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
  15 struct lttng_action;
  16 struct lttng_condition;
  17 struct lttng_trigger;
  18 /* A set of triggers. */
  19 struct lttng_triggers;
  20
  21 #ifdef __cplusplus
  22 extern "C" {
  23 #endif
  24
  25 enum lttng_register_trigger_status {
  26         LTTNG_REGISTER_TRIGGER_STATUS_OK = 0,
  27         LTTNG_REGISTER_TRIGGER_STATUS_INVALID = -1,
  28 };
  29
  30 enum lttng_trigger_status {
  31         LTTNG_TRIGGER_STATUS_OK = 0,
  32         LTTNG_TRIGGER_STATUS_ERROR = -1,
  33         LTTNG_TRIGGER_STATUS_UNKNOWN = -2,
  34         LTTNG_TRIGGER_STATUS_INVALID = -3,
  35         LTTNG_TRIGGER_STATUS_UNSET = -4,
  36         LTTNG_TRIGGER_STATUS_UNSUPPORTED = -5,
  37         LTTNG_TRIGGER_STATUS_PERMISSION_DENIED = -6,
  38 };
  39
  40 /*
  41  * Create a trigger object associating a condition and an action.
  42  *
  43  * A trigger associates a condition and an action to take whenever the
  44  * condition evaluates to true. Such actions can, for example, consist
  45  * in the emission of a notification to clients listening through
  46  * notification channels.
  47  *
  48  * Prior to 2.13, the caller had to retain the ownership of both the condition
  49  * and action. Both objects had to be kept alive for the lifetime of the trigger
  50  * object. This is no longer the case as the condition and action objects are
  51  * internally reference counted. It is safe to destroy a condition and an action
  52  * after using them to create a trigger. However, they should no longer be used.
  53  *
  54  * If the action is a notification action with capture descriptors,
  55  * the condition must be an event rule condition.
  56  *
  57  * A trigger must be registered in order to become activate and can
  58  * be destroyed after its registration.
  59  *
  60  * Returns a trigger object on success, NULL on error.
  61  * Trigger objects must be destroyed using the lttng_trigger_destroy()
  62  * function.
  63  */
  64 extern struct lttng_trigger *lttng_trigger_create(
  65                 struct lttng_condition *condition, struct lttng_action *action);
  66
  67 /*
  68  * Set the user identity (uid) of a trigger.
  69  *
  70  * Only available for the root user (uid 0).
  71  *
  72  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  73  * LTTNG_TRIGGER_STATUS_EPERM if not authorized,
  74  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  75  */
  76 extern enum lttng_trigger_status lttng_trigger_set_owner_uid(
  77                 struct lttng_trigger *trigger, uid_t uid);
  78
  79 /*
  80  * Get the user identity (uid) of a trigger.
  81  *
  82  * Returns LTTNG_TRIGGER_STATUS_OK on success,
  83  * LTTNG_TRIGGER_STATUS_UNSET if unset,
  84  * LTTNG_TRIGGER_STATUS_INVALID if invalid parameters are passed.
  85  */
  86 extern enum lttng_trigger_status lttng_trigger_get_owner_uid(
  87                 const struct lttng_trigger *trigger, uid_t *uid);
  88
  89 /*
  90  * Get the condition of a trigger.
  91  *
  92  * The caller acquires no ownership of the returned condition.
  93  *
  94  * Returns a condition on success, NULL on error.
  95  */
  96 extern struct lttng_condition *lttng_trigger_get_condition(
  97                 struct lttng_trigger *trigger);
  98
  99 const struct lttng_condition *lttng_trigger_get_const_condition(
 100                 const struct lttng_trigger *trigger);
 101
 102 /*
 103  * Get the action of a trigger.
 104  *
 105  * The caller acquires no ownership of the returned action.
 106  *
 107  * Returns an action on success, NULL on error.
 108  */
 109 extern struct lttng_action *lttng_trigger_get_action(
 110                 struct lttng_trigger *trigger);
 111
 112 const struct lttng_action *lttng_trigger_get_const_action(
 113                 const struct lttng_trigger *trigger);
 114
 115 /*
 116  * Get the name of a trigger.
 117  *
 118  * The caller does not assume the ownership of the returned name.
 119  * The name shall only only be used for the duration of the trigger's
 120  * lifetime, or until a different name is set.
 121  *
 122  * Returns LTTNG_TRIGGER_STATUS_OK and a pointer to the trigger's name on
 123  * success, LTTNG_TRIGGER_STATUS_INVALID if an invalid parameter is passed,
 124  * or LTTNG_TRIGGER_STATUS_UNSET if the trigger is unnamed.
 125  */
 126 extern enum lttng_trigger_status lttng_trigger_get_name(
 127                 const struct lttng_trigger *trigger, const char **name);
 128
 129 /*
 130  * Destroy (frees) a trigger object.
 131  */
 132 extern void lttng_trigger_destroy(struct lttng_trigger *trigger);
 133
 134 /*
 135  * Register a trigger to the session daemon with a given name.
 136  *
 137  * The trigger object can be destroyed after this call.
 138  * On success, this function will set the trigger's name to `name`.
 139  *
 140  * Returns an LTTng status code.
 141  */
 142 extern enum lttng_error_code lttng_register_trigger_with_name(
 143                 struct lttng_trigger *trigger,
 144                 const char *name);
 145
 146 /*
 147  * Register a trigger to the session daemon, generating a unique name for its
 148  * owner.
 149  *
 150  * The trigger can be destroyed after this call.
 151  * On success, this function will set the trigger's name to the generated
 152  * name.
 153  *
 154  * Returns an LTTng status code.
 155  */
 156 extern enum lttng_error_code lttng_register_trigger_with_automatic_name(
 157                 struct lttng_trigger *trigger);
 158
 159 /*
 160  * Unregister a trigger from the session daemon.
 161  *
 162  * The trigger can be destroyed after this call.
 163  *
 164  * Return 0 on success, a negative LTTng error code on error.
 165  */
 166 extern int lttng_unregister_trigger(const struct lttng_trigger *trigger);
 167
 168 /*
 169  * List triggers for the current user.
 170  *
 171  * On success, a newly-allocated trigger set is returned.
 172  *
 173  * The trigger set must be destroyed by the caller (see
 174  * lttng_triggers_destroy()).
 175  *
 176  * Returns LTTNG_OK on success, else a suitable LTTng error code.
 177  */
 178 extern enum lttng_error_code lttng_list_triggers(
 179                 struct lttng_triggers **triggers);
 180
 181 /*
 182  * Get a trigger from the set at a given index.
 183  *
 184  * Note that the trigger set maintains the ownership of the returned trigger.
 185  * It must not be destroyed by the user, nor should a reference to it be held
 186  * beyond the lifetime of the trigger set.
 187  *
 188  * Returns a trigger, or NULL on error.
 189  */
 190 extern const struct lttng_trigger *lttng_triggers_get_at_index(
 191                 const struct lttng_triggers *triggers, unsigned int index);
 192
 193 /*
 194  * Get the number of triggers in a trigger set.
 195  *
 196  * Return LTTNG_TRIGGER_STATUS_OK on success,
 197  * LTTNG_TRIGGER_STATUS_INVALID when invalid parameters are passed.
 198  */
 199 extern enum lttng_trigger_status lttng_triggers_get_count(
 200                 const struct lttng_triggers *triggers, unsigned int *count);
 201
 202 /*
 203  * Destroy a trigger set.
 204  */
 205 extern void lttng_triggers_destroy(struct lttng_triggers *triggers);
 206
 207 /*
 208  * Deprecated: invocations should be replaced by
 209  * lttng_register_trigger_with_automatic_name().
 210  *
 211  * Register a trigger to the session daemon.
 212  *
 213  * The trigger can be destroyed after this call.
 214  *
 215  * Return 0 on success, a negative LTTng error code on error.
 216  */
 217 LTTNG_DEPRECATED("Use lttng_register_trigger_with_automatic_name")
 218 extern int lttng_register_trigger(struct lttng_trigger *trigger);
 219
 220 #ifdef __cplusplus
 221 }
 222 #endif
 223
 224 #endif /* LTTNG_TRIGGER_H */