include/lttng/trigger/trigger.h

   1 /*
   2  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_TRIGGER_H
   9 #define LTTNG_TRIGGER_H
  10
  11 #include <lttng/constant.h>
  12 #include <lttng/lttng-error.h>
  13 #include <lttng/lttng-export.h>
  14
  15 #include <inttypes.h>
  16 #include <sys/types.h>
  17
  18 struct lttng_action;
  19 struct lttng_condition;
  20 struct lttng_trigger;
  21 /* A set of triggers. */
  22 struct lttng_triggers;
  23
  24 #ifdef __cplusplus
  25 extern "C" {
  26 #endif
  27
  28 enum lttng_register_trigger_status {
  29         LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
  30         LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
  31 };
  32
  33 enum lttng_trigger_status {
  34         LTTNG_TRIGGER_STATUS_OK = 0,
  35         LTTNG_TRIGGER_STATUS_ERROR = -1,
  36         LTTNG_TRIGGER_STATUS_UNKNOWN = -2,
  37         LTTNG_TRIGGER_STATUS_INVALID = -3,
  38         LTTNG_TRIGGER_STATUS_UNSET = -4,
  39         LTTNG_TRIGGER_STATUS_UNSUPPORTED = -5,
  40         LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
  41 };
  42
  43 /*
  44  * Create a trigger object associating a condition and an action.
  45  *
  46  * A trigger associates a condition and an action to take whenever the
  47  * condition evaluates to true. Such actions can, for example, consist
  48  * in the emission of a notification to clients listening through
  49  * notification channels.
  50  *
  51  * Prior to 2.13, the caller had to retain the ownership of both the condition
  52  * and action. Both objects had to be kept alive for the lifetime of the trigger
  53  * object. This is no longer the case as the condition and action objects are
  54  * internally reference counted. It is safe to destroy a condition and an action
  55  * after using them to create a trigger. However, they should no longer be used.
  56  *
  57  * If the action is a notification action with capture descriptors,
  58  * the condition must be an event rule condition.
  59  *
  60  * A trigger must be registered in order to become activate and can
  61  * be destroyed after its registration.
  62  *
  63  * Returns a trigger object on success, NULL on error.
  64  * Trigger objects must be destroyed using the lttng_trigger_destroy()
  65  * function.
  66  */
  67 LTTNG_EXPORT extern struct lttng_trigger *lttng_trigger_create(struct lttng_condition *condition,
  68                                                                struct lttng_action *action);
  69
  70 /*
  71  * Set the user identity (uid) of a trigger.
  72  *
  73  * Only available for the root user (uid 0).
  74  *
  75  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  76  * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
  77  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  78  */
  79 LTTNG_EXPORT extern enum lttng_trigger_status
  80 lttng_trigger_set_owner_uid(struct lttng_trigger *trigger, uid_t uid);
  81
  82 /*
  83  * Get the user identity (uid) of a trigger.
  84  *
  85  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  86  * LTTNG_TRIGGER_STATUS_UNSET if unset,
  87  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  88  */
  89 LTTNG_EXPORT extern enum lttng_trigger_status
  90 lttng_trigger_get_owner_uid(const struct lttng_trigger *trigger, uid_t *uid);
  91
  92 /*
  93  * Get the condition of a trigger.
  94  *
  95  * The caller acquires no ownership of the returned condition.
  96  *
  97  * Returns a condition on success, NULL on error.
  98  */
  99 LTTNG_EXPORT extern struct lttng_condition *
 100 lttng_trigger_get_condition(struct lttng_trigger *trigger);
 101
 102 LTTNG_EXPORT extern const struct lttng_condition *
 103 lttng_trigger_get_const_condition(const struct lttng_trigger *trigger);
 104
 105 /*
 106  * Get the action of a trigger.
 107  *
 108  * The caller acquires no ownership of the returned action.
 109  *
 110  * Returns an action on success, NULL on error.
 111  */
 112 LTTNG_EXPORT extern struct lttng_action *lttng_trigger_get_action(struct lttng_trigger *trigger);
 113
 114 LTTNG_EXPORT extern const struct lttng_action *
 115 lttng_trigger_get_const_action(const struct lttng_trigger *trigger);
 116
 117 /*
 118  * Get the name of a trigger.
 119  *
 120  * The caller does not assume the ownership of the returned name.
 121  * The name shall only only be used for the duration of the trigger's
 122  * lifetime, or until a different name is set.
 123  *
 124  * Returns LTTNG_TRIGGER_STATUS_OK and a pointer to the trigger's name on
 125  * success, LTTNG_TRIGGER_STATUS_INVALID if an invalid parameter is passed,
 126  * or LTTNG_TRIGGER_STATUS_UNSET if the trigger is unnamed.
 127  */
 128 LTTNG_EXPORT extern enum lttng_trigger_status
 129 lttng_trigger_get_name(const struct lttng_trigger *trigger, const char **name);
 130
 131 /*
 132  * Destroy (frees) a trigger object.
 133  */
 134 LTTNG_EXPORT extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 135
 136 /*
 137  * Register a trigger to the session daemon with a given name.
 138  *
 139  * The trigger object can be destroyed after this call.
 140  * On success, this function will set the trigger's name to `name`.
 141  *
 142  * Returns an LTTng status code.
 143  */
 144 LTTNG_EXPORT extern enum lttng_error_code
 145 lttng_register_trigger_with_name(struct lttng_trigger *trigger, const char *name);
 146
 147 /*
 148  * Register a trigger to the session daemon, generating a unique name for its
 149  * owner.
 150  *
 151  * The trigger can be destroyed after this call.
 152  * On success, this function will set the trigger's name to the generated
 153  * name.
 154  *
 155  * Returns an LTTng status code.
 156  */
 157 LTTNG_EXPORT extern enum lttng_error_code
 158 lttng_register_trigger_with_automatic_name(struct lttng_trigger *trigger);
 159
 160 /*
 161  * Unregister a trigger from the session daemon.
 162  *
 163  * The trigger can be destroyed after this call.
 164  *
 165  * Return 0 on success, a negative LTTng error code on error.
 166  */
 167 LTTNG_EXPORT extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
 168
 169 /*
 170  * List triggers for the current user.
 171  *
 172  * On success, a newly-allocated trigger set is returned.
 173  *
 174  * The trigger set must be destroyed by the caller (see
 175  * lttng_triggers_destroy()).
 176  *
 177  * Returns LTTNG_OK on success, else a suitable LTTng error code.
 178  */
 179 LTTNG_EXPORT extern enum lttng_error_code lttng_list_triggers(struct lttng_triggers **triggers);
 180
 181 /*
 182  * Get a trigger from the set at a given index.
 183  *
 184  * Note that the trigger set maintains the ownership of the returned trigger.
 185  * It must not be destroyed by the user, nor should a reference to it be held
 186  * beyond the lifetime of the trigger set.
 187  *
 188  * Returns a trigger, or NULL on error.
 189  */
 190 LTTNG_EXPORT extern const struct lttng_trigger *
 191 lttng_triggers_get_at_index(const struct lttng_triggers *triggers, unsigned int index);
 192
 193 /*
 194  * Get the number of triggers in a trigger set.
 195  *
 196  * Return LTTNG_TRIGGER_STATUS_OK on success,
 197  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 198  */
 199 LTTNG_EXPORT extern enum lttng_trigger_status
 200 lttng_triggers_get_count(const struct lttng_triggers *triggers, unsigned int *count);
 201
 202 /*
 203  * Destroy a trigger set.
 204  */
 205 LTTNG_EXPORT extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 206
 207 /*
 208  * Deprecated: invocations should be replaced by
 209  * lttng_register_trigger_with_automatic_name().
 210  *
 211  * Register a trigger to the session daemon.
 212  *
 213  * The trigger can be destroyed after this call.
 214  *
 215  * Return 0 on success, a negative LTTng error code on error.
 216  */
 217 LTTNG_DEPRECATED("Use lttng_register_trigger_with_automatic_name")
 218 LTTNG_EXPORT extern int lttng_register_trigger(struct lttng_trigger *trigger);
 219
 220 #ifdef __cplusplus
 221 }
 222 #endif
 223
 224 #endif /* LTTNG_TRIGGER_H */