liblttng-ustconsumer/lttng-ustconsumer.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
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; only version 2
   8  * of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <assert.h>
  22 #include <fcntl.h>
  23 #include <poll.h>
  24 #include <pthread.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/mman.h>
  28 #include <sys/socket.h>
  29 #include <sys/types.h>
  30 #include <unistd.h>
  31
  32 #include <lttng-sessiond-comm.h>
  33 #include <lttng/lttng-ustconsumer.h>
  34 #include <lttng/ust-ctl.h>
  35 #include <lttngerr.h>
  36
  37 #include "common/runas.h"
  38
  39 extern struct lttng_consumer_global_data consumer_data;
  40 extern int consumer_poll_timeout;
  41 extern volatile int consumer_quit;
  42
  43 /*
  44  * Mmap the ring buffer, read it and write the data to the tracefile.
  45  *
  46  * Returns the number of bytes written
  47  */
  48 int lttng_ustconsumer_on_read_subbuffer_mmap(
  49                 struct lttng_consumer_local_data *ctx,
  50                 struct lttng_consumer_stream *stream, unsigned long len)
  51 {
  52         unsigned long mmap_offset;
  53         long ret = 0;
  54         off_t orig_offset = stream->out_fd_offset;
  55         int outfd = stream->out_fd;
  56
  57         /* get the offset inside the fd to mmap */
  58         ret = ustctl_get_mmap_read_offset(stream->chan->handle,
  59                 stream->buf, &mmap_offset);
  60         if (ret != 0) {
  61                 ret = -errno;
  62                 perror("ustctl_get_mmap_read_offset");
  63                 goto end;
  64         }
  65         while (len > 0) {
  66                 ret = write(outfd, stream->mmap_base + mmap_offset, len);
  67                 if (ret >= len) {
  68                         len = 0;
  69                 } else if (ret < 0) {
  70                         ret = -errno;
  71                         perror("Error in file write");
  72                         goto end;
  73                 }
  74                 /* This won't block, but will start writeout asynchronously */
  75                 sync_file_range(outfd, stream->out_fd_offset, ret,
  76                                 SYNC_FILE_RANGE_WRITE);
  77                 stream->out_fd_offset += ret;
  78         }
  79
  80         lttng_consumer_sync_trace_file(stream, orig_offset);
  81
  82         goto end;
  83
  84 end:
  85         return ret;
  86 }
  87
  88 /*
  89  * Splice the data from the ring buffer to the tracefile.
  90  *
  91  * Returns the number of bytes spliced.
  92  */
  93 int lttng_ustconsumer_on_read_subbuffer_splice(
  94                 struct lttng_consumer_local_data *ctx,
  95                 struct lttng_consumer_stream *stream, unsigned long len)
  96 {
  97         return -ENOSYS;
  98 }
  99
 100 /*
 101  * Take a snapshot for a specific fd
 102  *
 103  * Returns 0 on success, < 0 on error
 104  */
 105 int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 106                 struct lttng_consumer_stream *stream)
 107 {
 108         int ret = 0;
 109
 110         ret = ustctl_snapshot(stream->chan->handle, stream->buf);
 111         if (ret != 0) {
 112                 ret = errno;
 113                 perror("Getting sub-buffer snapshot.");
 114         }
 115
 116         return ret;
 117 }
 118
 119 /*
 120  * Get the produced position
 121  *
 122  * Returns 0 on success, < 0 on error
 123  */
 124 int lttng_ustconsumer_get_produced_snapshot(
 125                 struct lttng_consumer_local_data *ctx,
 126                 struct lttng_consumer_stream *stream,
 127                 unsigned long *pos)
 128 {
 129         int ret;
 130
 131         ret = ustctl_snapshot_get_produced(stream->chan->handle,
 132                         stream->buf, pos);
 133         if (ret != 0) {
 134                 ret = errno;
 135                 perror("kernctl_snapshot_get_produced");
 136         }
 137
 138         return ret;
 139 }
 140
 141 int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 142                 int sock, struct pollfd *consumer_sockpoll)
 143 {
 144         ssize_t ret;
 145         struct lttcomm_consumer_msg msg;
 146
 147         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 148         if (ret != sizeof(msg)) {
 149                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 150                 return ret;
 151         }
 152         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 153                 return -ENOENT;
 154         }
 155
 156         switch (msg.cmd_type) {
 157         case LTTNG_CONSUMER_ADD_CHANNEL:
 158         {
 159                 struct lttng_consumer_channel *new_channel;
 160                 int fds[1];
 161                 size_t nb_fd = 1;
 162
 163                 /* block */
 164                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 165                         return -EINTR;
 166                 }
 167                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 168                 if (ret != sizeof(fds)) {
 169                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 170                         return ret;
 171                 }
 172
 173                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 174
 175                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 176                                 fds[0], -1,
 177                                 msg.u.channel.mmap_len,
 178                                 msg.u.channel.max_sb_size);
 179                 if (new_channel == NULL) {
 180                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 181                         goto end_nosignal;
 182                 }
 183                 if (ctx->on_recv_channel != NULL) {
 184                         ret = ctx->on_recv_channel(new_channel);
 185                         if (ret == 0) {
 186                                 consumer_add_channel(new_channel);
 187                         } else if (ret < 0) {
 188                                 goto end_nosignal;
 189                         }
 190                 } else {
 191                         consumer_add_channel(new_channel);
 192                 }
 193                 goto end_nosignal;
 194         }
 195         case LTTNG_CONSUMER_ADD_STREAM:
 196         {
 197                 struct lttng_consumer_stream *new_stream;
 198                 int fds[2];
 199                 size_t nb_fd = 2;
 200
 201                 /* block */
 202                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 203                         return -EINTR;
 204                 }
 205                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 206                 if (ret != sizeof(fds)) {
 207                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 208                         return ret;
 209                 }
 210
 211                 DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
 212                         fds[0], fds[1]);
 213                 assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
 214                 new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
 215                                 msg.u.stream.stream_key,
 216                                 fds[0], fds[1],
 217                                 msg.u.stream.state,
 218                                 msg.u.stream.mmap_len,
 219                                 msg.u.stream.output,
 220                                 msg.u.stream.path_name,
 221                                 msg.u.stream.uid,
 222                                 msg.u.stream.gid);
 223                 if (new_stream == NULL) {
 224                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 225                         goto end;
 226                 }
 227                 if (ctx->on_recv_stream != NULL) {
 228                         ret = ctx->on_recv_stream(new_stream);
 229                         if (ret == 0) {
 230                                 consumer_add_stream(new_stream);
 231                         } else if (ret < 0) {
 232                                 goto end;
 233                         }
 234                 } else {
 235                         consumer_add_stream(new_stream);
 236                 }
 237                 break;
 238         }
 239         case LTTNG_CONSUMER_UPDATE_STREAM:
 240         {
 241                 return -ENOSYS;
 242 #if 0
 243                 if (ctx->on_update_stream != NULL) {
 244                         ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
 245                         if (ret == 0) {
 246                                 consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
 247                         } else if (ret < 0) {
 248                                 goto end;
 249                         }
 250                 } else {
 251                         consumer_change_stream_state(msg.u.stream.stream_key,
 252                                 msg.u.stream.state);
 253                 }
 254 #endif
 255                 break;
 256         }
 257         default:
 258                 break;
 259         }
 260 end:
 261         /* signal the poll thread */
 262         ret = write(ctx->consumer_poll_pipe[1], "4", 1);
 263         if (ret < 0) {
 264                 perror("write consumer poll");
 265         }
 266 end_nosignal:
 267         return 0;
 268 }
 269
 270 int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
 271 {
 272         struct lttng_ust_object_data obj;
 273
 274         obj.handle = -1;
 275         obj.shm_fd = chan->shm_fd;
 276         obj.wait_fd = chan->wait_fd;
 277         obj.memory_map_size = chan->mmap_len;
 278         chan->handle = ustctl_map_channel(&obj);
 279         if (!chan->handle) {
 280                 return -ENOMEM;
 281         }
 282         chan->wait_fd_is_copy = 1;
 283         chan->shm_fd = -1;
 284
 285         return 0;
 286 }
 287
 288 void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
 289 {
 290         ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
 291         stream->hangup_flush_done = 1;
 292 }
 293
 294 void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
 295 {
 296         ustctl_unmap_channel(chan->handle);
 297 }
 298
 299 int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
 300 {
 301         struct lttng_ust_object_data obj;
 302         int ret;
 303
 304         obj.handle = -1;
 305         obj.shm_fd = stream->shm_fd;
 306         obj.wait_fd = stream->wait_fd;
 307         obj.memory_map_size = stream->mmap_len;
 308         ret = ustctl_add_stream(stream->chan->handle, &obj);
 309         if (ret)
 310                 return ret;
 311         stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
 312         if (!stream->buf)
 313                 return -EBUSY;
 314         /* ustctl_open_stream_read has closed the shm fd. */
 315         stream->wait_fd_is_copy = 1;
 316         stream->shm_fd = -1;
 317
 318         stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
 319         if (!stream->mmap_base) {
 320                 return -EINVAL;
 321         }
 322
 323         return 0;
 324 }
 325
 326 void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
 327 {
 328         ustctl_close_stream_read(stream->chan->handle, stream->buf);
 329 }
 330
 331
 332 int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 333                 struct lttng_consumer_local_data *ctx)
 334 {
 335         unsigned long len;
 336         int err;
 337         long ret = 0;
 338         struct lttng_ust_shm_handle *handle;
 339         struct lttng_ust_lib_ring_buffer *buf;
 340         char dummy;
 341         ssize_t readlen;
 342
 343         DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
 344                 stream->wait_fd, stream->key);
 345
 346         /* We can consume the 1 byte written into the wait_fd by UST */
 347         if (!stream->hangup_flush_done) {
 348                 do {
 349                         readlen = read(stream->wait_fd, &dummy, 1);
 350                 } while (readlen == -1 && errno == -EINTR);
 351                 if (readlen == -1) {
 352                         ret = readlen;
 353                         goto end;
 354                 }
 355         }
 356
 357         buf = stream->buf;
 358         handle = stream->chan->handle;
 359         /* Get the next subbuffer */
 360         err = ustctl_get_next_subbuf(handle, buf);
 361         if (err != 0) {
 362                 ret = -ret;     /* ustctl_get_next_subbuf returns negative, caller expect positive. */
 363                 /*
 364                  * This is a debug message even for single-threaded consumer,
 365                  * because poll() have more relaxed criterions than get subbuf,
 366                  * so get_subbuf may fail for short race windows where poll()
 367                  * would issue wakeups.
 368                  */
 369                 DBG("Reserving sub buffer failed (everything is normal, "
 370                                 "it is due to concurrency)");
 371                 goto end;
 372         }
 373         assert(stream->output == LTTNG_EVENT_MMAP);
 374         /* read the used subbuffer size */
 375         err = ustctl_get_padded_subbuf_size(handle, buf, &len);
 376         assert(err == 0);
 377         /* write the subbuffer to the tracefile */
 378         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 379         if (ret < 0) {
 380                 /*
 381                  * display the error but continue processing to try
 382                  * to release the subbuffer
 383                  */
 384                 ERR("Error writing to tracefile");
 385         }
 386         err = ustctl_put_next_subbuf(handle, buf);
 387         assert(err == 0);
 388 end:
 389         return ret;
 390 }
 391
 392 int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 393 {
 394         int ret;
 395
 396         /* Opening the tracefile in write mode */
 397         if (stream->path_name != NULL) {
 398                 ret = run_as_open(stream->path_name,
 399                                 O_WRONLY|O_CREAT|O_TRUNC,
 400                                 S_IRWXU|S_IRWXG|S_IRWXO,
 401                                 stream->uid, stream->gid);
 402                 if (ret < 0) {
 403                         ERR("Opening %s", stream->path_name);
 404                         perror("open");
 405                         goto error;
 406                 }
 407                 stream->out_fd = ret;
 408         }
 409
 410         /* we return 0 to let the library handle the FD internally */
 411         return 0;
 412
 413 error:
 414         return ret;
 415 }