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  * If the action is a notification action with capture descriptors,
  56  * the condition must be an event rule condition.
  57  *
  58  * A trigger must be registered in order to become activate and can
  59  * be destroyed after its registration.
  60  *
  61  * Returns a trigger object on success, NULL on error.
  62  * Trigger objects must be destroyed using the lttng_trigger_destroy()
  63  * function.
  64  */
  65 extern struct lttng_trigger *lttng_trigger_create(
  66                 struct lttng_condition *condition, struct lttng_action *action);
  67
  68 /*
  69  * Set the user identity (uid) of a trigger.
  70  *
  71  * Only available for the root user (uid 0).
  72  *
  73  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  74  * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
  75  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  76  */
  77 extern enum lttng_trigger_status lttng_trigger_set_owner_uid(
  78                 struct lttng_trigger *trigger, uid_t uid);
  79
  80 /*
  81  * Get the user identity (uid) of a trigger.
  82  *
  83  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  84  * LTTNG_TRIGGER_STATUS_UNSET if unset,
  85  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  86  */
  87 extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
  88                 const struct lttng_trigger *trigger, uid_t *uid);
  89
  90 /*
  91  * Get the condition of a trigger.
  92  *
  93  * The caller acquires no ownership of the returned condition.
  94  *
  95  * Returns a condition on success, NULL on error.
  96  */
  97 extern struct lttng_condition *lttng_trigger_get_condition(
  98                 struct lttng_trigger *trigger);
  99
 100 const struct lttng_condition *lttng_trigger_get_const_condition(
 101                 const struct lttng_trigger *trigger);
 102
 103 /*
 104  * Get the action of a trigger.
 105  *
 106  * The caller acquires no ownership of the returned action.
 107  *
 108  * Returns an action on success, NULL on error.
 109  */
 110 extern struct lttng_action *lttng_trigger_get_action(
 111                 struct lttng_trigger *trigger);
 112
 113 const struct lttng_action *lttng_trigger_get_const_action(
 114                 const struct lttng_trigger *trigger);
 115
 116 /*
 117  * Get the name of a trigger.
 118  *
 119  * The caller does not assume the ownership of the returned name.
 120  * The name shall only only be used for the duration of the trigger's
 121  * lifetime, or until a different name is set.
 122  *
 123  * Returns LTTNG_TRIGGER_STATUS_OK and a pointer to the trigger's name on
 124  * success, LTTNG_TRIGGER_STATUS_INVALID if an invalid parameter is passed,
 125  * or LTTNG_TRIGGER_STATUS_UNSET if a name was not set prior to this call.
 126  */
 127 extern enum lttng_trigger_status lttng_trigger_get_name(
 128                 const struct lttng_trigger *trigger, const char **name);
 129
 130 /*
 131  * Set the trigger name.
 132  *
 133  * A name is optional.
 134  * A name will be assigned on trigger registration if no name is set.
 135  *
 136  * The name is copied.
 137  *
 138  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 139  * if invalid parameters are passed.
 140  */
 141 extern enum lttng_trigger_status lttng_trigger_set_name(
 142                 struct lttng_trigger *trigger, const char *name);
 143
 144 /*
 145  * Set the trigger firing policy.
 146  *
 147  * This is optional. By default a trigger is set to fire each time the
 148  * associated condition occurs.
 149  *
 150  * Threshold is the number of times the condition must be hit before the policy
 151  * is enacted.
 152  *
 153  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 154  * if invalid parameters are passed.
 155  */
 156 extern enum lttng_trigger_status lttng_trigger_set_firing_policy(
 157                 struct lttng_trigger *trigger,
 158                 enum lttng_trigger_firing_policy policy_type,
 159                 uint64_t threshold);
 160
 161 /*
 162  * Get the trigger firing policy.
 163  *
 164  * Threshold is the number of time the condition must be hit before the policy is
 165  * enacted.
 166  *
 167  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 168  * if invalid parameters are passed.
 169  */
 170 extern enum lttng_trigger_status lttng_trigger_get_firing_policy(
 171                 const struct lttng_trigger *trigger,
 172                 enum lttng_trigger_firing_policy *policy_type,
 173                 uint64_t *threshold);
 174
 175 /*
 176  * Destroy (frees) a trigger object.
 177  */
 178 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 179
 180 /*
 181  * Register a trigger to the session daemon.
 182  *
 183  * The trigger can be destroyed after this call.
 184  *
 185  * Return 0 on success, a negative LTTng error code on error.
 186  */
 187 extern int lttng_register_trigger(struct lttng_trigger *trigger);
 188
 189 /*
 190  * Unregister a trigger from the session daemon.
 191  *
 192  * The trigger can be destroyed after this call.
 193  *
 194  * Return 0 on success, a negative LTTng error code on error.
 195  */
 196 extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
 197
 198 /*
 199  * List triggers for the current user.
 200  *
 201  * On success, a newly-allocated trigger set is returned.
 202  *
 203  * The trigger set must be destroyed by the caller (see
 204  * lttng_triggers_destroy()).
 205  *
 206  * Returns LTTNG_OK on success, else a suitable LTTng error code.
 207  */
 208 extern enum lttng_error_code lttng_list_triggers(
 209                 struct lttng_triggers **triggers);
 210
 211 /*
 212  * Get a trigger from the set at a given index.
 213  *
 214  * Note that the trigger set maintains the ownership of the returned trigger.
 215  * It must not be destroyed by the user, nor should a reference to it be held
 216  * beyond the lifetime of the trigger set.
 217  *
 218  * Returns a trigger, or NULL on error.
 219  */
 220 extern const struct lttng_trigger *lttng_triggers_get_at_index(
 221                 const struct lttng_triggers *triggers, unsigned int index);
 222
 223 /*
 224  * Get the number of triggers in a trigger set.
 225  *
 226  * Return LTTNG_TRIGGER_STATUS_OK on success,
 227  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 228  */
 229 extern enum lttng_trigger_status lttng_triggers_get_count(
 230                 const struct lttng_triggers *triggers, unsigned int *count);
 231
 232 /*
 233  * Destroy a trigger set.
 234  */
 235 extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 236
 237
 238 #ifdef __cplusplus
 239 }
 240 #endif
 241
 242 #endif /* LTTNG_TRIGGER_H */