| 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; only version 2 |
| 7 | * of the License. |
| 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 <limits.h> |
| 21 | #include <stdio.h> |
| 22 | #include <stdlib.h> |
| 23 | #include <string.h> |
| 24 | #include <urcu.h> |
| 25 | |
| 26 | #include <lttng-sessiond-comm.h> |
| 27 | #include <lttngerr.h> |
| 28 | |
| 29 | #include "hashtable.h" |
| 30 | #include "session.h" |
| 31 | |
| 32 | #include "../hashtable/hash.h" |
| 33 | |
| 34 | /* |
| 35 | * NOTES: |
| 36 | * |
| 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 |
| 40 | * using session_lock() and session_unlock(). |
| 41 | */ |
| 42 | |
| 43 | /* |
| 44 | * Init tracing session list. |
| 45 | * |
| 46 | * Please see session.h for more explanation and correct usage of the list. |
| 47 | */ |
| 48 | static 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 | }; |
| 53 | |
| 54 | /* |
| 55 | * Add a ltt_session structure to the global list. |
| 56 | * |
| 57 | * The caller MUST acquire the session list lock before. |
| 58 | * Returns the unique identifier for the session. |
| 59 | */ |
| 60 | static int add_session_list(struct ltt_session *ls) |
| 61 | { |
| 62 | cds_list_add(&ls->list, <t_session_list.head); |
| 63 | return ++ltt_session_list.count; |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * Delete a ltt_session structure to the global list. |
| 68 | * |
| 69 | * The caller MUST acquire the session list lock before. |
| 70 | */ |
| 71 | static void del_session_list(struct ltt_session *ls) |
| 72 | { |
| 73 | cds_list_del(&ls->list); |
| 74 | /* Sanity check */ |
| 75 | if (ltt_session_list.count > 0) { |
| 76 | ltt_session_list.count--; |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * Return a pointer to the session list. |
| 82 | */ |
| 83 | struct ltt_session_list *session_get_list(void) |
| 84 | { |
| 85 | return <t_session_list; |
| 86 | } |
| 87 | |
| 88 | /* |
| 89 | * Acquire session list lock |
| 90 | */ |
| 91 | void session_lock_list(void) |
| 92 | { |
| 93 | pthread_mutex_lock(<t_session_list.lock); |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | * Release session list lock |
| 98 | */ |
| 99 | void session_unlock_list(void) |
| 100 | { |
| 101 | pthread_mutex_unlock(<t_session_list.lock); |
| 102 | } |
| 103 | |
| 104 | /* |
| 105 | * Acquire session lock |
| 106 | */ |
| 107 | void session_lock(struct ltt_session *session) |
| 108 | { |
| 109 | pthread_mutex_lock(&session->lock); |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * Release session lock |
| 114 | */ |
| 115 | void session_unlock(struct ltt_session *session) |
| 116 | { |
| 117 | pthread_mutex_unlock(&session->lock); |
| 118 | } |
| 119 | |
| 120 | /* |
| 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. |
| 124 | */ |
| 125 | struct ltt_session *session_find_by_name(char *name) |
| 126 | { |
| 127 | struct ltt_session *iter; |
| 128 | |
| 129 | DBG2("Trying to find session by name %s", name); |
| 130 | |
| 131 | cds_list_for_each_entry(iter, <t_session_list.head, list) { |
| 132 | if (strncmp(iter->name, name, NAME_MAX) == 0) { |
| 133 | goto found; |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | iter = NULL; |
| 138 | |
| 139 | found: |
| 140 | return iter; |
| 141 | } |
| 142 | |
| 143 | /* |
| 144 | * Delete session from the session list and free the memory. |
| 145 | * |
| 146 | * Return -1 if no session is found. On success, return 1; |
| 147 | */ |
| 148 | int session_destroy(struct ltt_session *session) |
| 149 | { |
| 150 | /* Safety check */ |
| 151 | if (session == NULL) { |
| 152 | ERR("Session pointer was null on session destroy"); |
| 153 | return LTTCOMM_OK; |
| 154 | } |
| 155 | |
| 156 | DBG("Destroying session %s", session->name); |
| 157 | del_session_list(session); |
| 158 | pthread_mutex_destroy(&session->lock); |
| 159 | free(session); |
| 160 | |
| 161 | return LTTCOMM_OK; |
| 162 | } |
| 163 | |
| 164 | /* |
| 165 | * Create a brand new session and add it to the session list. |
| 166 | */ |
| 167 | int session_create(char *name, char *path, uid_t uid, gid_t gid) |
| 168 | { |
| 169 | int ret; |
| 170 | struct ltt_session *new_session; |
| 171 | |
| 172 | new_session = session_find_by_name(name); |
| 173 | if (new_session != NULL) { |
| 174 | ret = LTTCOMM_EXIST_SESS; |
| 175 | goto error_exist; |
| 176 | } |
| 177 | |
| 178 | /* Allocate session data structure */ |
| 179 | new_session = zmalloc(sizeof(struct ltt_session)); |
| 180 | if (new_session == NULL) { |
| 181 | perror("zmalloc"); |
| 182 | ret = LTTCOMM_FATAL; |
| 183 | goto error_malloc; |
| 184 | } |
| 185 | |
| 186 | /* Define session name */ |
| 187 | if (name != NULL) { |
| 188 | if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) { |
| 189 | ret = LTTCOMM_FATAL; |
| 190 | goto error_asprintf; |
| 191 | } |
| 192 | } else { |
| 193 | ERR("No session name given"); |
| 194 | ret = LTTCOMM_FATAL; |
| 195 | goto error; |
| 196 | } |
| 197 | |
| 198 | /* Define session system path */ |
| 199 | if (path != NULL) { |
| 200 | if (snprintf(new_session->path, PATH_MAX, "%s", path) < 0) { |
| 201 | ret = LTTCOMM_FATAL; |
| 202 | goto error_asprintf; |
| 203 | } |
| 204 | } else { |
| 205 | ERR("No session path given"); |
| 206 | ret = LTTCOMM_FATAL; |
| 207 | goto error; |
| 208 | } |
| 209 | |
| 210 | /* Init kernel session */ |
| 211 | new_session->kernel_session = NULL; |
| 212 | new_session->ust_session = NULL; |
| 213 | |
| 214 | /* Init lock */ |
| 215 | pthread_mutex_init(&new_session->lock, NULL); |
| 216 | |
| 217 | new_session->uid = uid; |
| 218 | new_session->gid = gid; |
| 219 | |
| 220 | /* Add new session to the session list */ |
| 221 | session_lock_list(); |
| 222 | new_session->id = add_session_list(new_session); |
| 223 | session_unlock_list(); |
| 224 | |
| 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); |
| 228 | |
| 229 | return LTTCOMM_OK; |
| 230 | |
| 231 | error: |
| 232 | error_asprintf: |
| 233 | if (new_session != NULL) { |
| 234 | free(new_session); |
| 235 | } |
| 236 | |
| 237 | error_exist: |
| 238 | error_malloc: |
| 239 | return ret; |
| 240 | } |