| 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, <t_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 <t_session_list; |
| 83 | } |
| 84 | |
| 85 | /* |
| 86 | * Acquire session list lock |
| 87 | */ |
| 88 | void session_lock_list(void) |
| 89 | { |
| 90 | pthread_mutex_lock(<t_session_list.lock); |
| 91 | } |
| 92 | |
| 93 | /* |
| 94 | * Release session list lock |
| 95 | */ |
| 96 | void session_unlock_list(void) |
| 97 | { |
| 98 | pthread_mutex_unlock(<t_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, <t_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 | } |