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 _LGPL_SOURCE
  19 #include <popt.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <sys/stat.h>
  24 #include <sys/types.h>
  25 #include <unistd.h>
  26
  27 #include <common/sessiond-comm/sessiond-comm.h>
  28 #include <common/mi-lttng.h>
  29
  30 #include "../command.h"
  31
  32
  33 static char *opt_session_name;
  34 static struct mi_writer *writer;
  35
  36 #ifdef LTTNG_EMBED_HELP
  37 static const char help_msg[] =
  38 #include <lttng-start.1.h>
  39 ;
  40 #endif
  41
  42 enum {
  43         OPT_HELP = 1,
  44         OPT_LIST_OPTIONS,
  45 };
  46
  47 static struct poptOption long_options[] = {
  48         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  49         {"help",      'h', POPT_ARG_NONE, 0, OPT_HELP, 0, 0},
  50         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  51         {0, 0, 0, 0, 0, 0, 0}
  52 };
  53
  54 static int mi_print_session(char *session_name, int enabled)
  55 {
  56         int ret;
  57
  58         /* Open session element */
  59         ret = mi_lttng_writer_open_element(writer, config_element_session);
  60         if (ret) {
  61                 goto end;
  62         }
  63
  64         /* Print session name element */
  65         ret = mi_lttng_writer_write_element_string(writer, config_element_name,
  66                         session_name);
  67         if (ret) {
  68                 goto end;
  69         }
  70
  71         ret = mi_lttng_writer_write_element_bool(writer, config_element_enabled,
  72                         enabled);
  73         if (ret) {
  74                 goto end;
  75         }
  76
  77         /* Close session element */
  78         ret = mi_lttng_writer_close_element(writer);
  79
  80 end:
  81         return ret;
  82 }
  83
  84 /*
  85  *  start_tracing
  86  *
  87  *  Start tracing for all trace of the session.
  88  */
  89 static int start_tracing(void)
  90 {
  91         int ret;
  92         char *session_name;
  93
  94         if (opt_session_name == NULL) {
  95                 session_name = get_session_name();
  96                 if (session_name == NULL) {
  97                         ret = CMD_ERROR;
  98                         goto error;
  99                 }
 100         } else {
 101                 session_name = opt_session_name;
 102         }
 103
 104         DBG("Starting tracing for session %s", session_name);
 105
 106         ret = lttng_start_tracing(session_name);
 107         if (ret < 0) {
 108                 switch (-ret) {
 109                 case LTTNG_ERR_TRACE_ALREADY_STARTED:
 110                         WARN("Tracing already started for session %s", session_name);
 111                         break;
 112                 default:
 113                         ERR("%s", lttng_strerror(ret));
 114                         break;
 115                 }
 116                 goto free_name;
 117         }
 118
 119         ret = CMD_SUCCESS;
 120
 121         MSG("Tracing started for session %s", session_name);
 122         if (lttng_opt_mi) {
 123                 ret = mi_print_session(session_name, 1);
 124                 if (ret) {
 125                         ret = CMD_ERROR;
 126                         goto free_name;
 127                 }
 128         }
 129
 130 free_name:
 131         if (opt_session_name == NULL) {
 132                 free(session_name);
 133         }
 134 error:
 135         return ret;
 136 }
 137
 138 /*
 139  *  cmd_start
 140  *
 141  *  The 'start <options>' first level command
 142  */
 143 int cmd_start(int argc, const char **argv)
 144 {
 145         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 146         static poptContext pc;
 147
 148         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 149         poptReadDefaultConfig(pc, 0);
 150
 151         while ((opt = poptGetNextOpt(pc)) != -1) {
 152                 switch (opt) {
 153                 case OPT_HELP:
 154                         SHOW_HELP();
 155                         goto end;
 156                 case OPT_LIST_OPTIONS:
 157                         list_cmd_options(stdout, long_options);
 158                         goto end;
 159                 default:
 160                         ret = CMD_UNDEFINED;
 161                         goto end;
 162                 }
 163         }
 164
 165         opt_session_name = (char*) poptGetArg(pc);
 166
 167         /* Mi check */
 168         if (lttng_opt_mi) {
 169                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 170                 if (!writer) {
 171                         ret = -LTTNG_ERR_NOMEM;
 172                         goto end;
 173                 }
 174
 175                 /* Open command element */
 176                 ret = mi_lttng_writer_command_open(writer,
 177                                 mi_lttng_element_command_start);
 178                 if (ret) {
 179                         ret = CMD_ERROR;
 180                         goto end;
 181                 }
 182
 183                 /* Open output element */
 184                 ret = mi_lttng_writer_open_element(writer,
 185                                 mi_lttng_element_command_output);
 186                 if (ret) {
 187                         ret = CMD_ERROR;
 188                         goto end;
 189                 }
 190
 191                 /*
 192                  * Open sessions element
 193                  * For validation purpose
 194                  */
 195                 ret = mi_lttng_writer_open_element(writer,
 196                         config_element_sessions);
 197                 if (ret) {
 198                         ret = CMD_ERROR;
 199                         goto end;
 200                 }
 201         }
 202
 203         command_ret = start_tracing();
 204         if (command_ret) {
 205                 success = 0;
 206         }
 207
 208         /* Mi closing */
 209         if (lttng_opt_mi) {
 210                 /* Close  sessions and output element */
 211                 ret = mi_lttng_close_multi_element(writer, 2);
 212                 if (ret) {
 213                         ret = CMD_ERROR;
 214                         goto end;
 215                 }
 216
 217                 /* Success ? */
 218                 ret = mi_lttng_writer_write_element_bool(writer,
 219                                 mi_lttng_element_command_success, success);
 220                 if (ret) {
 221                         ret = CMD_ERROR;
 222                         goto end;
 223                 }
 224
 225                 /* Command element close */
 226                 ret = mi_lttng_writer_command_close(writer);
 227                 if (ret) {
 228                         ret = CMD_ERROR;
 229                         goto end;
 230                 }
 231         }
 232
 233 end:
 234         /* Mi clean-up */
 235         if (writer && mi_lttng_writer_destroy(writer)) {
 236                 /* Preserve original error code */
 237                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 238         }
 239
 240         /* Overwrite ret if an error occurred with start_tracing */
 241         ret = command_ret ? command_ret : ret;
 242         poptFreeContext(pc);
 243         return ret;
 244 }