1 /*-------------------------------------------------------------------------
2 *
3 * syslogger.c
4 *
5 * The system logger (syslogger) appeared in Postgres 8.0. It catches all
6 * stderr output from the postmaster, backends, and other subprocesses
7 * by redirecting to a pipe, and writes it to a set of logfiles.
8 * It's possible to have size and age limits for the logfile configured
9 * in postgresql.conf. If these limits are reached or passed, the
10 * current logfile is closed and a new one is created (rotated).
11 * The logfiles are stored in a subdirectory (configurable in
12 * postgresql.conf), using a user-selectable naming scheme.
13 *
14 * Author: Andreas Pflug <pgadmin@pse-consulting.de>
15 *
16 * Copyright (c) 2004-2021, PostgreSQL Global Development Group
17 *
18 *
19 * IDENTIFICATION
20 * src/backend/postmaster/syslogger.c
21 *
22 *-------------------------------------------------------------------------
23 */
24 #include "postgres.h"
25
26 #include <fcntl.h>
27 #include <limits.h>
28 #include <signal.h>
29 #include <time.h>
30 #include <unistd.h>
31 #include <sys/stat.h>
32 #include <sys/time.h>
33
34 #include "common/file_perm.h"
35 #include "lib/stringinfo.h"
36 #include "libpq/pqsignal.h"
37 #include "miscadmin.h"
38 #include "nodes/pg_list.h"
39 #include "pgstat.h"
40 #include "pgtime.h"
41 #include "postmaster/fork_process.h"
42 #include "postmaster/interrupt.h"
43 #include "postmaster/postmaster.h"
44 #include "postmaster/syslogger.h"
45 #include "storage/dsm.h"
46 #include "storage/fd.h"
47 #include "storage/ipc.h"
48 #include "storage/latch.h"
49 #include "storage/pg_shmem.h"
50 #include "tcop/tcopprot.h"
51 #include "utils/guc.h"
52 #include "utils/ps_status.h"
53 #include "utils/timestamp.h"
54
55 /*
56 * We read() into a temp buffer twice as big as a chunk, so that any fragment
57 * left after processing can be moved down to the front and we'll still have
58 * room to read a full chunk.
59 */
60 #define READ_BUF_SIZE (2 * PIPE_CHUNK_SIZE)
61
62 /* Log rotation signal file path, relative to $PGDATA */
63 #define LOGROTATE_SIGNAL_FILE "logrotate"
64
65
66 /*
67 * GUC parameters. Logging_collector cannot be changed after postmaster
68 * start, but the rest can change at SIGHUP.
69 */
70 bool Logging_collector = false;
71 int Log_RotationAge = HOURS_PER_DAY * MINS_PER_HOUR;
72 int Log_RotationSize = 10 * 1024;
73 char *Log_directory = NULL;
74 char *Log_filename = NULL;
75 bool Log_truncate_on_rotation = false;
76 int Log_file_mode = S_IRUSR | S_IWUSR;
77
78 extern bool redirection_done;
79
80 /*
81 * Private state
82 */
83 static pg_time_t next_rotation_time;
84 static bool pipe_eof_seen = false;
85 static bool rotation_disabled = false;
86 static FILE *syslogFile = NULL;
87 static FILE *csvlogFile = NULL;
88 NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0;
89 static char *last_file_name = NULL;
90 static char *last_csv_file_name = NULL;
91
92 /*
93 * Buffers for saving partial messages from different backends.
94 *
95 * Keep NBUFFER_LISTS lists of these, with the entry for a given source pid
96 * being in the list numbered (pid % NBUFFER_LISTS), so as to cut down on
97 * the number of entries we have to examine for any one incoming message.
98 * There must never be more than one entry for the same source pid.
99 *
100 * An inactive buffer is not removed from its list, just held for re-use.
101 * An inactive buffer has pid == 0 and undefined contents of data.
102 */
103 typedef struct
104 {
105 int32 pid; /* PID of source process */
106 StringInfoData data; /* accumulated data, as a StringInfo */
107 } save_buffer;
108
109 #define NBUFFER_LISTS 256
110 static List *buffer_lists[NBUFFER_LISTS];
111
112 /* These must be exported for EXEC_BACKEND case ... annoying */
113 #ifndef WIN32
114 int syslogPipe[2] = {-1, -1};
115 #else
116 HANDLE syslogPipe[2] = {0, 0};
117 #endif
118
119 #ifdef WIN32
120 static HANDLE threadHandle = 0;
121 static CRITICAL_SECTION sysloggerSection;
122 #endif
123
124 /*
125 * Flags set by interrupt handlers for later service in the main loop.
126 */
127 static volatile sig_atomic_t rotation_requested = false;
128
129
130 /* Local subroutines */
131 #ifdef EXEC_BACKEND
132 static pid_t syslogger_forkexec(void);
133 static void syslogger_parseArgs(int argc, char *argv[]);
134 #endif
135 NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
136 static void process_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
137 static void flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
138 static FILE *logfile_open(const char *filename, const char *mode,
139 bool allow_errors);
140
141 #ifdef WIN32
142 static unsigned int __stdcall pipeThread(void *arg);
143 #endif
144 static void logfile_rotate(bool time_based_rotation, int size_rotation_for);
145 static char *logfile_getname(pg_time_t timestamp, const char *suffix);
146 static void set_next_rotation_time(void);
147 static void sigUsr1Handler(SIGNAL_ARGS);
148 static void update_metainfo_datafile(void);
149
150
151 /*
152 * Main entry point for syslogger process
153 * argc/argv parameters are valid only in EXEC_BACKEND case.
154 */
155 NON_EXEC_STATIC void
SysLoggerMain(int argc,char * argv[])156 SysLoggerMain(int argc, char *argv[])
157 {
158 #ifndef WIN32
159 char logbuffer[READ_BUF_SIZE];
160 int bytes_in_logbuffer = 0;
161 #endif
162 char *currentLogDir;
163 char *currentLogFilename;
164 int currentLogRotationAge;
165 pg_time_t now;
166 WaitEventSet *wes;
167
168 now = MyStartTime;
169
170 #ifdef EXEC_BACKEND
171 syslogger_parseArgs(argc, argv);
172 #endif /* EXEC_BACKEND */
173
174 MyBackendType = B_LOGGER;
175 init_ps_display(NULL);
176
177 /*
178 * If we restarted, our stderr is already redirected into our own input
179 * pipe. This is of course pretty useless, not to mention that it
180 * interferes with detecting pipe EOF. Point stderr to /dev/null. This
181 * assumes that all interesting messages generated in the syslogger will
182 * come through elog.c and will be sent to write_syslogger_file.
183 */
184 if (redirection_done)
185 {
186 int fd = open(DEVNULL, O_WRONLY, 0);
187
188 /*
189 * The closes might look redundant, but they are not: we want to be
190 * darn sure the pipe gets closed even if the open failed. We can
191 * survive running with stderr pointing nowhere, but we can't afford
192 * to have extra pipe input descriptors hanging around.
193 *
194 * As we're just trying to reset these to go to DEVNULL, there's not
195 * much point in checking for failure from the close/dup2 calls here,
196 * if they fail then presumably the file descriptors are closed and
197 * any writes will go into the bitbucket anyway.
198 */
199 close(fileno(stdout));
200 close(fileno(stderr));
201 if (fd != -1)
202 {
203 (void) dup2(fd, fileno(stdout));
204 (void) dup2(fd, fileno(stderr));
205 close(fd);
206 }
207 }
208
209 /*
210 * Syslogger's own stderr can't be the syslogPipe, so set it back to text
211 * mode if we didn't just close it. (It was set to binary in
212 * SubPostmasterMain).
213 */
214 #ifdef WIN32
215 else
216 _setmode(_fileno(stderr), _O_TEXT);
217 #endif
218
219 /*
220 * Also close our copy of the write end of the pipe. This is needed to
221 * ensure we can detect pipe EOF correctly. (But note that in the restart
222 * case, the postmaster already did this.)
223 */
224 #ifndef WIN32
225 if (syslogPipe[1] >= 0)
226 close(syslogPipe[1]);
227 syslogPipe[1] = -1;
228 #else
229 if (syslogPipe[1])
230 CloseHandle(syslogPipe[1]);
231 syslogPipe[1] = 0;
232 #endif
233
234 /*
235 * Properly accept or ignore signals the postmaster might send us
236 *
237 * Note: we ignore all termination signals, and instead exit only when all
238 * upstream processes are gone, to ensure we don't miss any dying gasps of
239 * broken backends...
240 */
241
242 pqsignal(SIGHUP, SignalHandlerForConfigReload); /* set flag to read config
243 * file */
244 pqsignal(SIGINT, SIG_IGN);
245 pqsignal(SIGTERM, SIG_IGN);
246 pqsignal(SIGQUIT, SIG_IGN);
247 pqsignal(SIGALRM, SIG_IGN);
248 pqsignal(SIGPIPE, SIG_IGN);
249 pqsignal(SIGUSR1, sigUsr1Handler); /* request log rotation */
250 pqsignal(SIGUSR2, SIG_IGN);
251
252 /*
253 * Reset some signals that are accepted by postmaster but not here
254 */
255 pqsignal(SIGCHLD, SIG_DFL);
256
257 PG_SETMASK(&UnBlockSig);
258
259 #ifdef WIN32
260 /* Fire up separate data transfer thread */
261 InitializeCriticalSection(&sysloggerSection);
262 EnterCriticalSection(&sysloggerSection);
263
264 threadHandle = (HANDLE) _beginthreadex(NULL, 0, pipeThread, NULL, 0, NULL);
265 if (threadHandle == 0)
266 elog(FATAL, "could not create syslogger data transfer thread: %m");
267 #endif /* WIN32 */
268
269 /*
270 * Remember active logfiles' name(s). We recompute 'em from the reference
271 * time because passing down just the pg_time_t is a lot cheaper than
272 * passing a whole file path in the EXEC_BACKEND case.
273 */
274 last_file_name = logfile_getname(first_syslogger_file_time, NULL);
275 if (csvlogFile != NULL)
276 last_csv_file_name = logfile_getname(first_syslogger_file_time, ".csv");
277
278 /* remember active logfile parameters */
279 currentLogDir = pstrdup(Log_directory);
280 currentLogFilename = pstrdup(Log_filename);
281 currentLogRotationAge = Log_RotationAge;
282 /* set next planned rotation time */
283 set_next_rotation_time();
284 update_metainfo_datafile();
285
286 /*
287 * Reset whereToSendOutput, as the postmaster will do (but hasn't yet, at
288 * the point where we forked). This prevents duplicate output of messages
289 * from syslogger itself.
290 */
291 whereToSendOutput = DestNone;
292
293 /*
294 * Set up a reusable WaitEventSet object we'll use to wait for our latch,
295 * and (except on Windows) our socket.
296 *
297 * Unlike all other postmaster child processes, we'll ignore postmaster
298 * death because we want to collect final log output from all backends and
299 * then exit last. We'll do that by running until we see EOF on the
300 * syslog pipe, which implies that all other backends have exited
301 * (including the postmaster).
302 */
303 wes = CreateWaitEventSet(CurrentMemoryContext, 2);
304 AddWaitEventToSet(wes, WL_LATCH_SET, PGINVALID_SOCKET, MyLatch, NULL);
305 #ifndef WIN32
306 AddWaitEventToSet(wes, WL_SOCKET_READABLE, syslogPipe[0], NULL, NULL);
307 #endif
308
309 /* main worker loop */
310 for (;;)
311 {
312 bool time_based_rotation = false;
313 int size_rotation_for = 0;
314 long cur_timeout;
315 WaitEvent event;
316
317 #ifndef WIN32
318 int rc;
319 #endif
320
321 /* Clear any already-pending wakeups */
322 ResetLatch(MyLatch);
323
324 /*
325 * Process any requests or signals received recently.
326 */
327 if (ConfigReloadPending)
328 {
329 ConfigReloadPending = false;
330 ProcessConfigFile(PGC_SIGHUP);
331
332 /*
333 * Check if the log directory or filename pattern changed in
334 * postgresql.conf. If so, force rotation to make sure we're
335 * writing the logfiles in the right place.
336 */
337 if (strcmp(Log_directory, currentLogDir) != 0)
338 {
339 pfree(currentLogDir);
340 currentLogDir = pstrdup(Log_directory);
341 rotation_requested = true;
342
343 /*
344 * Also, create new directory if not present; ignore errors
345 */
346 (void) MakePGDirectory(Log_directory);
347 }
348 if (strcmp(Log_filename, currentLogFilename) != 0)
349 {
350 pfree(currentLogFilename);
351 currentLogFilename = pstrdup(Log_filename);
352 rotation_requested = true;
353 }
354
355 /*
356 * Force a rotation if CSVLOG output was just turned on or off and
357 * we need to open or close csvlogFile accordingly.
358 */
359 if (((Log_destination & LOG_DESTINATION_CSVLOG) != 0) !=
360 (csvlogFile != NULL))
361 rotation_requested = true;
362
363 /*
364 * If rotation time parameter changed, reset next rotation time,
365 * but don't immediately force a rotation.
366 */
367 if (currentLogRotationAge != Log_RotationAge)
368 {
369 currentLogRotationAge = Log_RotationAge;
370 set_next_rotation_time();
371 }
372
373 /*
374 * If we had a rotation-disabling failure, re-enable rotation
375 * attempts after SIGHUP, and force one immediately.
376 */
377 if (rotation_disabled)
378 {
379 rotation_disabled = false;
380 rotation_requested = true;
381 }
382
383 /*
384 * Force rewriting last log filename when reloading configuration.
385 * Even if rotation_requested is false, log_destination may have
386 * been changed and we don't want to wait the next file rotation.
387 */
388 update_metainfo_datafile();
389 }
390
391 if (Log_RotationAge > 0 && !rotation_disabled)
392 {
393 /* Do a logfile rotation if it's time */
394 now = (pg_time_t) time(NULL);
395 if (now >= next_rotation_time)
396 rotation_requested = time_based_rotation = true;
397 }
398
399 if (!rotation_requested && Log_RotationSize > 0 && !rotation_disabled)
400 {
401 /* Do a rotation if file is too big */
402 if (ftell(syslogFile) >= Log_RotationSize * 1024L)
403 {
404 rotation_requested = true;
405 size_rotation_for |= LOG_DESTINATION_STDERR;
406 }
407 if (csvlogFile != NULL &&
408 ftell(csvlogFile) >= Log_RotationSize * 1024L)
409 {
410 rotation_requested = true;
411 size_rotation_for |= LOG_DESTINATION_CSVLOG;
412 }
413 }
414
415 if (rotation_requested)
416 {
417 /*
418 * Force rotation when both values are zero. It means the request
419 * was sent by pg_rotate_logfile() or "pg_ctl logrotate".
420 */
421 if (!time_based_rotation && size_rotation_for == 0)
422 size_rotation_for = LOG_DESTINATION_STDERR | LOG_DESTINATION_CSVLOG;
423 logfile_rotate(time_based_rotation, size_rotation_for);
424 }
425
426 /*
427 * Calculate time till next time-based rotation, so that we don't
428 * sleep longer than that. We assume the value of "now" obtained
429 * above is still close enough. Note we can't make this calculation
430 * until after calling logfile_rotate(), since it will advance
431 * next_rotation_time.
432 *
433 * Also note that we need to beware of overflow in calculation of the
434 * timeout: with large settings of Log_RotationAge, next_rotation_time
435 * could be more than INT_MAX msec in the future. In that case we'll
436 * wait no more than INT_MAX msec, and try again.
437 */
438 if (Log_RotationAge > 0 && !rotation_disabled)
439 {
440 pg_time_t delay;
441
442 delay = next_rotation_time - now;
443 if (delay > 0)
444 {
445 if (delay > INT_MAX / 1000)
446 delay = INT_MAX / 1000;
447 cur_timeout = delay * 1000L; /* msec */
448 }
449 else
450 cur_timeout = 0;
451 }
452 else
453 cur_timeout = -1L;
454
455 /*
456 * Sleep until there's something to do
457 */
458 #ifndef WIN32
459 rc = WaitEventSetWait(wes, cur_timeout, &event, 1,
460 WAIT_EVENT_SYSLOGGER_MAIN);
461
462 if (rc == 1 && event.events == WL_SOCKET_READABLE)
463 {
464 int bytesRead;
465
466 bytesRead = read(syslogPipe[0],
467 logbuffer + bytes_in_logbuffer,
468 sizeof(logbuffer) - bytes_in_logbuffer);
469 if (bytesRead < 0)
470 {
471 if (errno != EINTR)
472 ereport(LOG,
473 (errcode_for_socket_access(),
474 errmsg("could not read from logger pipe: %m")));
475 }
476 else if (bytesRead > 0)
477 {
478 bytes_in_logbuffer += bytesRead;
479 process_pipe_input(logbuffer, &bytes_in_logbuffer);
480 continue;
481 }
482 else
483 {
484 /*
485 * Zero bytes read when select() is saying read-ready means
486 * EOF on the pipe: that is, there are no longer any processes
487 * with the pipe write end open. Therefore, the postmaster
488 * and all backends are shut down, and we are done.
489 */
490 pipe_eof_seen = true;
491
492 /* if there's any data left then force it out now */
493 flush_pipe_input(logbuffer, &bytes_in_logbuffer);
494 }
495 }
496 #else /* WIN32 */
497
498 /*
499 * On Windows we leave it to a separate thread to transfer data and
500 * detect pipe EOF. The main thread just wakes up to handle SIGHUP
501 * and rotation conditions.
502 *
503 * Server code isn't generally thread-safe, so we ensure that only one
504 * of the threads is active at a time by entering the critical section
505 * whenever we're not sleeping.
506 */
507 LeaveCriticalSection(&sysloggerSection);
508
509 (void) WaitEventSetWait(wes, cur_timeout, &event, 1,
510 WAIT_EVENT_SYSLOGGER_MAIN);
511
512 EnterCriticalSection(&sysloggerSection);
513 #endif /* WIN32 */
514
515 if (pipe_eof_seen)
516 {
517 /*
518 * seeing this message on the real stderr is annoying - so we make
519 * it DEBUG1 to suppress in normal use.
520 */
521 ereport(DEBUG1,
522 (errmsg_internal("logger shutting down")));
523
524 /*
525 * Normal exit from the syslogger is here. Note that we
526 * deliberately do not close syslogFile before exiting; this is to
527 * allow for the possibility of elog messages being generated
528 * inside proc_exit. Regular exit() will take care of flushing
529 * and closing stdio channels.
530 */
531 proc_exit(0);
532 }
533 }
534 }
535
536 /*
537 * Postmaster subroutine to start a syslogger subprocess.
538 */
539 int
SysLogger_Start(void)540 SysLogger_Start(void)
541 {
542 pid_t sysloggerPid;
543 char *filename;
544
545 if (!Logging_collector)
546 return 0;
547
548 /*
549 * If first time through, create the pipe which will receive stderr
550 * output.
551 *
552 * If the syslogger crashes and needs to be restarted, we continue to use
553 * the same pipe (indeed must do so, since extant backends will be writing
554 * into that pipe).
555 *
556 * This means the postmaster must continue to hold the read end of the
557 * pipe open, so we can pass it down to the reincarnated syslogger. This
558 * is a bit klugy but we have little choice.
559 *
560 * Also note that we don't bother counting the pipe FDs by calling
561 * Reserve/ReleaseExternalFD. There's no real need to account for them
562 * accurately in the postmaster or syslogger process, and both ends of the
563 * pipe will wind up closed in all other postmaster children.
564 */
565 #ifndef WIN32
566 if (syslogPipe[0] < 0)
567 {
568 if (pipe(syslogPipe) < 0)
569 ereport(FATAL,
570 (errcode_for_socket_access(),
571 errmsg("could not create pipe for syslog: %m")));
572 }
573 #else
574 if (!syslogPipe[0])
575 {
576 SECURITY_ATTRIBUTES sa;
577
578 memset(&sa, 0, sizeof(SECURITY_ATTRIBUTES));
579 sa.nLength = sizeof(SECURITY_ATTRIBUTES);
580 sa.bInheritHandle = TRUE;
581
582 if (!CreatePipe(&syslogPipe[0], &syslogPipe[1], &sa, 32768))
583 ereport(FATAL,
584 (errcode_for_file_access(),
585 errmsg("could not create pipe for syslog: %m")));
586 }
587 #endif
588
589 /*
590 * Create log directory if not present; ignore errors
591 */
592 (void) MakePGDirectory(Log_directory);
593
594 /*
595 * The initial logfile is created right in the postmaster, to verify that
596 * the Log_directory is writable. We save the reference time so that the
597 * syslogger child process can recompute this file name.
598 *
599 * It might look a bit strange to re-do this during a syslogger restart,
600 * but we must do so since the postmaster closed syslogFile after the
601 * previous fork (and remembering that old file wouldn't be right anyway).
602 * Note we always append here, we won't overwrite any existing file. This
603 * is consistent with the normal rules, because by definition this is not
604 * a time-based rotation.
605 */
606 first_syslogger_file_time = time(NULL);
607
608 filename = logfile_getname(first_syslogger_file_time, NULL);
609
610 syslogFile = logfile_open(filename, "a", false);
611
612 pfree(filename);
613
614 /*
615 * Likewise for the initial CSV log file, if that's enabled. (Note that
616 * we open syslogFile even when only CSV output is nominally enabled,
617 * since some code paths will write to syslogFile anyway.)
618 */
619 if (Log_destination & LOG_DESTINATION_CSVLOG)
620 {
621 filename = logfile_getname(first_syslogger_file_time, ".csv");
622
623 csvlogFile = logfile_open(filename, "a", false);
624
625 pfree(filename);
626 }
627
628 #ifdef EXEC_BACKEND
629 switch ((sysloggerPid = syslogger_forkexec()))
630 #else
631 switch ((sysloggerPid = fork_process()))
632 #endif
633 {
634 case -1:
635 ereport(LOG,
636 (errmsg("could not fork system logger: %m")));
637 return 0;
638
639 #ifndef EXEC_BACKEND
640 case 0:
641 /* in postmaster child ... */
642 InitPostmasterChild();
643
644 /* Close the postmaster's sockets */
645 ClosePostmasterPorts(true);
646
647 /* Drop our connection to postmaster's shared memory, as well */
648 dsm_detach_all();
649 PGSharedMemoryDetach();
650
651 /* do the work */
652 SysLoggerMain(0, NULL);
653 break;
654 #endif
655
656 default:
657 /* success, in postmaster */
658
659 /* now we redirect stderr, if not done already */
660 if (!redirection_done)
661 {
662 #ifdef WIN32
663 int fd;
664 #endif
665
666 /*
667 * Leave a breadcrumb trail when redirecting, in case the user
668 * forgets that redirection is active and looks only at the
669 * original stderr target file.
670 */
671 ereport(LOG,
672 (errmsg("redirecting log output to logging collector process"),
673 errhint("Future log output will appear in directory \"%s\".",
674 Log_directory)));
675
676 #ifndef WIN32
677 fflush(stdout);
678 if (dup2(syslogPipe[1], fileno(stdout)) < 0)
679 ereport(FATAL,
680 (errcode_for_file_access(),
681 errmsg("could not redirect stdout: %m")));
682 fflush(stderr);
683 if (dup2(syslogPipe[1], fileno(stderr)) < 0)
684 ereport(FATAL,
685 (errcode_for_file_access(),
686 errmsg("could not redirect stderr: %m")));
687 /* Now we are done with the write end of the pipe. */
688 close(syslogPipe[1]);
689 syslogPipe[1] = -1;
690 #else
691
692 /*
693 * open the pipe in binary mode and make sure stderr is binary
694 * after it's been dup'ed into, to avoid disturbing the pipe
695 * chunking protocol.
696 */
697 fflush(stderr);
698 fd = _open_osfhandle((intptr_t) syslogPipe[1],
699 _O_APPEND | _O_BINARY);
700 if (dup2(fd, _fileno(stderr)) < 0)
701 ereport(FATAL,
702 (errcode_for_file_access(),
703 errmsg("could not redirect stderr: %m")));
704 close(fd);
705 _setmode(_fileno(stderr), _O_BINARY);
706
707 /*
708 * Now we are done with the write end of the pipe.
709 * CloseHandle() must not be called because the preceding
710 * close() closes the underlying handle.
711 */
712 syslogPipe[1] = 0;
713 #endif
714 redirection_done = true;
715 }
716
717 /* postmaster will never write the file(s); close 'em */
718 fclose(syslogFile);
719 syslogFile = NULL;
720 if (csvlogFile != NULL)
721 {
722 fclose(csvlogFile);
723 csvlogFile = NULL;
724 }
725 return (int) sysloggerPid;
726 }
727
728 /* we should never reach here */
729 return 0;
730 }
731
732
733 #ifdef EXEC_BACKEND
734
735 /*
736 * syslogger_forkexec() -
737 *
738 * Format up the arglist for, then fork and exec, a syslogger process
739 */
740 static pid_t
syslogger_forkexec(void)741 syslogger_forkexec(void)
742 {
743 char *av[10];
744 int ac = 0;
745 char filenobuf[32];
746 char csvfilenobuf[32];
747
748 av[ac++] = "postgres";
749 av[ac++] = "--forklog";
750 av[ac++] = NULL; /* filled in by postmaster_forkexec */
751
752 /* static variables (those not passed by write_backend_variables) */
753 #ifndef WIN32
754 if (syslogFile != NULL)
755 snprintf(filenobuf, sizeof(filenobuf), "%d",
756 fileno(syslogFile));
757 else
758 strcpy(filenobuf, "-1");
759 #else /* WIN32 */
760 if (syslogFile != NULL)
761 snprintf(filenobuf, sizeof(filenobuf), "%ld",
762 (long) _get_osfhandle(_fileno(syslogFile)));
763 else
764 strcpy(filenobuf, "0");
765 #endif /* WIN32 */
766 av[ac++] = filenobuf;
767
768 #ifndef WIN32
769 if (csvlogFile != NULL)
770 snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%d",
771 fileno(csvlogFile));
772 else
773 strcpy(csvfilenobuf, "-1");
774 #else /* WIN32 */
775 if (csvlogFile != NULL)
776 snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%ld",
777 (long) _get_osfhandle(_fileno(csvlogFile)));
778 else
779 strcpy(csvfilenobuf, "0");
780 #endif /* WIN32 */
781 av[ac++] = csvfilenobuf;
782
783 av[ac] = NULL;
784 Assert(ac < lengthof(av));
785
786 return postmaster_forkexec(ac, av);
787 }
788
789 /*
790 * syslogger_parseArgs() -
791 *
792 * Extract data from the arglist for exec'ed syslogger process
793 */
794 static void
syslogger_parseArgs(int argc,char * argv[])795 syslogger_parseArgs(int argc, char *argv[])
796 {
797 int fd;
798
799 Assert(argc == 5);
800 argv += 3;
801
802 /*
803 * Re-open the error output files that were opened by SysLogger_Start().
804 *
805 * We expect this will always succeed, which is too optimistic, but if it
806 * fails there's not a lot we can do to report the problem anyway. As
807 * coded, we'll just crash on a null pointer dereference after failure...
808 */
809 #ifndef WIN32
810 fd = atoi(*argv++);
811 if (fd != -1)
812 {
813 syslogFile = fdopen(fd, "a");
814 setvbuf(syslogFile, NULL, PG_IOLBF, 0);
815 }
816 fd = atoi(*argv++);
817 if (fd != -1)
818 {
819 csvlogFile = fdopen(fd, "a");
820 setvbuf(csvlogFile, NULL, PG_IOLBF, 0);
821 }
822 #else /* WIN32 */
823 fd = atoi(*argv++);
824 if (fd != 0)
825 {
826 fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
827 if (fd > 0)
828 {
829 syslogFile = fdopen(fd, "a");
830 setvbuf(syslogFile, NULL, PG_IOLBF, 0);
831 }
832 }
833 fd = atoi(*argv++);
834 if (fd != 0)
835 {
836 fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
837 if (fd > 0)
838 {
839 csvlogFile = fdopen(fd, "a");
840 setvbuf(csvlogFile, NULL, PG_IOLBF, 0);
841 }
842 }
843 #endif /* WIN32 */
844 }
845 #endif /* EXEC_BACKEND */
846
847
848 /* --------------------------------
849 * pipe protocol handling
850 * --------------------------------
851 */
852
853 /*
854 * Process data received through the syslogger pipe.
855 *
856 * This routine interprets the log pipe protocol which sends log messages as
857 * (hopefully atomic) chunks - such chunks are detected and reassembled here.
858 *
859 * The protocol has a header that starts with two nul bytes, then has a 16 bit
860 * length, the pid of the sending process, and a flag to indicate if it is
861 * the last chunk in a message. Incomplete chunks are saved until we read some
862 * more, and non-final chunks are accumulated until we get the final chunk.
863 *
864 * All of this is to avoid 2 problems:
865 * . partial messages being written to logfiles (messes rotation), and
866 * . messages from different backends being interleaved (messages garbled).
867 *
868 * Any non-protocol messages are written out directly. These should only come
869 * from non-PostgreSQL sources, however (e.g. third party libraries writing to
870 * stderr).
871 *
872 * logbuffer is the data input buffer, and *bytes_in_logbuffer is the number
873 * of bytes present. On exit, any not-yet-eaten data is left-justified in
874 * logbuffer, and *bytes_in_logbuffer is updated.
875 */
876 static void
process_pipe_input(char * logbuffer,int * bytes_in_logbuffer)877 process_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
878 {
879 char *cursor = logbuffer;
880 int count = *bytes_in_logbuffer;
881 int dest = LOG_DESTINATION_STDERR;
882
883 /* While we have enough for a header, process data... */
884 while (count >= (int) (offsetof(PipeProtoHeader, data) + 1))
885 {
886 PipeProtoHeader p;
887 int chunklen;
888
889 /* Do we have a valid header? */
890 memcpy(&p, cursor, offsetof(PipeProtoHeader, data));
891 if (p.nuls[0] == '\0' && p.nuls[1] == '\0' &&
892 p.len > 0 && p.len <= PIPE_MAX_PAYLOAD &&
893 p.pid != 0 &&
894 (p.is_last == 't' || p.is_last == 'f' ||
895 p.is_last == 'T' || p.is_last == 'F'))
896 {
897 List *buffer_list;
898 ListCell *cell;
899 save_buffer *existing_slot = NULL,
900 *free_slot = NULL;
901 StringInfo str;
902
903 chunklen = PIPE_HEADER_SIZE + p.len;
904
905 /* Fall out of loop if we don't have the whole chunk yet */
906 if (count < chunklen)
907 break;
908
909 dest = (p.is_last == 'T' || p.is_last == 'F') ?
910 LOG_DESTINATION_CSVLOG : LOG_DESTINATION_STDERR;
911
912 /* Locate any existing buffer for this source pid */
913 buffer_list = buffer_lists[p.pid % NBUFFER_LISTS];
914 foreach(cell, buffer_list)
915 {
916 save_buffer *buf = (save_buffer *) lfirst(cell);
917
918 if (buf->pid == p.pid)
919 {
920 existing_slot = buf;
921 break;
922 }
923 if (buf->pid == 0 && free_slot == NULL)
924 free_slot = buf;
925 }
926
927 if (p.is_last == 'f' || p.is_last == 'F')
928 {
929 /*
930 * Save a complete non-final chunk in a per-pid buffer
931 */
932 if (existing_slot != NULL)
933 {
934 /* Add chunk to data from preceding chunks */
935 str = &(existing_slot->data);
936 appendBinaryStringInfo(str,
937 cursor + PIPE_HEADER_SIZE,
938 p.len);
939 }
940 else
941 {
942 /* First chunk of message, save in a new buffer */
943 if (free_slot == NULL)
944 {
945 /*
946 * Need a free slot, but there isn't one in the list,
947 * so create a new one and extend the list with it.
948 */
949 free_slot = palloc(sizeof(save_buffer));
950 buffer_list = lappend(buffer_list, free_slot);
951 buffer_lists[p.pid % NBUFFER_LISTS] = buffer_list;
952 }
953 free_slot->pid = p.pid;
954 str = &(free_slot->data);
955 initStringInfo(str);
956 appendBinaryStringInfo(str,
957 cursor + PIPE_HEADER_SIZE,
958 p.len);
959 }
960 }
961 else
962 {
963 /*
964 * Final chunk --- add it to anything saved for that pid, and
965 * either way write the whole thing out.
966 */
967 if (existing_slot != NULL)
968 {
969 str = &(existing_slot->data);
970 appendBinaryStringInfo(str,
971 cursor + PIPE_HEADER_SIZE,
972 p.len);
973 write_syslogger_file(str->data, str->len, dest);
974 /* Mark the buffer unused, and reclaim string storage */
975 existing_slot->pid = 0;
976 pfree(str->data);
977 }
978 else
979 {
980 /* The whole message was one chunk, evidently. */
981 write_syslogger_file(cursor + PIPE_HEADER_SIZE, p.len,
982 dest);
983 }
984 }
985
986 /* Finished processing this chunk */
987 cursor += chunklen;
988 count -= chunklen;
989 }
990 else
991 {
992 /* Process non-protocol data */
993
994 /*
995 * Look for the start of a protocol header. If found, dump data
996 * up to there and repeat the loop. Otherwise, dump it all and
997 * fall out of the loop. (Note: we want to dump it all if at all
998 * possible, so as to avoid dividing non-protocol messages across
999 * logfiles. We expect that in many scenarios, a non-protocol
1000 * message will arrive all in one read(), and we want to respect
1001 * the read() boundary if possible.)
1002 */
1003 for (chunklen = 1; chunklen < count; chunklen++)
1004 {
1005 if (cursor[chunklen] == '\0')
1006 break;
1007 }
1008 /* fall back on the stderr log as the destination */
1009 write_syslogger_file(cursor, chunklen, LOG_DESTINATION_STDERR);
1010 cursor += chunklen;
1011 count -= chunklen;
1012 }
1013 }
1014
1015 /* We don't have a full chunk, so left-align what remains in the buffer */
1016 if (count > 0 && cursor != logbuffer)
1017 memmove(logbuffer, cursor, count);
1018 *bytes_in_logbuffer = count;
1019 }
1020
1021 /*
1022 * Force out any buffered data
1023 *
1024 * This is currently used only at syslogger shutdown, but could perhaps be
1025 * useful at other times, so it is careful to leave things in a clean state.
1026 */
1027 static void
flush_pipe_input(char * logbuffer,int * bytes_in_logbuffer)1028 flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
1029 {
1030 int i;
1031
1032 /* Dump any incomplete protocol messages */
1033 for (i = 0; i < NBUFFER_LISTS; i++)
1034 {
1035 List *list = buffer_lists[i];
1036 ListCell *cell;
1037
1038 foreach(cell, list)
1039 {
1040 save_buffer *buf = (save_buffer *) lfirst(cell);
1041
1042 if (buf->pid != 0)
1043 {
1044 StringInfo str = &(buf->data);
1045
1046 write_syslogger_file(str->data, str->len,
1047 LOG_DESTINATION_STDERR);
1048 /* Mark the buffer unused, and reclaim string storage */
1049 buf->pid = 0;
1050 pfree(str->data);
1051 }
1052 }
1053 }
1054
1055 /*
1056 * Force out any remaining pipe data as-is; we don't bother trying to
1057 * remove any protocol headers that may exist in it.
1058 */
1059 if (*bytes_in_logbuffer > 0)
1060 write_syslogger_file(logbuffer, *bytes_in_logbuffer,
1061 LOG_DESTINATION_STDERR);
1062 *bytes_in_logbuffer = 0;
1063 }
1064
1065
1066 /* --------------------------------
1067 * logfile routines
1068 * --------------------------------
1069 */
1070
1071 /*
1072 * Write text to the currently open logfile
1073 *
1074 * This is exported so that elog.c can call it when MyBackendType is B_LOGGER.
1075 * This allows the syslogger process to record elog messages of its own,
1076 * even though its stderr does not point at the syslog pipe.
1077 */
1078 void
write_syslogger_file(const char * buffer,int count,int destination)1079 write_syslogger_file(const char *buffer, int count, int destination)
1080 {
1081 int rc;
1082 FILE *logfile;
1083
1084 /*
1085 * If we're told to write to csvlogFile, but it's not open, dump the data
1086 * to syslogFile (which is always open) instead. This can happen if CSV
1087 * output is enabled after postmaster start and we've been unable to open
1088 * csvlogFile. There are also race conditions during a parameter change
1089 * whereby backends might send us CSV output before we open csvlogFile or
1090 * after we close it. Writing CSV-formatted output to the regular log
1091 * file isn't great, but it beats dropping log output on the floor.
1092 *
1093 * Think not to improve this by trying to open csvlogFile on-the-fly. Any
1094 * failure in that would lead to recursion.
1095 */
1096 logfile = (destination == LOG_DESTINATION_CSVLOG &&
1097 csvlogFile != NULL) ? csvlogFile : syslogFile;
1098
1099 rc = fwrite(buffer, 1, count, logfile);
1100
1101 /*
1102 * Try to report any failure. We mustn't use ereport because it would
1103 * just recurse right back here, but write_stderr is OK: it will write
1104 * either to the postmaster's original stderr, or to /dev/null, but never
1105 * to our input pipe which would result in a different sort of looping.
1106 */
1107 if (rc != count)
1108 write_stderr("could not write to log file: %s\n", strerror(errno));
1109 }
1110
1111 #ifdef WIN32
1112
1113 /*
1114 * Worker thread to transfer data from the pipe to the current logfile.
1115 *
1116 * We need this because on Windows, WaitForMultipleObjects does not work on
1117 * unnamed pipes: it always reports "signaled", so the blocking ReadFile won't
1118 * allow for SIGHUP; and select is for sockets only.
1119 */
1120 static unsigned int __stdcall
pipeThread(void * arg)1121 pipeThread(void *arg)
1122 {
1123 char logbuffer[READ_BUF_SIZE];
1124 int bytes_in_logbuffer = 0;
1125
1126 for (;;)
1127 {
1128 DWORD bytesRead;
1129 BOOL result;
1130
1131 result = ReadFile(syslogPipe[0],
1132 logbuffer + bytes_in_logbuffer,
1133 sizeof(logbuffer) - bytes_in_logbuffer,
1134 &bytesRead, 0);
1135
1136 /*
1137 * Enter critical section before doing anything that might touch
1138 * global state shared by the main thread. Anything that uses
1139 * palloc()/pfree() in particular are not safe outside the critical
1140 * section.
1141 */
1142 EnterCriticalSection(&sysloggerSection);
1143 if (!result)
1144 {
1145 DWORD error = GetLastError();
1146
1147 if (error == ERROR_HANDLE_EOF ||
1148 error == ERROR_BROKEN_PIPE)
1149 break;
1150 _dosmaperr(error);
1151 ereport(LOG,
1152 (errcode_for_file_access(),
1153 errmsg("could not read from logger pipe: %m")));
1154 }
1155 else if (bytesRead > 0)
1156 {
1157 bytes_in_logbuffer += bytesRead;
1158 process_pipe_input(logbuffer, &bytes_in_logbuffer);
1159 }
1160
1161 /*
1162 * If we've filled the current logfile, nudge the main thread to do a
1163 * log rotation.
1164 */
1165 if (Log_RotationSize > 0)
1166 {
1167 if (ftell(syslogFile) >= Log_RotationSize * 1024L ||
1168 (csvlogFile != NULL && ftell(csvlogFile) >= Log_RotationSize * 1024L))
1169 SetLatch(MyLatch);
1170 }
1171 LeaveCriticalSection(&sysloggerSection);
1172 }
1173
1174 /* We exit the above loop only upon detecting pipe EOF */
1175 pipe_eof_seen = true;
1176
1177 /* if there's any data left then force it out now */
1178 flush_pipe_input(logbuffer, &bytes_in_logbuffer);
1179
1180 /* set the latch to waken the main thread, which will quit */
1181 SetLatch(MyLatch);
1182
1183 LeaveCriticalSection(&sysloggerSection);
1184 _endthread();
1185 return 0;
1186 }
1187 #endif /* WIN32 */
1188
1189 /*
1190 * Open a new logfile with proper permissions and buffering options.
1191 *
1192 * If allow_errors is true, we just log any open failure and return NULL
1193 * (with errno still correct for the fopen failure).
1194 * Otherwise, errors are treated as fatal.
1195 */
1196 static FILE *
logfile_open(const char * filename,const char * mode,bool allow_errors)1197 logfile_open(const char *filename, const char *mode, bool allow_errors)
1198 {
1199 FILE *fh;
1200 mode_t oumask;
1201
1202 /*
1203 * Note we do not let Log_file_mode disable IWUSR, since we certainly want
1204 * to be able to write the files ourselves.
1205 */
1206 oumask = umask((mode_t) ((~(Log_file_mode | S_IWUSR)) & (S_IRWXU | S_IRWXG | S_IRWXO)));
1207 fh = fopen(filename, mode);
1208 umask(oumask);
1209
1210 if (fh)
1211 {
1212 setvbuf(fh, NULL, PG_IOLBF, 0);
1213
1214 #ifdef WIN32
1215 /* use CRLF line endings on Windows */
1216 _setmode(_fileno(fh), _O_TEXT);
1217 #endif
1218 }
1219 else
1220 {
1221 int save_errno = errno;
1222
1223 ereport(allow_errors ? LOG : FATAL,
1224 (errcode_for_file_access(),
1225 errmsg("could not open log file \"%s\": %m",
1226 filename)));
1227 errno = save_errno;
1228 }
1229
1230 return fh;
1231 }
1232
1233 /*
1234 * perform logfile rotation
1235 */
1236 static void
logfile_rotate(bool time_based_rotation,int size_rotation_for)1237 logfile_rotate(bool time_based_rotation, int size_rotation_for)
1238 {
1239 char *filename;
1240 char *csvfilename = NULL;
1241 pg_time_t fntime;
1242 FILE *fh;
1243
1244 rotation_requested = false;
1245
1246 /*
1247 * When doing a time-based rotation, invent the new logfile name based on
1248 * the planned rotation time, not current time, to avoid "slippage" in the
1249 * file name when we don't do the rotation immediately.
1250 */
1251 if (time_based_rotation)
1252 fntime = next_rotation_time;
1253 else
1254 fntime = time(NULL);
1255 filename = logfile_getname(fntime, NULL);
1256 if (Log_destination & LOG_DESTINATION_CSVLOG)
1257 csvfilename = logfile_getname(fntime, ".csv");
1258
1259 /*
1260 * Decide whether to overwrite or append. We can overwrite if (a)
1261 * Log_truncate_on_rotation is set, (b) the rotation was triggered by
1262 * elapsed time and not something else, and (c) the computed file name is
1263 * different from what we were previously logging into.
1264 *
1265 * Note: last_file_name should never be NULL here, but if it is, append.
1266 */
1267 if (time_based_rotation || (size_rotation_for & LOG_DESTINATION_STDERR))
1268 {
1269 if (Log_truncate_on_rotation && time_based_rotation &&
1270 last_file_name != NULL &&
1271 strcmp(filename, last_file_name) != 0)
1272 fh = logfile_open(filename, "w", true);
1273 else
1274 fh = logfile_open(filename, "a", true);
1275
1276 if (!fh)
1277 {
1278 /*
1279 * ENFILE/EMFILE are not too surprising on a busy system; just
1280 * keep using the old file till we manage to get a new one.
1281 * Otherwise, assume something's wrong with Log_directory and stop
1282 * trying to create files.
1283 */
1284 if (errno != ENFILE && errno != EMFILE)
1285 {
1286 ereport(LOG,
1287 (errmsg("disabling automatic rotation (use SIGHUP to re-enable)")));
1288 rotation_disabled = true;
1289 }
1290
1291 if (filename)
1292 pfree(filename);
1293 if (csvfilename)
1294 pfree(csvfilename);
1295 return;
1296 }
1297
1298 fclose(syslogFile);
1299 syslogFile = fh;
1300
1301 /* instead of pfree'ing filename, remember it for next time */
1302 if (last_file_name != NULL)
1303 pfree(last_file_name);
1304 last_file_name = filename;
1305 filename = NULL;
1306 }
1307
1308 /*
1309 * Same as above, but for csv file. Note that if LOG_DESTINATION_CSVLOG
1310 * was just turned on, we might have to open csvlogFile here though it was
1311 * not open before. In such a case we'll append not overwrite (since
1312 * last_csv_file_name will be NULL); that is consistent with the normal
1313 * rules since it's not a time-based rotation.
1314 */
1315 if ((Log_destination & LOG_DESTINATION_CSVLOG) &&
1316 (csvlogFile == NULL ||
1317 time_based_rotation || (size_rotation_for & LOG_DESTINATION_CSVLOG)))
1318 {
1319 if (Log_truncate_on_rotation && time_based_rotation &&
1320 last_csv_file_name != NULL &&
1321 strcmp(csvfilename, last_csv_file_name) != 0)
1322 fh = logfile_open(csvfilename, "w", true);
1323 else
1324 fh = logfile_open(csvfilename, "a", true);
1325
1326 if (!fh)
1327 {
1328 /*
1329 * ENFILE/EMFILE are not too surprising on a busy system; just
1330 * keep using the old file till we manage to get a new one.
1331 * Otherwise, assume something's wrong with Log_directory and stop
1332 * trying to create files.
1333 */
1334 if (errno != ENFILE && errno != EMFILE)
1335 {
1336 ereport(LOG,
1337 (errmsg("disabling automatic rotation (use SIGHUP to re-enable)")));
1338 rotation_disabled = true;
1339 }
1340
1341 if (filename)
1342 pfree(filename);
1343 if (csvfilename)
1344 pfree(csvfilename);
1345 return;
1346 }
1347
1348 if (csvlogFile != NULL)
1349 fclose(csvlogFile);
1350 csvlogFile = fh;
1351
1352 /* instead of pfree'ing filename, remember it for next time */
1353 if (last_csv_file_name != NULL)
1354 pfree(last_csv_file_name);
1355 last_csv_file_name = csvfilename;
1356 csvfilename = NULL;
1357 }
1358 else if (!(Log_destination & LOG_DESTINATION_CSVLOG) &&
1359 csvlogFile != NULL)
1360 {
1361 /* CSVLOG was just turned off, so close the old file */
1362 fclose(csvlogFile);
1363 csvlogFile = NULL;
1364 if (last_csv_file_name != NULL)
1365 pfree(last_csv_file_name);
1366 last_csv_file_name = NULL;
1367 }
1368
1369 if (filename)
1370 pfree(filename);
1371 if (csvfilename)
1372 pfree(csvfilename);
1373
1374 update_metainfo_datafile();
1375
1376 set_next_rotation_time();
1377 }
1378
1379
1380 /*
1381 * construct logfile name using timestamp information
1382 *
1383 * If suffix isn't NULL, append it to the name, replacing any ".log"
1384 * that may be in the pattern.
1385 *
1386 * Result is palloc'd.
1387 */
1388 static char *
logfile_getname(pg_time_t timestamp,const char * suffix)1389 logfile_getname(pg_time_t timestamp, const char *suffix)
1390 {
1391 char *filename;
1392 int len;
1393
1394 filename = palloc(MAXPGPATH);
1395
1396 snprintf(filename, MAXPGPATH, "%s/", Log_directory);
1397
1398 len = strlen(filename);
1399
1400 /* treat Log_filename as a strftime pattern */
1401 pg_strftime(filename + len, MAXPGPATH - len, Log_filename,
1402 pg_localtime(×tamp, log_timezone));
1403
1404 if (suffix != NULL)
1405 {
1406 len = strlen(filename);
1407 if (len > 4 && (strcmp(filename + (len - 4), ".log") == 0))
1408 len -= 4;
1409 strlcpy(filename + len, suffix, MAXPGPATH - len);
1410 }
1411
1412 return filename;
1413 }
1414
1415 /*
1416 * Determine the next planned rotation time, and store in next_rotation_time.
1417 */
1418 static void
set_next_rotation_time(void)1419 set_next_rotation_time(void)
1420 {
1421 pg_time_t now;
1422 struct pg_tm *tm;
1423 int rotinterval;
1424
1425 /* nothing to do if time-based rotation is disabled */
1426 if (Log_RotationAge <= 0)
1427 return;
1428
1429 /*
1430 * The requirements here are to choose the next time > now that is a
1431 * "multiple" of the log rotation interval. "Multiple" can be interpreted
1432 * fairly loosely. In this version we align to log_timezone rather than
1433 * GMT.
1434 */
1435 rotinterval = Log_RotationAge * SECS_PER_MINUTE; /* convert to seconds */
1436 now = (pg_time_t) time(NULL);
1437 tm = pg_localtime(&now, log_timezone);
1438 now += tm->tm_gmtoff;
1439 now -= now % rotinterval;
1440 now += rotinterval;
1441 now -= tm->tm_gmtoff;
1442 next_rotation_time = now;
1443 }
1444
1445 /*
1446 * Store the name of the file(s) where the log collector, when enabled, writes
1447 * log messages. Useful for finding the name(s) of the current log file(s)
1448 * when there is time-based logfile rotation. Filenames are stored in a
1449 * temporary file and which is renamed into the final destination for
1450 * atomicity. The file is opened with the same permissions as what gets
1451 * created in the data directory and has proper buffering options.
1452 */
1453 static void
update_metainfo_datafile(void)1454 update_metainfo_datafile(void)
1455 {
1456 FILE *fh;
1457 mode_t oumask;
1458
1459 if (!(Log_destination & LOG_DESTINATION_STDERR) &&
1460 !(Log_destination & LOG_DESTINATION_CSVLOG))
1461 {
1462 if (unlink(LOG_METAINFO_DATAFILE) < 0 && errno != ENOENT)
1463 ereport(LOG,
1464 (errcode_for_file_access(),
1465 errmsg("could not remove file \"%s\": %m",
1466 LOG_METAINFO_DATAFILE)));
1467 return;
1468 }
1469
1470 /* use the same permissions as the data directory for the new file */
1471 oumask = umask(pg_mode_mask);
1472 fh = fopen(LOG_METAINFO_DATAFILE_TMP, "w");
1473 umask(oumask);
1474
1475 if (fh)
1476 {
1477 setvbuf(fh, NULL, PG_IOLBF, 0);
1478
1479 #ifdef WIN32
1480 /* use CRLF line endings on Windows */
1481 _setmode(_fileno(fh), _O_TEXT);
1482 #endif
1483 }
1484 else
1485 {
1486 ereport(LOG,
1487 (errcode_for_file_access(),
1488 errmsg("could not open file \"%s\": %m",
1489 LOG_METAINFO_DATAFILE_TMP)));
1490 return;
1491 }
1492
1493 if (last_file_name && (Log_destination & LOG_DESTINATION_STDERR))
1494 {
1495 if (fprintf(fh, "stderr %s\n", last_file_name) < 0)
1496 {
1497 ereport(LOG,
1498 (errcode_for_file_access(),
1499 errmsg("could not write file \"%s\": %m",
1500 LOG_METAINFO_DATAFILE_TMP)));
1501 fclose(fh);
1502 return;
1503 }
1504 }
1505
1506 if (last_csv_file_name && (Log_destination & LOG_DESTINATION_CSVLOG))
1507 {
1508 if (fprintf(fh, "csvlog %s\n", last_csv_file_name) < 0)
1509 {
1510 ereport(LOG,
1511 (errcode_for_file_access(),
1512 errmsg("could not write file \"%s\": %m",
1513 LOG_METAINFO_DATAFILE_TMP)));
1514 fclose(fh);
1515 return;
1516 }
1517 }
1518 fclose(fh);
1519
1520 if (rename(LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE) != 0)
1521 ereport(LOG,
1522 (errcode_for_file_access(),
1523 errmsg("could not rename file \"%s\" to \"%s\": %m",
1524 LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE)));
1525 }
1526
1527 /* --------------------------------
1528 * signal handler routines
1529 * --------------------------------
1530 */
1531
1532 /*
1533 * Check to see if a log rotation request has arrived. Should be
1534 * called by postmaster after receiving SIGUSR1.
1535 */
1536 bool
CheckLogrotateSignal(void)1537 CheckLogrotateSignal(void)
1538 {
1539 struct stat stat_buf;
1540
1541 if (stat(LOGROTATE_SIGNAL_FILE, &stat_buf) == 0)
1542 return true;
1543
1544 return false;
1545 }
1546
1547 /*
1548 * Remove the file signaling a log rotation request.
1549 */
1550 void
RemoveLogrotateSignalFiles(void)1551 RemoveLogrotateSignalFiles(void)
1552 {
1553 unlink(LOGROTATE_SIGNAL_FILE);
1554 }
1555
1556 /* SIGUSR1: set flag to rotate logfile */
1557 static void
sigUsr1Handler(SIGNAL_ARGS)1558 sigUsr1Handler(SIGNAL_ARGS)
1559 {
1560 int save_errno = errno;
1561
1562 rotation_requested = true;
1563 SetLatch(MyLatch);
1564
1565 errno = save_errno;
1566 }
1567