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 <lttng/constant.h>
  13 #include <inttypes.h>
  14 #include <lttng/lttng-error.h>
  15
  16 struct lttng_action;
  17 struct lttng_condition;
  18 struct lttng_trigger;
  19 /* A set of triggers. */
  20 struct lttng_triggers;
  21
  22 #ifdef __cplusplus
  23 extern "C" {
  24 #endif
  25
  26 enum lttng_register_trigger_status {
  27         LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
  28         LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
  29 };
  30
  31 enum lttng_trigger_status {
  32         LTTNG_TRIGGER_STATUS_OK = 0,
  33         LTTNG_TRIGGER_STATUS_ERROR = -1,
  34         LTTNG_TRIGGER_STATUS_UNKNOWN = -2,
  35         LTTNG_TRIGGER_STATUS_INVALID = -3,
  36         LTTNG_TRIGGER_STATUS_UNSET = -4,
  37         LTTNG_TRIGGER_STATUS_UNSUPPORTED = -5,
  38         LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
  39 };
  40
  41 /*
  42  * Create a trigger object associating a condition and an action.
  43  *
  44  * A trigger associates a condition and an action to take whenever the
  45  * condition evaluates to true. Such actions can, for example, consist
  46  * in the emission of a notification to clients listening through
  47  * notification channels.
  48  *
  49  * Prior to 2.13, the caller had to retain the ownership of both the condition
  50  * and action. Both objects had to be kept alive for the lifetime of the trigger
  51  * object. This is no longer the case as the condition and action objects are
  52  * internally reference counted. It is safe to destroy a condition and an action
  53  * after using them to create a trigger. However, they should no longer be used.
  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 extern 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 extern 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 the trigger is unnamed.
 126  */
 127 extern enum lttng_trigger_status lttng_trigger_get_name(
 128                 const struct lttng_trigger *trigger, const char **name);
 129
 130 /*
 131  * Destroy (frees) a trigger object.
 132  */
 133 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 134
 135 /*
 136  * Register a trigger to the session daemon with a given name.
 137  *
 138  * The trigger object can be destroyed after this call.
 139  * On success, this function will set the trigger's name to `name`.
 140  *
 141  * Returns an LTTng status code.
 142  */
 143 extern enum lttng_error_code lttng_register_trigger_with_name(
 144                 struct lttng_trigger *trigger,
 145                 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 extern enum lttng_error_code lttng_register_trigger_with_automatic_name(
 158                 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 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 extern enum lttng_error_code lttng_list_triggers(
 180                 struct lttng_triggers **triggers);
 181
 182 /*
 183  * Get a trigger from the set at a given index.
 184  *
 185  * Note that the trigger set maintains the ownership of the returned trigger.
 186  * It must not be destroyed by the user, nor should a reference to it be held
 187  * beyond the lifetime of the trigger set.
 188  *
 189  * Returns a trigger, or NULL on error.
 190  */
 191 extern const struct lttng_trigger *lttng_triggers_get_at_index(
 192                 const struct lttng_triggers *triggers, unsigned int index);
 193
 194 /*
 195  * Get the number of triggers in a trigger set.
 196  *
 197  * Return LTTNG_TRIGGER_STATUS_OK on success,
 198  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 199  */
 200 extern enum lttng_trigger_status lttng_triggers_get_count(
 201                 const struct lttng_triggers *triggers, unsigned int *count);
 202
 203 /*
 204  * Destroy a trigger set.
 205  */
 206 extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 207
 208 /*
 209  * Deprecated: invocations should be replaced by
 210  * lttng_register_trigger_with_automatic_name().
 211  *
 212  * Register a trigger to the session daemon.
 213  *
 214  * The trigger can be destroyed after this call.
 215  *
 216  * Return 0 on success, a negative LTTng error code on error.
 217  */
 218 LTTNG_DEPRECATED("Use lttng_register_trigger_with_automatic_name")
 219 extern int lttng_register_trigger(struct lttng_trigger *trigger);
 220
 221 #ifdef __cplusplus
 222 }
 223 #endif
 224
 225 #endif /* LTTNG_TRIGGER_H */