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 /*
  40  * Create a trigger object associating a condition and an action.
  41  *
  42  * A trigger associates a condition and an action to take whenever the
  43  * condition evaluates to true. Such actions can, for example, consist
  44  * in the emission of a notification to clients listening through
  45  * notification channels.
  46  *
  47  * Prior to 2.13, the caller had to retain the ownership of both the condition
  48  * and action. Both objects had to be kept alive for the lifetime of the trigger
  49  * object. This is no longer the case as the condition and action objects are
  50  * internally reference counted. It is safe to destroy a condition and an action
  51  * after using them to create a trigger. However, they should no longer be used.
  52  *
  53  * If the action is a notification action with capture descriptors,
  54  * the condition must be an event rule condition.
  55  *
  56  * A trigger must be registered in order to become activate and can
  57  * be destroyed after its registration.
  58  *
  59  * Returns a trigger object on success, NULL on error.
  60  * Trigger objects must be destroyed using the lttng_trigger_destroy()
  61  * function.
  62  */
  63 extern struct lttng_trigger *lttng_trigger_create(
  64                 struct lttng_condition *condition, struct lttng_action *action);
  65
  66 /*
  67  * Set the user identity (uid) of a trigger.
  68  *
  69  * Only available for the root user (uid 0).
  70  *
  71  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  72  * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
  73  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  74  */
  75 extern enum lttng_trigger_status lttng_trigger_set_owner_uid(
  76                 struct lttng_trigger *trigger, uid_t uid);
  77
  78 /*
  79  * Get the user identity (uid) of a trigger.
  80  *
  81  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  82  * LTTNG_TRIGGER_STATUS_UNSET if unset,
  83  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  84  */
  85 extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
  86                 const struct lttng_trigger *trigger, uid_t *uid);
  87
  88 /*
  89  * Get the condition of a trigger.
  90  *
  91  * The caller acquires no ownership of the returned condition.
  92  *
  93  * Returns a condition on success, NULL on error.
  94  */
  95 extern struct lttng_condition *lttng_trigger_get_condition(
  96                 struct lttng_trigger *trigger);
  97
  98 const struct lttng_condition *lttng_trigger_get_const_condition(
  99                 const struct lttng_trigger *trigger);
 100
 101 /*
 102  * Get the action of a trigger.
 103  *
 104  * The caller acquires no ownership of the returned action.
 105  *
 106  * Returns an action on success, NULL on error.
 107  */
 108 extern struct lttng_action *lttng_trigger_get_action(
 109                 struct lttng_trigger *trigger);
 110
 111 const struct lttng_action *lttng_trigger_get_const_action(
 112                 const struct lttng_trigger *trigger);
 113
 114 /*
 115  * Get the name of a trigger.
 116  *
 117  * The caller does not assume the ownership of the returned name.
 118  * The name shall only only be used for the duration of the trigger's
 119  * lifetime, or until a different name is set.
 120  *
 121  * Returns LTTNG_TRIGGER_STATUS_OK and a pointer to the trigger's name on
 122  * success, LTTNG_TRIGGER_STATUS_INVALID if an invalid parameter is passed,
 123  * or LTTNG_TRIGGER_STATUS_UNSET if a name was not set prior to this call.
 124  */
 125 extern enum lttng_trigger_status lttng_trigger_get_name(
 126                 const struct lttng_trigger *trigger, const char **name);
 127
 128 /*
 129  * Set the trigger name.
 130  *
 131  * A name is optional.
 132  * A name will be assigned on trigger registration if no name is set.
 133  *
 134  * The name is copied.
 135  *
 136  * Return LTTNG_TRIGGER_STATUS_OK on success, LTTNG_TRIGGER_STATUS_INVALID
 137  * if invalid parameters are passed.
 138  */
 139 extern enum lttng_trigger_status lttng_trigger_set_name(
 140                 struct lttng_trigger *trigger, const char *name);
 141
 142 /*
 143  * Destroy (frees) a trigger object.
 144  */
 145 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 146
 147 /*
 148  * Register a trigger to the session daemon.
 149  *
 150  * The trigger can be destroyed after this call.
 151  *
 152  * Return 0 on success, a negative LTTng error code on error.
 153  */
 154 extern int lttng_register_trigger(struct lttng_trigger *trigger);
 155
 156 /*
 157  * Unregister a trigger from the session daemon.
 158  *
 159  * The trigger can be destroyed after this call.
 160  *
 161  * Return 0 on success, a negative LTTng error code on error.
 162  */
 163 extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
 164
 165 /*
 166  * List triggers for the current user.
 167  *
 168  * On success, a newly-allocated trigger set is returned.
 169  *
 170  * The trigger set must be destroyed by the caller (see
 171  * lttng_triggers_destroy()).
 172  *
 173  * Returns LTTNG_OK on success, else a suitable LTTng error code.
 174  */
 175 extern enum lttng_error_code lttng_list_triggers(
 176                 struct lttng_triggers **triggers);
 177
 178 /*
 179  * Get a trigger from the set at a given index.
 180  *
 181  * Note that the trigger set maintains the ownership of the returned trigger.
 182  * It must not be destroyed by the user, nor should a reference to it be held
 183  * beyond the lifetime of the trigger set.
 184  *
 185  * Returns a trigger, or NULL on error.
 186  */
 187 extern const struct lttng_trigger *lttng_triggers_get_at_index(
 188                 const struct lttng_triggers *triggers, unsigned int index);
 189
 190 /*
 191  * Get the number of triggers in a trigger set.
 192  *
 193  * Return LTTNG_TRIGGER_STATUS_OK on success,
 194  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 195  */
 196 extern enum lttng_trigger_status lttng_triggers_get_count(
 197                 const struct lttng_triggers *triggers, unsigned int *count);
 198
 199 /*
 200  * Destroy a trigger set.
 201  */
 202 extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 203
 204
 205 #ifdef __cplusplus
 206 }
 207 #endif
 208
 209 #endif /* LTTNG_TRIGGER_H */