ltt-sessiond/ust-ctl.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 <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25
  26 #include <ust/ustctl.h>
  27
  28 #include "liblttsessiondcomm.h"
  29 #include "lttngerr.h"
  30 #include "ltt-sessiond.h"
  31 #include "session.h"
  32 #include "ust-ctl.h"
  33 #include "trace.h"
  34
  35 /*
  36  *  find_session_ust_trace_by_pid
  37  *
  38  *  Iterate over the session ust_traces and
  39  *  return a pointer or NULL if not found.
  40  */
  41 static struct ltt_ust_trace *find_session_ust_trace_by_pid(
  42                 struct ltt_session *session, pid_t pid)
  43 {
  44         struct ltt_ust_trace *iter;
  45
  46         cds_list_for_each_entry(iter, &session->ust_traces, list) {
  47                 if (iter->pid == pid) {
  48                         /* Found */
  49                         return iter;
  50                 }
  51         }
  52
  53         return NULL;
  54 }
  55
  56 /*
  57  *  get_trace_count_per_session
  58  *
  59  *  Return the total count of traces (ust and kernel)
  60  *  for the specified session.
  61  */
  62 int get_trace_count_per_session(struct ltt_session *session)
  63 {
  64         return session->ust_trace_count + session->kern_session_count;
  65 }
  66
  67 /*
  68  *  get_traces_per_session
  69  *
  70  *  Fill the lttng_trace array of all the
  71  *  available trace of the session.
  72  */
  73 void get_traces_per_session(struct ltt_session *session, struct lttng_trace *traces)
  74 {
  75         int i = 0;
  76         struct ltt_ust_trace *ust_iter;
  77         struct lttng_trace trace;
  78
  79         DBG("Getting userspace traces for session %s", session->name);
  80
  81         /* Getting userspace traces */
  82         cds_list_for_each_entry(ust_iter, &session->ust_traces, list) {
  83                 trace.type = USERSPACE;
  84                 trace.pid = ust_iter->pid;
  85                 strncpy(trace.name, ust_iter->name, sizeof(trace.name));
  86                 trace.name[sizeof(trace.name) - 1] = '\0';
  87                 memcpy(&traces[i], &trace, sizeof(trace));
  88                 memset(&trace, 0, sizeof(trace));
  89                 i++;
  90         }
  91
  92         DBG("Getting kernel traces for session %s", session->name);
  93
  94         /* Getting kernel traces */
  95         if (session->kern_session_count > 0) {
  96                 trace.type = KERNEL;
  97                 strncpy(trace.name, "kernel", 6);
  98                 memcpy(&traces[i], &trace, sizeof(trace));
  99         }
 100 }
 101
 102 /*
 103  *  ust_create_trace
 104  *
 105  *  Create an userspace trace using pid.
 106  *  This trace is then appended to the current session
 107  *  ust trace list.
 108  */
 109 int ust_create_trace(struct command_ctx *cmd_ctx)
 110 {
 111         int ret;
 112         struct ltt_ust_trace *trace;
 113
 114         DBG("Creating trace for pid %d", cmd_ctx->lsm->pid);
 115
 116         trace = malloc(sizeof(struct ltt_ust_trace));
 117         if (trace == NULL) {
 118                 perror("malloc");
 119                 ret = -1;
 120                 goto error;
 121         }
 122
 123         /* Init */
 124         trace->pid = cmd_ctx->lsm->pid;
 125         trace->shmid = 0;
 126         /* NOTE: to be removed. Trace name will no longer be
 127          * required for LTTng userspace tracer. For now, we set it
 128          * to 'auto' for API compliance.
 129          */
 130         snprintf(trace->name, 5, "auto");
 131
 132         ret = ustctl_create_trace(cmd_ctx->ust_sock, trace->name);
 133         if (ret < 0) {
 134                 ret = LTTCOMM_CREATE_FAIL;
 135                 goto error_create;
 136         }
 137
 138         /* Check if current session is valid */
 139         if (cmd_ctx->session) {
 140                 cds_list_add(&trace->list, &cmd_ctx->session->ust_traces);
 141                 cmd_ctx->session->ust_trace_count++;
 142         }
 143
 144         return LTTCOMM_OK;
 145
 146 error_create:
 147         free(trace);
 148 error:
 149         return ret;
 150 }
 151
 152 /*
 153  *  ust_start_trace
 154  *
 155  *  Start a trace. This trace, identified by the pid, must be
 156  *  in the current session ust_traces list.
 157  */
 158 int ust_start_trace(struct command_ctx *cmd_ctx)
 159 {
 160         int ret;
 161         struct ltt_ust_trace *trace;
 162
 163         DBG("Starting trace for pid %d", cmd_ctx->lsm->pid);
 164
 165         trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
 166         if (trace == NULL) {
 167                 ret = LTTCOMM_NO_TRACE;
 168                 goto error;
 169         }
 170
 171         ret = ustctl_start_trace(cmd_ctx->ust_sock, "auto");
 172         if (ret < 0) {
 173                 ret = LTTCOMM_START_FAIL;
 174                 goto error;
 175         }
 176
 177         ret = LTTCOMM_OK;
 178
 179 error:
 180         return ret;
 181 }
 182
 183 /*
 184  *  ust_stop_trace
 185  *
 186  *  Stop a trace. This trace, identified by the pid, must be
 187  *  in the current session ust_traces list.
 188  */
 189 int ust_stop_trace(struct command_ctx *cmd_ctx)
 190 {
 191         int ret;
 192         struct ltt_ust_trace *trace;
 193
 194         DBG("Stopping trace for pid %d", cmd_ctx->lsm->pid);
 195
 196         trace = find_session_ust_trace_by_pid(cmd_ctx->session, cmd_ctx->lsm->pid);
 197         if (trace == NULL) {
 198                 ret = LTTCOMM_NO_TRACE;
 199                 goto error;
 200         }
 201
 202         ret = ustctl_stop_trace(cmd_ctx->ust_sock, trace->name);
 203         if (ret < 0) {
 204                 ret = LTTCOMM_STOP_FAIL;
 205                 goto error;
 206         }
 207
 208         ret = LTTCOMM_OK;
 209
 210 error:
 211         return ret;
 212 }
 213