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 <sys/types.h>
  12 #include <inttypes.h>
  13
  14 struct lttng_action;
  15 struct lttng_condition;
  16 struct lttng_trigger;
  17 /* A set of triggers. */
  18 struct lttng_triggers;
  19
  20 #ifdef __cplusplus
  21 extern "C" {
  22 #endif
  23
  24 enum lttng_register_trigger_status {
  25         LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
  26         LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
  27 };
  28
  29 enum lttng_trigger_status {
  30         LTTNG_TRIGGER_STATUS_OK = 0,
  31         LTTNG_TRIGGER_STATUS_ERROR = -1,
  32         LTTNG_TRIGGER_STATUS_UNKNOWN = -2,
  33         LTTNG_TRIGGER_STATUS_INVALID = -3,
  34         LTTNG_TRIGGER_STATUS_UNSET = -4,
  35         LTTNG_TRIGGER_STATUS_UNSUPPORTED = -5,
  36         LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
  37 };
  38
  39 enum lttng_trigger_firing_policy {
  40         LTTNG_TRIGGER_FIRING_POLICY_EVERY_N = 0,
  41         LTTNG_TRIGGER_FIRING_POLICY_ONCE_AFTER_N = 1,
  42 };
  43
  44 /*
  45  * Create a trigger object associating a condition and an action.
  46  *
  47  * A trigger associates a condition and an action to take whenever the
  48  * condition evaluates to true. Such actions can, for example, consist
  49  * in the emission of a notification to clients listening through
  50  * notification channels.
  51  *
  52  * The caller retains the ownership of both the condition and action
  53  * and both must be kept alive for the lifetime of the trigger object.
  54  *
  55  * A trigger must be registered in order to become activate and can
  56  * be destroyed after its registration.
  57  *
  58  * Returns a trigger object on success, NULL on error.
  59  * Trigger objects must be destroyed using the lttng_trigger_destroy()
  60  * function.
  61  */
  62 extern struct lttng_trigger *lttng_trigger_create(
  63                 struct lttng_condition *condition, struct lttng_action *action);
  64
  65 /*
  66  * Set the user identity (uid) of a trigger.
  67  *
  68  * Only available for the root user (uid 0).
  69  *
  70  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  71  * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
  72  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  73  */
  74 extern enum lttng_trigger_status lttng_trigger_set_owner_uid(
  75                 struct lttng_trigger *trigger, uid_t uid);
  76
  77 /*
  78  * Get the user identity (uid) of a trigger.
  79  *
  80  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  81  * LTTNG_TRIGGER_STATUS_UNSET if unset,
  82  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  83  */
  84 extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
  85                 const struct lttng_trigger *trigger, uid_t *uid);
  86
  87 /*
  88  * Get the condition of a trigger.
  89  *
  90  * The caller acquires no ownership of the returned condition.
  91  *
  92  * Returns a condition on success, NULL on error.
  93  */
  94 extern struct lttng_condition *lttng_trigger_get_condition(
  95                 struct lttng_trigger *trigger);
  96
  97 /*
  98  * Get the action of a trigger.
  99  *
 100  * The caller acquires no ownership of the returned action.
 101  *
 102  * Returns an action on success, NULL on error.
 103  */
 104 extern struct lttng_action *lttng_trigger_get_action(
 105                 struct lttng_trigger *trigger);
 106
 107
 108 /*
 109  * Get the name of a trigger.
 110  *
 111  * The caller does not assume the ownership of the returned name.
 112  * The name shall only only be used for the duration of the trigger's
 113  * lifetime, or until a different name is set.
 114  *
 115  * Returns LTTNG_TRIGGER_STATUS_OK and a pointer to the trigger's name on
 116  * success, LTTNG_TRIGGER_STATUS_INVALID if an invalid parameter is passed,
 117  * or LTTNG_TRIGGER_STATUS_UNSET if a name was not set prior to this call.
 118  */
 119 extern enum lttng_trigger_status lttng_trigger_get_name(
 120                 const struct lttng_trigger *trigger, const char **name);
 121
 122 /*
 123  * Set the trigger name.
 124  *
 125  * A name is optional.
 126  * A name will be assigned on trigger registration if no name is set.
 127  *
 128  * The name is copied.
 129  *
 130  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 131  * if invalid parameters are passed.
 132  */
 133 extern enum lttng_trigger_status lttng_trigger_set_name(
 134                 struct lttng_trigger *trigger, const char *name);
 135
 136 /*
 137  * Set the trigger firing policy.
 138  *
 139  * This is optional. By default a trigger is set to fire each time the
 140  * associated condition occurs.
 141  *
 142  * Threshold is the number of times the condition must be hit before the policy
 143  * is enacted.
 144  *
 145  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 146  * if invalid parameters are passed.
 147  */
 148 extern enum lttng_trigger_status lttng_trigger_set_firing_policy(
 149                 struct lttng_trigger *trigger,
 150                 enum lttng_trigger_firing_policy policy_type,
 151                 uint64_t threshold);
 152
 153 /*
 154  * Get the trigger firing policy.
 155  *
 156  * Threshold is the number of time the condition must be hit before the policy is
 157  * enacted.
 158  *
 159  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 160  * if invalid parameters are passed.
 161  */
 162 extern enum lttng_trigger_status lttng_trigger_get_firing_policy(
 163                 const struct lttng_trigger *trigger,
 164                 enum lttng_trigger_firing_policy *policy_type,
 165                 uint64_t *threshold);
 166
 167 /*
 168  * Destroy (frees) a trigger object.
 169  */
 170 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 171
 172 /*
 173  * Register a trigger to the session daemon.
 174  *
 175  * The trigger can be destroyed after this call.
 176  *
 177  * Return 0 on success, a negative LTTng error code on error.
 178  */
 179 extern int lttng_register_trigger(struct lttng_trigger *trigger);
 180
 181 /*
 182  * Unregister a trigger from the session daemon.
 183  *
 184  * The trigger can be destroyed after this call.
 185  *
 186  * Return 0 on success, a negative LTTng error code on error.
 187  */
 188 extern int lttng_unregister_trigger(struct lttng_trigger *trigger);
 189
 190 /*
 191  * Get a trigger from the set at a given index.
 192  *
 193  * Note that the trigger set maintains the ownership of the returned trigger.
 194  * It must not be destroyed by the user, nor should a reference to it be held
 195  * beyond the lifetime of the trigger set.
 196  *
 197  * Returns a trigger, or NULL on error.
 198  */
 199 extern const struct lttng_trigger *lttng_triggers_get_at_index(
 200                 const struct lttng_triggers *triggers, unsigned int index);
 201
 202 /*
 203  * Get the number of triggers in a trigger set.
 204  *
 205  * Return LTTNG_TRIGGER_STATUS_OK on success,
 206  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 207  */
 208 extern enum lttng_trigger_status lttng_triggers_get_count(
 209                 const struct lttng_triggers *triggers, unsigned int *count);
 210
 211 /*
 212  * Destroy a trigger set.
 213  */
 214 extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 215
 216
 217 #ifdef __cplusplus
 218 }
 219 #endif
 220
 221 #endif /* LTTNG_TRIGGER_H */