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 #include <lttng/lttng-export.h>
  16
  17 struct lttng_action;
  18 struct lttng_condition;
  19 struct lttng_trigger;
  20 /* A set of triggers. */
  21 struct lttng_triggers;
  22
  23 #ifdef __cplusplus
  24 extern "C" {
  25 #endif
  26
  27 enum lttng_register_trigger_status {
  28         LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
  29         LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
  30 };
  31
  32 enum lttng_trigger_status {
  33         LTTNG_TRIGGER_STATUS_OK = 0,
  34         LTTNG_TRIGGER_STATUS_ERROR = -1,
  35         LTTNG_TRIGGER_STATUS_UNKNOWN = -2,
  36         LTTNG_TRIGGER_STATUS_INVALID = -3,
  37         LTTNG_TRIGGER_STATUS_UNSET = -4,
  38         LTTNG_TRIGGER_STATUS_UNSUPPORTED = -5,
  39         LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
  40 };
  41
  42 /*
  43  * Create a trigger object associating a condition and an action.
  44  *
  45  * A trigger associates a condition and an action to take whenever the
  46  * condition evaluates to true. Such actions can, for example, consist
  47  * in the emission of a notification to clients listening through
  48  * notification channels.
  49  *
  50  * Prior to 2.13, the caller had to retain the ownership of both the condition
  51  * and action. Both objects had to be kept alive for the lifetime of the trigger
  52  * object. This is no longer the case as the condition and action objects are
  53  * internally reference counted. It is safe to destroy a condition and an action
  54  * after using them to create a trigger. However, they should no longer be used.
  55  *
  56  * If the action is a notification action with capture descriptors,
  57  * the condition must be an event rule condition.
  58  *
  59  * A trigger must be registered in order to become activate and can
  60  * be destroyed after its registration.
  61  *
  62  * Returns a trigger object on success, NULL on error.
  63  * Trigger objects must be destroyed using the lttng_trigger_destroy()
  64  * function.
  65  */
  66 LTTNG_EXPORT extern struct lttng_trigger *lttng_trigger_create(
  67                 struct lttng_condition *condition, struct lttng_action *action);
  68
  69 /*
  70  * Set the user identity (uid) of a trigger.
  71  *
  72  * Only available for the root user (uid 0).
  73  *
  74  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  75  * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
  76  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  77  */
  78 LTTNG_EXPORT extern enum lttng_trigger_status lttng_trigger_set_owner_uid(
  79                 struct lttng_trigger *trigger, uid_t uid);
  80
  81 /*
  82  * Get the user identity (uid) of a trigger.
  83  *
  84  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  85  * LTTNG_TRIGGER_STATUS_UNSET if unset,
  86  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  87  */
  88 LTTNG_EXPORT extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
  89                 const struct lttng_trigger *trigger, uid_t *uid);
  90
  91 /*
  92  * Get the condition of a trigger.
  93  *
  94  * The caller acquires no ownership of the returned condition.
  95  *
  96  * Returns a condition on success, NULL on error.
  97  */
  98 LTTNG_EXPORT extern struct lttng_condition *lttng_trigger_get_condition(
  99                 struct lttng_trigger *trigger);
 100
 101 LTTNG_EXPORT extern const struct lttng_condition *lttng_trigger_get_const_condition(
 102                 const struct lttng_trigger *trigger);
 103
 104 /*
 105  * Get the action of a trigger.
 106  *
 107  * The caller acquires no ownership of the returned action.
 108  *
 109  * Returns an action on success, NULL on error.
 110  */
 111 LTTNG_EXPORT extern struct lttng_action *lttng_trigger_get_action(
 112                 struct lttng_trigger *trigger);
 113
 114 LTTNG_EXPORT extern const struct lttng_action *lttng_trigger_get_const_action(
 115                 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 lttng_trigger_get_name(
 129                 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 lttng_register_trigger_with_name(
 145                 struct lttng_trigger *trigger,
 146                 const char *name);
 147
 148 /*
 149  * Register a trigger to the session daemon, generating a unique name for its
 150  * owner.
 151  *
 152  * The trigger can be destroyed after this call.
 153  * On success, this function will set the trigger's name to the generated
 154  * name.
 155  *
 156  * Returns an LTTng status code.
 157  */
 158 LTTNG_EXPORT extern enum lttng_error_code lttng_register_trigger_with_automatic_name(
 159                 struct lttng_trigger *trigger);
 160
 161 /*
 162  * Unregister a trigger from the session daemon.
 163  *
 164  * The trigger can be destroyed after this call.
 165  *
 166  * Return 0 on success, a negative LTTng error code on error.
 167  */
 168 LTTNG_EXPORT extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
 169
 170 /*
 171  * List triggers for the current user.
 172  *
 173  * On success, a newly-allocated trigger set is returned.
 174  *
 175  * The trigger set must be destroyed by the caller (see
 176  * lttng_triggers_destroy()).
 177  *
 178  * Returns LTTNG_OK on success, else a suitable LTTng error code.
 179  */
 180 LTTNG_EXPORT extern enum lttng_error_code lttng_list_triggers(
 181                 struct lttng_triggers **triggers);
 182
 183 /*
 184  * Get a trigger from the set at a given index.
 185  *
 186  * Note that the trigger set maintains the ownership of the returned trigger.
 187  * It must not be destroyed by the user, nor should a reference to it be held
 188  * beyond the lifetime of the trigger set.
 189  *
 190  * Returns a trigger, or NULL on error.
 191  */
 192 LTTNG_EXPORT extern const struct lttng_trigger *lttng_triggers_get_at_index(
 193                 const struct lttng_triggers *triggers, unsigned int index);
 194
 195 /*
 196  * Get the number of triggers in a trigger set.
 197  *
 198  * Return LTTNG_TRIGGER_STATUS_OK on success,
 199  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 200  */
 201 LTTNG_EXPORT extern enum lttng_trigger_status lttng_triggers_get_count(
 202                 const struct lttng_triggers *triggers, unsigned int *count);
 203
 204 /*
 205  * Destroy a trigger set.
 206  */
 207 LTTNG_EXPORT extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 208
 209 /*
 210  * Deprecated: invocations should be replaced by
 211  * lttng_register_trigger_with_automatic_name().
 212  *
 213  * Register a trigger to the session daemon.
 214  *
 215  * The trigger can be destroyed after this call.
 216  *
 217  * Return 0 on success, a negative LTTng error code on error.
 218  */
 219 LTTNG_DEPRECATED("Use lttng_register_trigger_with_automatic_name")
 220 LTTNG_EXPORT extern int lttng_register_trigger(struct lttng_trigger *trigger);
 221
 222 #ifdef __cplusplus
 223 }
 224 #endif
 225
 226 #endif /* LTTNG_TRIGGER_H */