Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1651 insertions, 0 deletions

diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
new file mode 100644
index 0000000..d6d02e3
--- /dev/null
+++ b/src/backend/postmaster/syslogger.c
@@ -0,0 +1,1651 @@
+/*-------------------------------------------------------------------------
+ *
+ * syslogger.c
+ *
+ * The system logger (syslogger) appeared in Postgres 8.0. It catches all
+ * stderr output from the postmaster, backends, and other subprocesses
+ * by redirecting to a pipe, and writes it to a set of logfiles.
+ * It's possible to have size and age limits for the logfile configured
+ * in postgresql.conf. If these limits are reached or passed, the
+ * current logfile is closed and a new one is created (rotated).
+ * The logfiles are stored in a subdirectory (configurable in
+ * postgresql.conf), using a user-selectable naming scheme.
+ *
+ * Author: Andreas Pflug <pgadmin@pse-consulting.de>
+ *
+ * Copyright (c) 2004-2022, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/postmaster/syslogger.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+
+#include "common/file_perm.h"
+#include "lib/stringinfo.h"
+#include "libpq/pqsignal.h"
+#include "miscadmin.h"
+#include "nodes/pg_list.h"
+#include "pgstat.h"
+#include "pgtime.h"
+#include "port/pg_bitutils.h"
+#include "postmaster/fork_process.h"
+#include "postmaster/interrupt.h"
+#include "postmaster/postmaster.h"
+#include "postmaster/syslogger.h"
+#include "storage/dsm.h"
+#include "storage/fd.h"
+#include "storage/ipc.h"
+#include "storage/latch.h"
+#include "storage/pg_shmem.h"
+#include "tcop/tcopprot.h"
+#include "utils/guc.h"
+#include "utils/ps_status.h"
+#include "utils/timestamp.h"
+
+/*
+ * We read() into a temp buffer twice as big as a chunk, so that any fragment
+ * left after processing can be moved down to the front and we'll still have
+ * room to read a full chunk.
+ */
+#define READ_BUF_SIZE (2 * PIPE_CHUNK_SIZE)
+
+/* Log rotation signal file path, relative to $PGDATA */
+#define LOGROTATE_SIGNAL_FILE	"logrotate"
+
+
+/*
+ * GUC parameters.  Logging_collector cannot be changed after postmaster
+ * start, but the rest can change at SIGHUP.
+ */
+bool		Logging_collector = false;
+int			Log_RotationAge = HOURS_PER_DAY * MINS_PER_HOUR;
+int			Log_RotationSize = 10 * 1024;
+char	   *Log_directory = NULL;
+char	   *Log_filename = NULL;
+bool		Log_truncate_on_rotation = false;
+int			Log_file_mode = S_IRUSR | S_IWUSR;
+
+extern bool redirection_done;
+
+/*
+ * Private state
+ */
+static pg_time_t next_rotation_time;
+static bool pipe_eof_seen = false;
+static bool rotation_disabled = false;
+static FILE *syslogFile = NULL;
+static FILE *csvlogFile = NULL;
+static FILE *jsonlogFile = NULL;
+NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0;
+static char *last_sys_file_name = NULL;
+static char *last_csv_file_name = NULL;
+static char *last_json_file_name = NULL;
+
+/*
+ * Buffers for saving partial messages from different backends.
+ *
+ * Keep NBUFFER_LISTS lists of these, with the entry for a given source pid
+ * being in the list numbered (pid % NBUFFER_LISTS), so as to cut down on
+ * the number of entries we have to examine for any one incoming message.
+ * There must never be more than one entry for the same source pid.
+ *
+ * An inactive buffer is not removed from its list, just held for re-use.
+ * An inactive buffer has pid == 0 and undefined contents of data.
+ */
+typedef struct
+{
+	int32		pid;			/* PID of source process */
+	StringInfoData data;		/* accumulated data, as a StringInfo */
+} save_buffer;
+
+#define NBUFFER_LISTS 256
+static List *buffer_lists[NBUFFER_LISTS];
+
+/* These must be exported for EXEC_BACKEND case ... annoying */
+#ifndef WIN32
+int			syslogPipe[2] = {-1, -1};
+#else
+HANDLE		syslogPipe[2] = {0, 0};
+#endif
+
+#ifdef WIN32
+static HANDLE threadHandle = 0;
+static CRITICAL_SECTION sysloggerSection;
+#endif
+
+/*
+ * Flags set by interrupt handlers for later service in the main loop.
+ */
+static volatile sig_atomic_t rotation_requested = false;
+
+
+/* Local subroutines */
+#ifdef EXEC_BACKEND
+static int	syslogger_fdget(FILE *file);
+static FILE *syslogger_fdopen(int fd);
+static pid_t syslogger_forkexec(void);
+static void syslogger_parseArgs(int argc, char *argv[]);
+#endif
+NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
+static void process_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
+static void flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
+static FILE *logfile_open(const char *filename, const char *mode,
+						  bool allow_errors);
+
+#ifdef WIN32
+static unsigned int __stdcall pipeThread(void *arg);
+#endif
+static void logfile_rotate(bool time_based_rotation, int size_rotation_for);
+static bool logfile_rotate_dest(bool time_based_rotation,
+								int size_rotation_for, pg_time_t fntime,
+								int target_dest, char **last_file_name,
+								FILE **logFile);
+static char *logfile_getname(pg_time_t timestamp, const char *suffix);
+static void set_next_rotation_time(void);
+static void sigUsr1Handler(SIGNAL_ARGS);
+static void update_metainfo_datafile(void);
+
+
+/*
+ * Main entry point for syslogger process
+ * argc/argv parameters are valid only in EXEC_BACKEND case.
+ */
+NON_EXEC_STATIC void
+SysLoggerMain(int argc, char *argv[])
+{
+#ifndef WIN32
+	char		logbuffer[READ_BUF_SIZE];
+	int			bytes_in_logbuffer = 0;
+#endif
+	char	   *currentLogDir;
+	char	   *currentLogFilename;
+	int			currentLogRotationAge;
+	pg_time_t	now;
+	WaitEventSet *wes;
+
+	now = MyStartTime;
+
+#ifdef EXEC_BACKEND
+	syslogger_parseArgs(argc, argv);
+#endif							/* EXEC_BACKEND */
+
+	MyBackendType = B_LOGGER;
+	init_ps_display(NULL);
+
+	/*
+	 * If we restarted, our stderr is already redirected into our own input
+	 * pipe.  This is of course pretty useless, not to mention that it
+	 * interferes with detecting pipe EOF.  Point stderr to /dev/null. This
+	 * assumes that all interesting messages generated in the syslogger will
+	 * come through elog.c and will be sent to write_syslogger_file.
+	 */
+	if (redirection_done)
+	{
+		int			fd = open(DEVNULL, O_WRONLY, 0);
+
+		/*
+		 * The closes might look redundant, but they are not: we want to be
+		 * darn sure the pipe gets closed even if the open failed.  We can
+		 * survive running with stderr pointing nowhere, but we can't afford
+		 * to have extra pipe input descriptors hanging around.
+		 *
+		 * As we're just trying to reset these to go to DEVNULL, there's not
+		 * much point in checking for failure from the close/dup2 calls here,
+		 * if they fail then presumably the file descriptors are closed and
+		 * any writes will go into the bitbucket anyway.
+		 */
+		close(STDOUT_FILENO);
+		close(STDERR_FILENO);
+		if (fd != -1)
+		{
+			(void) dup2(fd, STDOUT_FILENO);
+			(void) dup2(fd, STDERR_FILENO);
+			close(fd);
+		}
+	}
+
+	/*
+	 * Syslogger's own stderr can't be the syslogPipe, so set it back to text
+	 * mode if we didn't just close it. (It was set to binary in
+	 * SubPostmasterMain).
+	 */
+#ifdef WIN32
+	else
+		_setmode(STDERR_FILENO, _O_TEXT);
+#endif
+
+	/*
+	 * Also close our copy of the write end of the pipe.  This is needed to
+	 * ensure we can detect pipe EOF correctly.  (But note that in the restart
+	 * case, the postmaster already did this.)
+	 */
+#ifndef WIN32
+	if (syslogPipe[1] >= 0)
+		close(syslogPipe[1]);
+	syslogPipe[1] = -1;
+#else
+	if (syslogPipe[1])
+		CloseHandle(syslogPipe[1]);
+	syslogPipe[1] = 0;
+#endif
+
+	/*
+	 * Properly accept or ignore signals the postmaster might send us
+	 *
+	 * Note: we ignore all termination signals, and instead exit only when all
+	 * upstream processes are gone, to ensure we don't miss any dying gasps of
+	 * broken backends...
+	 */
+
+	pqsignal(SIGHUP, SignalHandlerForConfigReload); /* set flag to read config
+													 * file */
+	pqsignal(SIGINT, SIG_IGN);
+	pqsignal(SIGTERM, SIG_IGN);
+	pqsignal(SIGQUIT, SIG_IGN);
+	pqsignal(SIGALRM, SIG_IGN);
+	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGUSR1, sigUsr1Handler);	/* request log rotation */
+	pqsignal(SIGUSR2, SIG_IGN);
+
+	/*
+	 * Reset some signals that are accepted by postmaster but not here
+	 */
+	pqsignal(SIGCHLD, SIG_DFL);
+
+	PG_SETMASK(&UnBlockSig);
+
+#ifdef WIN32
+	/* Fire up separate data transfer thread */
+	InitializeCriticalSection(&sysloggerSection);
+	EnterCriticalSection(&sysloggerSection);
+
+	threadHandle = (HANDLE) _beginthreadex(NULL, 0, pipeThread, NULL, 0, NULL);
+	if (threadHandle == 0)
+		elog(FATAL, "could not create syslogger data transfer thread: %m");
+#endif							/* WIN32 */
+
+	/*
+	 * Remember active logfiles' name(s).  We recompute 'em from the reference
+	 * time because passing down just the pg_time_t is a lot cheaper than
+	 * passing a whole file path in the EXEC_BACKEND case.
+	 */
+	last_sys_file_name = logfile_getname(first_syslogger_file_time, NULL);
+	if (csvlogFile != NULL)
+		last_csv_file_name = logfile_getname(first_syslogger_file_time, ".csv");
+	if (jsonlogFile != NULL)
+		last_json_file_name = logfile_getname(first_syslogger_file_time, ".json");
+
+	/* remember active logfile parameters */
+	currentLogDir = pstrdup(Log_directory);
+	currentLogFilename = pstrdup(Log_filename);
+	currentLogRotationAge = Log_RotationAge;
+	/* set next planned rotation time */
+	set_next_rotation_time();
+	update_metainfo_datafile();
+
+	/*
+	 * Reset whereToSendOutput, as the postmaster will do (but hasn't yet, at
+	 * the point where we forked).  This prevents duplicate output of messages
+	 * from syslogger itself.
+	 */
+	whereToSendOutput = DestNone;
+
+	/*
+	 * Set up a reusable WaitEventSet object we'll use to wait for our latch,
+	 * and (except on Windows) our socket.
+	 *
+	 * Unlike all other postmaster child processes, we'll ignore postmaster
+	 * death because we want to collect final log output from all backends and
+	 * then exit last.  We'll do that by running until we see EOF on the
+	 * syslog pipe, which implies that all other backends have exited
+	 * (including the postmaster).
+	 */
+	wes = CreateWaitEventSet(CurrentMemoryContext, 2);
+	AddWaitEventToSet(wes, WL_LATCH_SET, PGINVALID_SOCKET, MyLatch, NULL);
+#ifndef WIN32
+	AddWaitEventToSet(wes, WL_SOCKET_READABLE, syslogPipe[0], NULL, NULL);
+#endif
+
+	/* main worker loop */
+	for (;;)
+	{
+		bool		time_based_rotation = false;
+		int			size_rotation_for = 0;
+		long		cur_timeout;
+		WaitEvent	event;
+
+#ifndef WIN32
+		int			rc;
+#endif
+
+		/* Clear any already-pending wakeups */
+		ResetLatch(MyLatch);
+
+		/*
+		 * Process any requests or signals received recently.
+		 */
+		if (ConfigReloadPending)
+		{
+			ConfigReloadPending = false;
+			ProcessConfigFile(PGC_SIGHUP);
+
+			/*
+			 * Check if the log directory or filename pattern changed in
+			 * postgresql.conf. If so, force rotation to make sure we're
+			 * writing the logfiles in the right place.
+			 */
+			if (strcmp(Log_directory, currentLogDir) != 0)
+			{
+				pfree(currentLogDir);
+				currentLogDir = pstrdup(Log_directory);
+				rotation_requested = true;
+
+				/*
+				 * Also, create new directory if not present; ignore errors
+				 */
+				(void) MakePGDirectory(Log_directory);
+			}
+			if (strcmp(Log_filename, currentLogFilename) != 0)
+			{
+				pfree(currentLogFilename);
+				currentLogFilename = pstrdup(Log_filename);
+				rotation_requested = true;
+			}
+
+			/*
+			 * Force a rotation if CSVLOG output was just turned on or off and
+			 * we need to open or close csvlogFile accordingly.
+			 */
+			if (((Log_destination & LOG_DESTINATION_CSVLOG) != 0) !=
+				(csvlogFile != NULL))
+				rotation_requested = true;
+
+			/*
+			 * Force a rotation if JSONLOG output was just turned on or off
+			 * and we need to open or close jsonlogFile accordingly.
+			 */
+			if (((Log_destination & LOG_DESTINATION_JSONLOG) != 0) !=
+				(jsonlogFile != NULL))
+				rotation_requested = true;
+
+			/*
+			 * If rotation time parameter changed, reset next rotation time,
+			 * but don't immediately force a rotation.
+			 */
+			if (currentLogRotationAge != Log_RotationAge)
+			{
+				currentLogRotationAge = Log_RotationAge;
+				set_next_rotation_time();
+			}
+
+			/*
+			 * If we had a rotation-disabling failure, re-enable rotation
+			 * attempts after SIGHUP, and force one immediately.
+			 */
+			if (rotation_disabled)
+			{
+				rotation_disabled = false;
+				rotation_requested = true;
+			}
+
+			/*
+			 * Force rewriting last log filename when reloading configuration.
+			 * Even if rotation_requested is false, log_destination may have
+			 * been changed and we don't want to wait the next file rotation.
+			 */
+			update_metainfo_datafile();
+		}
+
+		if (Log_RotationAge > 0 && !rotation_disabled)
+		{
+			/* Do a logfile rotation if it's time */
+			now = (pg_time_t) time(NULL);
+			if (now >= next_rotation_time)
+				rotation_requested = time_based_rotation = true;
+		}
+
+		if (!rotation_requested && Log_RotationSize > 0 && !rotation_disabled)
+		{
+			/* Do a rotation if file is too big */
+			if (ftell(syslogFile) >= Log_RotationSize * 1024L)
+			{
+				rotation_requested = true;
+				size_rotation_for |= LOG_DESTINATION_STDERR;
+			}
+			if (csvlogFile != NULL &&
+				ftell(csvlogFile) >= Log_RotationSize * 1024L)
+			{
+				rotation_requested = true;
+				size_rotation_for |= LOG_DESTINATION_CSVLOG;
+			}
+			if (jsonlogFile != NULL &&
+				ftell(jsonlogFile) >= Log_RotationSize * 1024L)
+			{
+				rotation_requested = true;
+				size_rotation_for |= LOG_DESTINATION_JSONLOG;
+			}
+		}
+
+		if (rotation_requested)
+		{
+			/*
+			 * Force rotation when both values are zero. It means the request
+			 * was sent by pg_rotate_logfile() or "pg_ctl logrotate".
+			 */
+			if (!time_based_rotation && size_rotation_for == 0)
+				size_rotation_for = LOG_DESTINATION_STDERR |
+					LOG_DESTINATION_CSVLOG |
+					LOG_DESTINATION_JSONLOG;
+			logfile_rotate(time_based_rotation, size_rotation_for);
+		}
+
+		/*
+		 * Calculate time till next time-based rotation, so that we don't
+		 * sleep longer than that.  We assume the value of "now" obtained
+		 * above is still close enough.  Note we can't make this calculation
+		 * until after calling logfile_rotate(), since it will advance
+		 * next_rotation_time.
+		 *
+		 * Also note that we need to beware of overflow in calculation of the
+		 * timeout: with large settings of Log_RotationAge, next_rotation_time
+		 * could be more than INT_MAX msec in the future.  In that case we'll
+		 * wait no more than INT_MAX msec, and try again.
+		 */
+		if (Log_RotationAge > 0 && !rotation_disabled)
+		{
+			pg_time_t	delay;
+
+			delay = next_rotation_time - now;
+			if (delay > 0)
+			{
+				if (delay > INT_MAX / 1000)
+					delay = INT_MAX / 1000;
+				cur_timeout = delay * 1000L;	/* msec */
+			}
+			else
+				cur_timeout = 0;
+		}
+		else
+			cur_timeout = -1L;
+
+		/*
+		 * Sleep until there's something to do
+		 */
+#ifndef WIN32
+		rc = WaitEventSetWait(wes, cur_timeout, &event, 1,
+							  WAIT_EVENT_SYSLOGGER_MAIN);
+
+		if (rc == 1 && event.events == WL_SOCKET_READABLE)
+		{
+			int			bytesRead;
+
+			bytesRead = read(syslogPipe[0],
+							 logbuffer + bytes_in_logbuffer,
+							 sizeof(logbuffer) - bytes_in_logbuffer);
+			if (bytesRead < 0)
+			{
+				if (errno != EINTR)
+					ereport(LOG,
+							(errcode_for_socket_access(),
+							 errmsg("could not read from logger pipe: %m")));
+			}
+			else if (bytesRead > 0)
+			{
+				bytes_in_logbuffer += bytesRead;
+				process_pipe_input(logbuffer, &bytes_in_logbuffer);
+				continue;
+			}
+			else
+			{
+				/*
+				 * Zero bytes read when select() is saying read-ready means
+				 * EOF on the pipe: that is, there are no longer any processes
+				 * with the pipe write end open.  Therefore, the postmaster
+				 * and all backends are shut down, and we are done.
+				 */
+				pipe_eof_seen = true;
+
+				/* if there's any data left then force it out now */
+				flush_pipe_input(logbuffer, &bytes_in_logbuffer);
+			}
+		}
+#else							/* WIN32 */
+
+		/*
+		 * On Windows we leave it to a separate thread to transfer data and
+		 * detect pipe EOF.  The main thread just wakes up to handle SIGHUP
+		 * and rotation conditions.
+		 *
+		 * Server code isn't generally thread-safe, so we ensure that only one
+		 * of the threads is active at a time by entering the critical section
+		 * whenever we're not sleeping.
+		 */
+		LeaveCriticalSection(&sysloggerSection);
+
+		(void) WaitEventSetWait(wes, cur_timeout, &event, 1,
+								WAIT_EVENT_SYSLOGGER_MAIN);
+
+		EnterCriticalSection(&sysloggerSection);
+#endif							/* WIN32 */
+
+		if (pipe_eof_seen)
+		{
+			/*
+			 * seeing this message on the real stderr is annoying - so we make
+			 * it DEBUG1 to suppress in normal use.
+			 */
+			ereport(DEBUG1,
+					(errmsg_internal("logger shutting down")));
+
+			/*
+			 * Normal exit from the syslogger is here.  Note that we
+			 * deliberately do not close syslogFile before exiting; this is to
+			 * allow for the possibility of elog messages being generated
+			 * inside proc_exit.  Regular exit() will take care of flushing
+			 * and closing stdio channels.
+			 */
+			proc_exit(0);
+		}
+	}
+}
+
+/*
+ * Postmaster subroutine to start a syslogger subprocess.
+ */
+int
+SysLogger_Start(void)
+{
+	pid_t		sysloggerPid;
+	char	   *filename;
+
+	if (!Logging_collector)
+		return 0;
+
+	/*
+	 * If first time through, create the pipe which will receive stderr
+	 * output.
+	 *
+	 * If the syslogger crashes and needs to be restarted, we continue to use
+	 * the same pipe (indeed must do so, since extant backends will be writing
+	 * into that pipe).
+	 *
+	 * This means the postmaster must continue to hold the read end of the
+	 * pipe open, so we can pass it down to the reincarnated syslogger. This
+	 * is a bit klugy but we have little choice.
+	 *
+	 * Also note that we don't bother counting the pipe FDs by calling
+	 * Reserve/ReleaseExternalFD.  There's no real need to account for them
+	 * accurately in the postmaster or syslogger process, and both ends of the
+	 * pipe will wind up closed in all other postmaster children.
+	 */
+#ifndef WIN32
+	if (syslogPipe[0] < 0)
+	{
+		if (pipe(syslogPipe) < 0)
+			ereport(FATAL,
+					(errcode_for_socket_access(),
+					 errmsg("could not create pipe for syslog: %m")));
+	}
+#else
+	if (!syslogPipe[0])
+	{
+		SECURITY_ATTRIBUTES sa;
+
+		memset(&sa, 0, sizeof(SECURITY_ATTRIBUTES));
+		sa.nLength = sizeof(SECURITY_ATTRIBUTES);
+		sa.bInheritHandle = TRUE;
+
+		if (!CreatePipe(&syslogPipe[0], &syslogPipe[1], &sa, 32768))
+			ereport(FATAL,
+					(errcode_for_file_access(),
+					 errmsg("could not create pipe for syslog: %m")));
+	}
+#endif
+
+	/*
+	 * Create log directory if not present; ignore errors
+	 */
+	(void) MakePGDirectory(Log_directory);
+
+	/*
+	 * The initial logfile is created right in the postmaster, to verify that
+	 * the Log_directory is writable.  We save the reference time so that the
+	 * syslogger child process can recompute this file name.
+	 *
+	 * It might look a bit strange to re-do this during a syslogger restart,
+	 * but we must do so since the postmaster closed syslogFile after the
+	 * previous fork (and remembering that old file wouldn't be right anyway).
+	 * Note we always append here, we won't overwrite any existing file.  This
+	 * is consistent with the normal rules, because by definition this is not
+	 * a time-based rotation.
+	 */
+	first_syslogger_file_time = time(NULL);
+
+	filename = logfile_getname(first_syslogger_file_time, NULL);
+
+	syslogFile = logfile_open(filename, "a", false);
+
+	pfree(filename);
+
+	/*
+	 * Likewise for the initial CSV log file, if that's enabled.  (Note that
+	 * we open syslogFile even when only CSV output is nominally enabled,
+	 * since some code paths will write to syslogFile anyway.)
+	 */
+	if (Log_destination & LOG_DESTINATION_CSVLOG)
+	{
+		filename = logfile_getname(first_syslogger_file_time, ".csv");
+
+		csvlogFile = logfile_open(filename, "a", false);
+
+		pfree(filename);
+	}
+
+	/*
+	 * Likewise for the initial JSON log file, if that's enabled.  (Note that
+	 * we open syslogFile even when only JSON output is nominally enabled,
+	 * since some code paths will write to syslogFile anyway.)
+	 */
+	if (Log_destination & LOG_DESTINATION_JSONLOG)
+	{
+		filename = logfile_getname(first_syslogger_file_time, ".json");
+
+		jsonlogFile = logfile_open(filename, "a", false);
+
+		pfree(filename);
+	}
+
+#ifdef EXEC_BACKEND
+	switch ((sysloggerPid = syslogger_forkexec()))
+#else
+	switch ((sysloggerPid = fork_process()))
+#endif
+	{
+		case -1:
+			ereport(LOG,
+					(errmsg("could not fork system logger: %m")));
+			return 0;
+
+#ifndef EXEC_BACKEND
+		case 0:
+			/* in postmaster child ... */
+			InitPostmasterChild();
+
+			/* Close the postmaster's sockets */
+			ClosePostmasterPorts(true);
+
+			/* Drop our connection to postmaster's shared memory, as well */
+			dsm_detach_all();
+			PGSharedMemoryDetach();
+
+			/* do the work */
+			SysLoggerMain(0, NULL);
+			break;
+#endif
+
+		default:
+			/* success, in postmaster */
+
+			/* now we redirect stderr, if not done already */
+			if (!redirection_done)
+			{
+#ifdef WIN32
+				int			fd;
+#endif
+
+				/*
+				 * Leave a breadcrumb trail when redirecting, in case the user
+				 * forgets that redirection is active and looks only at the
+				 * original stderr target file.
+				 */
+				ereport(LOG,
+						(errmsg("redirecting log output to logging collector process"),
+						 errhint("Future log output will appear in directory \"%s\".",
+								 Log_directory)));
+
+#ifndef WIN32
+				fflush(stdout);
+				if (dup2(syslogPipe[1], STDOUT_FILENO) < 0)
+					ereport(FATAL,
+							(errcode_for_file_access(),
+							 errmsg("could not redirect stdout: %m")));
+				fflush(stderr);
+				if (dup2(syslogPipe[1], STDERR_FILENO) < 0)
+					ereport(FATAL,
+							(errcode_for_file_access(),
+							 errmsg("could not redirect stderr: %m")));
+				/* Now we are done with the write end of the pipe. */
+				close(syslogPipe[1]);
+				syslogPipe[1] = -1;
+#else
+
+				/*
+				 * open the pipe in binary mode and make sure stderr is binary
+				 * after it's been dup'ed into, to avoid disturbing the pipe
+				 * chunking protocol.
+				 */
+				fflush(stderr);
+				fd = _open_osfhandle((intptr_t) syslogPipe[1],
+									 _O_APPEND | _O_BINARY);
+				if (dup2(fd, STDERR_FILENO) < 0)
+					ereport(FATAL,
+							(errcode_for_file_access(),
+							 errmsg("could not redirect stderr: %m")));
+				close(fd);
+				_setmode(STDERR_FILENO, _O_BINARY);
+
+				/*
+				 * Now we are done with the write end of the pipe.
+				 * CloseHandle() must not be called because the preceding
+				 * close() closes the underlying handle.
+				 */
+				syslogPipe[1] = 0;
+#endif
+				redirection_done = true;
+			}
+
+			/* postmaster will never write the file(s); close 'em */
+			fclose(syslogFile);
+			syslogFile = NULL;
+			if (csvlogFile != NULL)
+			{
+				fclose(csvlogFile);
+				csvlogFile = NULL;
+			}
+			if (jsonlogFile != NULL)
+			{
+				fclose(jsonlogFile);
+				jsonlogFile = NULL;
+			}
+			return (int) sysloggerPid;
+	}
+
+	/* we should never reach here */
+	return 0;
+}
+
+
+#ifdef EXEC_BACKEND
+
+/*
+ * syslogger_fdget() -
+ *
+ * Utility wrapper to grab the file descriptor of an opened error output
+ * file.  Used when building the command to fork the logging collector.
+ */
+static int
+syslogger_fdget(FILE *file)
+{
+#ifndef WIN32
+	if (file != NULL)
+		return fileno(file);
+	else
+		return -1;
+#else
+	if (file != NULL)
+		return (int) _get_osfhandle(_fileno(file));
+	else
+		return 0;
+#endif							/* WIN32 */
+}
+
+/*
+ * syslogger_fdopen() -
+ *
+ * Utility wrapper to re-open an error output file, using the given file
+ * descriptor.  Used when parsing arguments in a forked logging collector.
+ */
+static FILE *
+syslogger_fdopen(int fd)
+{
+	FILE	   *file = NULL;
+
+#ifndef WIN32
+	if (fd != -1)
+	{
+		file = fdopen(fd, "a");
+		setvbuf(file, NULL, PG_IOLBF, 0);
+	}
+#else							/* WIN32 */
+	if (fd != 0)
+	{
+		fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
+		if (fd > 0)
+		{
+			file = fdopen(fd, "a");
+			setvbuf(file, NULL, PG_IOLBF, 0);
+		}
+	}
+#endif							/* WIN32 */
+
+	return file;
+}
+
+/*
+ * syslogger_forkexec() -
+ *
+ * Format up the arglist for, then fork and exec, a syslogger process
+ */
+static pid_t
+syslogger_forkexec(void)
+{
+	char	   *av[10];
+	int			ac = 0;
+	char		filenobuf[32];
+	char		csvfilenobuf[32];
+	char		jsonfilenobuf[32];
+
+	av[ac++] = "postgres";
+	av[ac++] = "--forklog";
+	av[ac++] = NULL;			/* filled in by postmaster_forkexec */
+
+	/* static variables (those not passed by write_backend_variables) */
+	snprintf(filenobuf, sizeof(filenobuf), "%d",
+			 syslogger_fdget(syslogFile));
+	av[ac++] = filenobuf;
+	snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%d",
+			 syslogger_fdget(csvlogFile));
+	av[ac++] = csvfilenobuf;
+	snprintf(jsonfilenobuf, sizeof(jsonfilenobuf), "%d",
+			 syslogger_fdget(jsonlogFile));
+	av[ac++] = jsonfilenobuf;
+
+	av[ac] = NULL;
+	Assert(ac < lengthof(av));
+
+	return postmaster_forkexec(ac, av);
+}
+
+/*
+ * syslogger_parseArgs() -
+ *
+ * Extract data from the arglist for exec'ed syslogger process
+ */
+static void
+syslogger_parseArgs(int argc, char *argv[])
+{
+	int			fd;
+
+	Assert(argc == 6);
+	argv += 3;
+
+	/*
+	 * Re-open the error output files that were opened by SysLogger_Start().
+	 *
+	 * We expect this will always succeed, which is too optimistic, but if it
+	 * fails there's not a lot we can do to report the problem anyway.  As
+	 * coded, we'll just crash on a null pointer dereference after failure...
+	 */
+	fd = atoi(*argv++);
+	syslogFile = syslogger_fdopen(fd);
+	fd = atoi(*argv++);
+	csvlogFile = syslogger_fdopen(fd);
+	fd = atoi(*argv++);
+	jsonlogFile = syslogger_fdopen(fd);
+}
+#endif							/* EXEC_BACKEND */
+
+
+/* --------------------------------
+ *		pipe protocol handling
+ * --------------------------------
+ */
+
+/*
+ * Process data received through the syslogger pipe.
+ *
+ * This routine interprets the log pipe protocol which sends log messages as
+ * (hopefully atomic) chunks - such chunks are detected and reassembled here.
+ *
+ * The protocol has a header that starts with two nul bytes, then has a 16 bit
+ * length, the pid of the sending process, and a flag to indicate if it is
+ * the last chunk in a message. Incomplete chunks are saved until we read some
+ * more, and non-final chunks are accumulated until we get the final chunk.
+ *
+ * All of this is to avoid 2 problems:
+ * . partial messages being written to logfiles (messes rotation), and
+ * . messages from different backends being interleaved (messages garbled).
+ *
+ * Any non-protocol messages are written out directly. These should only come
+ * from non-PostgreSQL sources, however (e.g. third party libraries writing to
+ * stderr).
+ *
+ * logbuffer is the data input buffer, and *bytes_in_logbuffer is the number
+ * of bytes present.  On exit, any not-yet-eaten data is left-justified in
+ * logbuffer, and *bytes_in_logbuffer is updated.
+ */
+static void
+process_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
+{
+	char	   *cursor = logbuffer;
+	int			count = *bytes_in_logbuffer;
+	int			dest = LOG_DESTINATION_STDERR;
+
+	/* While we have enough for a header, process data... */
+	while (count >= (int) (offsetof(PipeProtoHeader, data) + 1))
+	{
+		PipeProtoHeader p;
+		int			chunklen;
+		bits8		dest_flags;
+
+		/* Do we have a valid header? */
+		memcpy(&p, cursor, offsetof(PipeProtoHeader, data));
+		dest_flags = p.flags & (PIPE_PROTO_DEST_STDERR |
+								PIPE_PROTO_DEST_CSVLOG |
+								PIPE_PROTO_DEST_JSONLOG);
+		if (p.nuls[0] == '\0' && p.nuls[1] == '\0' &&
+			p.len > 0 && p.len <= PIPE_MAX_PAYLOAD &&
+			p.pid != 0 &&
+			pg_popcount((char *) &dest_flags, 1) == 1)
+		{
+			List	   *buffer_list;
+			ListCell   *cell;
+			save_buffer *existing_slot = NULL,
+					   *free_slot = NULL;
+			StringInfo	str;
+
+			chunklen = PIPE_HEADER_SIZE + p.len;
+
+			/* Fall out of loop if we don't have the whole chunk yet */
+			if (count < chunklen)
+				break;
+
+			if ((p.flags & PIPE_PROTO_DEST_STDERR) != 0)
+				dest = LOG_DESTINATION_STDERR;
+			else if ((p.flags & PIPE_PROTO_DEST_CSVLOG) != 0)
+				dest = LOG_DESTINATION_CSVLOG;
+			else if ((p.flags & PIPE_PROTO_DEST_JSONLOG) != 0)
+				dest = LOG_DESTINATION_JSONLOG;
+			else
+			{
+				/* this should never happen as of the header validation */
+				Assert(false);
+			}
+
+			/* Locate any existing buffer for this source pid */
+			buffer_list = buffer_lists[p.pid % NBUFFER_LISTS];
+			foreach(cell, buffer_list)
+			{
+				save_buffer *buf = (save_buffer *) lfirst(cell);
+
+				if (buf->pid == p.pid)
+				{
+					existing_slot = buf;
+					break;
+				}
+				if (buf->pid == 0 && free_slot == NULL)
+					free_slot = buf;
+			}
+
+			if ((p.flags & PIPE_PROTO_IS_LAST) == 0)
+			{
+				/*
+				 * Save a complete non-final chunk in a per-pid buffer
+				 */
+				if (existing_slot != NULL)
+				{
+					/* Add chunk to data from preceding chunks */
+					str = &(existing_slot->data);
+					appendBinaryStringInfo(str,
+										   cursor + PIPE_HEADER_SIZE,
+										   p.len);
+				}
+				else
+				{
+					/* First chunk of message, save in a new buffer */
+					if (free_slot == NULL)
+					{
+						/*
+						 * Need a free slot, but there isn't one in the list,
+						 * so create a new one and extend the list with it.
+						 */
+						free_slot = palloc(sizeof(save_buffer));
+						buffer_list = lappend(buffer_list, free_slot);
+						buffer_lists[p.pid % NBUFFER_LISTS] = buffer_list;
+					}
+					free_slot->pid = p.pid;
+					str = &(free_slot->data);
+					initStringInfo(str);
+					appendBinaryStringInfo(str,
+										   cursor + PIPE_HEADER_SIZE,
+										   p.len);
+				}
+			}
+			else
+			{
+				/*
+				 * Final chunk --- add it to anything saved for that pid, and
+				 * either way write the whole thing out.
+				 */
+				if (existing_slot != NULL)
+				{
+					str = &(existing_slot->data);
+					appendBinaryStringInfo(str,
+										   cursor + PIPE_HEADER_SIZE,
+										   p.len);
+					write_syslogger_file(str->data, str->len, dest);
+					/* Mark the buffer unused, and reclaim string storage */
+					existing_slot->pid = 0;
+					pfree(str->data);
+				}
+				else
+				{
+					/* The whole message was one chunk, evidently. */
+					write_syslogger_file(cursor + PIPE_HEADER_SIZE, p.len,
+										 dest);
+				}
+			}
+
+			/* Finished processing this chunk */
+			cursor += chunklen;
+			count -= chunklen;
+		}
+		else
+		{
+			/* Process non-protocol data */
+
+			/*
+			 * Look for the start of a protocol header.  If found, dump data
+			 * up to there and repeat the loop.  Otherwise, dump it all and
+			 * fall out of the loop.  (Note: we want to dump it all if at all
+			 * possible, so as to avoid dividing non-protocol messages across
+			 * logfiles.  We expect that in many scenarios, a non-protocol
+			 * message will arrive all in one read(), and we want to respect
+			 * the read() boundary if possible.)
+			 */
+			for (chunklen = 1; chunklen < count; chunklen++)
+			{
+				if (cursor[chunklen] == '\0')
+					break;
+			}
+			/* fall back on the stderr log as the destination */
+			write_syslogger_file(cursor, chunklen, LOG_DESTINATION_STDERR);
+			cursor += chunklen;
+			count -= chunklen;
+		}
+	}
+
+	/* We don't have a full chunk, so left-align what remains in the buffer */
+	if (count > 0 && cursor != logbuffer)
+		memmove(logbuffer, cursor, count);
+	*bytes_in_logbuffer = count;
+}
+
+/*
+ * Force out any buffered data
+ *
+ * This is currently used only at syslogger shutdown, but could perhaps be
+ * useful at other times, so it is careful to leave things in a clean state.
+ */
+static void
+flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
+{
+	int			i;
+
+	/* Dump any incomplete protocol messages */
+	for (i = 0; i < NBUFFER_LISTS; i++)
+	{
+		List	   *list = buffer_lists[i];
+		ListCell   *cell;
+
+		foreach(cell, list)
+		{
+			save_buffer *buf = (save_buffer *) lfirst(cell);
+
+			if (buf->pid != 0)
+			{
+				StringInfo	str = &(buf->data);
+
+				write_syslogger_file(str->data, str->len,
+									 LOG_DESTINATION_STDERR);
+				/* Mark the buffer unused, and reclaim string storage */
+				buf->pid = 0;
+				pfree(str->data);
+			}
+		}
+	}
+
+	/*
+	 * Force out any remaining pipe data as-is; we don't bother trying to
+	 * remove any protocol headers that may exist in it.
+	 */
+	if (*bytes_in_logbuffer > 0)
+		write_syslogger_file(logbuffer, *bytes_in_logbuffer,
+							 LOG_DESTINATION_STDERR);
+	*bytes_in_logbuffer = 0;
+}
+
+
+/* --------------------------------
+ *		logfile routines
+ * --------------------------------
+ */
+
+/*
+ * Write text to the currently open logfile
+ *
+ * This is exported so that elog.c can call it when MyBackendType is B_LOGGER.
+ * This allows the syslogger process to record elog messages of its own,
+ * even though its stderr does not point at the syslog pipe.
+ */
+void
+write_syslogger_file(const char *buffer, int count, int destination)
+{
+	int			rc;
+	FILE	   *logfile;
+
+	/*
+	 * If we're told to write to a structured log file, but it's not open,
+	 * dump the data to syslogFile (which is always open) instead.  This can
+	 * happen if structured output is enabled after postmaster start and we've
+	 * been unable to open logFile.  There are also race conditions during a
+	 * parameter change whereby backends might send us structured output
+	 * before we open the logFile or after we close it.  Writing formatted
+	 * output to the regular log file isn't great, but it beats dropping log
+	 * output on the floor.
+	 *
+	 * Think not to improve this by trying to open logFile on-the-fly.  Any
+	 * failure in that would lead to recursion.
+	 */
+	if ((destination & LOG_DESTINATION_CSVLOG) && csvlogFile != NULL)
+		logfile = csvlogFile;
+	else if ((destination & LOG_DESTINATION_JSONLOG) && jsonlogFile != NULL)
+		logfile = jsonlogFile;
+	else
+		logfile = syslogFile;
+
+	rc = fwrite(buffer, 1, count, logfile);
+
+	/*
+	 * Try to report any failure.  We mustn't use ereport because it would
+	 * just recurse right back here, but write_stderr is OK: it will write
+	 * either to the postmaster's original stderr, or to /dev/null, but never
+	 * to our input pipe which would result in a different sort of looping.
+	 */
+	if (rc != count)
+		write_stderr("could not write to log file: %s\n", strerror(errno));
+}
+
+#ifdef WIN32
+
+/*
+ * Worker thread to transfer data from the pipe to the current logfile.
+ *
+ * We need this because on Windows, WaitForMultipleObjects does not work on
+ * unnamed pipes: it always reports "signaled", so the blocking ReadFile won't
+ * allow for SIGHUP; and select is for sockets only.
+ */
+static unsigned int __stdcall
+pipeThread(void *arg)
+{
+	char		logbuffer[READ_BUF_SIZE];
+	int			bytes_in_logbuffer = 0;
+
+	for (;;)
+	{
+		DWORD		bytesRead;
+		BOOL		result;
+
+		result = ReadFile(syslogPipe[0],
+						  logbuffer + bytes_in_logbuffer,
+						  sizeof(logbuffer) - bytes_in_logbuffer,
+						  &bytesRead, 0);
+
+		/*
+		 * Enter critical section before doing anything that might touch
+		 * global state shared by the main thread. Anything that uses
+		 * palloc()/pfree() in particular are not safe outside the critical
+		 * section.
+		 */
+		EnterCriticalSection(&sysloggerSection);
+		if (!result)
+		{
+			DWORD		error = GetLastError();
+
+			if (error == ERROR_HANDLE_EOF ||
+				error == ERROR_BROKEN_PIPE)
+				break;
+			_dosmaperr(error);
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not read from logger pipe: %m")));
+		}
+		else if (bytesRead > 0)
+		{
+			bytes_in_logbuffer += bytesRead;
+			process_pipe_input(logbuffer, &bytes_in_logbuffer);
+		}
+
+		/*
+		 * If we've filled the current logfile, nudge the main thread to do a
+		 * log rotation.
+		 */
+		if (Log_RotationSize > 0)
+		{
+			if (ftell(syslogFile) >= Log_RotationSize * 1024L ||
+				(csvlogFile != NULL && ftell(csvlogFile) >= Log_RotationSize * 1024L) ||
+				(jsonlogFile != NULL && ftell(jsonlogFile) >= Log_RotationSize * 1024L))
+				SetLatch(MyLatch);
+		}
+		LeaveCriticalSection(&sysloggerSection);
+	}
+
+	/* We exit the above loop only upon detecting pipe EOF */
+	pipe_eof_seen = true;
+
+	/* if there's any data left then force it out now */
+	flush_pipe_input(logbuffer, &bytes_in_logbuffer);
+
+	/* set the latch to waken the main thread, which will quit */
+	SetLatch(MyLatch);
+
+	LeaveCriticalSection(&sysloggerSection);
+	_endthread();
+	return 0;
+}
+#endif							/* WIN32 */
+
+/*
+ * Open a new logfile with proper permissions and buffering options.
+ *
+ * If allow_errors is true, we just log any open failure and return NULL
+ * (with errno still correct for the fopen failure).
+ * Otherwise, errors are treated as fatal.
+ */
+static FILE *
+logfile_open(const char *filename, const char *mode, bool allow_errors)
+{
+	FILE	   *fh;
+	mode_t		oumask;
+
+	/*
+	 * Note we do not let Log_file_mode disable IWUSR, since we certainly want
+	 * to be able to write the files ourselves.
+	 */
+	oumask = umask((mode_t) ((~(Log_file_mode | S_IWUSR)) & (S_IRWXU | S_IRWXG | S_IRWXO)));
+	fh = fopen(filename, mode);
+	umask(oumask);
+
+	if (fh)
+	{
+		setvbuf(fh, NULL, PG_IOLBF, 0);
+
+#ifdef WIN32
+		/* use CRLF line endings on Windows */
+		_setmode(_fileno(fh), _O_TEXT);
+#endif
+	}
+	else
+	{
+		int			save_errno = errno;
+
+		ereport(allow_errors ? LOG : FATAL,
+				(errcode_for_file_access(),
+				 errmsg("could not open log file \"%s\": %m",
+						filename)));
+		errno = save_errno;
+	}
+
+	return fh;
+}
+
+/*
+ * Do logfile rotation for a single destination, as specified by target_dest.
+ * The information stored in *last_file_name and *logFile is updated on a
+ * successful file rotation.
+ *
+ * Returns false if the rotation has been stopped, or true to move on to
+ * the processing of other formats.
+ */
+static bool
+logfile_rotate_dest(bool time_based_rotation, int size_rotation_for,
+					pg_time_t fntime, int target_dest,
+					char **last_file_name, FILE **logFile)
+{
+	char	   *logFileExt = NULL;
+	char	   *filename;
+	FILE	   *fh;
+
+	/*
+	 * If the target destination was just turned off, close the previous file
+	 * and unregister its data.  This cannot happen for stderr as syslogFile
+	 * is assumed to be always opened even if stderr is disabled in
+	 * log_destination.
+	 */
+	if ((Log_destination & target_dest) == 0 &&
+		target_dest != LOG_DESTINATION_STDERR)
+	{
+		if (*logFile != NULL)
+			fclose(*logFile);
+		*logFile = NULL;
+		if (*last_file_name != NULL)
+			pfree(*last_file_name);
+		*last_file_name = NULL;
+		return true;
+	}
+
+	/*
+	 * Leave if it is not time for a rotation or if the target destination has
+	 * no need to do a rotation based on the size of its file.
+	 */
+	if (!time_based_rotation && (size_rotation_for & target_dest) == 0)
+		return true;
+
+	/* file extension depends on the destination type */
+	if (target_dest == LOG_DESTINATION_STDERR)
+		logFileExt = NULL;
+	else if (target_dest == LOG_DESTINATION_CSVLOG)
+		logFileExt = ".csv";
+	else if (target_dest == LOG_DESTINATION_JSONLOG)
+		logFileExt = ".json";
+	else
+	{
+		/* cannot happen */
+		Assert(false);
+	}
+
+	/* build the new file name */
+	filename = logfile_getname(fntime, logFileExt);
+
+	/*
+	 * Decide whether to overwrite or append.  We can overwrite if (a)
+	 * Log_truncate_on_rotation is set, (b) the rotation was triggered by
+	 * elapsed time and not something else, and (c) the computed file name is
+	 * different from what we were previously logging into.
+	 */
+	if (Log_truncate_on_rotation && time_based_rotation &&
+		*last_file_name != NULL &&
+		strcmp(filename, *last_file_name) != 0)
+		fh = logfile_open(filename, "w", true);
+	else
+		fh = logfile_open(filename, "a", true);
+
+	if (!fh)
+	{
+		/*
+		 * ENFILE/EMFILE are not too surprising on a busy system; just keep
+		 * using the old file till we manage to get a new one.  Otherwise,
+		 * assume something's wrong with Log_directory and stop trying to
+		 * create files.
+		 */
+		if (errno != ENFILE && errno != EMFILE)
+		{
+			ereport(LOG,
+					(errmsg("disabling automatic rotation (use SIGHUP to re-enable)")));
+			rotation_disabled = true;
+		}
+
+		if (filename)
+			pfree(filename);
+		return false;
+	}
+
+	/* fill in the new information */
+	if (*logFile != NULL)
+		fclose(*logFile);
+	*logFile = fh;
+
+	/* instead of pfree'ing filename, remember it for next time */
+	if (*last_file_name != NULL)
+		pfree(*last_file_name);
+	*last_file_name = filename;
+
+	return true;
+}
+
+/*
+ * perform logfile rotation
+ */
+static void
+logfile_rotate(bool time_based_rotation, int size_rotation_for)
+{
+	pg_time_t	fntime;
+
+	rotation_requested = false;
+
+	/*
+	 * When doing a time-based rotation, invent the new logfile name based on
+	 * the planned rotation time, not current time, to avoid "slippage" in the
+	 * file name when we don't do the rotation immediately.
+	 */
+	if (time_based_rotation)
+		fntime = next_rotation_time;
+	else
+		fntime = time(NULL);
+
+	/* file rotation for stderr */
+	if (!logfile_rotate_dest(time_based_rotation, size_rotation_for, fntime,
+							 LOG_DESTINATION_STDERR, &last_sys_file_name,
+							 &syslogFile))
+		return;
+
+	/* file rotation for csvlog */
+	if (!logfile_rotate_dest(time_based_rotation, size_rotation_for, fntime,
+							 LOG_DESTINATION_CSVLOG, &last_csv_file_name,
+							 &csvlogFile))
+		return;
+
+	/* file rotation for jsonlog */
+	if (!logfile_rotate_dest(time_based_rotation, size_rotation_for, fntime,
+							 LOG_DESTINATION_JSONLOG, &last_json_file_name,
+							 &jsonlogFile))
+		return;
+
+	update_metainfo_datafile();
+
+	set_next_rotation_time();
+}
+
+
+/*
+ * construct logfile name using timestamp information
+ *
+ * If suffix isn't NULL, append it to the name, replacing any ".log"
+ * that may be in the pattern.
+ *
+ * Result is palloc'd.
+ */
+static char *
+logfile_getname(pg_time_t timestamp, const char *suffix)
+{
+	char	   *filename;
+	int			len;
+
+	filename = palloc(MAXPGPATH);
+
+	snprintf(filename, MAXPGPATH, "%s/", Log_directory);
+
+	len = strlen(filename);
+
+	/* treat Log_filename as a strftime pattern */
+	pg_strftime(filename + len, MAXPGPATH - len, Log_filename,
+				pg_localtime(&timestamp, log_timezone));
+
+	if (suffix != NULL)
+	{
+		len = strlen(filename);
+		if (len > 4 && (strcmp(filename + (len - 4), ".log") == 0))
+			len -= 4;
+		strlcpy(filename + len, suffix, MAXPGPATH - len);
+	}
+
+	return filename;
+}
+
+/*
+ * Determine the next planned rotation time, and store in next_rotation_time.
+ */
+static void
+set_next_rotation_time(void)
+{
+	pg_time_t	now;
+	struct pg_tm *tm;
+	int			rotinterval;
+
+	/* nothing to do if time-based rotation is disabled */
+	if (Log_RotationAge <= 0)
+		return;
+
+	/*
+	 * The requirements here are to choose the next time > now that is a
+	 * "multiple" of the log rotation interval.  "Multiple" can be interpreted
+	 * fairly loosely.  In this version we align to log_timezone rather than
+	 * GMT.
+	 */
+	rotinterval = Log_RotationAge * SECS_PER_MINUTE;	/* convert to seconds */
+	now = (pg_time_t) time(NULL);
+	tm = pg_localtime(&now, log_timezone);
+	now += tm->tm_gmtoff;
+	now -= now % rotinterval;
+	now += rotinterval;
+	now -= tm->tm_gmtoff;
+	next_rotation_time = now;
+}
+
+/*
+ * Store the name of the file(s) where the log collector, when enabled, writes
+ * log messages.  Useful for finding the name(s) of the current log file(s)
+ * when there is time-based logfile rotation.  Filenames are stored in a
+ * temporary file and which is renamed into the final destination for
+ * atomicity.  The file is opened with the same permissions as what gets
+ * created in the data directory and has proper buffering options.
+ */
+static void
+update_metainfo_datafile(void)
+{
+	FILE	   *fh;
+	mode_t		oumask;
+
+	if (!(Log_destination & LOG_DESTINATION_STDERR) &&
+		!(Log_destination & LOG_DESTINATION_CSVLOG) &&
+		!(Log_destination & LOG_DESTINATION_JSONLOG))
+	{
+		if (unlink(LOG_METAINFO_DATAFILE) < 0 && errno != ENOENT)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not remove file \"%s\": %m",
+							LOG_METAINFO_DATAFILE)));
+		return;
+	}
+
+	/* use the same permissions as the data directory for the new file */
+	oumask = umask(pg_mode_mask);
+	fh = fopen(LOG_METAINFO_DATAFILE_TMP, "w");
+	umask(oumask);
+
+	if (fh)
+	{
+		setvbuf(fh, NULL, PG_IOLBF, 0);
+
+#ifdef WIN32
+		/* use CRLF line endings on Windows */
+		_setmode(_fileno(fh), _O_TEXT);
+#endif
+	}
+	else
+	{
+		ereport(LOG,
+				(errcode_for_file_access(),
+				 errmsg("could not open file \"%s\": %m",
+						LOG_METAINFO_DATAFILE_TMP)));
+		return;
+	}
+
+	if (last_sys_file_name && (Log_destination & LOG_DESTINATION_STDERR))
+	{
+		if (fprintf(fh, "stderr %s\n", last_sys_file_name) < 0)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not write file \"%s\": %m",
+							LOG_METAINFO_DATAFILE_TMP)));
+			fclose(fh);
+			return;
+		}
+	}
+
+	if (last_csv_file_name && (Log_destination & LOG_DESTINATION_CSVLOG))
+	{
+		if (fprintf(fh, "csvlog %s\n", last_csv_file_name) < 0)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not write file \"%s\": %m",
+							LOG_METAINFO_DATAFILE_TMP)));
+			fclose(fh);
+			return;
+		}
+	}
+
+	if (last_json_file_name && (Log_destination & LOG_DESTINATION_JSONLOG))
+	{
+		if (fprintf(fh, "jsonlog %s\n", last_json_file_name) < 0)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not write file \"%s\": %m",
+							LOG_METAINFO_DATAFILE_TMP)));
+			fclose(fh);
+			return;
+		}
+	}
+	fclose(fh);
+
+	if (rename(LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE) != 0)
+		ereport(LOG,
+				(errcode_for_file_access(),
+				 errmsg("could not rename file \"%s\" to \"%s\": %m",
+						LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE)));
+}
+
+/* --------------------------------
+ *		signal handler routines
+ * --------------------------------
+ */
+
+/*
+ * Check to see if a log rotation request has arrived.  Should be
+ * called by postmaster after receiving SIGUSR1.
+ */
+bool
+CheckLogrotateSignal(void)
+{
+	struct stat stat_buf;
+
+	if (stat(LOGROTATE_SIGNAL_FILE, &stat_buf) == 0)
+		return true;
+
+	return false;
+}
+
+/*
+ * Remove the file signaling a log rotation request.
+ */
+void
+RemoveLogrotateSignalFiles(void)
+{
+	unlink(LOGROTATE_SIGNAL_FILE);
+}
+
+/* SIGUSR1: set flag to rotate logfile */
+static void
+sigUsr1Handler(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	rotation_requested = true;
+	SetLatch(MyLatch);
+
+	errno = save_errno;
+}