src/common/ust-consumer/ust-consumer.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   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 along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <assert.h>
  21 #include <poll.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/mman.h>
  26 #include <sys/socket.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #include <unistd.h>
  30 #include <lttng/ust-ctl.h>
  31
  32 #include <common/common.h>
  33 #include <common/sessiond-comm/sessiond-comm.h>
  34 #include <common/compat/fcntl.h>
  35
  36 #include "ust-consumer.h"
  37
  38 extern struct lttng_consumer_global_data consumer_data;
  39 extern int consumer_poll_timeout;
  40 extern volatile int consumer_quit;
  41
  42 /*
  43  * Mmap the ring buffer, read it and write the data to the tracefile.
  44  *
  45  * Returns the number of bytes written, else negative value on error.
  46  */
  47 ssize_t lttng_ustconsumer_on_read_subbuffer_mmap(
  48                 struct lttng_consumer_local_data *ctx,
  49                 struct lttng_consumer_stream *stream, unsigned long len)
  50 {
  51         unsigned long mmap_offset;
  52         long ret = 0, written = 0;
  53         off_t orig_offset = stream->out_fd_offset;
  54         int outfd = stream->out_fd;
  55
  56         /* get the offset inside the fd to mmap */
  57         ret = ustctl_get_mmap_read_offset(stream->chan->handle,
  58                 stream->buf, &mmap_offset);
  59         if (ret != 0) {
  60                 errno = -ret;
  61                 PERROR("ustctl_get_mmap_read_offset");
  62                 written = ret;
  63                 goto end;
  64         }
  65         while (len > 0) {
  66                 ret = write(outfd, stream->mmap_base + mmap_offset, len);
  67                 if (ret < 0) {
  68                         if (errno == EINTR) {
  69                                 /* restart the interrupted system call */
  70                                 continue;
  71                         } else {
  72                                 PERROR("Error in file write");
  73                                 if (written == 0) {
  74                                         written = ret;
  75                                 }
  76                                 goto end;
  77                         }
  78                 } else if (ret > len) {
  79                         PERROR("Error in file write");
  80                         written += ret;
  81                         goto end;
  82                 } else {
  83                         len -= ret;
  84                         mmap_offset += ret;
  85                 }
  86                 /* This won't block, but will start writeout asynchronously */
  87                 lttng_sync_file_range(outfd, stream->out_fd_offset, ret,
  88                                 SYNC_FILE_RANGE_WRITE);
  89                 stream->out_fd_offset += ret;
  90                 written += ret;
  91         }
  92         lttng_consumer_sync_trace_file(stream, orig_offset);
  93 end:
  94         return written;
  95 }
  96
  97 /*
  98  * Splice the data from the ring buffer to the tracefile.
  99  *
 100  * Returns the number of bytes spliced.
 101  */
 102 ssize_t lttng_ustconsumer_on_read_subbuffer_splice(
 103                 struct lttng_consumer_local_data *ctx,
 104                 struct lttng_consumer_stream *stream, unsigned long len)
 105 {
 106         return -ENOSYS;
 107 }
 108
 109 /*
 110  * Take a snapshot for a specific fd
 111  *
 112  * Returns 0 on success, < 0 on error
 113  */
 114 int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 115                 struct lttng_consumer_stream *stream)
 116 {
 117         int ret = 0;
 118
 119         ret = ustctl_snapshot(stream->chan->handle, stream->buf);
 120         if (ret != 0) {
 121                 errno = -ret;
 122                 PERROR("Getting sub-buffer snapshot.");
 123         }
 124
 125         return ret;
 126 }
 127
 128 /*
 129  * Get the produced position
 130  *
 131  * Returns 0 on success, < 0 on error
 132  */
 133 int lttng_ustconsumer_get_produced_snapshot(
 134                 struct lttng_consumer_local_data *ctx,
 135                 struct lttng_consumer_stream *stream,
 136                 unsigned long *pos)
 137 {
 138         int ret;
 139
 140         ret = ustctl_snapshot_get_produced(stream->chan->handle,
 141                         stream->buf, pos);
 142         if (ret != 0) {
 143                 errno = -ret;
 144                 PERROR("kernctl_snapshot_get_produced");
 145         }
 146
 147         return ret;
 148 }
 149
 150 int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 151                 int sock, struct pollfd *consumer_sockpoll)
 152 {
 153         ssize_t ret;
 154         struct lttcomm_consumer_msg msg;
 155
 156         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 157         if (ret != sizeof(msg)) {
 158                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 159                 return ret;
 160         }
 161         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 162                 return -ENOENT;
 163         }
 164
 165         switch (msg.cmd_type) {
 166         case LTTNG_CONSUMER_ADD_CHANNEL:
 167         {
 168                 struct lttng_consumer_channel *new_channel;
 169                 int fds[1];
 170                 char *path;
 171
 172                 /* block */
 173                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 174                         return -EINTR;
 175                 }
 176
 177                 path = lttcomm_recv_string(sock);
 178
 179                 if (!path) {
 180                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 181                         return -1;
 182                 }
 183
 184                 DBG("consumer_add_channel received path %s", path);
 185
 186                 fds[0] = open(path, O_RDWR);
 187
 188                 if (fds[0] < 0) {
 189                         DBG("consumer_add_channel open error on path %s", path);
 190                         free(path);
 191                         return -1;
 192                 }
 193
 194                 if (fcntl(fds[0], F_SETFD, FD_CLOEXEC) < 0) {
 195                         DBG("consumer_add_channel fcntl error");
 196                         free(path);
 197                         return -1;
 198                 }
 199
 200                 free(path);
 201
 202                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 203
 204                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 205                                 fds[0], -1,
 206                                 msg.u.channel.mmap_len,
 207                                 msg.u.channel.max_sb_size);
 208                 if (new_channel == NULL) {
 209                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 210                         goto end_nosignal;
 211                 }
 212                 if (ctx->on_recv_channel != NULL) {
 213                         ret = ctx->on_recv_channel(new_channel);
 214                         if (ret == 0) {
 215                                 consumer_add_channel(new_channel);
 216                         } else if (ret < 0) {
 217                                 goto end_nosignal;
 218                         }
 219                 } else {
 220                         consumer_add_channel(new_channel);
 221                 }
 222                 goto end_nosignal;
 223         }
 224         case LTTNG_CONSUMER_ADD_STREAM:
 225         {
 226                 struct lttng_consumer_stream *new_stream;
 227                 int fds[2], i;
 228                 char *shm_path, *wait_pipe_path;
 229
 230                 /* block */
 231                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 232                         return -EINTR;
 233                 }
 234
 235                 shm_path = lttcomm_recv_string(sock);
 236
 237                 if (!shm_path) {
 238                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 239                         return -1;
 240                 }
 241
 242                 wait_pipe_path = lttcomm_recv_string(sock);
 243
 244                 if (!wait_pipe_path) {
 245                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 246                         free(shm_path);
 247                         return -1;
 248                 }
 249
 250                 DBG("consumer_add_stream received path %s", shm_path);
 251                 DBG("consumer_add_stream received path %s", wait_pipe_path);
 252
 253                 fds[0] = open(shm_path, O_RDWR);
 254
 255                 if (fds[0] < 0) {
 256                         DBG("consumer_add_stream open error on path %s", shm_path);
 257                         free(shm_path);
 258                         free(wait_pipe_path);
 259                         return -1;
 260                 }
 261
 262                 fds[1] = open(wait_pipe_path, O_RDONLY);
 263
 264                 if (fds[1] < 0) {
 265                         DBG("consumer_add_stream open error on path %s", wait_pipe_path);
 266                         PERROR("open");
 267                         free(shm_path);
 268                         free(wait_pipe_path);
 269                         return -1;
 270                 }
 271
 272                 free(shm_path);
 273                 free(wait_pipe_path);
 274
 275                 for (i = 0; i < 2; ++i) {
 276                         if (fcntl(fds[i], F_SETFD, FD_CLOEXEC) < 0) {
 277                                 DBG("consumer_add_stream fcntl error");
 278                                 return -1;
 279                         }
 280                 }
 281
 282                 DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
 283                         fds[0], fds[1]);
 284                 assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
 285                 new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
 286                                 msg.u.stream.stream_key,
 287                                 fds[0], fds[1],
 288                                 msg.u.stream.state,
 289                                 msg.u.stream.mmap_len,
 290                                 msg.u.stream.output,
 291                                 msg.u.stream.path_name,
 292                                 msg.u.stream.uid,
 293                                 msg.u.stream.gid);
 294                 if (new_stream == NULL) {
 295                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 296                         goto end;
 297                 }
 298                 if (ctx->on_recv_stream != NULL) {
 299                         ret = ctx->on_recv_stream(new_stream);
 300                         if (ret == 0) {
 301                                 consumer_add_stream(new_stream);
 302                         } else if (ret < 0) {
 303                                 goto end;
 304                         }
 305                 } else {
 306                         consumer_add_stream(new_stream);
 307                 }
 308                 break;
 309         }
 310         case LTTNG_CONSUMER_UPDATE_STREAM:
 311         {
 312                 return -ENOSYS;
 313 #if 0
 314                 if (ctx->on_update_stream != NULL) {
 315                         ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
 316                         if (ret == 0) {
 317                                 consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
 318                         } else if (ret < 0) {
 319                                 goto end;
 320                         }
 321                 } else {
 322                         consumer_change_stream_state(msg.u.stream.stream_key,
 323                                 msg.u.stream.state);
 324                 }
 325 #endif
 326                 break;
 327         }
 328         default:
 329                 break;
 330         }
 331 end:
 332         /*
 333          * Wake-up the other end by writing a null byte in the pipe
 334          * (non-blocking). Important note: Because writing into the
 335          * pipe is non-blocking (and therefore we allow dropping wakeup
 336          * data, as long as there is wakeup data present in the pipe
 337          * buffer to wake up the other end), the other end should
 338          * perform the following sequence for waiting:
 339          * 1) empty the pipe (reads).
 340          * 2) perform update operation.
 341          * 3) wait on the pipe (poll).
 342          */
 343         do {
 344                 ret = write(ctx->consumer_poll_pipe[1], "", 1);
 345         } while (ret == -1UL && errno == EINTR);
 346 end_nosignal:
 347
 348         /*
 349          * Return 1 to indicate success since the 0 value can be a socket shutdown
 350          * during the recv() or send() call.
 351          */
 352         return 1;
 353 }
 354
 355 int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
 356 {
 357         struct lttng_ust_object_data obj;
 358
 359         obj.handle = -1;
 360         obj.shm_fd = chan->shm_fd;
 361         obj.wait_fd = chan->wait_fd;
 362         obj.memory_map_size = chan->mmap_len;
 363         chan->handle = ustctl_map_channel(&obj);
 364         if (!chan->handle) {
 365                 return -ENOMEM;
 366         }
 367         chan->wait_fd_is_copy = 1;
 368         chan->shm_fd = -1;
 369
 370         return 0;
 371 }
 372
 373 void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
 374 {
 375         ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
 376         stream->hangup_flush_done = 1;
 377 }
 378
 379 void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
 380 {
 381         ustctl_unmap_channel(chan->handle);
 382 }
 383
 384 int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
 385 {
 386         struct lttng_ust_object_data obj;
 387         int ret;
 388
 389         obj.handle = -1;
 390         obj.shm_fd = stream->shm_fd;
 391         obj.wait_fd = stream->wait_fd;
 392         obj.memory_map_size = stream->mmap_len;
 393         ret = ustctl_add_stream(stream->chan->handle, &obj);
 394         if (ret)
 395                 return ret;
 396         stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
 397         if (!stream->buf)
 398                 return -EBUSY;
 399         /* ustctl_open_stream_read has closed the shm fd. */
 400         stream->wait_fd_is_copy = 1;
 401         stream->shm_fd = -1;
 402
 403         stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
 404         if (!stream->mmap_base) {
 405                 return -EINVAL;
 406         }
 407
 408         return 0;
 409 }
 410
 411 void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
 412 {
 413         ustctl_close_stream_read(stream->chan->handle, stream->buf);
 414 }
 415
 416
 417 int lttng_ustconsumer_check_pipe(struct lttng_consumer_stream *stream,
 418                 struct lttng_consumer_local_data *ctx)
 419 {
 420         ssize_t readlen;
 421         char dummy;
 422
 423         DBG("In check_pipe (wait_fd: %d, stream key: %d)\n",
 424                 stream->wait_fd, stream->key);
 425
 426         /* We consume the 1 byte written into the wait_fd by UST */
 427
 428         do {
 429                 readlen = read(stream->wait_fd, &dummy, 1);
 430         } while (readlen == -1 && errno == EINTR);
 431         if (readlen == -1) {
 432                 return -1;      /* error */
 433         }
 434
 435         DBG("Read %zu byte from pipe: %c\n", readlen, readlen ? dummy : '\0');
 436
 437         if (readlen == 0)
 438                 return 1;       /* POLLHUP */
 439
 440         return 0;       /* no error nor HUP */
 441
 442 }
 443
 444 int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 445                 struct lttng_consumer_local_data *ctx)
 446 {
 447         unsigned long len;
 448         int err;
 449         long ret = 0;
 450         struct lttng_ust_shm_handle *handle;
 451         struct lttng_ust_lib_ring_buffer *buf;
 452         char dummy;
 453         ssize_t readlen;
 454
 455         DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
 456                 stream->wait_fd, stream->key);
 457
 458         /* We can consume the 1 byte written into the wait_fd by UST */
 459         if (!stream->hangup_flush_done) {
 460                 do {
 461                         readlen = read(stream->wait_fd, &dummy, 1);
 462                 } while (readlen == -1 && errno == EINTR);
 463                 if (readlen == -1) {
 464                         ret = readlen;
 465                         goto end;
 466                 }
 467                 DBG("Read %zu byte from pipe: %c\n", readlen, dummy);
 468         }
 469
 470         buf = stream->buf;
 471         handle = stream->chan->handle;
 472         /* Get the next subbuffer */
 473         err = ustctl_get_next_subbuf(handle, buf);
 474         if (err != 0) {
 475                 ret = -ret;     /* ustctl_get_next_subbuf returns negative, caller expect positive. */
 476                 /*
 477                  * This is a debug message even for single-threaded consumer,
 478                  * because poll() have more relaxed criterions than get subbuf,
 479                  * so get_subbuf may fail for short race windows where poll()
 480                  * would issue wakeups.
 481                  */
 482                 DBG("Reserving sub buffer failed (everything is normal, "
 483                                 "it is due to concurrency)");
 484                 goto end;
 485         }
 486         assert(stream->output == LTTNG_EVENT_MMAP);
 487         /* read the used subbuffer size */
 488         err = ustctl_get_padded_subbuf_size(handle, buf, &len);
 489         assert(err == 0);
 490         /* write the subbuffer to the tracefile */
 491         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 492         if (ret != len) {
 493                 /*
 494                  * display the error but continue processing to try
 495                  * to release the subbuffer
 496                  */
 497                 ERR("Error writing to tracefile");
 498         }
 499         err = ustctl_put_next_subbuf(handle, buf);
 500         assert(err == 0);
 501 end:
 502         return ret;
 503 }
 504
 505 int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 506 {
 507         int ret;
 508
 509         /* Opening the tracefile in write mode */
 510         if (stream->path_name != NULL) {
 511                 ret = run_as_open(stream->path_name,
 512                                 O_WRONLY|O_CREAT|O_TRUNC,
 513                                 S_IRWXU|S_IRWXG|S_IRWXO,
 514                                 stream->uid, stream->gid);
 515                 if (ret < 0) {
 516                         ERR("Opening %s", stream->path_name);
 517                         PERROR("open");
 518                         goto error;
 519                 }
 520                 stream->out_fd = ret;
 521         }
 522
 523         /* we return 0 to let the library handle the FD internally */
 524         return 0;
 525
 526 error:
 527         return ret;
 528 }