ltt/branches/poly/lttd/lttd.c

   1 /* lttd
   2  *
   3  * Linux Trace Toolkit Daemon
   4  *
   5  * This is a simple daemon that reads a few relayfs channels and save them in a
   6  * trace.
   7  *
   8  *
   9  * Copyright 2005 -
  10  *      Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  11  */
  12
  13 #include <stdio.h>
  14 #include <errno.h>
  15 #include <sys/types.h>
  16 #include <sys/stat.h>
  17 #include <unistd.h>
  18 #include <stdlib.h>
  19 #include <dirent.h>
  20 #include <string.h>
  21 #include <fcntl.h>
  22 #include <sys/poll.h>
  23
  24 enum {
  25         GET_SUBBUF,
  26         PUT_SUBBUF,
  27         GET_N_BUBBUFS,
  28         GET_SUBBUF_SIZE
  29 };
  30
  31 struct fd_pair {
  32         int channel;
  33         int trace;
  34 };
  35
  36 struct channel_trace_fd {
  37         struct fd_pair *pair;
  38         int num_pairs;
  39 };
  40
  41 static char *trace_name = NULL;
  42 static char *channel_name = NULL;
  43 static int      daemon_mode = 0;
  44 static int      append_mode = 0;
  45
  46 /* Args :
  47  *
  48  * -t directory         Directory name of the trace to write to. Will be created.
  49  * -c directory         Root directory of the relayfs trace channels.
  50  * -d                   Run in background (daemon).
  51  * -a                                                   Trace append mode.
  52  */
  53 void show_arguments(void)
  54 {
  55         printf("Please use the following arguments :\n");
  56         printf("\n");
  57         printf("-t directory  Directory name of the trace to write to.\n"
  58                                  "              It will be created.\n");
  59         printf("-c directory  Root directory of the relayfs trace channels.\n");
  60         printf("-d            Run in background (daemon).\n");
  61         printf("-a            Append to an possibly existing trace.\n");
  62         printf("\n");
  63 }
  64
  65
  66 /* parse_arguments
  67  *
  68  * Parses the command line arguments.
  69  *
  70  * Returns 1 if the arguments were correct, but doesn't ask for program
  71  * continuation. Returns -1 if the arguments are incorrect, or 0 if OK.
  72  */
  73 int parse_arguments(int argc, char **argv)
  74 {
  75         int ret = 0;
  76         int argn = 1;
  77
  78         if(argc == 2) {
  79                 if(strcmp(argv[1], "-h") == 0) {
  80                         return 1;
  81                 }
  82         }
  83
  84         while(argn < argc) {
  85
  86                 switch(argv[argn][0]) {
  87                         case '-':
  88                                 switch(argv[argn][1]) {
  89                                         case 't':
  90                                                 if(argn+1 < argc) {
  91                                                         trace_name = argv[argn+1];
  92                                                         argn++;
  93                                                 }
  94                                                 break;
  95                                         case 'c':
  96                                                 if(argn+1 < argc) {
  97                                                         channel_name = argv[argn+1];
  98                                                         argn++;
  99                                                 }
 100                                                 break;
 101                                         case 'd':
 102                                                 daemon_mode = 1;
 103                                                 break;
 104                                         case 'a':
 105                                                 append_mode = 1;
 106                                                 break;
 107                                         default:
 108                                                 printf("Invalid argument '%s'.\n", argv[argn]);
 109                                                 printf("\n");
 110                                                 ret = -1;
 111                                 }
 112                                 break;
 113                         default:
 114                                 printf("Invalid argument '%s'.\n", argv[argn]);
 115                                 printf("\n");
 116                                 ret = -1;
 117                 }
 118                 argn++;
 119         }
 120
 121         if(trace_name == NULL) {
 122                 printf("Please specify a trace name.\n");
 123                 printf("\n");
 124                 ret = -1;
 125         }
 126
 127         if(channel_name == NULL) {
 128                 printf("Please specify a channel name.\n");
 129                 printf("\n");
 130                 ret = -1;
 131         }
 132
 133         return ret;
 134 }
 135
 136 void show_info(void)
 137 {
 138         printf("Linux Trace Toolkit Trace Daemon\n");
 139         printf("\n");
 140         printf("Reading from relayfs directory : %s\n", channel_name);
 141         printf("Writing to trace directory : %s\n", trace_name);
 142         printf("\n");
 143 }
 144
 145
 146 int open_channel_trace_pairs(char *subchannel_name, char *subtrace_name,
 147                 struct channel_trace_fd *fd_pairs)
 148 {
 149         DIR *channel_dir = opendir(subchannel_name);
 150         struct dirent *entry;
 151         struct stat stat_buf;
 152         int ret;
 153         char path_channel[PATH_MAX];
 154         int path_channel_len;
 155         char *path_channel_ptr;
 156         char path_trace[PATH_MAX];
 157         int path_trace_len;
 158         char *path_trace_ptr;
 159
 160         if(channel_dir == NULL) {
 161                 perror(subchannel_name);
 162                 return ENOENT;
 163         }
 164
 165         //FIXME : check if the directory already exist, and ask the user if he wants
 166         //to append to the traces.
 167         printf("Creating trace subdirectory %s\n", subtrace_name);
 168         ret = mkdir(subtrace_name, S_IRWXU|S_IRWXG|S_IRWXO);
 169         if(ret == -1) {
 170                 if(errno == EEXIST && append_mode) {
 171                         printf("Appending to directory %s as resquested\n", subtrace_name);
 172                 } else {
 173                         perror(subtrace_name);
 174                         return -1;
 175                 }
 176         }
 177
 178         strncpy(path_channel, subchannel_name, PATH_MAX-1);
 179         path_channel_len = strlen(path_channel);
 180         path_channel[path_channel_len] = '/';
 181         path_channel_len++;
 182         path_channel_ptr = path_channel + path_channel_len;
 183
 184         strncpy(path_trace, subtrace_name, PATH_MAX-1);
 185         path_trace_len = strlen(path_trace);
 186         path_trace[path_trace_len] = '/';
 187         path_trace_len++;
 188         path_trace_ptr = path_trace + path_trace_len;
 189
 190         while((entry = readdir(channel_dir)) != NULL) {
 191
 192                 if(entry->d_name[0] == '.') continue;
 193
 194                 strncpy(path_channel_ptr, entry->d_name, PATH_MAX - path_channel_len);
 195                 strncpy(path_trace_ptr, entry->d_name, PATH_MAX - path_trace_len);
 196
 197                 ret = stat(path_channel, &stat_buf);
 198                 if(ret == -1) {
 199                         perror(path_channel);
 200                         continue;
 201                 }
 202
 203                 printf("Channel file : %s\n", path_channel);
 204
 205                 if(S_ISDIR(stat_buf.st_mode)) {
 206
 207                         printf("Entering channel subdirectory...\n");
 208                         ret = open_channel_trace_pairs(path_channel, path_trace, fd_pairs);
 209                         if(ret < 0) continue;
 210                 } else if(S_ISREG(stat_buf.st_mode)) {
 211                         printf("Opening file.\n");
 212
 213                         fd_pairs->pair = realloc(fd_pairs->pair,
 214                                         ++fd_pairs->num_pairs * sizeof(struct fd_pair));
 215
 216                         /* Open the channel in read mode */
 217                         fd_pairs->pair[fd_pairs->num_pairs-1].channel =
 218                                 open(path_channel, O_RDONLY | O_NONBLOCK);
 219                         if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
 220                                 perror(path_channel);
 221                         }
 222                         /* Open the trace in write mode, only append if append_mode */
 223                         ret = stat(path_trace, &stat_buf);
 224                         if(ret == 0) {
 225                                 if(append_mode) {
 226                                         printf("Appending to file %s as resquested\n", path_trace);
 227
 228                                         fd_pairs->pair[fd_pairs->num_pairs-1].trace =
 229                                                 open(path_trace, O_WRONLY|O_APPEND,
 230                                                                 S_IRWXU|S_IRWXG|S_IRWXO);
 231
 232                                         if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
 233                                                 perror(path_trace);
 234                                         }
 235                                 } else {
 236                                         printf("File %s exists, cannot open. Try append mode.\n", path_trace);
 237                                         return -1;
 238                                 }
 239                         } else {
 240                                 if(errno == ENOENT) {
 241                                         fd_pairs->pair[fd_pairs->num_pairs-1].trace =
 242                                                 open(path_trace, O_WRONLY|O_CREAT|O_EXCL,
 243                                                                 S_IRWXU|S_IRWXG|S_IRWXO);
 244                                         if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
 245                                                 perror(path_trace);
 246                                         }
 247                                 }
 248                         }
 249                 }
 250         }
 251
 252         closedir(channel_dir);
 253
 254         return 0;
 255 }
 256
 257 /* read_channels
 258  *
 259  * Read the realyfs channels and write them in the paired tracefiles.
 260  *
 261  * @fd_pairs : paired channels and trace files.
 262  *
 263  * returns 0 on success, -1 on error.
 264  *
 265  * Note that the high priority polled channels are consumed first. We then poll
 266  * again to see if these channels are still in priority. Only when no
 267  * high priority channel is left, we start reading low priority channels.
 268  *
 269  * Note that a channel is considered high priority when the buffer is almost
 270  * full.
 271  */
 272
 273 int read_channels(struct channel_trace_fd *fd_pairs)
 274 {
 275         struct pollfd *pollfd;
 276         int i;
 277         int num_rdy;
 278         int high_prio;
 279
 280         pollfd = malloc(fd_pairs->num_pairs * sizeof(struct pollfd));
 281
 282         for(i=0;i<fd_pairs->num_pairs;i++) {
 283                 pollfd[i].fd = fd_pairs->pair[i].channel;
 284                 pollfd[i].events = POLLIN|POLLPRI;
 285         }
 286
 287         while(1) {
 288                 high_prio = 0;
 289
 290                 num_rdy = poll(pollfd, fd_pairs->num_pairs, -1);
 291                 if(num_rdy == -1) {
 292                         perror("Poll error");
 293                         return -1;
 294                 }
 295
 296                 printf("Data received\n");
 297
 298                 for(i=0;i<fd_pairs->num_pairs;i++) {
 299                         switch(pollfd[i].revents) {
 300                                 case POLLERR:
 301                                         printf("Error returned in polling fd %d.\n", pollfd[i].fd);
 302                                         break;
 303                                 case POLLHUP:
 304                                         printf("Polling fd %d tells it has hung up.\n", pollfd[i].fd);
 305                                         break;
 306                                 case POLLNVAL:
 307                                         printf("Polling fd %d tells fd is not open.\n", pollfd[i].fd);
 308                                         break;
 309                                 case POLLPRI:
 310                                         /* Take care of high priority channels first. */
 311                                         high_prio = 1;
 312                                         break;
 313                         }
 314                 }
 315
 316                 if(!high_prio) {
 317                         for(i=0;i<fd_pairs->num_pairs;i++) {
 318                                 switch(pollfd[i].revents) {
 319                                         case POLLIN:
 320                                                 /* Take care of low priority channels. */
 321                                                 break;
 322                                 }
 323                         }
 324                 }
 325
 326         }
 327
 328         free(pollfd);
 329
 330         return 0;
 331 }
 332
 333
 334 void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs)
 335 {
 336         int i;
 337         int ret;
 338
 339         for(i=0;i<fd_pairs->num_pairs;i++) {
 340                 ret = close(fd_pairs->pair[i].channel);
 341                 if(ret == -1) perror("Close error on channel");
 342                 ret = close(fd_pairs->pair[i].trace);
 343                 if(ret == -1) perror("Close error on trace");
 344         }
 345         free(fd_pairs->pair);
 346 }
 347
 348 int main(int argc, char ** argv)
 349 {
 350         int ret;
 351         pid_t pid;
 352         struct channel_trace_fd fd_pairs = { NULL, 0 };
 353
 354         ret = parse_arguments(argc, argv);
 355
 356         if(ret != 0) show_arguments();
 357         if(ret < 0) return EINVAL;
 358         if(ret > 0) return 0;
 359
 360         show_info();
 361
 362         if(daemon_mode) {
 363                 pid = fork();
 364
 365                 if(pid > 0) {
 366                         /* parent */
 367                         return 0;
 368                 } else if(pid < 0) {
 369                         /* error */
 370                         printf("An error occured while forking.\n");
 371                         return -1;
 372                 }
 373                 /* else, we are the child, continue... */
 374         }
 375
 376         if(ret = open_channel_trace_pairs(channel_name, trace_name, &fd_pairs))
 377                 goto close_channel;
 378
 379         ret = read_channels(&fd_pairs);
 380
 381 close_channel:
 382         close_channel_trace_pairs(&fd_pairs);
 383
 384         return ret;
 385 }