Create a built-in log rotation program, so that we no longer have to

recommend that people go get Apache's rotatelogs program.  Additional
benefits are that configuration is done through GUC, rather than
externally, and that the postmaster can monitor the log rotator and
restart it after failure (though we certainly hope that won't happen
often).
Andreas Pflug, some rework by Tom Lane.

src/backend/postmaster/postmaster.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.419 2004/08/04 20:09:47 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.420 2004/08/05 23:32:10 tgl Exp $
  *
  * NOTES
  *
@@ -104,6 +104,7 @@
 #include "nodes/nodes.h"
 #include "postmaster/postmaster.h"
 #include "postmaster/pgarch.h"
+#include "postmaster/syslogger.h"
 #include "storage/fd.h"
 #include "storage/ipc.h"
 #include "storage/pg_shmem.h"
@@ -199,7 +200,8 @@ char	   *preload_libraries_string = NULL;
 static pid_t StartupPID = 0,
 			BgWriterPID = 0,
 			PgArchPID = 0,
-			PgStatPID = 0;
+			PgStatPID = 0,
+			SysLoggerPID = 0;
 
 /* Startup/shutdown state */
 #define			NoShutdown		0
@@ -828,7 +830,7 @@ PostmasterMain(int argc, char *argv[])
 	 * CAUTION: when changing this list, check for side-effects on the signal
 	 * handling setup of child processes.  See tcop/postgres.c,
 	 * bootstrap/bootstrap.c, postmaster/bgwriter.c, postmaster/pgarch.c,
-	 * and postmaster/pgstat.c.
+	 * postmaster/pgstat.c, and postmaster/syslogger.c.
 	 */
 	pqinitmask();
 	PG_SETMASK(&BlockSig);
@@ -850,6 +852,11 @@ PostmasterMain(int argc, char *argv[])
 	pqsignal(SIGXFSZ, SIG_IGN); /* ignored */
 #endif
 
+	/*
+	 * If enabled, start up syslogger collection subprocess
+	 */
+	SysLoggerPID = SysLogger_Start();
+
 	/*
 	 * Reset whereToSendOutput from Debug (its starting state) to None.
 	 * This stops ereport from sending log messages to stderr unless
@@ -933,8 +940,8 @@ checkDataDir(const char *checkdir)
 	{
 		write_stderr("%s does not know where to find the database system data.\n"
 					 "You must specify the directory that contains the database system\n"
-					 "or configuration files by either specifying the -D invocation option\n"
-					 "or by setting the PGDATA environment variable.\n",
+					 "either by specifying the -D invocation option or by setting the\n"
+					 "PGDATA environment variable.\n",
 					 progname);
 		ExitPostmaster(2);
 	}
@@ -944,12 +951,12 @@ checkDataDir(const char *checkdir)
 		if (errno == ENOENT)
 			ereport(FATAL,
 					(errcode_for_file_access(),
-					 errmsg("data or configuration location \"%s\" does not exist",
+					 errmsg("data directory \"%s\" does not exist",
 							checkdir)));
 		else
 			ereport(FATAL,
 					(errcode_for_file_access(),
-			 errmsg("could not read permissions of \"%s\": %m",
+			 errmsg("could not read permissions of directory \"%s\": %m",
 					checkdir)));
 	}
 
@@ -1050,7 +1057,7 @@ pmdaemonize(void)
 		ExitPostmaster(1);
 	}
 #endif
-	i = open(NULL_DEV, O_RDWR | PG_BINARY);
+	i = open(NULL_DEV, O_RDWR);
 	dup2(i, 0);
 	dup2(i, 1);
 	dup2(i, 2);
@@ -1207,6 +1214,10 @@ ServerLoop(void)
 			}
 		}
 
+		/* If we have lost the system logger, try to start a new one */
+		if (SysLoggerPID == 0 && Redirect_stderr)
+			SysLoggerPID = SysLogger_Start();
+
 		/*
 		 * If no background writer process is running, and we are not in
 		 * a state that prevents it, start one.  It doesn't matter if this
@@ -1714,9 +1725,12 @@ ConnFree(Port *conn)
  * This is called during child process startup to release file descriptors
  * that are not needed by that child process.  The postmaster still has
  * them open, of course.
+ *
+ * Note: we pass am_syslogger as a boolean because we don't want to set
+ * the global variable yet when this is called.
  */
 void
-ClosePostmasterPorts(void)
+ClosePostmasterPorts(bool am_syslogger)
 {
 	int			i;
 
@@ -1729,6 +1743,20 @@ ClosePostmasterPorts(void)
 			ListenSocket[i] = -1;
 		}
 	}
+
+	/* If using syslogger, close the read side of the pipe */
+	if (!am_syslogger)
+	{
+#ifndef WIN32
+		if (syslogPipe[0] >= 0)
+			close(syslogPipe[0]);
+		syslogPipe[0] = -1;
+#else
+		if (syslogPipe[0])
+			CloseHandle(syslogPipe[0]);
+		syslogPipe[0] = 0;
+#endif
+	}
 }
 
 
@@ -1770,6 +1798,8 @@ SIGHUP_handler(SIGNAL_ARGS)
 			kill(BgWriterPID, SIGHUP);
 		if (PgArchPID != 0)
 			kill(PgArchPID, SIGHUP);
+		if (SysLoggerPID != 0)
+			kill(SysLoggerPID, SIGHUP);
 		/* PgStatPID does not currently need SIGHUP */
 		load_hba();
 		load_ident();
@@ -2063,6 +2093,18 @@ reaper(SIGNAL_ARGS)
 			continue;
 		}
 
+		/* Was it the system logger? try to start a new one */
+		if (SysLoggerPID != 0 && pid == SysLoggerPID)
+		{
+			SysLoggerPID = 0;
+			/* for safety's sake, launch new logger *first* */
+			SysLoggerPID = SysLogger_Start();
+			if (exitstatus != 0)
+				LogChildExit(LOG, gettext("system logger process"),
+							 pid, exitstatus);
+			continue;
+		}
+
 		/*
 		 * Else do standard backend child cleanup.
 		 */
@@ -2258,6 +2300,8 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
 		kill(PgStatPID, SIGQUIT);
 	}
 
+	/* We do NOT restart the syslogger */
+
 	FatalError = true;
 }
 
@@ -2528,7 +2572,7 @@ BackendRun(Port *port)
 	 * Let's clean up ourselves as the postmaster child, and close the
 	 * postmaster's listen sockets
 	 */
-	ClosePostmasterPorts();
+	ClosePostmasterPorts(false);
 
 	/* We don't want the postmaster's proc_exit() handlers */
 	on_exit_reset();
@@ -2921,7 +2965,7 @@ SubPostmasterMain(int argc, char *argv[])
 	if (strcmp(argv[1], "-forkboot") == 0)
 	{
 		/* Close the postmaster's sockets */
-		ClosePostmasterPorts();
+		ClosePostmasterPorts(false);
 
 		/* Attach process to shared segments */
 		CreateSharedMemoryAndSemaphores(false, MaxBackends, 0);
@@ -2932,7 +2976,7 @@ SubPostmasterMain(int argc, char *argv[])
 	if (strcmp(argv[1], "-forkarch") == 0)
 	{
 		/* Close the postmaster's sockets */
-		ClosePostmasterPorts();
+		ClosePostmasterPorts(false);
 
 		/* Do not want to attach to shared memory */
 
@@ -2942,7 +2986,7 @@ SubPostmasterMain(int argc, char *argv[])
 	if (strcmp(argv[1], "-forkbuf") == 0)
 	{
 		/* Close the postmaster's sockets */
-		ClosePostmasterPorts();
+		ClosePostmasterPorts(false);
 
 		/* Do not want to attach to shared memory */
 
@@ -2961,6 +3005,16 @@ SubPostmasterMain(int argc, char *argv[])
 		PgstatCollectorMain(argc, argv);
 		proc_exit(0);
 	}
+	if (strcmp(argv[1], "-forklog") == 0)
+	{
+		/* Close the postmaster's sockets */
+		ClosePostmasterPorts(true);
+
+		/* Do not want to attach to shared memory */
+
+		SysLoggerMain(argc, argv);
+		proc_exit(0);
+	}
 
 	return 1;					/* shouldn't get here */
 }
@@ -3017,7 +3071,7 @@ sigusr1_handler(SIGNAL_ARGS)
 		if (Shutdown <= SmartShutdown)
 			SignalChildren(SIGUSR1);
 	}
- 
+
 	if (PgArchPID != 0 && Shutdown == NoShutdown)
 	{
 		if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER))
@@ -3214,7 +3268,7 @@ StartChildProcess(int xlop)
 		IsUnderPostmaster = true;	/* we are a postmaster subprocess now */
 
 		/* Close the postmaster's sockets */
-		ClosePostmasterPorts();
+		ClosePostmasterPorts(false);
 
 		/* Lose the postmaster's on-exit routines and port connections */
 		on_exit_reset();
@@ -3400,6 +3454,9 @@ write_backend_variables(char *filename, Port *port)
 	write_var(PostmasterHandle, fp);
 #endif
 
+	write_var(syslogPipe[0], fp);
+	write_var(syslogPipe[1], fp);
+
 	StrNCpy(str_buf, my_exec_path, MAXPGPATH);
 	write_array_var(str_buf, fp);
 
@@ -3471,6 +3528,9 @@ read_backend_variables(char *filename, Port *port)
 	read_var(PostmasterHandle, fp);
 #endif
 
+	read_var(syslogPipe[0], fp);
+	read_var(syslogPipe[1], fp);
+
 	read_array_var(str_buf, fp);
 	StrNCpy(my_exec_path, str_buf, MAXPGPATH);