Implement open_run_as, using clone() CLONE_FILES
[lttng-tools.git] / lttng-sessiond / session.c
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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
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6 * as published by the Free Software Foundation; only version 2
7 * of the License.
91d76f53 8 *
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9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
050349bb 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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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
6c9cc2ab 20#include <limits.h>
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21#include <stdio.h>
22#include <stdlib.h>
23#include <string.h>
f6a9efaa 24#include <urcu.h>
5b74c7b1 25
54d01ffb 26#include <lttng-sessiond-comm.h>
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27#include <lttngerr.h>
28
f6a9efaa 29#include "hashtable.h"
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30#include "session.h"
31
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32#include "../hashtable/hash.h"
33
8c0faa1d 34/*
b5541356 35 * NOTES:
8c0faa1d 36 *
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37 * No ltt_session.lock is taken here because those data structure are widely
38 * spread across the lttng-tools code base so before caling functions below
39 * that can read/write a session, the caller MUST acquire the session lock
54d01ffb 40 * using session_lock() and session_unlock().
8c0faa1d 41 */
8c0faa1d 42
5b74c7b1 43/*
b5541356 44 * Init tracing session list.
5b74c7b1 45 *
b5541356 46 * Please see session.h for more explanation and correct usage of the list.
5b74c7b1 47 */
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48static struct ltt_session_list ltt_session_list = {
49 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
50 .lock = PTHREAD_MUTEX_INITIALIZER,
51 .count = 0,
52};
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53
54/*
050349bb 55 * Add a ltt_session structure to the global list.
5b74c7b1 56 *
050349bb 57 * The caller MUST acquire the session list lock before.
44e96653 58 * Returns the unique identifier for the session.
5b74c7b1 59 */
44e96653 60static int add_session_list(struct ltt_session *ls)
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61{
62 cds_list_add(&ls->list, &ltt_session_list.head);
44e96653 63 return ++ltt_session_list.count;
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64}
65
66/*
050349bb 67 * Delete a ltt_session structure to the global list.
b5541356 68 *
050349bb 69 * The caller MUST acquire the session list lock before.
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70 */
71static void del_session_list(struct ltt_session *ls)
72{
73 cds_list_del(&ls->list);
74 /* Sanity check */
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75 if (ltt_session_list.count > 0) {
76 ltt_session_list.count--;
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77 }
78}
79
b5541356 80/*
050349bb 81 * Return a pointer to the session list.
b5541356 82 */
54d01ffb 83struct ltt_session_list *session_get_list(void)
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84{
85 return &ltt_session_list;
86}
87
88/*
6c9cc2ab 89 * Acquire session list lock
b5541356 90 */
54d01ffb 91void session_lock_list(void)
b5541356 92{
6c9cc2ab 93 pthread_mutex_lock(&ltt_session_list.lock);
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94}
95
96/*
6c9cc2ab 97 * Release session list lock
b5541356 98 */
54d01ffb 99void session_unlock_list(void)
b5541356 100{
6c9cc2ab 101 pthread_mutex_unlock(&ltt_session_list.lock);
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102}
103
104/*
6c9cc2ab 105 * Acquire session lock
b5541356 106 */
54d01ffb 107void session_lock(struct ltt_session *session)
b5541356 108{
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109 pthread_mutex_lock(&session->lock);
110}
b5541356 111
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112/*
113 * Release session lock
114 */
54d01ffb 115void session_unlock(struct ltt_session *session)
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116{
117 pthread_mutex_unlock(&session->lock);
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118}
119
5b74c7b1 120/*
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121 * Return a ltt_session structure ptr that matches name. If no session found,
122 * NULL is returned. This must be called with the session lock held using
123 * session_lock_list and session_unlock_list.
5b74c7b1 124 */
54d01ffb 125struct ltt_session *session_find_by_name(char *name)
5b74c7b1 126{
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127 struct ltt_session *iter;
128
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129 DBG2("Trying to find session by name %s", name);
130
5b74c7b1 131 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
1b110e1b 132 if (strncmp(iter->name, name, NAME_MAX) == 0) {
74babd95 133 goto found;
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134 }
135 }
136
74babd95 137 iter = NULL;
5b74c7b1 138
74babd95 139found:
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140 return iter;
141}
142
143/*
050349bb 144 * Delete session from the session list and free the memory.
5b74c7b1 145 *
050349bb 146 * Return -1 if no session is found. On success, return 1;
5b74c7b1 147 */
271933a4 148int session_destroy(struct ltt_session *session)
5b74c7b1 149{
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150 /* Safety check */
151 if (session == NULL) {
152 ERR("Session pointer was null on session destroy");
153 return LTTCOMM_OK;
5b74c7b1 154 }
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155
156 DBG("Destroying session %s", session->name);
157 del_session_list(session);
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158 pthread_mutex_destroy(&session->lock);
159 free(session);
5b74c7b1 160
54d01ffb 161 return LTTCOMM_OK;
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162}
163
164/*
050349bb 165 * Create a brand new session and add it to the session list.
5b74c7b1 166 */
6df2e2c9 167int session_create(char *name, char *path, uid_t uid, gid_t gid)
5b74c7b1 168{
f3ed775e 169 int ret;
5b74c7b1 170 struct ltt_session *new_session;
e07ae692 171
54d01ffb 172 new_session = session_find_by_name(name);
5b74c7b1 173 if (new_session != NULL) {
54d01ffb 174 ret = LTTCOMM_EXIST_SESS;
f3ed775e 175 goto error_exist;
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176 }
177
178 /* Allocate session data structure */
ba7f0ae5 179 new_session = zmalloc(sizeof(struct ltt_session));
5b74c7b1 180 if (new_session == NULL) {
ba7f0ae5 181 perror("zmalloc");
54d01ffb 182 ret = LTTCOMM_FATAL;
f3ed775e 183 goto error_malloc;
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184 }
185
f3ed775e 186 /* Define session name */
5b74c7b1 187 if (name != NULL) {
74babd95 188 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
54d01ffb 189 ret = LTTCOMM_FATAL;
f3ed775e 190 goto error_asprintf;
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191 }
192 } else {
f3ed775e 193 ERR("No session name given");
54d01ffb 194 ret = LTTCOMM_FATAL;
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195 goto error;
196 }
197
198 /* Define session system path */
199 if (path != NULL) {
74babd95 200 if (snprintf(new_session->path, PATH_MAX, "%s", path) < 0) {
54d01ffb 201 ret = LTTCOMM_FATAL;
f3ed775e 202 goto error_asprintf;
5b74c7b1 203 }
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204 } else {
205 ERR("No session path given");
54d01ffb 206 ret = LTTCOMM_FATAL;
f3ed775e 207 goto error;
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208 }
209
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210 /* Init kernel session */
211 new_session->kernel_session = NULL;
f6a9efaa 212 new_session->ust_session = NULL;
1657e9bb 213
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214 /* Init lock */
215 pthread_mutex_init(&new_session->lock, NULL);
5b74c7b1 216
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217 new_session->uid = uid;
218 new_session->gid = gid;
219
b5541356 220 /* Add new session to the session list */
54d01ffb 221 session_lock_list();
a991f516 222 new_session->id = add_session_list(new_session);
54d01ffb 223 session_unlock_list();
b5541356 224
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225 DBG("Tracing session %s created in %s with ID %d by UID %d GID %d",
226 name, path, new_session->id,
227 new_session->uid, new_session->gid);
b082db07 228
54d01ffb 229 return LTTCOMM_OK;
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230
231error:
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232error_asprintf:
233 if (new_session != NULL) {
234 free(new_session);
235 }
5b74c7b1 236
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237error_exist:
238error_malloc:
239 return ret;
5b74c7b1 240}
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