icuplug.h File Reference

C API: ICU Plugin API. More...

`#include "unicode/utypes.h"`

Go to the source code of this file.

## Macros

#define | UPLUG_TOKEN 0x54762486
| Random Token to identify a valid ICU plugin. More...
#define | UPLUG_NAME_MAX 100
| Max width of names, symbols, and configuration strings. More...

## Typedefs

typedef uint32_t | UPlugTokenReturn
| Return value from a plugin entrypoint. More...
typedef UPlugTokenReturn() | UPlugEntrypoint(UPlugData *plug, UPlugReason reason, UErrorCode *status)
| Entrypoint for an ICU plugin. More...
typedef struct UPlugData | UPlugData
| Typedef for opaque structure passed to/from a plugin. More...

## Enumerations

enum | UPlugReason { UPLUG_REASON_QUERY = 0 , UPLUG_REASON_LOAD = 1 , UPLUG_REASON_UNLOAD = 2 , UPLUG_REASON_COUNT }
| Reason code for the entrypoint's call. More...
enum | UPlugLevel { UPLUG_LEVEL_INVALID = 0 , UPLUG_LEVEL_UNKNOWN = 1 , UPLUG_LEVEL_LOW = 2 , UPLUG_LEVEL_HIGH = 3 , UPLUG_LEVEL_COUNT }
| Level of plugin loading INITIAL: UNKNOWN QUERY: INVALID -> { LOW | HIGH } ERR -> INVALID. More...

## Functions

U_CAPI void | uplug_setPlugNoUnload (UPlugData *plug, UBool dontUnload)
| Request that this plugin not be unloaded at cleanup time. More...
U_CAPI void | uplug_setPlugLevel (UPlugData *plug, UPlugLevel level)
| Set the level of this plugin. More...
U_CAPI UPlugLevel | uplug_getPlugLevel (UPlugData *plug)
| Get the level of this plugin. More...
U_CAPI UPlugLevel | uplug_getCurrentLevel (void)
| Get the lowest level of plug which can currently load. More...
U_CAPI UErrorCode | uplug_getPlugLoadStatus (UPlugData *plug)
| Get plug load status. More...
U_CAPI void | uplug_setPlugName (UPlugData *plug, const char *name)
| Set the human-readable name of this plugin. More...
U_CAPI const char * | uplug_getPlugName (UPlugData *plug)
| Get the human-readable name of this plugin. More...
U_CAPI const char * | uplug_getSymbolName (UPlugData *plug)
| Return the symbol name for this plugin, if known. More...
U_CAPI const char * | uplug_getLibraryName (UPlugData *plug, UErrorCode *status)
| Return the library name for this plugin, if known. More...
U_CAPI void * | uplug_getLibrary (UPlugData *plug)
| Return the library used for this plugin, if known. More...
U_CAPI void * | uplug_getContext (UPlugData *plug)
| Return the plugin-specific context data. More...
U_CAPI void | uplug_setContext (UPlugData *plug, void *context)
| Set the plugin-specific context data. More...
U_CAPI const char * | uplug_getConfiguration (UPlugData *plug)
| Get the configuration string, if available. More...
U_CAPI UPlugData * | uplug_nextPlug (UPlugData *prior)
| Return all currently installed plugins, from newest to oldest Usage Example: More...
U_CAPI UPlugData * | uplug_loadPlugFromEntrypoint (UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status)
| Inject a plugin as if it were loaded from a library. More...
U_CAPI UPlugData * | uplug_loadPlugFromLibrary (const char *libName, const char *sym, const char *config, UErrorCode *status)
| Inject a plugin from a library, as if the information came from a config file. More...
U_CAPI void | uplug_removePlug (UPlugData *plug, UErrorCode *status)
| Remove a plugin. More...

## Detailed Description

C API: ICU Plugin API.

## C API: ICU Plugin API

C API allowing run-time loadable modules that extend or modify ICU functionality.

### Loading and Configuration

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.

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)

The configuration file has this format:

- Hash (#) begins a comment line

- Non-comment lines have two or three components: LIBRARYNAME ENTRYPOINT [ CONFIGURATION .. ]

- Tabs or spaces separate the three items.

- LIBRARYNAME is the name of a shared library, either a short name if it is on the loader path, or a full pathname.

- ENTRYPOINT is the short (undecorated) symbol name of the plugin's entrypoint, as above.

- CONFIGURATION is the entire rest of the line . It's passed as-is to the plugin.

An example configuration file is, in its entirety:

# this is icuplugins44.txt
testplug.dll myPlugin hello=world

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'.

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.

### Implementing a Plugin

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;
}
UPlugTokenReturn
uint32_t UPlugTokenReturn
Return value from a plugin entrypoint.
Definition: icuplug.h:151
UPlugReason
UPlugReason
Reason code for the entrypoint's call.
Definition: icuplug.h:157
UPLUG_REASON_LOAD
@ UPLUG_REASON_LOAD
The plugin is being loaded.
Definition: icuplug.h:159
UPLUG_REASON_UNLOAD
@ UPLUG_REASON_UNLOAD
The plugin is being unloaded.
Definition: icuplug.h:160
UPLUG_REASON_QUERY
@ UPLUG_REASON_QUERY
The plugin is being queried for info.
Definition: icuplug.h:158
UPlugData
struct UPlugData UPlugData
Typedef for opaque structure passed to/from a plugin.
Definition: icuplug.h:127
uplug_setPlugName
U_CAPI void uplug_setPlugName(UPlugData *plug, const char *name)
Set the human-readable name of this plugin.
uplug_setPlugLevel
U_CAPI void uplug_setPlugLevel(UPlugData *plug, UPlugLevel level)
Set the level of this plugin.
UPLUG_TOKEN
#define UPLUG_TOKEN
Random Token to identify a valid ICU plugin.
Definition: icuplug.h:136
UPLUG_LEVEL_HIGH
@ UPLUG_LEVEL_HIGH
The plugin can run at any time.
Definition: icuplug.h:180
U_CAPI
#define U_CAPI
This is used to declare a function as a public ICU C API.
Definition: umachine.h:110
UErrorCode
UErrorCode
Standard ICU4C error code type, a substitute for exceptions.
Definition: utypes.h:415

The UPlugData* is an opaque pointer to the plugin-specific data, and is used in all other API calls.

The API contract is:

1. The plugin MUST always return UPLUG_TOKEN as a return value- to indicate that it is a valid plugin.

2. 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.

3. When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin SHOULD call uplug_setPlugName to indicate a human readable plugin name.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition in file icuplug.h.

## Macro Definition Documentation

## UPLUG_NAME_MAX

#define UPLUG_NAME_MAX 100

Max width of names, symbols, and configuration strings.

Internal:
  Do not use.

This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 142 of file icuplug.h.

## UPLUG_TOKEN

#define UPLUG_TOKEN 0x54762486

Random Token to identify a valid ICU plugin.

Plugins must return this from the entrypoint.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 136 of file icuplug.h.

## Typedef Documentation

## UPlugData

typedef struct UPlugData UPlugData

Typedef for opaque structure passed to/from a plugin.

Use the APIs to access it.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 1 of file icuplug.h.

## UPlugEntrypoint

typedef UPlugTokenReturn() UPlugEntrypoint(UPlugData *plug, UPlugReason reason, UErrorCode *status)

Entrypoint for an ICU plugin.

Parameters

  plug | the UPlugData handle.
  reason | the reason code for the entrypoint's call.
  status | Standard ICU error code. Its input value must pass the U_SUCCESS() test, or else the function returns immediately. Check for U_FAILURE() on output or use with function chaining. (See User Guide for details.)

Returns
  A valid plugin must return UPLUG_TOKEN

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 199 of file icuplug.h.

## UPlugTokenReturn

typedef uint32_t UPlugTokenReturn

Return value from a plugin entrypoint.

Must always be set to UPLUG_TOKEN

See also
  UPLUG_TOKEN

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 151 of file icuplug.h.

## Enumeration Type Documentation

## UPlugLevel

enum UPlugLevel

Level of plugin loading INITIAL: UNKNOWN QUERY: INVALID -> { LOW | HIGH } ERR -> INVALID.

Internal:
  Do not use.

This API is for internal use only. ICU 4.4 Technology Preview

Enumerator
UPLUG_LEVEL_INVALID | The plugin is invalid, hasn't called uplug_setLevel, or can't load.
UPLUG_LEVEL_UNKNOWN | The plugin is waiting to be installed.
UPLUG_LEVEL_LOW | The plugin must be called before u_init completes.
UPLUG_LEVEL_HIGH | The plugin can run at any time.

UPLUG_LEVEL_COUNT

Number of known levels.

Internal:
  Do not use. This API is for internal use only. The numeric value may change over time, see ICU ticket #12420.

Definition at line 176 of file icuplug.h.

## UPlugReason

enum UPlugReason

Reason code for the entrypoint's call.

Internal:
  Do not use.

This API is for internal use only. ICU 4.4 Technology Preview

Enumerator
UPLUG_REASON_QUERY | The plugin is being queried for info.
UPLUG_REASON_LOAD | The plugin is being loaded.
UPLUG_REASON_UNLOAD | The plugin is being unloaded.

UPLUG_REASON_COUNT

Number of known reasons.

Internal:
  Do not use. This API is for internal use only. The numeric value may change over time, see ICU ticket #12420.

Definition at line 157 of file icuplug.h.

## Function Documentation

## uplug_getConfiguration()

U_CAPI const char* uplug_getConfiguration | ( | UPlugData * | plug | ) |

Get the configuration string, if available.

The string is in the platform default codepage.

Parameters

  plug | plugin data handle

Returns
  configuration string, or else null.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getContext()

U_CAPI void* uplug_getContext | ( | UPlugData * | plug | ) |

Return the plugin-specific context data.

Parameters

  plug | plugin data handle

Returns
  the context, or NULL if not set

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getCurrentLevel()

U_CAPI UPlugLevel uplug_getCurrentLevel | ( | void |  | ) |

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.

Returns
  the lowest level of plug which can currently load

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getLibrary()

U_CAPI void* uplug_getLibrary | ( | UPlugData * | plug | ) |

Return the library used for this plugin, if known.

Plugins could use this to load data out of their

Parameters

  plug | plugin data handle

Returns
  the library, or NULL

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getLibraryName()

U_CAPI const char* uplug_getLibraryName | ( | UPlugData * | plug,
|  | UErrorCode * | status
| ) |  |

Return the library name for this plugin, if known.

Parameters

  plug | plugin data handle
  status | error code

Returns
  the library name, or NULL

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getPlugLevel()

U_CAPI UPlugLevel uplug_getPlugLevel | ( | UPlugData * | plug | ) |

Get the level of this plugin.

Parameters

  plug | plugin data handle

Returns
  the level of this plugin

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getPlugLoadStatus()

U_CAPI UErrorCode uplug_getPlugLoadStatus | ( | UPlugData * | plug | ) |

Get plug load status.

Returns
  The error code of this plugin's load attempt.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getPlugName()

U_CAPI const char* uplug_getPlugName | ( | UPlugData * | plug | ) |

Get the human-readable name of this plugin.

Parameters

  plug | plugin data handle

Returns
  the name of this plugin

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_getSymbolName()

U_CAPI const char* uplug_getSymbolName | ( | UPlugData * | plug | ) |

Return the symbol name for this plugin, if known.

Parameters

  plug | plugin data handle

Returns
  the symbol name, or NULL

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_loadPlugFromEntrypoint()

U_CAPI UPlugData* uplug_loadPlugFromEntrypoint | ( | UPlugEntrypoint * | entrypoint,
|  | const char * | config,
|  | UErrorCode * | status
| ) |  |

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.

Parameters

  entrypoint | entrypoint to install
  config | user specified configuration string, if available, or NULL.
  status | error result

Returns
  the new UPlugData associated with this plugin, or NULL if error.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_loadPlugFromLibrary()

U_CAPI UPlugData* uplug_loadPlugFromLibrary | ( | const char * | libName,
|  | const char * | sym,
|  | 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.

Parameters

  libName | DLL name to load
  sym | symbol of plugin (UPlugEntrypoint function)
  config | configuration string, or NULL
  status | error result

Returns
  the new UPlugData associated with this plugin, or NULL if error.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_nextPlug()

U_CAPI UPlugData* uplug_nextPlug | ( | UPlugData * | prior | ) |

Return all currently installed plugins, from newest to oldest Usage Example:

UPlugData *plug = NULL;
while(plug=uplug_nextPlug(plug)) {
... do something with 'plug' ...
}
uplug_nextPlug
U_CAPI UPlugData * uplug_nextPlug(UPlugData *prior)
Return all currently installed plugins, from newest to oldest Usage Example:
NULL
#define NULL
Define NULL if necessary, to nullptr for C++ and to ((void *)0) for C.
Definition: utypes.h:188

Not thread safe- do not call while plugs are added or removed.

Parameters

  prior | pass in 'NULL' to get the first (most recent) plug, otherwise pass the value returned on a prior call to uplug_nextPlug

Returns
  the next oldest plugin, or NULL if no more.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_removePlug()

U_CAPI void uplug_removePlug | ( | UPlugData * | plug,
|  | UErrorCode * | status
| ) |  |

Remove a plugin.

Will request the plugin to be unloaded, and close the library if needed

Parameters

  plug | plugin handle to close
  status | error result

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_setContext()

U_CAPI void uplug_setContext | ( | UPlugData * | plug,
|  | void * | context
| ) |  |

Set the plugin-specific context data.

Parameters

  plug | plugin data handle
  context | new context to set

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_setPlugLevel()

U_CAPI void uplug_setPlugLevel | ( | UPlugData * | plug,
|  | UPlugLevel | level
| ) |  |

Set the level of this plugin.

Parameters

  plug | plugin data handle
  level | the level of this plugin

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_setPlugName()

U_CAPI void uplug_setPlugName | ( | UPlugData * | plug,
|  | const char * | name
| ) |  |

Set the human-readable name of this plugin.

Parameters

  plug | plugin data handle
  name | the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview

## uplug_setPlugNoUnload()

U_CAPI void uplug_setPlugNoUnload | ( | UPlugData * | plug,
|  | UBool | dontUnload
| ) |  |

Request that this plugin not be unloaded at cleanup time.

This is appropriate for plugins which cannot be cleaned up.

See also
  u_cleanup()

Parameters

  plug | plugin
  dontUnload | set true if this plugin can't be unloaded

Internal:
  Do not use. This API is for internal use only. ICU 4.4 Technology Preview