michael@0: /*
michael@0: ******************************************************************************
michael@0: *
michael@0: *   Copyright (C) 2009-2012, International Business Machines
michael@0: *   Corporation and others.  All Rights Reserved.
michael@0: *
michael@0: ******************************************************************************
michael@0: *
michael@0: *  FILE NAME : icuplug.h
michael@0: *
michael@0: *   Date         Name        Description
michael@0: *   10/29/2009   sl          New.
michael@0: ******************************************************************************
michael@0: */
michael@0: 
michael@0: /**
michael@0:  * \file
michael@0:  * \brief C API: ICU Plugin API 
michael@0:  *
michael@0:  * <h2>C API: ICU Plugin API</h2>
michael@0:  *
michael@0:  * <p>C API allowing run-time loadable modules that extend or modify ICU functionality.</p>
michael@0:  *
michael@0:  * <h3>Loading and Configuration</h3>
michael@0:  *
michael@0:  * <p>At ICU startup time, the environment variable "ICU_PLUGINS" will be 
michael@0:  * queried for a directory name.  If it is not set, the preprocessor symbol 
michael@0:  * "DEFAULT_ICU_PLUGINS" will be checked for a default value.</p>
michael@0:  *
michael@0:  * <p>Within the above-named directory, the file  "icuplugins##.txt" will be 
michael@0:  * opened, if present, where ## is the major+minor number of the currently 
michael@0:  * running ICU (such as, 44 for ICU 4.4, thus icuplugins44.txt)</p>
michael@0:  *
michael@0:  * <p>The configuration file has this format:</p>
michael@0:  *
michael@0:  * <ul>
michael@0:  * <li>Hash (#) begins a comment line</li>
michael@0:  * 
michael@0:  * <li>Non-comment lines have two or three components:
michael@0:  * LIBRARYNAME     ENTRYPOINT     [ CONFIGURATION .. ]</li>
michael@0:  *
michael@0:  * <li>Tabs or spaces separate the three items.</li>
michael@0:  *
michael@0:  * <li>LIBRARYNAME is the name of a shared library, either a short name if 
michael@0:  * it is on the loader path,  or a full pathname.</li>
michael@0:  *
michael@0:  * <li>ENTRYPOINT is the short (undecorated) symbol name of the plugin's 
michael@0:  * entrypoint, as above.</li>
michael@0:  *
michael@0:  * <li>CONFIGURATION is the entire rest of the line . It's passed as-is to 
michael@0:  * the plugin.</li>
michael@0:  * </ul>
michael@0:  *
michael@0:  * <p>An example configuration file is, in its entirety:</p>
michael@0:  *
michael@0:  * \code
michael@0:  * # this is icuplugins44.txt
michael@0:  * testplug.dll    myPlugin        hello=world
michael@0:  * \endcode
michael@0:  * <p>Plugins are categorized as "high" or "low" level.  Low level are those 
michael@0:  * which must be run BEFORE high level plugins, and before any operations 
michael@0:  * which cause ICU to be 'initialized'.  If a plugin is low level but 
michael@0:  * causes ICU to allocate memory or become initialized, that plugin is said 
michael@0:  * to cause a 'level change'. </p>
michael@0:  *
michael@0:  * <p>At load time, ICU first queries all plugins to determine their level, 
michael@0:  * then loads all 'low' plugins first, and then loads all 'high' plugins.  
michael@0:  * Plugins are otherwise loaded in the order listed in the configuration file.</p>
michael@0:  * 
michael@0:  * <h3>Implementing a Plugin</h3>
michael@0:  * \code
michael@0:  * U_CAPI UPlugTokenReturn U_EXPORT2 
michael@0:  * myPlugin (UPlugData *plug, UPlugReason reason, UErrorCode *status) {
michael@0:  *   if(reason==UPLUG_REASON_QUERY) {
michael@0:  *      uplug_setPlugName(plug, "Simple Plugin");
michael@0:  *      uplug_setPlugLevel(plug, UPLUG_LEVEL_HIGH);
michael@0:  *    } else if(reason==UPLUG_REASON_LOAD) {
michael@0:  *       ... Set up some ICU things here.... 
michael@0:  *    } else if(reason==UPLUG_REASON_UNLOAD) {
michael@0:  *       ... unload, clean up ...
michael@0:  *    }
michael@0:  *   return UPLUG_TOKEN;
michael@0:  *  }
michael@0:  * \endcode
michael@0:  *
michael@0:  * <p>The UPlugData*  is an opaque pointer to the plugin-specific data, and is 
michael@0:  * used in all other API calls.</p>
michael@0:  *
michael@0:  * <p>The API contract is:</p>
michael@0:  * <ol><li>The plugin MUST always return UPLUG_TOKEN as a return value- to 
michael@0:  * indicate that it is a valid plugin.</li>
michael@0:  *
michael@0:  * <li>When the 'reason' parameter is set to UPLUG_REASON_QUERY,  the 
michael@0:  * plugin MUST call uplug_setPlugLevel() to indicate whether it is a high 
michael@0:  * level or low level plugin.</li>
michael@0:  *
michael@0:  * <li>When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin 
michael@0:  * SHOULD call uplug_setPlugName to indicate a human readable plugin name.</li></ol>
michael@0:  * 
michael@0:  *
michael@0:  * \internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: 
michael@0: 
michael@0: #ifndef ICUPLUG_H
michael@0: #define ICUPLUG_H
michael@0: 
michael@0: #include "unicode/utypes.h"
michael@0: 
michael@0: 
michael@0: /* === Basic types === */
michael@0: 
michael@0: #ifndef U_HIDE_INTERNAL_API
michael@0: /**
michael@0:  * @{
michael@0:  * Opaque structure passed to/from a plugin. 
michael@0:  * use the APIs to access it.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: 
michael@0: struct UPlugData;
michael@0: typedef struct UPlugData UPlugData;
michael@0: 
michael@0: /** @} */
michael@0: 
michael@0: /**
michael@0:  * Random Token to identify a valid ICU plugin. Plugins must return this 
michael@0:  * from the entrypoint.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: #define UPLUG_TOKEN 0x54762486
michael@0: 
michael@0: /**
michael@0:  * Max width of names, symbols, and configuration strings
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: #define UPLUG_NAME_MAX              100
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Return value from a plugin entrypoint. 
michael@0:  * Must always be set to UPLUG_TOKEN
michael@0:  * @see UPLUG_TOKEN
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: typedef uint32_t UPlugTokenReturn;
michael@0: 
michael@0: /**
michael@0:  * Reason code for the entrypoint's call
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: typedef enum {
michael@0:     UPLUG_REASON_QUERY = 0,     /**< The plugin is being queried for info. **/
michael@0:     UPLUG_REASON_LOAD = 1,     /**< The plugin is being loaded. **/
michael@0:     UPLUG_REASON_UNLOAD = 2,   /**< The plugin is being unloaded. **/
michael@0:     UPLUG_REASON_COUNT         /**< count of known reasons **/
michael@0: } UPlugReason;
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Level of plugin loading
michael@0:  *     INITIAL:  UNKNOWN
michael@0:  *       QUERY:   INVALID ->  { LOW | HIGH }
michael@0:  *     ERR -> INVALID
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: typedef enum {
michael@0:     UPLUG_LEVEL_INVALID = 0,     /**< The plugin is invalid, hasn't called uplug_setLevel, or can't load. **/
michael@0:     UPLUG_LEVEL_UNKNOWN = 1,     /**< The plugin is waiting to be installed. **/
michael@0:     UPLUG_LEVEL_LOW     = 2,     /**< The plugin must be called before u_init completes **/
michael@0:     UPLUG_LEVEL_HIGH    = 3,     /**< The plugin can run at any time. **/
michael@0:     UPLUG_LEVEL_COUNT         /**< count of known reasons **/
michael@0: } UPlugLevel;
michael@0: 
michael@0: /**
michael@0:  * Entrypoint for an ICU plugin.
michael@0:  * @param plug the UPlugData handle. 
michael@0:  * @param status the plugin's extended status code.
michael@0:  * @return A valid plugin must return UPLUG_TOKEN
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) (
michael@0:                   UPlugData *plug,
michael@0:                   UPlugReason reason,
michael@0:                   UErrorCode *status);
michael@0: 
michael@0: /* === Needed for Implementing === */
michael@0: 
michael@0: /**
michael@0:  * Request that this plugin not be unloaded at cleanup time.
michael@0:  * This is appropriate for plugins which cannot be cleaned up.
michael@0:  * @see u_cleanup()
michael@0:  * @param plug plugin
michael@0:  * @param dontUnload  set true if this plugin can't be unloaded
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void U_EXPORT2 
michael@0: uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload);
michael@0: 
michael@0: /**
michael@0:  * Set the level of this plugin.
michael@0:  * @param plug plugin data handle
michael@0:  * @param level the level of this plugin
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void U_EXPORT2
michael@0: uplug_setPlugLevel(UPlugData *plug, UPlugLevel level);
michael@0: 
michael@0: /**
michael@0:  * Get the level of this plugin.
michael@0:  * @param plug plugin data handle
michael@0:  * @return the level of this plugin
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL UPlugLevel U_EXPORT2
michael@0: uplug_getPlugLevel(UPlugData *plug);
michael@0: 
michael@0: /**
michael@0:  * Get the lowest level of plug which can currently load.
michael@0:  * For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load
michael@0:  * if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load.
michael@0:  * @return the lowest level of plug which can currently load
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL UPlugLevel U_EXPORT2
michael@0: uplug_getCurrentLevel(void);
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Get plug load status
michael@0:  * @return The error code of this plugin's load attempt.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL UErrorCode U_EXPORT2
michael@0: uplug_getPlugLoadStatus(UPlugData *plug); 
michael@0: 
michael@0: /**
michael@0:  * Set the human-readable name of this plugin.
michael@0:  * @param plug plugin data handle
michael@0:  * @param name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void U_EXPORT2
michael@0: uplug_setPlugName(UPlugData *plug, const char *name);
michael@0: 
michael@0: /**
michael@0:  * Get the human-readable name of this plugin.
michael@0:  * @param plug plugin data handle
michael@0:  * @return the name of this plugin
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL const char * U_EXPORT2
michael@0: uplug_getPlugName(UPlugData *plug);
michael@0: 
michael@0: /**
michael@0:  * Return the symbol name for this plugin, if known.
michael@0:  * @param plug plugin data handle
michael@0:  * @return the symbol name, or NULL
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL const char * U_EXPORT2
michael@0: uplug_getSymbolName(UPlugData *plug);
michael@0: 
michael@0: /**
michael@0:  * Return the library name for this plugin, if known.
michael@0:  * @param plug plugin data handle
michael@0:  * @param status error code
michael@0:  * @return the library name, or NULL
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL const char * U_EXPORT2
michael@0: uplug_getLibraryName(UPlugData *plug, UErrorCode *status);
michael@0: 
michael@0: /**
michael@0:  * Return the library used for this plugin, if known.
michael@0:  * Plugins could use this to load data out of their 
michael@0:  * @param plug plugin data handle
michael@0:  * @return the library, or NULL
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void * U_EXPORT2
michael@0: uplug_getLibrary(UPlugData *plug);
michael@0: 
michael@0: /**
michael@0:  * Return the plugin-specific context data.
michael@0:  * @param plug plugin data handle
michael@0:  * @return the context, or NULL if not set
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void * U_EXPORT2
michael@0: uplug_getContext(UPlugData *plug);
michael@0: 
michael@0: /**
michael@0:  * Set the plugin-specific context data.
michael@0:  * @param plug plugin data handle
michael@0:  * @param context new context to set
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void U_EXPORT2
michael@0: uplug_setContext(UPlugData *plug, void *context);
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Get the configuration string, if available.
michael@0:  * The string is in the platform default codepage.
michael@0:  * @param plug plugin data handle
michael@0:  * @return configuration string, or else null.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL const char * U_EXPORT2
michael@0: uplug_getConfiguration(UPlugData *plug);
michael@0: 
michael@0: /**
michael@0:  * Return all currently installed plugins, from newest to oldest
michael@0:  * Usage Example:
michael@0:  * \code
michael@0:  *    UPlugData *plug = NULL;
michael@0:  *    while(plug=uplug_nextPlug(plug)) {
michael@0:  *        ... do something with 'plug' ...
michael@0:  *    }
michael@0:  * \endcode
michael@0:  * Not thread safe- do not call while plugs are added or removed.
michael@0:  * @param prior pass in 'NULL' to get the first (most recent) plug, 
michael@0:  *  otherwise pass the value returned on a prior call to uplug_nextPlug
michael@0:  * @return the next oldest plugin, or NULL if no more.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL UPlugData* U_EXPORT2
michael@0: uplug_nextPlug(UPlugData *prior);
michael@0: 
michael@0: /**
michael@0:  * Inject a plugin as if it were loaded from a library.
michael@0:  * This is useful for testing plugins. 
michael@0:  * Note that it will have a 'NULL' library pointer associated
michael@0:  * with it, and therefore no llibrary will be closed at cleanup time.
michael@0:  * Low level plugins may not be able to load, as ordering can't be enforced.
michael@0:  * @param entrypoint entrypoint to install
michael@0:  * @param config user specified configuration string, if available, or NULL.
michael@0:  * @param status error result
michael@0:  * @return the new UPlugData associated with this plugin, or NULL if error.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL UPlugData* U_EXPORT2
michael@0: uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status);
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Inject a plugin from a library, as if the information came from a config file.
michael@0:  * Low level plugins may not be able to load, and ordering can't be enforced.
michael@0:  * @param libName DLL name to load
michael@0:  * @param sym symbol of plugin (UPlugEntrypoint function)
michael@0:  * @param config configuration string, or NULL
michael@0:  * @param status error result
michael@0:  * @return the new UPlugData associated with this plugin, or NULL if error.
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL UPlugData* U_EXPORT2
michael@0: uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *config, UErrorCode *status);
michael@0: 
michael@0: /**
michael@0:  * Remove a plugin. 
michael@0:  * Will request the plugin to be unloaded, and close the library if needed
michael@0:  * @param plug plugin handle to close
michael@0:  * @param status error result
michael@0:  * @internal ICU 4.4 Technology Preview
michael@0:  */
michael@0: U_INTERNAL void U_EXPORT2
michael@0: uplug_removePlug(UPlugData *plug, UErrorCode *status);
michael@0: #endif  /* U_HIDE_INTERNAL_API */
michael@0: 
michael@0: #endif