Fix: Initialize ret to zero
[lttng-tools.git] / include / lttng / session.h
1 /*
2 * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
3 * Copyright (C) 2019 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
4 *
5 * This library is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU Lesser General Public License, version 2.1 only,
7 * as published by the Free Software Foundation.
8 *
9 * This library is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
12 * for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public License
15 * along with this library; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #ifndef LTTNG_SESSION_H
20 #define LTTNG_SESSION_H
21
22 #ifdef __cplusplus
23 extern "C" {
24 #endif
25
26 #include <lttng/constant.h>
27
28 enum lttng_tracker_type {
29 LTTNG_TRACKER_PID = 0,
30 LTTNG_TRACKER_VPID = 1,
31 LTTNG_TRACKER_UID = 2,
32 LTTNG_TRACKER_GID = 3,
33 LTTNG_TRACKER_VUID = 4,
34 LTTNG_TRACKER_VGID = 5,
35 };
36
37 enum lttng_tracker_id_type {
38 LTTNG_ID_UNKNOWN = -1,
39 LTTNG_ID_ALL = 0,
40 LTTNG_ID_VALUE = 1,
41 LTTNG_ID_STRING = 2,
42 };
43
44 struct lttng_tracker_id {
45 enum lttng_tracker_id_type type;
46 int value;
47 char *string;
48 };
49
50 struct lttng_handle;
51 struct lttng_session_descriptor;
52 struct lttng_destruction_handle;
53
54 /*
55 * Basic session information.
56 *
57 * The "enabled" field is only used when listing the sessions which indicate if
58 * it's started or not.
59 *
60 * The structures should be initialized to zero before use.
61 */
62 #define LTTNG_SESSION_PADDING1 8
63 struct lttng_session {
64 char name[LTTNG_NAME_MAX];
65 /*
66 * Human-readable representation of the trace's destination.
67 * In the case of a local tracing session, a path is provided:
68 * /path/to/the/output
69 *
70 * In the case of a remote (network) tracing session, the string has
71 * the following format:
72 * net://hostname/path:ctrl_port [data: data_port]
73 */
74 char path[PATH_MAX];
75 uint32_t enabled; /* enabled/started: 1, disabled/stopped: 0 */
76 uint32_t snapshot_mode;
77 unsigned int live_timer_interval; /* usec */
78
79 /*
80 * End of public attributes.
81 * The remaining fields are used to deal with ABI management concerns.
82 */
83
84 /*
85 * 32-bit architectures are already naturally aligned on 4 bytes after
86 * 'live_timer_interval'. However, the offset does not result in a
87 * natural alignment on 64-bit architectures. Adding 4 bytes of
88 * padding here results in an aligned offset after 'alignement_padding'
89 * for both bitnesses.
90 *
91 * This was added since not all compilers appear to align unions in the
92 * same way. Some (e.g. MSVC) do not seem to impose an alignement
93 * constraint while others (e.g. gcc, clang, icc) seem to align it to
94 * ensure 'ptr' is naturally aligned.
95 */
96 char alignment_padding[4];
97 union {
98 /*
99 * Ensure the 'extended' union has the same size for both
100 * 32-bit and 64-bit builds.
101 */
102 char padding[LTTNG_SESSION_PADDING1];
103 void *ptr;
104 } extended;
105 };
106
107 /*
108 * Create a session on the session daemon from a session descriptor.
109 *
110 * See the session descriptor API description in session-descriptor.h
111 *
112 * Note that unspecified session descriptor parameters, such as a session's
113 * name, are updated in the session descriptor if the creation of the session
114 * succeeds. This allows users to query the session's auto-generated name
115 * after its creation. Note that other attributes can be queried using the
116 * session listing API.
117 *
118 * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
119 * return codes.
120 */
121 extern enum lttng_error_code lttng_create_session_ext(
122 struct lttng_session_descriptor *session_descriptor);
123
124 /*
125 * Create a tracing session using a name and an optional URL.
126 *
127 * If _url_ is NULL, no consumer is created for the session. The name can't be
128 * NULL here.
129 *
130 * Return 0 on success else a negative LTTng error code.
131 */
132 extern int lttng_create_session(const char *name, const char *url);
133
134 /*
135 * Create a tracing session that will exclusively be used for snapshot meaning
136 * the session will be in no output mode and every channel enabled for that
137 * session will be set in overwrite mode and in mmap output since splice is not
138 * supported.
139 *
140 * Name can't be NULL. If an url is given, it will be used to create a default
141 * snapshot output using it as a destination. If NULL, no output will be
142 * defined and an add-output call will be needed.
143 *
144 * Return 0 on success else a negative LTTng error code.
145 */
146 extern int lttng_create_session_snapshot(const char *name,
147 const char *snapshot_url);
148
149 /*
150 * Create a session exclusively used for live reading.
151 *
152 * In this mode, the switch-timer parameter is forced for each UST channel, a
153 * live-switch-timer is enabled for kernel channels, manually setting
154 * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
155 * indexes are sent and metadata is checked for each packet.
156 *
157 * Name can't be NULL. If no URL is given, the default is to send the data to
158 * net://127.0.0.1. The timer_interval is in usec.
159 *
160 * Return 0 on success else a negative LTTng error code.
161 */
162 extern int lttng_create_session_live(const char *name, const char *url,
163 unsigned int timer_interval);
164
165 /*
166 * Destroy a tracing session.
167 *
168 * The session will not be usable, tracing will be stopped thus buffers will be
169 * flushed.
170 *
171 * This call will wait for data availability for each domain of the session,
172 * which can take an arbitrary amount of time. However, when returning the
173 * tracing data is guaranteed to be ready to be read and analyzed.
174 *
175 * lttng_destroy_session_no_wait() may be used if such a guarantee is not
176 * needed.
177 *
178 * The name can't be NULL here.
179 *
180 * Return 0 on success else a negative LTTng error code.
181 */
182 extern int lttng_destroy_session(const char *name);
183
184 /*
185 * Destroy a tracing session.
186 *
187 * Performs the same function as lttng_destroy_session(), but provides
188 * an lttng_destruction_handle which can be used to wait for the completion
189 * of the session's destruction. The lttng_destroy_handle can also be used
190 * obtain the status and archive location of any implicit session
191 * rotation that may have occurred during the session's destruction.
192 *
193 * Returns LTTNG_OK on success. The returned handle is owned by the caller
194 * and must be free'd using lttng_destruction_handle_destroy().
195 */
196 extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name,
197 struct lttng_destruction_handle **handle);
198
199 /*
200 * Behaves exactly like lttng_destroy_session but does not wait for data
201 * availability.
202 */
203 extern int lttng_destroy_session_no_wait(const char *name);
204
205 /*
206 * List all the tracing sessions.
207 *
208 * Return the number of entries of the "lttng_session" array. The caller
209 * must free the returned sessions array directly using free().
210 *
211 * On error, a negative LTTng error code is returned.
212 */
213 extern int lttng_list_sessions(struct lttng_session **sessions);
214
215 /*
216 * Get the creation time of an lttng_session object on the session daemon.
217 *
218 * This function must only be used with lttng_session objects returned
219 * by lttng_list_sessions() or lttng_session_create().
220 *
221 * The creation time returned is a UNIX timestamp; the number of seconds since
222 * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
223 *
224 * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
225 * return codes.
226 */
227 extern enum lttng_error_code lttng_session_get_creation_time(
228 const struct lttng_session *session, uint64_t *creation_time);
229
230 /*
231 * Set the shared memory path for a session.
232 *
233 * Sets the (optional) file system path where shared memory buffers will
234 * be created for the session. This is useful for buffer extraction on
235 * crash, when used with filesystems like pramfs.
236 *
237 * Return 0 on success else a negative LTTng error code.
238 */
239 extern int lttng_set_session_shm_path(const char *session_name,
240 const char *shm_path);
241
242 /*
243 * Add ID to session tracker.
244 *
245 * tracker_type is the type of tracker.
246 * id the id to track.
247 *
248 * Return 0 on success else a negative LTTng error code.
249 */
250 extern int lttng_track_id(struct lttng_handle *handle,
251 enum lttng_tracker_type tracker_type,
252 const struct lttng_tracker_id *id);
253
254 /*
255 * Remove ID from session tracker.
256 *
257 * tracker_type is the type of tracker.
258 * id the id to untrack.
259 *
260 * Return 0 on success else a negative LTTng error code.
261 */
262 extern int lttng_untrack_id(struct lttng_handle *handle,
263 enum lttng_tracker_type tracker_type,
264 const struct lttng_tracker_id *id);
265
266 /*
267 * List IDs in the tracker.
268 *
269 * tracker_type is the type of tracker.
270 * ids is set to an allocated array of IDs currently tracked. On
271 * success, ids and the strings it contains must be freed by the
272 * caller.
273 * nr_ids is set to the number of entries contained by the ids array.
274 *
275 * Returns 0 on success, else a negative LTTng error code.
276 */
277 extern int lttng_list_tracker_ids(struct lttng_handle *handle,
278 enum lttng_tracker_type tracker_type,
279 struct lttng_tracker_id **ids,
280 size_t *nr_ids);
281
282 /*
283 * Add PID to session tracker.
284 *
285 * A pid argument >= 0 adds the PID to the session tracker.
286 * A pid argument of -1 means "track all PIDs".
287 *
288 * Return 0 on success else a negative LTTng error code.
289 */
290 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
291
292 /*
293 * Remove PID from session tracker.
294 *
295 * A pid argument >= 0 removes the PID from the session tracker.
296 * A pid argument of -1 means "untrack all PIDs".
297 *
298 * Return 0 on success else a negative LTTng error code.
299 */
300 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
301
302 /*
303 * List PIDs in the tracker.
304 *
305 * enabled is set to whether the PID tracker is enabled.
306 * pids is set to an allocated array of PIDs currently tracked. On
307 * success, pids must be freed by the caller.
308 * nr_pids is set to the number of entries contained by the pids array.
309 *
310 * Returns 0 on success, else a negative LTTng error code.
311 */
312 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
313 int *enabled, int32_t **pids, size_t *nr_pids);
314
315 #ifdef __cplusplus
316 }
317 #endif
318
319 #endif /* LTTNG_SESSION_H */
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