.4 Technology Preview
380 */
381 U_INTERNAL void U_EXPORT2
382 uplug_removePlug(UPlugData *plug, UErrorCode *status);
383 #endif /* U_HIDE_INTERNAL_API */
384
385 #endif /* UCONFIG_ENABLE_PLUGINS */
386
387 #endif /* _ICUPLUG */
388