2 Unix SMB/CIFS implementation.
3 Blocking Locking functions
4 Copyright (C) Jeremy Allison 1998-2003
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
22 #define DBGC_CLASS DBGC_LOCKING
24 /****************************************************************************
25 This is the structure to queue to implement blocking locks.
26 notify. It consists of the requesting SMB and the expiry time.
27 *****************************************************************************/
29 typedef struct _blocking_lock_record {
30 struct _blocking_lock_record *next;
31 struct _blocking_lock_record *prev;
34 struct timeval expire_time;
39 uint32_t blocking_pid; /* PID that blocks us. */
40 enum brl_flavour lock_flav;
41 enum brl_type lock_type;
45 } blocking_lock_record;
47 /* dlink list we store pending lock records on. */
48 static blocking_lock_record *blocking_lock_queue;
50 /* dlink list we move cancelled lock records onto. */
51 static blocking_lock_record *blocking_lock_cancelled_queue;
53 /* The event that makes us process our blocking lock queue */
54 static struct timed_event *brl_timeout;
56 /****************************************************************************
57 Destructor for the above structure.
58 ****************************************************************************/
60 static void free_blocking_lock_record(blocking_lock_record *blr)
62 SAFE_FREE(blr->inbuf);
66 /****************************************************************************
67 Determine if this is a secondary element of a chained SMB.
68 **************************************************************************/
70 static bool in_chained_smb(void)
72 return (chain_size != 0);
75 static void received_unlock_msg(struct messaging_context *msg,
78 struct server_id server_id,
80 static void process_blocking_lock_queue(void);
82 static void brl_timeout_fn(struct event_context *event_ctx,
83 struct timed_event *te,
84 const struct timeval *now,
87 SMB_ASSERT(brl_timeout == te);
88 TALLOC_FREE(brl_timeout);
90 change_to_root_user(); /* TODO: Possibly run all timed events as
93 process_blocking_lock_queue();
96 /****************************************************************************
97 After a change to blocking_lock_queue, recalculate the timed_event for the
99 ****************************************************************************/
101 static bool recalc_brl_timeout(void)
103 blocking_lock_record *brl;
104 struct timeval next_timeout;
106 TALLOC_FREE(brl_timeout);
108 next_timeout = timeval_zero();
110 for (brl = blocking_lock_queue; brl; brl = brl->next) {
111 if (timeval_is_zero(&brl->expire_time)) {
113 * If we're blocked on pid 0xFFFFFFFF this is
114 * a POSIX lock, so calculate a timeout of
115 * 10 seconds into the future.
117 if (brl->blocking_pid == 0xFFFFFFFF) {
118 struct timeval psx_to = timeval_current_ofs(10, 0);
119 next_timeout = timeval_min(&next_timeout, &psx_to);
125 if (timeval_is_zero(&next_timeout)) {
126 next_timeout = brl->expire_time;
129 next_timeout = timeval_min(&next_timeout,
134 if (timeval_is_zero(&next_timeout)) {
138 if (!(brl_timeout = event_add_timed(smbd_event_context(), NULL,
139 next_timeout, "brl_timeout",
140 brl_timeout_fn, NULL))) {
148 /****************************************************************************
149 Function to push a blocking lock request onto the lock queue.
150 ****************************************************************************/
152 bool push_blocking_lock_request( struct byte_range_lock *br_lck,
153 const struct smb_request *req,
158 enum brl_type lock_type,
159 enum brl_flavour lock_flav,
162 uint32_t blocking_pid)
164 static bool set_lock_msg;
165 size_t length = smb_len(req->inbuf)+4;
166 blocking_lock_record *blr;
169 if(in_chained_smb() ) {
170 DEBUG(0,("push_blocking_lock_request: cannot queue a chained request (currently).\n"));
175 * Now queue an entry on the blocking lock queue. We setup
176 * the expiration time here.
179 if((blr = SMB_MALLOC_P(blocking_lock_record)) == NULL) {
180 DEBUG(0,("push_blocking_lock_request: Malloc fail !\n" ));
187 if((blr->inbuf = (char *)SMB_MALLOC(length)) == NULL) {
188 DEBUG(0,("push_blocking_lock_request: Malloc fail (2)!\n" ));
193 blr->com_type = req->cmd;
195 if (lock_timeout == -1) {
196 blr->expire_time.tv_sec = 0;
197 blr->expire_time.tv_usec = 0; /* Never expire. */
199 blr->expire_time = timeval_current_ofs(lock_timeout/1000,
200 (lock_timeout % 1000) * 1000);
202 blr->lock_num = lock_num;
203 blr->lock_pid = lock_pid;
204 blr->blocking_pid = blocking_pid;
205 blr->lock_flav = lock_flav;
206 blr->lock_type = lock_type;
207 blr->offset = offset;
209 memcpy(blr->inbuf, req->inbuf, length);
210 blr->length = length;
211 blr->encrypted = req->encrypted;
213 /* Add a pending lock record for this. */
214 status = brl_lock(smbd_messaging_context(), br_lck,
219 lock_type == READ_LOCK ? PENDING_READ_LOCK : PENDING_WRITE_LOCK,
221 lock_timeout ? True : False, /* blocking_lock. */
224 if (!NT_STATUS_IS_OK(status)) {
225 DEBUG(0,("push_blocking_lock_request: failed to add PENDING_LOCK record.\n"));
226 DLIST_REMOVE(blocking_lock_queue, blr);
227 free_blocking_lock_record(blr);
231 DLIST_ADD_END(blocking_lock_queue, blr, blocking_lock_record *);
232 recalc_brl_timeout();
234 /* Ensure we'll receive messages when this is unlocked. */
236 messaging_register(smbd_messaging_context(), NULL,
237 MSG_SMB_UNLOCK, received_unlock_msg);
241 DEBUG(3,("push_blocking_lock_request: lock request length=%u blocked with "
242 "expiry time (%u sec. %u usec) (+%d msec) for fnum = %d, name = %s\n",
243 (unsigned int)length, (unsigned int)blr->expire_time.tv_sec,
244 (unsigned int)blr->expire_time.tv_usec, lock_timeout,
245 blr->fsp->fnum, blr->fsp->fsp_name ));
247 /* Push the MID of this packet on the signing queue. */
248 srv_defer_sign_response(SVAL(req->inbuf,smb_mid));
253 /****************************************************************************
254 Return a lockingX success SMB.
255 *****************************************************************************/
257 static void reply_lockingX_success(blocking_lock_record *blr)
259 struct smb_request *req;
261 if (!(req = talloc(talloc_tos(), struct smb_request))) {
262 smb_panic("Could not allocate smb_request");
265 init_smb_request(req, (uint8 *)blr->inbuf, 0, blr->encrypted);
266 reply_outbuf(req, 2, 0);
269 * As this message is a lockingX call we must handle
270 * any following chained message correctly.
271 * This is normally handled in construct_reply(),
272 * but as that calls switch_message, we can't use
273 * that here and must set up the chain info manually.
278 if (!srv_send_smb(smbd_server_fd(),
280 IS_CONN_ENCRYPTED(blr->fsp->conn))) {
281 exit_server_cleanly("send_blocking_reply: srv_send_smb failed.");
285 /****************************************************************************
286 Return a generic lock fail error blocking call.
287 *****************************************************************************/
289 static void generic_blocking_lock_error(blocking_lock_record *blr, NTSTATUS status)
291 char outbuf[smb_size];
292 char *inbuf = blr->inbuf;
294 construct_reply_common(inbuf, outbuf);
296 /* whenever a timeout is given w2k maps LOCK_NOT_GRANTED to
297 FILE_LOCK_CONFLICT! (tridge) */
298 if (NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
299 status = NT_STATUS_FILE_LOCK_CONFLICT;
302 if (NT_STATUS_EQUAL(status, NT_STATUS_FILE_LOCK_CONFLICT)) {
303 /* Store the last lock error. */
304 files_struct *fsp = blr->fsp;
307 fsp->last_lock_failure.context.smbpid = blr->lock_pid;
308 fsp->last_lock_failure.context.tid = fsp->conn->cnum;
309 fsp->last_lock_failure.context.pid = procid_self();
310 fsp->last_lock_failure.start = blr->offset;
311 fsp->last_lock_failure.size = blr->count;
312 fsp->last_lock_failure.fnum = fsp->fnum;
313 fsp->last_lock_failure.lock_type = READ_LOCK; /* Don't care. */
314 fsp->last_lock_failure.lock_flav = blr->lock_flav;
319 if (!srv_send_smb(smbd_server_fd(),outbuf, blr->encrypted)) {
320 exit_server_cleanly("generic_blocking_lock_error: srv_send_smb failed.");
324 /****************************************************************************
325 Return a lock fail error for a lockingX call. Undo all the locks we have
327 *****************************************************************************/
329 static void reply_lockingX_error(blocking_lock_record *blr, NTSTATUS status)
331 char *inbuf = blr->inbuf;
332 files_struct *fsp = blr->fsp;
333 uint16 num_ulocks = SVAL(inbuf,smb_vwv6);
334 uint64_t count = (uint64_t)0, offset = (uint64_t) 0;
336 unsigned char locktype = CVAL(inbuf,smb_vwv3);
337 bool large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
341 data = (uint8_t *)smb_buf(inbuf)
342 + ((large_file_format ? 20 : 10)*num_ulocks);
345 * Data now points at the beginning of the list
346 * of smb_lkrng structs.
350 * Ensure we don't do a remove on the lock that just failed,
351 * as under POSIX rules, if we have a lock already there, we
352 * will delete it (and we shouldn't) .....
355 for(i = blr->lock_num - 1; i >= 0; i--) {
358 lock_pid = get_lock_pid( data, i, large_file_format);
359 count = get_lock_count( data, i, large_file_format);
360 offset = get_lock_offset( data, i, large_file_format, &err);
363 * We know err cannot be set as if it was the lock
364 * request would never have been queued. JRA.
367 do_unlock(smbd_messaging_context(),
375 generic_blocking_lock_error(blr, status);
378 /****************************************************************************
379 Return a lock fail error.
380 *****************************************************************************/
382 static void blocking_lock_reply_error(blocking_lock_record *blr, NTSTATUS status)
384 switch(blr->com_type) {
386 reply_lockingX_error(blr, status);
391 char outbuf[smb_size];
392 char *inbuf = blr->inbuf;
393 construct_reply_common(inbuf, outbuf);
394 /* construct_reply_common has done us the favor to pre-fill the
395 * command field with SMBtranss2 which is wrong :-)
397 SCVAL(outbuf,smb_com,SMBtrans2);
399 if (!srv_send_smb(smbd_server_fd(),
401 IS_CONN_ENCRYPTED(blr->fsp->conn))) {
402 exit_server_cleanly("blocking_lock_reply_error: srv_send_smb failed.");
407 DEBUG(0,("blocking_lock_reply_error: PANIC - unknown type on blocking lock queue - exiting.!\n"));
408 exit_server("PANIC - unknown type on blocking lock queue");
412 /****************************************************************************
413 Attempt to finish off getting all pending blocking locks for a lockingX call.
414 Returns True if we want to be removed from the list.
415 *****************************************************************************/
417 static bool process_lockingX(blocking_lock_record *blr)
419 char *inbuf = blr->inbuf;
420 unsigned char locktype = CVAL(inbuf,smb_vwv3);
421 files_struct *fsp = blr->fsp;
422 uint16 num_ulocks = SVAL(inbuf,smb_vwv6);
423 uint16 num_locks = SVAL(inbuf,smb_vwv7);
424 uint64_t count = (uint64_t)0, offset = (uint64_t)0;
426 bool large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
428 NTSTATUS status = NT_STATUS_OK;
430 data = (uint8_t *)smb_buf(inbuf)
431 + ((large_file_format ? 20 : 10)*num_ulocks);
434 * Data now points at the beginning of the list
435 * of smb_lkrng structs.
438 for(; blr->lock_num < num_locks; blr->lock_num++) {
439 struct byte_range_lock *br_lck = NULL;
442 lock_pid = get_lock_pid( data, blr->lock_num, large_file_format);
443 count = get_lock_count( data, blr->lock_num, large_file_format);
444 offset = get_lock_offset( data, blr->lock_num, large_file_format, &err);
447 * We know err cannot be set as if it was the lock
448 * request would never have been queued. JRA.
451 br_lck = do_lock(smbd_messaging_context(),
456 ((locktype & LOCKING_ANDX_SHARED_LOCK) ?
457 READ_LOCK : WRITE_LOCK),
465 if (NT_STATUS_IS_ERR(status)) {
470 if(blr->lock_num == num_locks) {
472 * Success - we got all the locks.
475 DEBUG(3,("process_lockingX file = %s, fnum=%d type=%d num_locks=%d\n",
476 fsp->fsp_name, fsp->fnum, (unsigned int)locktype, num_locks) );
478 reply_lockingX_success(blr);
480 } else if (!NT_STATUS_EQUAL(status,NT_STATUS_LOCK_NOT_GRANTED) &&
481 !NT_STATUS_EQUAL(status,NT_STATUS_FILE_LOCK_CONFLICT)) {
483 * We have other than a "can't get lock"
484 * error. Free any locks we had and return an error.
485 * Return True so we get dequeued.
488 blocking_lock_reply_error(blr, status);
493 * Still can't get all the locks - keep waiting.
496 DEBUG(10,("process_lockingX: only got %d locks of %d needed for file %s, fnum = %d. \
498 blr->lock_num, num_locks, fsp->fsp_name, fsp->fnum));
503 /****************************************************************************
504 Attempt to get the posix lock request from a SMBtrans2 call.
505 Returns True if we want to be removed from the list.
506 *****************************************************************************/
508 static bool process_trans2(blocking_lock_record *blr)
510 struct smb_request *req;
513 struct byte_range_lock *br_lck = do_lock(smbd_messaging_context(),
525 if (!NT_STATUS_IS_OK(status)) {
526 if (ERROR_WAS_LOCK_DENIED(status)) {
527 /* Still can't get the lock, just keep waiting. */
531 * We have other than a "can't get lock"
532 * error. Send an error and return True so we get dequeued.
534 blocking_lock_reply_error(blr, status);
538 /* We finally got the lock, return success. */
540 if (!(req = talloc(talloc_tos(), struct smb_request))) {
541 blocking_lock_reply_error(blr, NT_STATUS_NO_MEMORY);
545 init_smb_request(req, (uint8 *)blr->inbuf, 0, blr->encrypted);
547 SCVAL(req->inbuf, smb_com, SMBtrans2);
549 /* Fake up max_data_bytes here - we know it fits. */
550 send_trans2_replies(blr->fsp->conn, req, params, 2, NULL, 0, 0xffff);
555 /****************************************************************************
556 Process a blocking lock SMB.
557 Returns True if we want to be removed from the list.
558 *****************************************************************************/
560 static bool blocking_lock_record_process(blocking_lock_record *blr)
562 switch(blr->com_type) {
564 return process_lockingX(blr);
567 return process_trans2(blr);
569 DEBUG(0,("blocking_lock_record_process: PANIC - unknown type on blocking lock queue - exiting.!\n"));
570 exit_server("PANIC - unknown type on blocking lock queue");
572 return False; /* Keep compiler happy. */
575 /****************************************************************************
576 Cancel entries by fnum from the blocking lock pending queue.
577 *****************************************************************************/
579 void cancel_pending_lock_requests_by_fid(files_struct *fsp, struct byte_range_lock *br_lck)
581 blocking_lock_record *blr, *next = NULL;
583 for(blr = blocking_lock_queue; blr; blr = next) {
585 if(blr->fsp->fnum == fsp->fnum) {
586 unsigned char locktype = 0;
588 if (blr->com_type == SMBlockingX) {
589 locktype = CVAL(blr->inbuf,smb_vwv3);
593 DEBUG(10,("remove_pending_lock_requests_by_fid - removing request type %d for \
594 file %s fnum = %d\n", blr->com_type, fsp->fsp_name, fsp->fnum ));
596 brl_lock_cancel(br_lck,
603 blocking_lock_cancel(fsp,
609 NT_STATUS_RANGE_NOT_LOCKED);
611 /* We're closing the file fsp here, so ensure
612 * we don't have a dangling pointer. */
618 /****************************************************************************
619 Delete entries by mid from the blocking lock pending queue. Always send reply.
620 *****************************************************************************/
622 void remove_pending_lock_requests_by_mid(int mid)
624 blocking_lock_record *blr, *next = NULL;
626 for(blr = blocking_lock_queue; blr; blr = next) {
628 if(SVAL(blr->inbuf,smb_mid) == mid) {
629 files_struct *fsp = blr->fsp;
630 struct byte_range_lock *br_lck = brl_get_locks(talloc_tos(), fsp);
633 DEBUG(10,("remove_pending_lock_requests_by_mid - removing request type %d for \
634 file %s fnum = %d\n", blr->com_type, fsp->fsp_name, fsp->fnum ));
636 brl_lock_cancel(br_lck,
645 blocking_lock_reply_error(blr,NT_STATUS_FILE_LOCK_CONFLICT);
646 DLIST_REMOVE(blocking_lock_queue, blr);
647 free_blocking_lock_record(blr);
652 /****************************************************************************
653 Is this mid a blocking lock request on the queue ?
654 *****************************************************************************/
656 bool blocking_lock_was_deferred(int mid)
658 blocking_lock_record *blr, *next = NULL;
660 for(blr = blocking_lock_queue; blr; blr = next) {
662 if(SVAL(blr->inbuf,smb_mid) == mid) {
669 /****************************************************************************
670 Set a flag as an unlock request affects one of our pending locks.
671 *****************************************************************************/
673 static void received_unlock_msg(struct messaging_context *msg,
676 struct server_id server_id,
679 DEBUG(10,("received_unlock_msg\n"));
680 process_blocking_lock_queue();
683 /****************************************************************************
684 Process the blocking lock queue. Note that this is only called as root.
685 *****************************************************************************/
687 static void process_blocking_lock_queue(void)
689 struct timeval tv_curr = timeval_current();
690 blocking_lock_record *blr, *next = NULL;
691 bool recalc_timeout = False;
694 * Go through the queue and see if we can get any of the locks.
697 for (blr = blocking_lock_queue; blr; blr = next) {
698 connection_struct *conn = NULL;
700 files_struct *fsp = NULL;
705 * Ensure we don't have any old chain_fsp values
711 conn = conn_find(SVAL(blr->inbuf,smb_tid));
712 vuid = (lp_security() == SEC_SHARE) ? UID_FIELD_INVALID :
713 SVAL(blr->inbuf,smb_uid);
715 DEBUG(5,("process_blocking_lock_queue: examining pending lock fnum = %d for file %s\n",
716 fsp->fnum, fsp->fsp_name ));
718 if(!change_to_user(conn,vuid)) {
719 struct byte_range_lock *br_lck = brl_get_locks(talloc_tos(), fsp);
722 * Remove the entry and return an error to the client.
726 brl_lock_cancel(br_lck,
735 DEBUG(0,("process_blocking_lock_queue: Unable to become user vuid=%d.\n",
737 blocking_lock_reply_error(blr,NT_STATUS_ACCESS_DENIED);
738 DLIST_REMOVE(blocking_lock_queue, blr);
739 free_blocking_lock_record(blr);
740 recalc_timeout = True;
744 if(!set_current_service(conn,SVAL(blr->inbuf,smb_flg),True)) {
745 struct byte_range_lock *br_lck = brl_get_locks(talloc_tos(), fsp);
748 * Remove the entry and return an error to the client.
752 brl_lock_cancel(br_lck,
761 DEBUG(0,("process_blocking_lock_queue: Unable to become service Error was %s.\n", strerror(errno) ));
762 blocking_lock_reply_error(blr,NT_STATUS_ACCESS_DENIED);
763 DLIST_REMOVE(blocking_lock_queue, blr);
764 free_blocking_lock_record(blr);
765 recalc_timeout = True;
766 change_to_root_user();
771 * Go through the remaining locks and try and obtain them.
772 * The call returns True if all locks were obtained successfully
773 * and False if we still need to wait.
776 if(blocking_lock_record_process(blr)) {
777 struct byte_range_lock *br_lck = brl_get_locks(talloc_tos(), fsp);
780 brl_lock_cancel(br_lck,
789 DLIST_REMOVE(blocking_lock_queue, blr);
790 free_blocking_lock_record(blr);
791 recalc_timeout = True;
792 change_to_root_user();
796 change_to_root_user();
799 * We couldn't get the locks for this record on the list.
800 * If the time has expired, return a lock error.
803 if (!timeval_is_zero(&blr->expire_time) && timeval_compare(&blr->expire_time, &tv_curr) <= 0) {
804 struct byte_range_lock *br_lck = brl_get_locks(talloc_tos(), fsp);
807 * Lock expired - throw away all previously
808 * obtained locks and return lock error.
812 DEBUG(5,("process_blocking_lock_queue: pending lock fnum = %d for file %s timed out.\n",
813 fsp->fnum, fsp->fsp_name ));
815 brl_lock_cancel(br_lck,
824 blocking_lock_reply_error(blr,NT_STATUS_FILE_LOCK_CONFLICT);
825 DLIST_REMOVE(blocking_lock_queue, blr);
826 free_blocking_lock_record(blr);
827 recalc_timeout = True;
831 if (recalc_timeout) {
832 recalc_brl_timeout();
836 /****************************************************************************
837 Handle a cancel message. Lock already moved onto the cancel queue.
838 *****************************************************************************/
840 #define MSG_BLOCKING_LOCK_CANCEL_SIZE (sizeof(blocking_lock_record *) + sizeof(NTSTATUS))
842 static void process_blocking_lock_cancel_message(struct messaging_context *ctx,
845 struct server_id server_id,
849 const char *msg = (const char *)data->data;
850 blocking_lock_record *blr;
852 if (data->data == NULL) {
853 smb_panic("process_blocking_lock_cancel_message: null msg");
856 if (data->length != MSG_BLOCKING_LOCK_CANCEL_SIZE) {
857 DEBUG(0, ("process_blocking_lock_cancel_message: "
858 "Got invalid msg len %d\n", (int)data->length));
859 smb_panic("process_blocking_lock_cancel_message: bad msg");
862 memcpy(&blr, msg, sizeof(blr));
863 memcpy(&err, &msg[sizeof(blr)], sizeof(NTSTATUS));
865 DEBUG(10,("process_blocking_lock_cancel_message: returning error %s\n",
868 blocking_lock_reply_error(blr, err);
869 DLIST_REMOVE(blocking_lock_cancelled_queue, blr);
870 free_blocking_lock_record(blr);
873 /****************************************************************************
874 Send ourselves a blocking lock cancelled message. Handled asynchronously above.
875 *****************************************************************************/
877 bool blocking_lock_cancel(files_struct *fsp,
881 enum brl_flavour lock_flav,
882 unsigned char locktype,
885 static bool initialized;
886 char msg[MSG_BLOCKING_LOCK_CANCEL_SIZE];
887 blocking_lock_record *blr;
890 /* Register our message. */
891 messaging_register(smbd_messaging_context(), NULL,
892 MSG_SMB_BLOCKING_LOCK_CANCEL,
893 process_blocking_lock_cancel_message);
898 for (blr = blocking_lock_queue; blr; blr = blr->next) {
899 if (fsp == blr->fsp &&
900 lock_pid == blr->lock_pid &&
901 offset == blr->offset &&
902 count == blr->count &&
903 lock_flav == blr->lock_flav) {
912 /* Check the flags are right. */
913 if (blr->com_type == SMBlockingX &&
914 (locktype & LOCKING_ANDX_LARGE_FILES) !=
915 (CVAL(blr->inbuf,smb_vwv3) & LOCKING_ANDX_LARGE_FILES)) {
919 /* Move to cancelled queue. */
920 DLIST_REMOVE(blocking_lock_queue, blr);
921 DLIST_ADD(blocking_lock_cancelled_queue, blr);
923 /* Create the message. */
924 memcpy(msg, &blr, sizeof(blr));
925 memcpy(&msg[sizeof(blr)], &err, sizeof(NTSTATUS));
927 messaging_send_buf(smbd_messaging_context(), procid_self(),
928 MSG_SMB_BLOCKING_LOCK_CANCEL,
929 (uint8 *)&msg, sizeof(msg));