Fix: return value signedness
[lttng-tools.git] / src / bin / lttng-sessiond / session.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 modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #define _GNU_SOURCE
19 #include <limits.h>
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <sys/stat.h>
24 #include <urcu.h>
25
26 #include <common/common.h>
27 #include <common/sessiond-comm/sessiond-comm.h>
28
29 #include "session.h"
30
31 /*
32 * NOTES:
33 *
34 * No ltt_session.lock is taken here because those data structure are widely
35 * spread across the lttng-tools code base so before caling functions below
36 * that can read/write a session, the caller MUST acquire the session lock
37 * using session_lock() and session_unlock().
38 */
39
40 /*
41 * Init tracing session list.
42 *
43 * Please see session.h for more explanation and correct usage of the list.
44 */
45 static struct ltt_session_list ltt_session_list = {
46 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
47 .lock = PTHREAD_MUTEX_INITIALIZER,
48 .count = 0,
49 };
50
51 /*
52 * Add a ltt_session structure to the global list.
53 *
54 * The caller MUST acquire the session list lock before.
55 * Returns the unique identifier for the session.
56 */
57 static unsigned int add_session_list(struct ltt_session *ls)
58 {
59 cds_list_add(&ls->list, &ltt_session_list.head);
60 return ++ltt_session_list.count;
61 }
62
63 /*
64 * Delete a ltt_session structure to the global list.
65 *
66 * The caller MUST acquire the session list lock before.
67 */
68 static void del_session_list(struct ltt_session *ls)
69 {
70 cds_list_del(&ls->list);
71 /* Sanity check */
72 if (ltt_session_list.count > 0) {
73 ltt_session_list.count--;
74 }
75 }
76
77 /*
78 * Return a pointer to the session list.
79 */
80 struct ltt_session_list *session_get_list(void)
81 {
82 return &ltt_session_list;
83 }
84
85 /*
86 * Acquire session list lock
87 */
88 void session_lock_list(void)
89 {
90 pthread_mutex_lock(&ltt_session_list.lock);
91 }
92
93 /*
94 * Release session list lock
95 */
96 void session_unlock_list(void)
97 {
98 pthread_mutex_unlock(&ltt_session_list.lock);
99 }
100
101 /*
102 * Acquire session lock
103 */
104 void session_lock(struct ltt_session *session)
105 {
106 pthread_mutex_lock(&session->lock);
107 }
108
109 /*
110 * Release session lock
111 */
112 void session_unlock(struct ltt_session *session)
113 {
114 pthread_mutex_unlock(&session->lock);
115 }
116
117 /*
118 * Return a ltt_session structure ptr that matches name. If no session found,
119 * NULL is returned. This must be called with the session lock held using
120 * session_lock_list and session_unlock_list.
121 */
122 struct ltt_session *session_find_by_name(char *name)
123 {
124 struct ltt_session *iter;
125
126 DBG2("Trying to find session by name %s", name);
127
128 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
129 if (strncmp(iter->name, name, NAME_MAX) == 0) {
130 goto found;
131 }
132 }
133
134 iter = NULL;
135
136 found:
137 return iter;
138 }
139
140 /*
141 * Delete session from the session list and free the memory.
142 *
143 * Return -1 if no session is found. On success, return 1;
144 */
145 int session_destroy(struct ltt_session *session)
146 {
147 /* Safety check */
148 if (session == NULL) {
149 ERR("Session pointer was null on session destroy");
150 return LTTCOMM_OK;
151 }
152
153 DBG("Destroying session %s", session->name);
154 del_session_list(session);
155 pthread_mutex_destroy(&session->lock);
156 free(session);
157
158 return LTTCOMM_OK;
159 }
160
161 /*
162 * Create a brand new session and add it to the session list.
163 */
164 int session_create(char *name, char *path, uid_t uid, gid_t gid)
165 {
166 int ret;
167 struct ltt_session *new_session;
168
169 new_session = session_find_by_name(name);
170 if (new_session != NULL) {
171 ret = LTTCOMM_EXIST_SESS;
172 goto error_exist;
173 }
174
175 /* Allocate session data structure */
176 new_session = zmalloc(sizeof(struct ltt_session));
177 if (new_session == NULL) {
178 PERROR("zmalloc");
179 ret = LTTCOMM_FATAL;
180 goto error_malloc;
181 }
182
183 /* Define session name */
184 if (name != NULL) {
185 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
186 ret = LTTCOMM_FATAL;
187 goto error_asprintf;
188 }
189 } else {
190 ERR("No session name given");
191 ret = LTTCOMM_FATAL;
192 goto error;
193 }
194
195 /* Define session system path */
196 if (path != NULL) {
197 if (snprintf(new_session->path, PATH_MAX, "%s", path) < 0) {
198 ret = LTTCOMM_FATAL;
199 goto error_asprintf;
200 }
201 } else {
202 ERR("No session path given");
203 ret = LTTCOMM_FATAL;
204 goto error;
205 }
206
207 /* Init kernel session */
208 new_session->kernel_session = NULL;
209 new_session->ust_session = NULL;
210
211 /* Init lock */
212 pthread_mutex_init(&new_session->lock, NULL);
213
214 new_session->uid = uid;
215 new_session->gid = gid;
216
217 ret = run_as_mkdir_recursive(new_session->path, S_IRWXU | S_IRWXG,
218 new_session->uid, new_session->gid);
219 if (ret < 0) {
220 if (ret != -EEXIST) {
221 ERR("Trace directory creation error");
222 ret = LTTCOMM_CREATE_DIR_FAIL;
223 goto error;
224 }
225 }
226
227 /* Add new session to the session list */
228 session_lock_list();
229 new_session->id = add_session_list(new_session);
230 session_unlock_list();
231
232 DBG("Tracing session %s created in %s with ID %u by UID %d GID %d",
233 name, path, new_session->id,
234 new_session->uid, new_session->gid);
235
236 return LTTCOMM_OK;
237
238 error:
239 error_asprintf:
240 if (new_session != NULL) {
241 free(new_session);
242 }
243
244 error_exist:
245 error_malloc:
246 return ret;
247 }
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