74ddbea134633c8056581f57d9a3533fe0660707
[squirrelmail.git] / functions / plugin.php
1 <?php
2
3 /**
4 * plugin.php
5 *
6 * This file provides the framework for a plugin architecture.
7 *
8 * Documentation on how to write plugins might show up some time.
9 *
10 * @copyright &copy; 1999-2006 The SquirrelMail Project Team
11 * @license http://opensource.org/licenses/gpl-license.php GNU Public License
12 * @version $Id$
13 * @package squirrelmail
14 */
15
16 /**
17 * This function adds a plugin.
18 * @param string $name Internal plugin name (ie. delete_move_next)
19 * @return void
20 */
21 function use_plugin ($name) {
22 if (file_exists(SM_PATH . "plugins/$name/setup.php")) {
23 include_once(SM_PATH . "plugins/$name/setup.php");
24
25 /**
26 * As of SM 1.5.2, plugin hook registration is statically
27 * accomplished using the configuration utility (config/conf.pl).
28 * And this code is deprecated (but let's keep it until
29 * the new registration system is proven).
30 *
31 */
32 //$function = "squirrelmail_plugin_init_$name";
33 //if (function_exists($function)) {
34 // $function();
35 //}
36 }
37 }
38
39 /**
40 * This function executes a plugin hook.
41 *
42 * It includes an arbitrary return value that is managed by
43 * all plugins on the same hook and returned to the core hook
44 * location.
45 *
46 * The desired format of the return value should be defined
47 * by the context in which the hook is called.
48 *
49 * Note that the master return value for this hook is passed
50 * to each plugin after the main argument(s) value/array as a
51 * convenience only - to show what the current return value is
52 * even though it is liable to be changed by other plugins.
53 *
54 * If any plugin on this hook wants to modify the $args
55 * plugin parameter, it simply has to use call-by-reference
56 * syntax in the hook function that it has registered for the
57 * current hook. Note that this is in addition to (entirely
58 * independent of) the return value for this hook.
59 *
60 * @param string $name Name of hook being executed
61 * @param mixed $args A single value or an array of arguments
62 * that are to be passed to all plugins
63 * operating off the hook being called.
64 * Note that this argument is passed by
65 * reference thus it is liable to be
66 * changed after the hook completes.
67 *
68 * @return mixed The return value that is managed by the plugins
69 * on the current hook.
70 *
71 */
72 function do_hook($name, &$args) {
73
74 global $squirrelmail_plugin_hooks, $currentHookName;
75 $currentHookName = $name;
76 $ret = NULL;
77
78 if (isset($squirrelmail_plugin_hooks[$name])
79 && is_array($squirrelmail_plugin_hooks[$name])) {
80 foreach ($squirrelmail_plugin_hooks[$name] as $plugin_name => $function) {
81 use_plugin($plugin_name);
82 if (function_exists($function)) {
83 $ret = $function($args, $ret);
84 }
85 }
86 }
87
88 $currentHookName = '';
89 return $ret;
90
91 }
92
93 /**
94 * This function executes a hook that allows for an arbitrary
95 * return value from each plugin that will be merged into one
96 * array (or one string if all return values are strings) and
97 * returned to the core hook location.
98 *
99 * Note that unlike PHP's array_merge function, matching array keys
100 * will not overwrite each other, instead, values under such keys
101 * will be concatenated if they are both strings, or merged if they
102 * are arrays (in the same (non-overwrite) manner recursively).
103 *
104 * Plugins returning non-arrays (strings, objects, etc) will have
105 * their output added to the end of the ultimate return array,
106 * unless ALL values returned are strings, in which case one string
107 * with all returned strings concatenated together is returned
108 * (unless $force_array is TRUE).
109 *
110 * If any plugin on this hook wants to modify the $args
111 * plugin parameter, it simply has to use call-by-reference
112 * syntax in the hook function that it has registered for the
113 * current hook. Note that this is in addition to (entirely
114 * independent of) the return value for this hook.
115 *
116 * @param string $name Name of hook being executed
117 * @param mixed $args A single value or an array of arguments
118 * that are to be passed to all plugins
119 * operating off the hook being called.
120 * Note that this argument is passed by
121 * reference thus it is liable to be
122 * changed after the hook completes.
123 * @param boolean $force_array When TRUE, guarantees the return
124 * value will ALWAYS be an array,
125 * (simple strings will be forced
126 * into a one-element array).
127 * When FALSE, behavior is as
128 * described above (OPTIONAL;
129 * default behavior is to return
130 * mixed - array or string).
131 *
132 * @return mixed the merged return arrays or strings of each
133 * plugin on this hook.
134 *
135 */
136 function concat_hook_function($name, &$args, $force_array=FALSE) {
137
138 global $squirrelmail_plugin_hooks, $currentHookName;
139 $currentHookName = $name;
140 $ret = '';
141
142 if (isset($squirrelmail_plugin_hooks[$name])
143 && is_array($squirrelmail_plugin_hooks[$name])) {
144 foreach ($squirrelmail_plugin_hooks[$name] as $plugin_name => $function) {
145 use_plugin($plugin_name);
146 if (function_exists($function)) {
147 $plugin_ret = $function($args);
148 if (!empty($plugin_ret)) {
149 $ret = sqm_array_merge($ret, $plugin_ret);
150 }
151 }
152 }
153 }
154
155 if ($force_array && is_string($ret)) {
156 $ret = array($ret);
157 }
158
159 $currentHookName = '';
160 return $ret;
161
162 }
163
164 /**
165 * This function is used for hooks which are to return true or
166 * false. If $priority is > 0, any one or more trues will override
167 * any falses. If $priority < 0, then one or more falses will
168 * override any trues.
169 * Priority 0 means majority rules. Ties will be broken with $tie
170 *
171 * If any plugin on this hook wants to modify the $args
172 * plugin parameter, it simply has to use call-by-reference
173 * syntax in the hook function that it has registered for the
174 * current hook. Note that this is in addition to (entirely
175 * independent of) the return value for this hook.
176 *
177 * @param string $name The hook name
178 * @param mixed $args A single value or an array of arguments
179 * that are to be passed to all plugins
180 * operating off the hook being called.
181 * Note that this argument is passed by
182 * reference thus it is liable to be
183 * changed after the hook completes.
184 * @param int $priority See explanation above
185 * @param boolean $tie See explanation above
186 *
187 * @return boolean The result of the function
188 *
189 */
190 function boolean_hook_function($name, &$args, $priority=0, $tie=false) {
191
192 global $squirrelmail_plugin_hooks, $currentHookName;
193 $yea = 0;
194 $nay = 0;
195 $ret = $tie;
196
197 if (isset($squirrelmail_plugin_hooks[$name]) &&
198 is_array($squirrelmail_plugin_hooks[$name])) {
199
200 /* Loop over the plugins that registered the hook */
201 $currentHookName = $name;
202 foreach ($squirrelmail_plugin_hooks[$name] as $plugin_name => $function) {
203 use_plugin($plugin_name);
204 if (function_exists($function)) {
205 $ret = $function($args);
206 if ($ret) {
207 $yea++;
208 } else {
209 $nay++;
210 }
211 }
212 }
213 $currentHookName = '';
214
215 /* Examine the aftermath and assign the return value appropriately */
216 if (($priority > 0) && ($yea)) {
217 $ret = true;
218 } elseif (($priority < 0) && ($nay)) {
219 $ret = false;
220 } elseif ($yea > $nay) {
221 $ret = true;
222 } elseif ($nay > $yea) {
223 $ret = false;
224 } else {
225 // There's a tie, no action needed.
226 }
227 return $ret;
228 }
229 // If the code gets here, there was a problem - no hooks, etc.
230 return NULL;
231
232 }
233
234 /**
235 * Do not use, use checkForJavascript() instead.
236 *
237 * This function checks whether the user's USER_AGENT is known to
238 * be broken. If so, returns true and the plugin is invisible to the
239 * offending browser.
240 * *** THIS IS A TEST FOR JAVASCRIPT SUPPORT ***
241 *
242 * @return bool whether this browser properly supports JavaScript
243 * @deprecated use checkForJavascript() since 1.5.1
244 */
245 function soupNazi(){
246 return !checkForJavascript();
247 }
248
249 /**
250 * Check if plugin is enabled
251 * @param string $plugin_name plugin name
252 * @since 1.5.1
253 * @return boolean
254 */
255 function is_plugin_enabled($plugin_name) {
256 global $plugins;
257
258 /**
259 * check if variable is empty. if var is not set, php empty
260 * returns true without error notice.
261 *
262 * then check if it is an array
263 */
264 if (empty($plugins) || ! is_array($plugins))
265 return false;
266
267 if ( in_array($plugin_name,$plugins) ) {
268 return true;
269 } else {
270 return false;
271 }
272 }
273
274 /**
275 * Check a plugin's version.
276 *
277 * Returns TRUE if the given plugin is installed,
278 * activated and is at minimum version $a.$b.$c.
279 * If any one of those conditions fails, FALSE
280 * will be returned (careful of plugins that are
281 * sufficiently versioned but are not activated).
282 *
283 * By overriding the default value of $force_inclusion,
284 * this function will attempt to grab versioning
285 * information from the given plugin even if it
286 * is not activated (plugin still has to be
287 * unpackaged and set in place in the plugins
288 * directory). Use with care - some plugins
289 * might break SquirrelMail when this is used.
290 *
291 * Note that this function assumes plugin
292 * versioning is consistently applied in the same
293 * fashion that SquirrelMail versions are, with the
294 * exception that an applicable SquirrelMail
295 * version may be appended to the version number
296 * (which will be ignored herein). That is, plugin
297 * version number schemes are expected in the following
298 * format: 1.2.3, or 1.2.3-1.4.0.
299 *
300 * Any characters after the third number are discarded,
301 * so formats such as the following will also work,
302 * although extra information about beta versions can
303 * possibly confuse the desired results of the version
304 * check: 1.2.3-beta4, 1.2.3.RC2, and so forth.
305 *
306 * @since 1.5.2
307 *
308 * @param string plugin_name name of the plugin to
309 * check; must precisely
310 * match the plugin
311 * directory name
312 * @param int a major version number
313 * @param int b minor version number
314 * @param int c release number
315 * @param bool force_inclusion try to get version info
316 * for plugins not activated?
317 * (default FALSE)
318 *
319 * @return bool
320 *
321 */
322 function check_plugin_version($plugin_name,
323 $a = 0, $b = 0, $c = 0,
324 $force_inclusion = FALSE)
325 {
326
327 $info_function = $plugin_name . '_info';
328 $version_function = $plugin_name . '_version';
329 $plugin_info = array();
330 $plugin_version = FALSE;
331
332
333 // first attempt to find the plugin info function, wherein
334 // the plugin version should be available
335 //
336 if (function_exists($info_function))
337 $plugin_info = $info_function();
338 else if ($force_inclusion
339 && file_exists(SM_PATH . 'plugins/' . $plugin_name . '/setup.php'))
340 {
341 include_once(SM_PATH . 'plugins/' . $plugin_name . '/setup.php');
342 if (function_exists($info_function))
343 $plugin_info = $info_function();
344 }
345 if (!empty($plugin_info['version']))
346 $plugin_version = $plugin_info['version'];
347
348
349 // otherwise, look for older version function
350 //
351 if (!$plugin_version && function_exists($version_function))
352 $plugin_version = $version_function();
353
354
355 if (!$plugin_version) return FALSE;
356
357
358 // now massage version number into something we understand
359 //
360 $plugin_version = trim(preg_replace(array('/[^0-9.]+.*$/', '/[^0-9.]/'),
361 '', $plugin_version),
362 '.');
363 $plugin_version = explode('.', $plugin_version);
364 if (!isset($plugin_version[0])) $plugin_version[0] = 0;
365 if (!isset($plugin_version[1])) $plugin_version[1] = 0;
366 if (!isset($plugin_version[2])) $plugin_version[2] = 0;
367 // sm_print_r($plugin_version);
368
369
370 // now test the version number
371 //
372 if ($plugin_version[0] < $a ||
373 ($plugin_version[0] == $a && $plugin_version[1] < $b) ||
374 ($plugin_version[0] == $a && $plugin_version[1] == $b && $plugin_version[2] < $c))
375 return FALSE;
376
377
378 return TRUE;
379
380 }
381