/**
* Check whether a user has a particular capability in a given context.
*
* For example:
* $context = get_context_instance(CONTEXT_MODULE, $cm->id);
* has_capability('mod/forum:replypost',$context)
*
* By default checks the capabilities of the current user, but you can pass a
* different userid. By default will return true for admin users, but you can override that with the fourth argument.
*
* Guest and not-logged-in users can never get any dangerous capability - that is any write capability
* or capabilities with XSS, config or data loss risks.
*
* @param string $capability the name of the capability to check. For example mod/forum:view
* @param context $context the context to check the capability in. You normally get this with {@link get_context_instance}.
* @param integer|object $user A user id or object. By default (null) checks the permissions of the current user.
* @param boolean $doanything If false, ignores effect of admin role assignment
* @return boolean true if the user has this capability. Otherwise false.
*/
function has_capability($capability, context $context, $user = null, $doanything = true)
{
global $USER, $CFG, $SCRIPT, $ACCESSLIB_PRIVATE;
if (during_initial_install()) {
if ($SCRIPT === "/{$CFG->admin}/index.php" or $SCRIPT === "/{$CFG->admin}/cli/install.php" or $SCRIPT === "/{$CFG->admin}/cli/install_database.php") {
// we are in an installer - roles can not work yet
return true;
} else {
return false;
}
}
if (strpos($capability, 'moodle/legacy:') === 0) {
throw new coding_exception('Legacy capabilities can not be used any more!');
}
if (!is_bool($doanything)) {
throw new coding_exception('Capability parameter "doanything" is wierd, only true or false is allowed. This has to be fixed in code.');
}
// capability must exist
if (!($capinfo = get_capability_info($capability))) {
debugging('Capability "' . $capability . '" was not found! This has to be fixed in code.');
return false;
}
if (!isset($USER->id)) {
// should never happen
$USER->id = 0;
}
// make sure there is a real user specified
if ($user === null) {
$userid = $USER->id;
} else {
$userid = is_object($user) ? $user->id : $user;
}
// make sure forcelogin cuts off not-logged-in users if enabled
if (!empty($CFG->forcelogin) and $userid == 0) {
return false;
}
// make sure the guest account and not-logged-in users never get any risky caps no matter what the actual settings are.
if ($capinfo->captype === 'write' or $capinfo->riskbitmask & (RISK_XSS | RISK_CONFIG | RISK_DATALOSS)) {
if (isguestuser($userid) or $userid == 0) {
return false;
}
}
// somehow make sure the user is not deleted and actually exists
if ($userid != 0) {
if ($userid == $USER->id and isset($USER->deleted)) {
// this prevents one query per page, it is a bit of cheating,
// but hopefully session is terminated properly once user is deleted
if ($USER->deleted) {
return false;
}
} else {
if (!context_user::instance($userid, IGNORE_MISSING)) {
// no user context == invalid userid
return false;
}
}
}
// context path/depth must be valid
if (empty($context->path) or $context->depth == 0) {
// this should not happen often, each upgrade tries to rebuild the context paths
debugging('Context id ' . $context->id . ' does not have valid path, please use build_context_path()');
if (is_siteadmin($userid)) {
return true;
} else {
return false;
}
}
// Find out if user is admin - it is not possible to override the doanything in any way
// and it is not possible to switch to admin role either.
if ($doanything) {
if (is_siteadmin($userid)) {
if ($userid != $USER->id) {
return true;
}
// make sure switchrole is not used in this context
if (empty($USER->access['rsw'])) {
return true;
}
$parts = explode('/', trim($context->path, '/'));
$path = '';
$switched = false;
foreach ($parts as $part) {
$path .= '/' . $part;
if (!empty($USER->access['rsw'][$path])) {
$switched = true;
break;
}
}
if (!$switched) {
return true;
}
//ok, admin switched role in this context, let's use normal access control rules
}
}
// Careful check for staleness...
$context->reload_if_dirty();
if ($USER->id == $userid) {
if (!isset($USER->access)) {
load_all_capabilities();
}
$access =& $USER->access;
} else {
// make sure user accessdata is really loaded
get_user_accessdata($userid, true);
$access =& $ACCESSLIB_PRIVATE->accessdatabyuser[$userid];
}
// Load accessdata for below-the-course context if necessary,
// all contexts at and above all courses are already loaded
if ($context->contextlevel != CONTEXT_COURSE and $coursecontext = $context->get_course_context(false)) {
load_course_context($userid, $coursecontext, $access);
}
return has_capability_in_accessdata($capability, $context, $access);
}
