ltt-sessiond/traceable-app.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; 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 <errno.h>
  21 #include <pthread.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <urcu/list.h>
  25
  26 #include "lttngerr.h"
  27 #include "traceable-app.h"
  28
  29 /* Number of element for the list below. */
  30 static unsigned int traceable_app_count;
  31
  32 /* Init ust traceabl application's list */
  33 struct ltt_traceable_app_list ltt_traceable_app_list = {
  34         .head = CDS_LIST_HEAD_INIT(ltt_traceable_app_list.head),
  35 };
  36
  37 /* List mutex */
  38 pthread_mutex_t ltt_traceable_app_list_mutex;
  39
  40 /* Internal function */
  41 static void add_traceable_app(struct ltt_traceable_app *lta);
  42 static void del_traceable_app(struct ltt_traceable_app *lta);
  43
  44 /*
  45  * Add a traceable application structure to the global list protected by a
  46  * mutex.
  47  */
  48 static void add_traceable_app(struct ltt_traceable_app *lta)
  49 {
  50         pthread_mutex_lock(&ltt_traceable_app_list_mutex);
  51         cds_list_add(&lta->list, &ltt_traceable_app_list.head);
  52         traceable_app_count++;
  53         pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
  54 }
  55
  56 /*
  57  * Delete a traceable application structure from the global list protected by a
  58  * mutex.
  59  */
  60 static void del_traceable_app(struct ltt_traceable_app *lta)
  61 {
  62         pthread_mutex_lock(&ltt_traceable_app_list_mutex);
  63         cds_list_del(&lta->list);
  64         /* Sanity check */
  65         if (traceable_app_count != 0) {
  66                 traceable_app_count--;
  67         }
  68         pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
  69 }
  70
  71 /*
  72  * Using pid and uid (of the app), allocate a new ltt_traceable_app struct and
  73  * add it to the global traceable app list.
  74  *
  75  * On success, return 0, else return malloc ENOMEM.
  76  */
  77 int register_traceable_app(pid_t pid, uid_t uid)
  78 {
  79         struct ltt_traceable_app *lta;
  80
  81         lta = malloc(sizeof(struct ltt_traceable_app));
  82         if (lta == NULL) {
  83                 perror("malloc");
  84                 return -ENOMEM;
  85         }
  86
  87         lta->uid = uid;
  88         lta->pid = pid;
  89         add_traceable_app(lta);
  90         DBG("Application %d registered with UID %d", pid, uid);
  91
  92         return 0;
  93 }
  94
  95 /*
  96  * Unregister app by removing it from the global traceable app list and freeing
  97  * the data struct.
  98  */
  99 void unregister_traceable_app(pid_t pid)
 100 {
 101         struct ltt_traceable_app *lta;
 102
 103         lta = find_app_by_pid(pid);
 104         if (lta != NULL) {
 105                 del_traceable_app(lta);
 106                 free(lta);
 107                 DBG("PID %d unregistered", pid);
 108         }
 109 }
 110
 111 /*
 112  * Return traceable_app_count
 113  */
 114 unsigned int get_app_count(void)
 115 {
 116         return traceable_app_count;
 117 }
 118
 119 /*
 120  * Iterate over the traceable apps list and return a pointer or NULL if not
 121  * found.
 122  */
 123 struct ltt_traceable_app *find_app_by_pid(pid_t pid)
 124 {
 125         struct ltt_traceable_app *iter;
 126
 127         pthread_mutex_lock(&ltt_traceable_app_list_mutex);
 128         cds_list_for_each_entry(iter, &ltt_traceable_app_list.head, list) {
 129                 if (iter->pid == pid) {
 130                         pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
 131                         /* Found */
 132                         return iter;
 133                 }
 134         }
 135         pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
 136
 137         return NULL;
 138 }
 139
 140 /*
 141  * List traceable user-space application and fill an array of pids.
 142  */
 143 void get_app_list_pids(pid_t *pids)
 144 {
 145         int i = 0;
 146         struct ltt_traceable_app *iter;
 147
 148         /* Protected by a mutex here because the threads manage_client
 149          * and manage_apps can access this list.
 150          */
 151         pthread_mutex_lock(&ltt_traceable_app_list_mutex);
 152         cds_list_for_each_entry(iter, &ltt_traceable_app_list.head, list) {
 153                 pids[i] = iter->pid;
 154                 i++;
 155         }
 156         pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
 157 }