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 #include "ltt-sessiond.h"
  33
  34 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
  35                 struct ltt_session *session, pid_t pid);
  36
  37 /*
  38  *  find_session_ust_trace_by_pid
  39  *
  40  *  Iterate over the session ust_traces and
  41  *  return a pointer or NULL if not found.
  42  */
  43 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
  44                 struct ltt_session *session, pid_t pid)
  45 {
  46         struct ltt_ust_trace *iter;
  47
  48         cds_list_for_each_entry(iter, &session->ust_traces, list) {
  49                 if (iter->pid == pid) {
  50                         /* Found */
  51                         return iter;
  52                 }
  53         }
  54
  55         return NULL;
  56 }
  57
  58 /*
  59  *  get_trace_count_per_session
  60  *
  61  *  Return the total count of traces (ust and kernel)
  62  *  for the specified session.
  63  */
  64 int get_trace_count_per_session(struct ltt_session *session)
  65 {
  66         return session->ust_trace_count + session->kern_trace_count;
  67 }
  68
  69 /*
  70  *  get_traces_per_session
  71  *
  72  *  Fill the lttng_trace array of all the
  73  *  available trace of the session.
  74  */
  75 void get_traces_per_session(struct ltt_session *session, struct lttng_trace *traces)
  76 {
  77         int i = 0;
  78         struct ltt_ust_trace *ust_iter;
  79         struct ltt_kernel_trace *kern_iter;
  80         struct lttng_trace trace;
  81
  82         DBG("Getting userspace traces for session %s", session->name);
  83
  84         /* Getting userspace traces */
  85         cds_list_for_each_entry(ust_iter, &session->ust_traces, list) {
  86                 trace.type = USERSPACE;
  87                 trace.pid = ust_iter->pid;
  88                 strncpy(trace.name, ust_iter->name, sizeof(trace.name));
  89                 trace.name[sizeof(trace.name) - 1] = '\0';
  90                 memcpy(&traces[i], &trace, sizeof(trace));
  91                 memset(&trace, 0, sizeof(trace));
  92                 i++;
  93         }
  94
  95         DBG("Getting kernel traces for session %s", session->name);
  96
  97         /* Getting kernel traces */
  98         cds_list_for_each_entry(kern_iter, &session->kernel_traces, list) {
  99                 trace.type = KERNEL;
 100                 strncpy(trace.name, kern_iter->name, sizeof(trace.name));
 101                 trace.name[sizeof(trace.name) - 1] = '\0';
 102                 memcpy(&traces[i], &trace, sizeof(trace));
 103                 memset(&trace, 0, sizeof(trace));
 104                 i++;
 105         }
 106 }
 107
 108 /*
 109  *  ust_create_trace
 110  *
 111  *  Create an userspace trace using pid.
 112  *  This trace is then appended to the current session
 113  *  ust trace list.
 114  */
 115 int ust_create_trace(struct command_ctx *cmd_ctx)
 116 {
 117         int ret;
 118         struct ltt_ust_trace *trace;
 119
 120         DBG("Creating trace for pid %d", cmd_ctx->lsm->pid);
 121
 122         trace = malloc(sizeof(struct ltt_ust_trace));
 123         if (trace == NULL) {
 124                 perror("malloc");
 125                 ret = -1;
 126                 goto error;
 127         }
 128
 129         /* Init */
 130         trace->pid = cmd_ctx->lsm->pid;
 131         trace->shmid = 0;
 132         /* NOTE: to be removed. Trace name will no longer be
 133          * required for LTTng userspace tracer. For now, we set it
 134          * to 'auto' for API compliance.
 135          */
 136         snprintf(trace->name, 5, "auto");
 137
 138         ret = ustctl_create_trace(cmd_ctx->ust_sock, trace->name);
 139         if (ret < 0) {
 140                 ret = LTTCOMM_CREATE_FAIL;
 141                 goto error_create;
 142         }
 143
 144         /* Check if current session is valid */
 145         if (cmd_ctx->session) {
 146                 cds_list_add(&trace->list, &cmd_ctx->session->ust_traces);
 147                 cmd_ctx->session->ust_trace_count++;
 148         }
 149
 150         return LTTCOMM_OK;
 151
 152 error_create:
 153         free(trace);
 154 error:
 155         return ret;
 156 }
 157
 158 /*
 159  *  ust_start_trace
 160  *
 161  *  Start a trace. This trace, identified by the pid, must be
 162  *  in the current session ust_traces list.
 163  */
 164 int ust_start_trace(struct command_ctx *cmd_ctx)
 165 {
 166         int ret;
 167         struct ltt_ust_trace *trace;
 168
 169         DBG("Starting trace for pid %d", cmd_ctx->lsm->pid);
 170
 171         trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
 172         if (trace == NULL) {
 173                 ret = LTTCOMM_NO_TRACE;
 174                 goto error;
 175         }
 176
 177         ret = ustctl_start_trace(cmd_ctx->ust_sock, "auto");
 178         if (ret < 0) {
 179                 ret = LTTCOMM_START_FAIL;
 180                 goto error;
 181         }
 182
 183         ret = LTTCOMM_OK;
 184
 185 error:
 186         return ret;
 187 }
 188
 189 /*
 190  *  ust_stop_trace
 191  *
 192  *  Stop a trace. This trace, identified by the pid, must be
 193  *  in the current session ust_traces list.
 194  */
 195 int ust_stop_trace(struct command_ctx *cmd_ctx)
 196 {
 197         int ret;
 198         struct ltt_ust_trace *trace;
 199
 200         DBG("Stopping trace for pid %d", cmd_ctx->lsm->pid);
 201
 202         trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
 203         if (trace == NULL) {
 204                 ret = LTTCOMM_NO_TRACE;
 205                 goto error;
 206         }
 207
 208         ret = ustctl_stop_trace(cmd_ctx->ust_sock, trace->name);
 209         if (ret < 0) {
 210                 ret = LTTCOMM_STOP_FAIL;
 211                 goto error;
 212         }
 213
 214         ret = LTTCOMM_OK;
 215
 216 error:
 217         return ret;
 218 }
 219