Add kernel sesison and channel creation support
[lttng-tools.git] / ltt-sessiond / trace.c
1 /*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18
19 #define _GNU_SOURCE
20 #include <errno.h>
21 #include <limits.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <urcu/list.h>
26 #include <ust/ustctl.h>
27
28 #include "liblttsessiondcomm.h"
29 #include "lttngerr.h"
30 #include "trace.h"
31 #include "session.h"
32 #include "ltt-sessiond.h"
33
34 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
35 struct ltt_session *session, pid_t pid);
36
37 /*
38 * find_session_ust_trace_by_pid
39 *
40 * Iterate over the session ust_traces and
41 * return a pointer or NULL if not found.
42 */
43 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
44 struct ltt_session *session, pid_t pid)
45 {
46 struct ltt_ust_trace *iter;
47
48 cds_list_for_each_entry(iter, &session->ust_traces, list) {
49 if (iter->pid == pid) {
50 /* Found */
51 return iter;
52 }
53 }
54
55 return NULL;
56 }
57
58 /*
59 * get_trace_count_per_session
60 *
61 * Return the total count of traces (ust and kernel)
62 * for the specified session.
63 */
64 int get_trace_count_per_session(struct ltt_session *session)
65 {
66 return session->ust_trace_count + session->kern_session_count;
67 }
68
69 /*
70 * get_traces_per_session
71 *
72 * Fill the lttng_trace array of all the
73 * available trace of the session.
74 */
75 void get_traces_per_session(struct ltt_session *session, struct lttng_trace *traces)
76 {
77 int i = 0;
78 struct ltt_ust_trace *ust_iter;
79 struct lttng_trace trace;
80
81 DBG("Getting userspace traces for session %s", session->name);
82
83 /* Getting userspace traces */
84 cds_list_for_each_entry(ust_iter, &session->ust_traces, list) {
85 trace.type = USERSPACE;
86 trace.pid = ust_iter->pid;
87 strncpy(trace.name, ust_iter->name, sizeof(trace.name));
88 trace.name[sizeof(trace.name) - 1] = '\0';
89 memcpy(&traces[i], &trace, sizeof(trace));
90 memset(&trace, 0, sizeof(trace));
91 i++;
92 }
93
94 DBG("Getting kernel traces for session %s", session->name);
95
96 /* Getting kernel traces */
97 if (session->kern_session_count > 0) {
98 trace.type = KERNEL;
99 strncpy(trace.name, "kernel", 6);
100 memcpy(&traces[i], &trace, sizeof(trace));
101 }
102 }
103
104 /*
105 * ust_create_trace
106 *
107 * Create an userspace trace using pid.
108 * This trace is then appended to the current session
109 * ust trace list.
110 */
111 int ust_create_trace(struct command_ctx *cmd_ctx)
112 {
113 int ret;
114 struct ltt_ust_trace *trace;
115
116 DBG("Creating trace for pid %d", cmd_ctx->lsm->pid);
117
118 trace = malloc(sizeof(struct ltt_ust_trace));
119 if (trace == NULL) {
120 perror("malloc");
121 ret = -1;
122 goto error;
123 }
124
125 /* Init */
126 trace->pid = cmd_ctx->lsm->pid;
127 trace->shmid = 0;
128 /* NOTE: to be removed. Trace name will no longer be
129 * required for LTTng userspace tracer. For now, we set it
130 * to 'auto' for API compliance.
131 */
132 snprintf(trace->name, 5, "auto");
133
134 ret = ustctl_create_trace(cmd_ctx->ust_sock, trace->name);
135 if (ret < 0) {
136 ret = LTTCOMM_CREATE_FAIL;
137 goto error_create;
138 }
139
140 /* Check if current session is valid */
141 if (cmd_ctx->session) {
142 cds_list_add(&trace->list, &cmd_ctx->session->ust_traces);
143 cmd_ctx->session->ust_trace_count++;
144 }
145
146 return LTTCOMM_OK;
147
148 error_create:
149 free(trace);
150 error:
151 return ret;
152 }
153
154 /*
155 * ust_start_trace
156 *
157 * Start a trace. This trace, identified by the pid, must be
158 * in the current session ust_traces list.
159 */
160 int ust_start_trace(struct command_ctx *cmd_ctx)
161 {
162 int ret;
163 struct ltt_ust_trace *trace;
164
165 DBG("Starting trace for pid %d", cmd_ctx->lsm->pid);
166
167 trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
168 if (trace == NULL) {
169 ret = LTTCOMM_NO_TRACE;
170 goto error;
171 }
172
173 ret = ustctl_start_trace(cmd_ctx->ust_sock, "auto");
174 if (ret < 0) {
175 ret = LTTCOMM_START_FAIL;
176 goto error;
177 }
178
179 ret = LTTCOMM_OK;
180
181 error:
182 return ret;
183 }
184
185 /*
186 * ust_stop_trace
187 *
188 * Stop a trace. This trace, identified by the pid, must be
189 * in the current session ust_traces list.
190 */
191 int ust_stop_trace(struct command_ctx *cmd_ctx)
192 {
193 int ret;
194 struct ltt_ust_trace *trace;
195
196 DBG("Stopping trace for pid %d", cmd_ctx->lsm->pid);
197
198 trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
199 if (trace == NULL) {
200 ret = LTTCOMM_NO_TRACE;
201 goto error;
202 }
203
204 ret = ustctl_stop_trace(cmd_ctx->ust_sock, trace->name);
205 if (ret < 0) {
206 ret = LTTCOMM_STOP_FAIL;
207 goto error;
208 }
209
210 ret = LTTCOMM_OK;
211
212 error:
213 return ret;
214 }
215
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