ltt-sessiond/trace.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; either version 2
   7  * of the License, or (at your option) any later version.
   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 <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <urcu/list.h>
  26 #include <ust/ustctl.h>
  27
  28 #include "liblttsessiondcomm.h"
  29 #include "lttngerr.h"
  30 #include "trace.h"
  31 #include "session.h"
  32
  33 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
  34                 struct ltt_session *session, pid_t pid);
  35
  36 /*
  37  *  find_session_ust_trace_by_pid
  38  *
  39  *  Iterate over the session ust_traces and
  40  *  return a pointer or NULL if not found.
  41  */
  42 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
  43                 struct ltt_session *session, pid_t pid)
  44 {
  45         struct ltt_ust_trace *iter;
  46
  47         cds_list_for_each_entry(iter, &session->ust_traces, list) {
  48                 if (iter->pid == pid) {
  49                         /* Found */
  50                         return iter;
  51                 }
  52         }
  53
  54         return NULL;
  55 }
  56
  57 /*
  58  *  get_trace_count_per_session
  59  *
  60  *  Return the total count of traces (ust and kernel)
  61  *  for the specified session.
  62  */
  63 int get_trace_count_per_session(struct ltt_session *session)
  64 {
  65         return session->ust_trace_count + session->kern_trace_count;
  66 }
  67
  68 /*
  69  *  get_traces_per_session
  70  *
  71  *  Fill the lttng_trace array of all the
  72  *  available trace of the session.
  73  */
  74 void get_traces_per_session(struct ltt_session *session, struct lttng_trace *traces)
  75 {
  76         int i = 0;
  77         struct ltt_ust_trace *ust_iter;
  78         struct ltt_kernel_trace *kern_iter;
  79         struct lttng_trace trace;
  80
  81         DBG("Getting userspace traces for session %s", session->name);
  82
  83         /* Getting userspace traces */
  84         cds_list_for_each_entry(ust_iter, &session->ust_traces, list) {
  85                 trace.type = USERSPACE;
  86                 trace.pid = ust_iter->pid;
  87                 strncpy(trace.name, ust_iter->name, sizeof(trace.name));
  88                 trace.name[sizeof(trace.name) - 1] = '\0';
  89                 memcpy(&traces[i], &trace, sizeof(trace));
  90                 memset(&trace, 0, sizeof(trace));
  91                 i++;
  92         }
  93
  94         DBG("Getting kernel traces for session %s", session->name);
  95
  96         /* Getting kernel traces */
  97         cds_list_for_each_entry(kern_iter, &session->kernel_traces, list) {
  98                 trace.type = KERNEL;
  99                 strncpy(trace.name, kern_iter->name, sizeof(trace.name));
 100                 trace.name[sizeof(trace.name) - 1] = '\0';
 101                 memcpy(&traces[i], &trace, sizeof(trace));
 102                 memset(&trace, 0, sizeof(trace));
 103                 i++;
 104         }
 105 }
 106
 107 /*
 108  *  ust_create_trace
 109  *
 110  *  Create an userspace trace using pid.
 111  *  This trace is then appended to the current session
 112  *  ust trace list.
 113  */
 114 int ust_create_trace(int sock, pid_t pid)
 115 {
 116         int ret;
 117         struct ltt_ust_trace *trace;
 118
 119         DBG("Creating trace for pid %d", pid);
 120
 121         trace = malloc(sizeof(struct ltt_ust_trace));
 122         if (trace == NULL) {
 123                 perror("malloc");
 124                 ret = -1;
 125                 goto error;
 126         }
 127
 128         /* Init */
 129         trace->pid = pid;
 130         trace->shmid = 0;
 131         /* NOTE: to be removed. Trace name will no longer be
 132          * required for LTTng userspace tracer. For now, we set it
 133          * to 'auto' for API compliance.
 134          */
 135         snprintf(trace->name, 5, "auto");
 136
 137         ret = ustctl_create_trace(sock, trace->name);
 138         if (ret < 0) {
 139                 ret = LTTCOMM_CREATE_FAIL;
 140                 goto error;
 141         }
 142
 143         /* Check if current session is valid */
 144         if (current_session) {
 145                 cds_list_add(&trace->list, &current_session->ust_traces);
 146                 current_session->ust_trace_count++;
 147         }
 148
 149 error:
 150         return ret;
 151 }
 152
 153 /*
 154  *  ust_start_trace
 155  *
 156  *  Start a trace. This trace, identified by the pid, must be
 157  *  in the current session ust_traces list.
 158  */
 159 int ust_start_trace(int sock, pid_t pid)
 160 {
 161         int ret;
 162         struct ltt_ust_trace *trace;
 163
 164         DBG("Starting trace for pid %d", pid);
 165
 166         trace = find_session_ust_trace_by_pid(current_session, pid);
 167         if (trace == NULL) {
 168                 ret = LTTCOMM_NO_TRACE;
 169                 goto error;
 170         }
 171
 172         ret = ustctl_start_trace(sock, "auto");
 173         if (ret < 0) {
 174                 ret = LTTCOMM_START_FAIL;
 175                 goto error;
 176         }
 177
 178 error:
 179         return ret;
 180 }
 181
 182 /*
 183  *  ust_stop_trace
 184  *
 185  *  Stop a trace. This trace, identified by the pid, must be
 186  *  in the current session ust_traces list.
 187  */
 188 int ust_stop_trace(int sock, pid_t pid)
 189 {
 190         int ret;
 191         struct ltt_ust_trace *trace;
 192
 193         DBG("Stopping trace for pid %d", pid);
 194
 195         trace = find_session_ust_trace_by_pid(current_session, pid);
 196         if (trace == NULL) {
 197                 ret = LTTCOMM_NO_TRACE;
 198                 goto error;
 199         }
 200
 201         ret = ustctl_stop_trace(sock, trace->name);
 202         if (ret < 0) {
 203                 ret = LTTCOMM_STOP_FAIL;
 204                 goto error;
 205         }
 206
 207 error:
 208         return ret;
 209 }
 210