src/bin/lttng/commands/start.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 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 #define _LGPL_SOURCE
  20 #include <popt.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/stat.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27
  28 #include <common/sessiond-comm/sessiond-comm.h>
  29 #include <common/mi-lttng.h>
  30
  31 #include "../command.h"
  32
  33
  34 static char *opt_session_name;
  35 static struct mi_writer *writer;
  36
  37 enum {
  38         OPT_HELP = 1,
  39         OPT_LIST_OPTIONS,
  40 };
  41
  42 static struct poptOption long_options[] = {
  43         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  44         {"help",      'h', POPT_ARG_NONE, 0, OPT_HELP, 0, 0},
  45         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  46         {0, 0, 0, 0, 0, 0, 0}
  47 };
  48
  49 /*
  50  * usage
  51  */
  52 static void usage(FILE *ofp)
  53 {
  54         fprintf(ofp, "usage: lttng start [NAME] [OPTIONS]\n");
  55         fprintf(ofp, "\n");
  56         fprintf(ofp, "Where NAME is an optional session name. If not specified, lttng will\n");
  57         fprintf(ofp, "get it from the configuration directory (.lttng).\n");
  58         fprintf(ofp, "\n");
  59         fprintf(ofp, "Options:\n");
  60         fprintf(ofp, "  -h, --help               Show this help\n");
  61         fprintf(ofp, "      --list-options       Simple listing of options\n");
  62         fprintf(ofp, "\n");
  63 }
  64
  65 static int mi_print_session(char *session_name, int enabled)
  66 {
  67         int ret;
  68
  69         /* Open session element */
  70         ret = mi_lttng_writer_open_element(writer, config_element_session);
  71         if (ret) {
  72                 goto end;
  73         }
  74
  75         /* Print session name element */
  76         ret = mi_lttng_writer_write_element_string(writer, config_element_name,
  77                         session_name);
  78         if (ret) {
  79                 goto end;
  80         }
  81
  82         ret = mi_lttng_writer_write_element_bool(writer, config_element_enabled,
  83                         enabled);
  84         if (ret) {
  85                 goto end;
  86         }
  87
  88         /* Close session element */
  89         ret = mi_lttng_writer_close_element(writer);
  90
  91 end:
  92         return ret;
  93 }
  94
  95 /*
  96  *  start_tracing
  97  *
  98  *  Start tracing for all trace of the session.
  99  */
 100 static int start_tracing(void)
 101 {
 102         int ret;
 103         char *session_name;
 104
 105         if (opt_session_name == NULL) {
 106                 session_name = get_session_name();
 107                 if (session_name == NULL) {
 108                         ret = CMD_ERROR;
 109                         goto error;
 110                 }
 111         } else {
 112                 session_name = opt_session_name;
 113         }
 114
 115         DBG("Starting tracing for session %s", session_name);
 116
 117         ret = lttng_start_tracing(session_name);
 118         if (ret < 0) {
 119                 switch (-ret) {
 120                 case LTTNG_ERR_TRACE_ALREADY_STARTED:
 121                         WARN("Tracing already started for session %s", session_name);
 122                         break;
 123                 default:
 124                         ERR("%s", lttng_strerror(ret));
 125                         break;
 126                 }
 127                 goto free_name;
 128         }
 129
 130         ret = CMD_SUCCESS;
 131
 132         MSG("Tracing started for session %s", session_name);
 133         if (lttng_opt_mi) {
 134                 ret = mi_print_session(session_name, 1);
 135                 if (ret) {
 136                         ret = CMD_ERROR;
 137                         goto free_name;
 138                 }
 139         }
 140
 141 free_name:
 142         if (opt_session_name == NULL) {
 143                 free(session_name);
 144         }
 145 error:
 146         return ret;
 147 }
 148
 149 /*
 150  *  cmd_start
 151  *
 152  *  The 'start <options>' first level command
 153  */
 154 int cmd_start(int argc, const char **argv)
 155 {
 156         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 157         static poptContext pc;
 158
 159         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 160         poptReadDefaultConfig(pc, 0);
 161
 162         while ((opt = poptGetNextOpt(pc)) != -1) {
 163                 switch (opt) {
 164                 case OPT_HELP:
 165                         usage(stdout);
 166                         goto end;
 167                 case OPT_LIST_OPTIONS:
 168                         list_cmd_options(stdout, long_options);
 169                         goto end;
 170                 default:
 171                         usage(stderr);
 172                         ret = CMD_UNDEFINED;
 173                         goto end;
 174                 }
 175         }
 176
 177         opt_session_name = (char*) poptGetArg(pc);
 178
 179         /* Mi check */
 180         if (lttng_opt_mi) {
 181                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 182                 if (!writer) {
 183                         ret = -LTTNG_ERR_NOMEM;
 184                         goto end;
 185                 }
 186
 187                 /* Open command element */
 188                 ret = mi_lttng_writer_command_open(writer,
 189                                 mi_lttng_element_command_start);
 190                 if (ret) {
 191                         ret = CMD_ERROR;
 192                         goto end;
 193                 }
 194
 195                 /* Open output element */
 196                 ret = mi_lttng_writer_open_element(writer,
 197                                 mi_lttng_element_command_output);
 198                 if (ret) {
 199                         ret = CMD_ERROR;
 200                         goto end;
 201                 }
 202
 203                 /*
 204                  * Open sessions element
 205                  * For validation purpose
 206                  */
 207                 ret = mi_lttng_writer_open_element(writer,
 208                         config_element_sessions);
 209                 if (ret) {
 210                         ret = CMD_ERROR;
 211                         goto end;
 212                 }
 213         }
 214
 215         command_ret = start_tracing();
 216         if (command_ret) {
 217                 success = 0;
 218         }
 219
 220         /* Mi closing */
 221         if (lttng_opt_mi) {
 222                 /* Close  sessions and output element */
 223                 ret = mi_lttng_close_multi_element(writer, 2);
 224                 if (ret) {
 225                         ret = CMD_ERROR;
 226                         goto end;
 227                 }
 228
 229                 /* Success ? */
 230                 ret = mi_lttng_writer_write_element_bool(writer,
 231                                 mi_lttng_element_command_success, success);
 232                 if (ret) {
 233                         ret = CMD_ERROR;
 234                         goto end;
 235                 }
 236
 237                 /* Command element close */
 238                 ret = mi_lttng_writer_command_close(writer);
 239                 if (ret) {
 240                         ret = CMD_ERROR;
 241                         goto end;
 242                 }
 243         }
 244
 245 end:
 246         /* Mi clean-up */
 247         if (writer && mi_lttng_writer_destroy(writer)) {
 248                 /* Preserve original error code */
 249                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 250         }
 251
 252         /* Overwrite ret if an error occurred with start_tracing */
 253         ret = command_ret ? command_ret : ret;
 254         poptFreeContext(pc);
 255         return ret;
 256 }