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icuplug.h
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// © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ****************************************************************************** * * Copyright (C) 2009-2015, International Business Machines * Corporation and others. All Rights Reserved. * ****************************************************************************** * * FILE NAME : icuplug.h * * Date Name Description * 10/29/2009 sl New. ****************************************************************************** */ /** * \file * \brief C API: ICU Plugin API * * <h2>C API: ICU Plugin API</h2> * * <p>C API allowing run-time loadable modules that extend or modify ICU functionality.</p> * * <h3>Loading and Configuration</h3> * * <p>At ICU startup time, the environment variable "ICU_PLUGINS" will be * queried for a directory name. If it is not set, the preprocessor symbol * "DEFAULT_ICU_PLUGINS" will be checked for a default value.</p> * * <p>Within the above-named directory, the file "icuplugins##.txt" will be * opened, if present, where ## is the major+minor number of the currently * running ICU (such as, 44 for ICU 4.4, thus icuplugins44.txt)</p> * * <p>The configuration file has this format:</p> * * <ul> * <li>Hash (#) begins a comment line</li> * * <li>Non-comment lines have two or three components: * LIBRARYNAME ENTRYPOINT [ CONFIGURATION .. ]</li> * * <li>Tabs or spaces separate the three items.</li> * * <li>LIBRARYNAME is the name of a shared library, either a short name if * it is on the loader path, or a full pathname.</li> * * <li>ENTRYPOINT is the short (undecorated) symbol name of the plugin's * entrypoint, as above.</li> * * <li>CONFIGURATION is the entire rest of the line . It's passed as-is to * the plugin.</li> * </ul> * * <p>An example configuration file is, in its entirety:</p> * * \code * # this is icuplugins44.txt * testplug.dll myPlugin hello=world * \endcode * <p>Plugins are categorized as "high" or "low" level. Low level are those * which must be run BEFORE high level plugins, and before any operations * which cause ICU to be 'initialized'. If a plugin is low level but * causes ICU to allocate memory or become initialized, that plugin is said * to cause a 'level change'. </p> * * <p>At load time, ICU first queries all plugins to determine their level, * then loads all 'low' plugins first, and then loads all 'high' plugins. * Plugins are otherwise loaded in the order listed in the configuration file.</p> * * <h3>Implementing a Plugin</h3> * \code * U_CAPI UPlugTokenReturn U_EXPORT2 * myPlugin (UPlugData *plug, UPlugReason reason, UErrorCode *status) { * if(reason==UPLUG_REASON_QUERY) { * uplug_setPlugName(plug, "Simple Plugin"); * uplug_setPlugLevel(plug, UPLUG_LEVEL_HIGH); * } else if(reason==UPLUG_REASON_LOAD) { * ... Set up some ICU things here.... * } else if(reason==UPLUG_REASON_UNLOAD) { * ... unload, clean up ... * } * return UPLUG_TOKEN; * } * \endcode * * <p>The UPlugData* is an opaque pointer to the plugin-specific data, and is * used in all other API calls.</p> * * <p>The API contract is:</p> * <ol><li>The plugin MUST always return UPLUG_TOKEN as a return value- to * indicate that it is a valid plugin.</li> * * <li>When the 'reason' parameter is set to UPLUG_REASON_QUERY, the * plugin MUST call uplug_setPlugLevel() to indicate whether it is a high * level or low level plugin.</li> * * <li>When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin * SHOULD call uplug_setPlugName to indicate a human readable plugin name.</li></ol> * * * \internal ICU 4.4 Technology Preview */ #ifndef ICUPLUG_H #define ICUPLUG_H #include "unicode/utypes.h" #if UCONFIG_ENABLE_PLUGINS || defined(U_IN_DOXYGEN) /* === Basic types === */ #ifndef U_HIDE_INTERNAL_API /** * @{ * Opaque structure passed to/from a plugin. * use the APIs to access it. * @internal ICU 4.4 Technology Preview */ struct UPlugData; typedef struct UPlugData UPlugData; /** @} */ /** * Random Token to identify a valid ICU plugin. Plugins must return this * from the entrypoint. * @internal ICU 4.4 Technology Preview */ #define UPLUG_TOKEN 0x54762486 /** * Max width of names, symbols, and configuration strings * @internal ICU 4.4 Technology Preview */ #define UPLUG_NAME_MAX 100 /** * Return value from a plugin entrypoint. * Must always be set to UPLUG_TOKEN * @see UPLUG_TOKEN * @internal ICU 4.4 Technology Preview */ typedef uint32_t UPlugTokenReturn; /** * Reason code for the entrypoint's call * @internal ICU 4.4 Technology Preview */ typedef enum { UPLUG_REASON_QUERY = 0, /**< The plugin is being queried for info. **/ UPLUG_REASON_LOAD = 1, /**< The plugin is being loaded. **/ UPLUG_REASON_UNLOAD = 2, /**< The plugin is being unloaded. **/ /** * Number of known reasons. * @internal The numeric value may change over time, see ICU ticket #12420. */ UPLUG_REASON_COUNT } UPlugReason; /** * Level of plugin loading * INITIAL: UNKNOWN * QUERY: INVALID -> { LOW | HIGH } * ERR -> INVALID * @internal ICU 4.4 Technology Preview */ typedef enum { UPLUG_LEVEL_INVALID = 0, /**< The plugin is invalid, hasn't called uplug_setLevel, or can't load. **/ UPLUG_LEVEL_UNKNOWN = 1, /**< The plugin is waiting to be installed. **/ UPLUG_LEVEL_LOW = 2, /**< The plugin must be called before u_init completes **/ UPLUG_LEVEL_HIGH = 3, /**< The plugin can run at any time. **/ /** * Number of known levels. * @internal The numeric value may change over time, see ICU ticket #12420. */ UPLUG_LEVEL_COUNT } UPlugLevel; /** * Entrypoint for an ICU plugin. * @param plug the UPlugData handle. * @param status the plugin's extended status code. * @return A valid plugin must return UPLUG_TOKEN * @internal ICU 4.4 Technology Preview */ typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) ( UPlugData *plug, UPlugReason reason, UErrorCode *status); /* === Needed for Implementing === */ /** * Request that this plugin not be unloaded at cleanup time. * This is appropriate for plugins which cannot be cleaned up. * @see u_cleanup() * @param plug plugin * @param dontUnload set true if this plugin can't be unloaded * @internal ICU 4.4 Technology Preview */ U_INTERNAL void U_EXPORT2 uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload); /** * Set the level of this plugin. * @param plug plugin data handle * @param level the level of this plugin * @internal ICU 4.4 Technology Preview */ U_INTERNAL void U_EXPORT2 uplug_setPlugLevel(UPlugData *plug, UPlugLevel level); /** * Get the level of this plugin. * @param plug plugin data handle * @return the level of this plugin * @internal ICU 4.4 Technology Preview */ U_INTERNAL UPlugLevel U_EXPORT2 uplug_getPlugLevel(UPlugData *plug); /** * Get the lowest level of plug which can currently load. * For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load * if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load. * @return the lowest level of plug which can currently load * @internal ICU 4.4 Technology Preview */ U_INTERNAL UPlugLevel U_EXPORT2 uplug_getCurrentLevel(void); /** * Get plug load status * @return The error code of this plugin's load attempt. * @internal ICU 4.4 Technology Preview */ U_INTERNAL UErrorCode U_EXPORT2 uplug_getPlugLoadStatus(UPlugData *plug); /** * Set the human-readable name of this plugin. * @param plug plugin data handle * @param name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer. * @internal ICU 4.4 Technology Preview */ U_INTERNAL void U_EXPORT2 uplug_setPlugName(UPlugData *plug, const char *name); /** * Get the human-readable name of this plugin. * @param plug plugin data handle * @return the name of this plugin * @internal ICU 4.4 Technology Preview */ U_INTERNAL const char * U_EXPORT2 uplug_getPlugName(UPlugData *plug); /** * Return the symbol name for this plugin, if known. * @param plug plugin data handle * @return the symbol name, or NULL * @internal ICU 4.4 Technology Preview */ U_INTERNAL const char * U_EXPORT2 uplug_getSymbolName(UPlugData *plug); /** * Return the library name for this plugin, if known. * @param plug plugin data handle * @param status error code * @return the library name, or NULL * @internal ICU 4.4 Technology Preview */ U_INTERNAL const char * U_EXPORT2 uplug_getLibraryName(UPlugData *plug, UErrorCode *status); /** * Return the library used for this plugin, if known. * Plugins could use this to load data out of their * @param plug plugin data handle * @return the library, or NULL * @internal ICU 4.4 Technology Preview */ U_INTERNAL void * U_EXPORT2 uplug_getLibrary(UPlugData *plug); /** * Return the plugin-specific context data. * @param plug plugin data handle * @return the context, or NULL if not set * @internal ICU 4.4 Technology Preview */ U_INTERNAL void * U_EXPORT2 uplug_getContext(UPlugData *plug); /** * Set the plugin-specific context data. * @param plug plugin data handle * @param context new context to set * @internal ICU 4.4 Technology Preview */ U_INTERNAL void U_EXPORT2 uplug_setContext(UPlugData *plug, void *context); /** * Get the configuration string, if available. * The string is in the platform default codepage. * @param plug plugin data handle * @return configuration string, or else null. * @internal ICU 4.4 Technology Preview */ U_INTERNAL const char * U_EXPORT2 uplug_getConfiguration(UPlugData *plug); /** * Return all currently installed plugins, from newest to oldest * Usage Example: * \code * UPlugData *plug = NULL; * while(plug=uplug_nextPlug(plug)) { * ... do something with 'plug' ... * } * \endcode * Not thread safe- do not call while plugs are added or removed. * @param prior pass in 'NULL' to get the first (most recent) plug, * otherwise pass the value returned on a prior call to uplug_nextPlug * @return the next oldest plugin, or NULL if no more. * @internal ICU 4.4 Technology Preview */ U_INTERNAL UPlugData* U_EXPORT2 uplug_nextPlug(UPlugData *prior); /** * Inject a plugin as if it were loaded from a library. * This is useful for testing plugins. * Note that it will have a 'NULL' library pointer associated * with it, and therefore no llibrary will be closed at cleanup time. * Low level plugins may not be able to load, as ordering can't be enforced. * @param entrypoint entrypoint to install * @param config user specified configuration string, if available, or NULL. * @param status error result * @return the new UPlugData associated with this plugin, or NULL if error. * @internal ICU 4.4 Technology Preview */ U_INTERNAL UPlugData* U_EXPORT2 uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status); /** * Inject a plugin from a library, as if the information came from a config file. * Low level plugins may not be able to load, and ordering can't be enforced. * @param libName DLL name to load * @param sym symbol of plugin (UPlugEntrypoint function) * @param config configuration string, or NULL * @param status error result * @return the new UPlugData associated with this plugin, or NULL if error. * @internal ICU 4.4 Technology Preview */ U_INTERNAL UPlugData* U_EXPORT2 uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *config, UErrorCode *status); /** * Remove a plugin. * Will request the plugin to be unloaded, and close the library if needed * @param plug plugin handle to close * @param status error result * @internal ICU 4.4 Technology Preview */ U_INTERNAL void U_EXPORT2 uplug_removePlug(UPlugData *plug, UErrorCode *status); #endif /* U_HIDE_INTERNAL_API */ #endif /* UCONFIG_ENABLE_PLUGINS */ #endif /* _ICUPLUG */