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[lttng-tools.git] / ltt-sessiond / ltt-sessiond.c
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DG
1/* Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU General Public License
5 * as published by the Free Software Foundation; either version 2
6 * of the License, or (at your option) any later version.
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
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
16 *
17 */
18
19#define _GNU_SOURCE
20#include <fcntl.h>
21#include <getopt.h>
22#include <grp.h>
23#include <limits.h>
24#include <pthread.h>
25#include <signal.h>
26#include <stdio.h>
27#include <stdlib.h>
28#include <string.h>
29#include <sys/ipc.h>
30#include <sys/shm.h>
31#include <sys/socket.h>
32#include <sys/stat.h>
33#include <sys/types.h>
34#include <unistd.h>
35
36#include <urcu/list.h> /* URCU list library (-lurcu) */
37#include <ust/ustctl.h> /* UST control lib (-lust) */
38
39#include "liblttsessiondcomm.h"
40#include "ltt-sessiond.h"
41
42/* Static functions */
43static int set_signal_handler(void);
44static int set_socket_perms(void);
45static void sighandler(int);
46static void daemonize(void);
47static void cleanup(void);
48static int check_existing_daemon(void);
49static int notify_apps(const char*);
50static int connect_app(pid_t);
51static int init_daemon_socket(void);
52static struct lttcomm_lttng_msg *process_client_msg(struct lttcomm_session_msg*);
53
54static void *thread_manage_clients(void *);
55static void *thread_manage_apps(void *);
56
57static int create_session(const char*, uuid_t *);
58static void destroy_session(uuid_t);
59
60static struct ltt_session *find_session(uuid_t);
61
62/* Variables */
63const char *progname;
64const char *opt_tracing_group;
65static int opt_daemon;
66static int is_root; /* Set to 1 if the daemon is running as root */
67
68static char apps_unix_sock_path[PATH_MAX]; /* Global application Unix socket path */
69static char client_unix_sock_path[PATH_MAX]; /* Global client Unix socket path */
70
71static int client_socket;
72static int apps_socket;
73
74static struct ltt_session *current_session;
75static int session_count;
76
77/* Init session's list */
78static struct ltt_session_list ltt_session_list = {
79 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
80};
81
82static struct ltt_traceable_app_list ltt_traceable_app_list = {
83 .head = CDS_LIST_HEAD_INIT(ltt_traceable_app_list.head),
84};
85
86/*
87 * thread_manage_apps
88 *
89 * This thread manage the application socket communication
90 */
91static void *thread_manage_apps(void *data)
92{
93 int sock, ret;
94 struct ltt_traceable_app *lta;
95
96 /* TODO: Something more elegant is needed but fine for now */
97 struct {
98 int reg; /* 1:register, 0:unregister */
99 pid_t pid;
100 uid_t uid;
101 } reg_msg;
102
103 /* Notify all applications to register */
104 notify_apps(default_global_apps_pipe);
105
106 ret = lttcomm_listen_unix_sock(apps_socket);
107 if (ret < 0) {
108 goto error;
109 }
110
111 while (1) {
112 /* Blocking call, waiting for transmission */
113 sock = lttcomm_accept_unix_sock(apps_socket);
114 if (sock < 0) {
115 goto error;
116 }
117
118 /* Basic recv here to handle the very simple data
119 * that the libust send to register (reg_msg).
120 */
121 ret = recv(sock, &reg_msg, sizeof(reg_msg), 0);
122 if (ret < 0) {
123 perror("recv");
124 continue;
125 }
126
127 /* Add application to the global traceable list */
128 if (reg_msg.reg == 1) {
129 /* Registering */
130 lta = malloc(sizeof(struct ltt_traceable_app));
131 lta->pid = reg_msg.pid;
132 lta->uid = reg_msg.uid;
133 cds_list_add(&lta->list, &ltt_traceable_app_list.head);
134 } else {
135 /* Unregistering */
136 lta = NULL;
137 cds_list_for_each_entry(lta, &ltt_traceable_app_list.head, list) {
138 if (lta->pid == reg_msg.pid && lta->uid == reg_msg.uid) {
139 cds_list_del(&lta->list);
140 break;
141 }
142 }
143
144 /* If an item was found, free it from memory */
145 if (lta) {
146 free(lta);
147 }
148 }
149 }
150
151error:
152
153 return NULL;
154}
155
156/*
157 * thread_manage_clients
158 *
159 * This thread manage all clients request using the unix
160 * client socket for communication.
161 */
162static void *thread_manage_clients(void *data)
163{
164 int sock, ret;
165 struct lttcomm_session_msg lsm;
166 struct lttcomm_lttng_msg *llm;
167
168 ret = lttcomm_listen_unix_sock(client_socket);
169 if (ret < 0) {
170 goto error;
171 }
172
173 while (1) {
174 /* Blocking call, waiting for transmission */
175 sock = lttcomm_accept_unix_sock(client_socket);
176 if (sock < 0) {
177 goto error;
178 }
179
180 /*
181 * Data is received from the lttng client. The struct
182 * lttcomm_session_msg (lsm) contains the command and data
183 * request of the client.
184 */
185 ret = lttcomm_recv_unix_sock(sock, &lsm, sizeof(lsm));
186 if (ret < 0) {
187 continue;
188 }
189
190 /* This function dispatch the work to the LTTng or UST libs
191 * and make sure that the reply structure (llm) is filled.
192 */
193 llm = process_client_msg(&lsm);
194
195 /* Having a valid lttcomm_lttng_msg struct, reply is sent back
196 * to the client directly.
197 */
198 if (llm != NULL) {
199 ret = lttcomm_send_unix_sock(sock, llm,
200 sizeof(struct lttcomm_lttng_msg));
201 free(llm);
202 if (ret < 0) {
203 continue;
204 }
205 } else {
206 /* The lttcomm_lttng_msg struct was not allocated
207 * correctly. Fatal error since the daemon is not able
208 * to respond. However, we still permit client connection.
209 *
210 * TODO: We should have a default llm that tells the client
211 * that the sessiond had a fatal error and thus the client could
212 * take action to restart ltt-sessiond or inform someone.
213 */
214 }
215 }
216
217error:
218 return NULL;
219}
220
221/*
222 * connect_app
223 *
224 * Return a socket connected to the libust communication socket
225 * of the application identified by the pid.
226 */
227static int connect_app(pid_t pid)
228{
229 int sock;
230
231 sock = ustctl_connect_pid(pid);
232 if (sock < 0) {
233 fprintf(stderr, "Fail connecting to the PID %d\n", pid);
234 }
235
236 return sock;
237}
238
239/*
240 * notify_apps
241 *
242 * Notify apps by writing 42 to a named pipe using name.
243 * Every applications waiting for a ltt-sessiond will be notified
244 * and re-register automatically to the session daemon.
245 *
246 * Return open or write error value.
247 */
248static int notify_apps(const char *name)
249{
250 int fd;
251 int ret = -1;
252
253 /* Try opening the global pipe */
254 fd = open(name, O_WRONLY);
255 if (fd < 0) {
256 goto error;
257 }
258
259 /* Notify by writing on the pipe */
260 ret = write(fd, "42", 2);
261 if (ret < 0) {
262 perror("write");
263 }
264
265error:
266 return ret;
267}
268
269/*
270 * find_session
271 *
272 * Return a ltt_session structure ptr that matches the uuid.
273 */
274static struct ltt_session *find_session(uuid_t session_id)
275{
276 struct ltt_session *iter = NULL;
277
278 /* Sanity check for NULL session_id */
279 if (uuid_is_null(session_id)) {
280 goto end;
281 }
282
283 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
284 if (uuid_compare(iter->uuid, session_id)) {
285 break;
286 }
287 }
288
289end:
290 return iter;
291}
292
293/*
294 * destroy_session
295 *
296 * Delete session from the global session list
297 * and free the memory.
298 */
299static void destroy_session(uuid_t session_id)
300{
301 struct ltt_session *iter = NULL;
302
303 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
304 if (uuid_compare(iter->uuid, session_id)) {
305 cds_list_del(&iter->list);
306 break;
307 }
308 }
309
310 if (iter) {
311 free(iter);
312 session_count--;
313 }
314}
315
316/*
317 * create_session
318 *
319 * Create a brand new session,
320 */
321static int create_session(const char *name, uuid_t *session_id)
322{
323 struct ltt_session *new_session;
324
325 /* Allocate session data structure */
326 new_session = malloc(sizeof(struct ltt_session));
327 if (new_session == NULL) {
328 perror("malloc");
329 goto error;
330 }
331
332 if (name != NULL) {
333 if (asprintf(&new_session->name, "%s", name) < 0) {
334 goto error;
335 }
336 } else {
337 /* Generate session name based on the session count */
338 if (asprintf(&new_session->name, "%s%d", "auto", session_count) < 0) {
339 goto error;
340 }
341 }
342
343 /* UUID generation */
344 uuid_generate(new_session->uuid);
345 uuid_copy(*session_id, new_session->uuid);
346
347 /* Set consumer (identifier) to 0. This means that there is
348 * NO consumer attach to that session yet.
349 */
350 new_session->ust_consumer = 0;
351 new_session->lttng_consumer = 0;
352
353 /* Init list */
354 CDS_INIT_LIST_HEAD(&new_session->ust_traces);
355 CDS_INIT_LIST_HEAD(&new_session->lttng_traces);
356
357 /* Add new session to the global session list */
358 cds_list_add(&new_session->list, &ltt_session_list.head);
359
360 session_count++;
361
362 return 0;
363
364error:
365 return -1;
366}
367
368/*
369 * ust_list_apps
370 *
371 * List traceable user-space application and fill an
372 * array of pids.
373 *
374 * Return size of the array.
375 */
376static size_t ust_list_apps(pid_t *pids)
377{
378 size_t size = 0;
379 struct ltt_traceable_app *iter = NULL;
380
381 cds_list_for_each_entry(iter, &ltt_traceable_app_list.head, list) {
382 if (size >= MAX_APPS_PID) {
383 break;
384 }
385
386 pids[size] = iter->pid;
387 size++;
388 }
389
390 return size;
391}
392
393/*
394 * process_client_msg
395 *
396 * This takes the lttcomm_session_msg struct and process the command requested
397 * by the client. It then creates the reply by allocating a lttcomm_lttng_msg
398 * and fill it with the necessary information.
399 *
400 * It's the caller responsability to free that structure when done with it.
401 *
402 * Return pointer to lttcomm_lttng_msg allocated struct.
403 */
404static struct lttcomm_lttng_msg *process_client_msg(struct lttcomm_session_msg *lsm)
405{
406 struct lttcomm_lttng_msg *llm;
407
408 /* Allocate the reply message structure */
409 llm = malloc(sizeof(struct lttcomm_lttng_msg));
410 if (llm == NULL) {
411 perror("malloc");
412 goto end;
413 }
414
415 /* Copy common data to identify the response
416 * on the lttng client side.
417 */
418 llm->cmd_type = lsm->cmd_type;
419 llm->pid = lsm->pid;
420 if (!uuid_is_null(lsm->session_id)) {
421 uuid_copy(llm->session_id, lsm->session_id);
422 }
423 strncpy(llm->trace_name, lsm->trace_name, sizeof(llm->trace_name));
424
425 /* Default return code.
426 * In a our world, everything is OK... right?
427 */
428 llm->ret_code = LTTCOMM_OK;
429
430 /* Process by command type */
431 switch (lsm->cmd_type) {
432 case UST_LIST_APPS:
433 {
434 llm->u.list_apps.size = ust_list_apps(llm->u.list_apps.pids);
435 break;
436 }
437 default:
438 /* Undefined command */
439 llm->ret_code = LTTCOMM_UND;
440 break;
441 }
442
443end:
444 return llm;
445}
446
447/*
448 * usage function on stderr
449 */
450static void usage(void)
451{
452 fprintf(stderr, "Usage:\n%s OPTIONS\n\nOptions:\n"
453 "\t-h, --help\t\tDisplay this usage.\n"
454 "\t-c, --client-sock PATH\t\tSpecify path for the client unix socket\n"
455 "\t-a, --apps-sock PATH\t\tSpecify path for apps unix socket.\n"
456 "\t-d, --daemonize\t\tStart as a daemon.\n"
457 "\t-g, --group NAME\t\tSpecify the tracing group name. (default: tracing)\n"
458 "\t-V, --version\t\tShow version number.\n",
459 progname);
460}
461
462/*
463 * daemon argument parsing
464 */
465static int parse_args(int argc, char **argv)
466{
467 int c;
468
469 static struct option long_options[] = {
470 { "client-sock", 1, 0, 'c' },
471 { "apps-sock", 1, 0, 'a' },
472 { "daemonize", 0, 0, 'd' },
473 { "help", 0, 0, 'h' },
474 { "group", 1, 0, 'g' },
475 { "version", 0, 0, 'V' },
476 { NULL, 0, 0, 0 }
477 };
478
479 while (1) {
480 int option_index = 0;
481 c = getopt_long(argc, argv, "dhV" "a:c:g:s:", long_options, &option_index);
482 if (c == -1) {
483 break;
484 }
485
486 switch (c) {
487 case 0:
488 fprintf(stderr, "option %s", long_options[option_index].name);
489 if (optarg) {
490 fprintf(stderr, " with arg %s\n", optarg);
491 }
492 break;
493 case 's':
494 snprintf(client_unix_sock_path, PATH_MAX, "%s", optarg);
495 break;
496 case 'a':
497 snprintf(apps_unix_sock_path, PATH_MAX, "%s", optarg);
498 break;
499 case 'd':
500 opt_daemon = 1;
501 break;
502 case 'g':
503 opt_tracing_group = strdup(optarg);
504 break;
505 case 'h':
506 usage();
507 exit(EXIT_FAILURE);
508 case 'V':
509 fprintf(stdout, "%s\n", VERSION);
510 exit(EXIT_SUCCESS);
511 default:
512 /* Unknown option or other error.
513 * Error is printed by getopt, just return */
514 return -1;
515 }
516 }
517
518 return 0;
519}
520
521/*
522 * init_daemon_socket
523 *
524 * Creates the two needed socket by the daemon.
525 * apps_socket - The communication socket for all UST apps.
526 * client_socket - The communication of the cli tool (lttng).
527 */
528static int init_daemon_socket()
529{
530 int ret = 0;
531 mode_t old_umask;
532
533 old_umask = umask(0);
534
535 /* Create client tool unix socket */
536 client_socket = lttcomm_create_unix_sock(client_unix_sock_path);
537 if (client_socket < 0) {
538 ret = -1;
539 goto end;
540 }
541
542 /* File permission MUST be 660 */
543 ret = chmod(client_unix_sock_path, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
544 if (ret < 0) {
545 perror("chmod");
546 goto end;
547 }
548
549 /* Create the application unix socket */
550 apps_socket = lttcomm_create_unix_sock(apps_unix_sock_path);
551 if (apps_socket < 0) {
552 ret = -1;
553 goto end;
554 }
555
556 /* File permission MUST be 660 */
557 ret = chmod(apps_unix_sock_path, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
558 if (ret < 0) {
559 perror("chmod");
560 goto end;
561 }
562
563end:
564 umask(old_umask);
565 return ret;
566}
567
568/*
569 * check_existing_daemon
570 *
571 * Check if the global socket is available.
572 * If yes, error is returned.
573 */
574static int check_existing_daemon()
575{
576 int ret;
577
578 ret = access(client_unix_sock_path, F_OK);
579 if (ret == 0) {
580 ret = access(apps_unix_sock_path, F_OK);
581 }
582
583 return ret;
584}
585
586/*
587 * get_home_dir
588 *
589 * Return pointer to home directory path using
590 * the env variable HOME.
591 *
592 * Default : /tmp
593 */
594static const char *get_home_dir(void)
595{
596 const char *home_path;
597
598 if ((home_path = (const char*) getenv("HOME")) == NULL) {
599 home_path = default_home_dir;
600 }
601
602 return home_path;
603}
604
605/*
606 * set_socket_perms
607 *
608 * Set the tracing group gid onto the client socket.
609 */
610static int set_socket_perms(void)
611{
612 int ret;
613 struct group *grp;
614
615 /* Decide which group name to use */
616 (opt_tracing_group != NULL) ?
617 (grp = getgrnam(opt_tracing_group)) :
618 (grp = getgrnam(default_tracing_group));
619
620 if (grp == NULL) {
621 fprintf(stderr, "Missing tracing group. Aborting execution.\n");
622 ret = -1;
623 goto end;
624 }
625
626 ret = chown(client_unix_sock_path, 0, grp->gr_gid);
627 if (ret < 0) {
628 perror("chown");
629 }
630
631end:
632 return ret;
633}
634
635/*
636 * daemonize
637 *
638 * Daemonize ltt-sessiond.
639 */
640static void daemonize(void)
641{
642 pid_t pid, sid;
643 const char *home_dir = get_home_dir();
644
645 /* Fork off the parent process */
646 if ((pid = fork()) < 0) {
647 perror("fork");
648 exit(EXIT_FAILURE);
649 }
650
651 /* Parent can now exit */
652 if (pid > 0) {
653 exit(EXIT_SUCCESS);
654 }
655
656 /* Change the file mode mask */
657 umask(0);
658
659 /* Create a new SID for the child process */
660 if ((sid = setsid()) < 0) {
661 perror("setsid");
662 exit(EXIT_FAILURE);
663 }
664
665 /* Change the current working directory */
666 if ((chdir(home_dir)) < 0) {
667 perror("chdir");
668 exit(EXIT_FAILURE);
669 }
670
671 /* Close out the standard file descriptors */
672 close(STDIN_FILENO);
673 close(STDOUT_FILENO);
674 close(STDERR_FILENO);
675}
676
677/*
678 * set_signal_handler
679 *
680 * Setup signal handler for :
681 * SIGINT, SIGTERM, SIGPIPE
682 */
683static int set_signal_handler(void)
684{
685 int ret = 0;
686 struct sigaction sa;
687 sigset_t sigset;
688
689 if ((ret = sigemptyset(&sigset)) < 0) {
690 perror("sigemptyset");
691 return ret;
692 }
693
694 sa.sa_handler = sighandler;
695 sa.sa_mask = sigset;
696 sa.sa_flags = 0;
697 if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
698 perror("sigaction");
699 return ret;
700 }
701
702 if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
703 perror("sigaction");
704 return ret;
705 }
706
707 if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
708 perror("sigaction");
709 return ret;
710 }
711
712 return ret;
713}
714
715/**
716 * sighandler
717 *
718 * Signal handler for the daemon
719 */
720static void sighandler(int sig)
721{
722 switch (sig) {
723 case SIGPIPE:
724 case SIGINT:
725 case SIGTERM:
726 cleanup();
727 default:
728 break;
729 }
730
731 exit(EXIT_SUCCESS);
732}
733
734/*
735 * cleanup
736 *
737 * Cleanup the daemon on exit
738 */
739static void cleanup()
740{
741 /* <fun> */
742 fprintf(stdout, "\n\n%c[%d;%dm*** assert failed *** ==> %c[%dm", 27,1,31,27,0);
743 fprintf(stdout, "%c[%d;%dm Matthew, BEET driven development works!%c[%dm\n",27,1,33,27,0);
744 /* </fun> */
745
746 unlink(client_unix_sock_path);
747 unlink(apps_unix_sock_path);
748}
749
750/*
751 * main
752 */
753int main(int argc, char **argv)
754{
755 int i;
756 int ret = 0;
757 void *status;
758 pthread_t threads[2];
759
760 /* Parse arguments */
761 progname = argv[0];
762 if ((ret = parse_args(argc, argv) < 0)) {
763 goto error;
764 }
765
766 /* Daemonize */
767 if (opt_daemon) {
768 daemonize();
769 }
770
771 /* Check if daemon is UID = 0 */
772 is_root = !getuid();
773
774 /* Set all sockets path */
775 if (is_root) {
776 if (strlen(apps_unix_sock_path) == 0) {
777 (snprintf(apps_unix_sock_path, PATH_MAX,
778 DEFAULT_GLOBAL_APPS_UNIX_SOCK));
779 }
780
781 if (strlen(client_unix_sock_path) == 0) {
782 (snprintf(client_unix_sock_path, PATH_MAX,
783 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
784 }
785 } else {
786 if (strlen(apps_unix_sock_path) == 0) {
787 (snprintf(apps_unix_sock_path, PATH_MAX,
788 DEFAULT_HOME_APPS_UNIX_SOCK, get_home_dir()));
789 }
790
791 /* Set the cli tool unix socket path */
792 if (strlen(client_unix_sock_path) == 0) {
793 (snprintf(client_unix_sock_path, PATH_MAX,
794 DEFAULT_HOME_CLIENT_UNIX_SOCK, get_home_dir()));
795 }
796 }
797
798 /* See if daemon already exist. If any of the two
799 * socket needed by the daemon are present, this test fails
800 */
801 if ((ret = check_existing_daemon()) == 0) {
802 fprintf(stderr, "Already running daemon.\n");
803 goto error;
804 }
805
806 if (set_signal_handler() < 0) {
807 goto error;
808 }
809
810 /* Setup the two needed unix socket */
811 if (init_daemon_socket() < 0) {
812 goto error;
813 }
814
815 /* Set credentials to socket */
816 if (is_root && (set_socket_perms() < 0)) {
817 goto error;
818 }
819
820 while (1) {
821 /* Create thread to manage the client socket */
822 ret = pthread_create(&threads[0], NULL, thread_manage_clients, (void *) NULL);
823 if (ret != 0) {
824 perror("pthread_create");
825 goto error;
826 }
827
828 /* Create thread to manage application socket */
829 ret = pthread_create(&threads[1], NULL, thread_manage_apps, (void *) NULL);
830 if (ret != 0) {
831 perror("pthread_create");
832 goto error;
833 }
834
835 for (i = 0; i < 2; i++) {
836 ret = pthread_join(threads[i], &status);
837 if (ret != 0) {
838 perror("pthread_join");
839 goto error;
840 }
841 }
842 }
843
844 cleanup();
845 return 0;
846
847error:
848 cleanup();
849
850 return EXIT_FAILURE;
851}
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