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/*-------------------------------------------------------------------------
 *
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 * postgres.c
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 *	  POSTGRES C Backend Interface
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 *
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 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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 * Portions Copyright (c) 1994, Regents of the University of California
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 *
 *
 * IDENTIFICATION
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 *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.249 2002/02/27 19:35:12 tgl Exp $
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 *
 * NOTES
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 *	  this is the "main" module of the postgres backend and
 *	  hence the main module of the "traffic cop".
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 *
 *-------------------------------------------------------------------------
 */
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#include "postgres.h"

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#include <unistd.h>
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#include <signal.h>
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#include <time.h>
#include <sys/time.h>
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#include <sys/types.h>
#include <fcntl.h>
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#include <sys/socket.h>
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#include <errno.h>
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#if HAVE_SYS_SELECT_H
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#include <sys/select.h>
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#endif
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#ifdef HAVE_GETOPT_H
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#include <getopt.h>
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#endif
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#include "access/xlog.h"
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#include "commands/async.h"
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#include "commands/trigger.h"
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#include "commands/variable.h"
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#include "libpq/libpq.h"
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#include "libpq/pqformat.h"
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#include "libpq/pqsignal.h"
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#include "miscadmin.h"
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#include "nodes/print.h"
#include "optimizer/cost.h"
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#include "optimizer/planner.h"
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#include "parser/analyze.h"
#include "parser/parse.h"
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#include "parser/parser.h"
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#include "rewrite/rewriteHandler.h"
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#include "tcop/fastpath.h"
#include "tcop/pquery.h"
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#include "tcop/tcopprot.h"
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#include "tcop/utility.h"
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#include "storage/proc.h"
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#include "utils/exc.h"
#include "utils/guc.h"
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#include "utils/memutils.h"
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#include "utils/ps_status.h"
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#ifdef MULTIBYTE
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#include "mb/pg_wchar.h"
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#endif

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#include "pgstat.h"
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/* ----------------
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 *		global variables
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 * ----------------
 */
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extern int	optind;
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extern char *optarg;

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char	   *debug_query_string; /* used by pgmonitor */
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/* Note: whereToSendOutput is initialized for the bootstrap/standalone case */
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CommandDest whereToSendOutput = Debug;
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static bool dontExecute = false;
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/* note: these declarations had better match tcopprot.h */
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sigjmp_buf	Warn_restart;
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bool		Warn_restart_ready = false;
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bool		InError = false;
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static bool EchoQuery = false;	/* default don't echo */
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/*
 * Flag to mark SIGHUP. Whenever the main loop comes around it
 * will reread the configuration file. (Better than doing the
 * reading in the signal handler, ey?)
 */
static volatile bool got_SIGHUP = false;

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/* ----------------
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 *		people who want to use EOF should #define DONTUSENEWLINE in
 *		tcop/tcopdebug.h
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 * ----------------
 */
#ifndef TCOP_DONTUSENEWLINE
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int			UseNewLine = 1;		/* Use newlines query delimiters (the
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								 * default) */

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#else
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int			UseNewLine = 0;		/* Use EOF as query delimiters */
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#endif   /* TCOP_DONTUSENEWLINE */
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/*
** Flags for expensive function optimization -- JMH 3/9/92
*/
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int			XfuncMode = 0;
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/* ----------------------------------------------------------------
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 *		decls for routines only used in this file
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 * ----------------------------------------------------------------
 */
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static int	InteractiveBackend(StringInfo inBuf);
static int	SocketBackend(StringInfo inBuf);
static int	ReadCommand(StringInfo inBuf);
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static List *pg_parse_query(char *query_string, Oid *typev, int nargs);
static List *pg_analyze_and_rewrite(Node *parsetree);
static void start_xact_command(void);
static void finish_xact_command(void);
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static void SigHupHandler(SIGNAL_ARGS);
static void FloatExceptionHandler(SIGNAL_ARGS);
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static const char *CreateCommandTag(Node *parsetree);
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/* ----------------------------------------------------------------
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 *		routines to obtain user input
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 * ----------------------------------------------------------------
 */

/* ----------------
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 *	InteractiveBackend() is called for user interactive connections
 *	the string entered by the user is placed in its parameter inBuf.
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 *
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 *	EOF is returned if end-of-file input is seen; time to shut down.
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 * ----------------
 */

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static int
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InteractiveBackend(StringInfo inBuf)
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{
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	int			c;				/* character read from getc() */
	bool		end = false;	/* end-of-input flag */
	bool		backslashSeen = false;	/* have we seen a \ ? */
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	/*
	 * display a prompt and obtain input from the user
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	 */
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	printf("backend> ");
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	fflush(stdout);
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	/* Reset inBuf to empty */
	inBuf->len = 0;
	inBuf->data[0] = '\0';

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	for (;;)
	{
		if (UseNewLine)
		{
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			/*
			 * if we are using \n as a delimiter, then read characters
			 * until the \n.
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			 */
			while ((c = getc(stdin)) != EOF)
			{
				if (c == '\n')
				{
					if (backslashSeen)
					{
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						/* discard backslash from inBuf */
						inBuf->data[--inBuf->len] = '\0';
						backslashSeen = false;
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						continue;
					}
					else
					{
						/* keep the newline character */
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						appendStringInfoChar(inBuf, '\n');
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						break;
					}
				}
				else if (c == '\\')
					backslashSeen = true;
				else
					backslashSeen = false;

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				appendStringInfoChar(inBuf, (char) c);
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			}

			if (c == EOF)
				end = true;
		}
		else
		{
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			/*
			 * otherwise read characters until EOF.
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			 */
			while ((c = getc(stdin)) != EOF)
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				appendStringInfoChar(inBuf, (char) c);
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			if (inBuf->len == 0)
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				end = true;
		}

		if (end)
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			return EOF;
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		/*
		 * otherwise we have a user query so process it.
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		 */
		break;
	}

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	/*
	 * if the query echo flag was given, print the query..
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	 */
	if (EchoQuery)
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		printf("query: %s\n", inBuf->data);
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	fflush(stdout);
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	return 'Q';
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}

/* ----------------
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 *	SocketBackend()		Is called for frontend-backend connections
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 *
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 *	If the input is a query (case 'Q') then the string entered by
 *	the user is placed in its parameter inBuf.
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 *
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 *	If the input is a fastpath function call (case 'F') then
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 *	the function call is processed in HandleFunctionRequest()
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 *	(now called from PostgresMain()).
 *
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 *	EOF is returned if the connection is lost.
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 * ----------------
 */

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static int
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SocketBackend(StringInfo inBuf)
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{
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	int			qtype;
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	/*
	 * get input from the frontend
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	 */
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	qtype = pq_getbyte();
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	switch (qtype)
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	{
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		case EOF:
			/* frontend disconnected */
			break;

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			/*
			 * 'Q': user entered a query
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			 */
		case 'Q':
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			if (pq_getstr(inBuf))
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				return EOF;
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			break;
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			/*
			 * 'F':  calling user/system functions
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			 */
		case 'F':
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			if (pq_getstr(inBuf))
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				return EOF;		/* ignore "string" at start of F message */
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			break;
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			/*
			 * 'X':  frontend is exiting
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			 */
		case 'X':
			break;
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			/*
			 * otherwise we got garbage from the frontend.
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			 *
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			 * XXX are we certain that we want to do an elog(FATAL) here?
			 * -cim 1/24/90
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			 */
		default:
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			elog(FATAL, "Socket command type %c unknown", qtype);
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			break;
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	}
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	return qtype;
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}

/* ----------------
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 *		ReadCommand reads a command from either the frontend or
 *		standard input, places it in inBuf, and returns a char
 *		representing whether the string is a 'Q'uery or a 'F'astpath
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 *		call.  EOF is returned if end of file.
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 * ----------------
 */
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static int
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ReadCommand(StringInfo inBuf)
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{
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	int			result;
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	if (IsUnderPostmaster)
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		result = SocketBackend(inBuf);
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	else
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		result = InteractiveBackend(inBuf);
	return result;
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}

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/*
 * Parse a query string and pass it through the rewriter.
 *
 * A list of Query nodes is returned, since the string might contain
 * multiple queries and/or the rewriter might expand one query to several.
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 *
 * NOTE: this routine is no longer used for processing interactive queries,
 * but it is still needed for parsing of SQL function bodies.
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 */
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List *
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pg_parse_and_rewrite(char *query_string,		/* string to execute */
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					 Oid *typev,	/* parameter types */
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					 int nargs) /* number of parameters */
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{
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	List	   *raw_parsetree_list;
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	List	   *querytree_list;
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	List	   *list_item;

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	/*
	 * (1) parse the request string into a list of raw parse trees.
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	 */
	raw_parsetree_list = pg_parse_query(query_string, typev, nargs);

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	/*
	 * (2) Do parse analysis and rule rewrite.
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	 */
	querytree_list = NIL;
	foreach(list_item, raw_parsetree_list)
	{
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		Node	   *parsetree = (Node *) lfirst(list_item);
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		querytree_list = nconc(querytree_list,
							   pg_analyze_and_rewrite(parsetree));
	}

	return querytree_list;
}

/*
 * Do raw parsing (only).
 *
 * A list of parsetrees is returned, since there might be multiple
 * commands in the given string.
 *
 * NOTE: for interactive queries, it is important to keep this routine
 * separate from the analysis & rewrite stages.  Analysis and rewriting
 * cannot be done in an aborted transaction, since they require access to
 * database tables.  So, we rely on the raw parser to determine whether
 * we've seen a COMMIT or ABORT command; when we are in abort state, other
 * commands are not processed any further than the raw parse stage.
 */
static List *
pg_parse_query(char *query_string, Oid *typev, int nargs)
{
	List	   *raw_parsetree_list;
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	if (Debug_print_query)
		elog(DEBUG, "query: %s", query_string);
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	if (Show_parser_stats)
		ResetUsage();

	raw_parsetree_list = parser(query_string, typev, nargs);

	if (Show_parser_stats)
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		ShowUsage("PARSER STATISTICS");
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	return raw_parsetree_list;
}

/*
 * Given a raw parsetree (gram.y output), perform parse analysis and
 * rule rewriting.
 *
 * A list of Query nodes is returned, since either the analyzer or the
 * rewriter might expand one query to several.
 *
 * NOTE: for reasons mentioned above, this must be separate from raw parsing.
 */
static List *
pg_analyze_and_rewrite(Node *parsetree)
{
	List	   *querytree_list;
	List	   *list_item;
	Query	   *querytree;
	List	   *new_list;

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	/*
	 * (1) Perform parse analysis.
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	 */
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	if (Show_parser_stats)
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		ResetUsage();

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	querytree_list = parse_analyze(parsetree, NULL);
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	if (Show_parser_stats)
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	{
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		ShowUsage("PARSE ANALYSIS STATISTICS");
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		ResetUsage();
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	}

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	/*
	 * (2) Rewrite the queries, as necessary
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	 *
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	 * rewritten queries are collected in new_list.  Note there may be more
	 * or fewer than in the original list.
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	 */
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	new_list = NIL;
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	foreach(list_item, querytree_list)
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	{
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		querytree = (Query *) lfirst(list_item);
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		if (Debug_print_parse)
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		{
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			if (Debug_pretty_print)
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			{
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				elog(DEBUG, "parse tree:");
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				nodeDisplay(querytree);
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			}
			else
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				elog(DEBUG, "parse tree: %s", nodeToString(querytree));
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		}
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		if (querytree->commandType == CMD_UTILITY)
		{
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			/* don't rewrite utilities, just dump 'em into new_list */
			new_list = lappend(new_list, querytree);
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		}
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		else
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		{
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			/* rewrite regular queries */
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			List	   *rewritten = QueryRewrite(querytree);

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			new_list = nconc(new_list, rewritten);
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		}
	}

	querytree_list = new_list;

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	if (Show_parser_stats)
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		ShowUsage("REWRITER STATISTICS");
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#ifdef COPY_PARSE_PLAN_TREES
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	/*
	 * Optional debugging check: pass querytree output through
	 * copyObject()
	 */
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	new_list = (List *) copyObject(querytree_list);
	/* This checks both copyObject() and the equal() routines... */
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	if (!equal(new_list, querytree_list))
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		elog(NOTICE, "pg_analyze_and_rewrite: copyObject failed on parse tree");
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	else
		querytree_list = new_list;
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#endif

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	if (Debug_print_rewritten)
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	{
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		if (Debug_pretty_print)
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		{
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			elog(DEBUG, "rewritten parse tree:");
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			foreach(list_item, querytree_list)
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			{
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				querytree = (Query *) lfirst(list_item);
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				nodeDisplay(querytree);
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				printf("\n");
			}
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		}
		else
		{
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			elog(DEBUG, "rewritten parse tree:");
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			foreach(list_item, querytree_list)
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			{
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				querytree = (Query *) lfirst(list_item);
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				elog(DEBUG, "%s", nodeToString(querytree));
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			}
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		}
	}

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	return querytree_list;
}
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/* Generate a plan for a single query. */
Plan *
pg_plan_query(Query *querytree)
{
	Plan	   *plan;
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	/* Utility commands have no plans. */
	if (querytree->commandType == CMD_UTILITY)
		return NULL;
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	if (Show_planner_stats)
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		ResetUsage();
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	/* call that optimizer */
	plan = planner(querytree);
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	if (Show_planner_stats)
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		ShowUsage("PLANNER STATISTICS");
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#ifdef COPY_PARSE_PLAN_TREES
	/* Optional debugging check: pass plan output through copyObject() */
	{
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		Plan	   *new_plan = (Plan *) copyObject(plan);
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		/*
		 * equal() currently does not have routines to compare Plan nodes,
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		 * so don't try to test equality here.  Perhaps fix someday?
		 */
#ifdef NOT_USED
		/* This checks both copyObject() and the equal() routines... */
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		if (!equal(new_plan, plan))
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			elog(NOTICE, "pg_plan_query: copyObject failed on plan tree");
		else
#endif
			plan = new_plan;
	}
#endif

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	/*
	 * Print plan if debugging.
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	 */
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	if (Debug_print_plan)
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	{
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		if (Debug_pretty_print)
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		{
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			elog(DEBUG, "plan:");
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			nodeDisplay(plan);
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		}
		else
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			elog(DEBUG, "plan: %s", nodeToString(plan));
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	}

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	return plan;
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}

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/* ----------------------------------------------------------------
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 *		pg_exec_query_string()
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 *
 *		Takes a querystring, runs the parser/utilities or
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 *		parser/planner/executor over it as necessary.
 *
 * Assumptions:
 *
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 * At call, we are not inside a transaction command.
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 *
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 * The CurrentMemoryContext after starting a transaction command must be
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 * appropriate for execution of individual queries (typically this will be
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 * TransactionCommandContext).	Note that this routine resets that context
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 * after each individual query, so don't store anything there that
 * must outlive the call!
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 *
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 * parse_context references a context suitable for holding the
 * parse/rewrite trees (typically this will be QueryContext).
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 * This context *must* be longer-lived than the transaction context!
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 * In fact, if the query string might contain BEGIN/COMMIT commands,
 * parse_context had better outlive TopTransactionContext!
 *
 * We could have hard-wired knowledge about QueryContext and
 * TransactionCommandContext into this routine, but it seems better
 * not to, in case callers from outside this module need to use some
 * other contexts.
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 *
 * ----------------------------------------------------------------
 */

void
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pg_exec_query_string(char *query_string,		/* string to execute */
					 CommandDest dest,	/* where results should go */
					 MemoryContext parse_context)		/* context for
														 * parsetrees */
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{
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	bool		xact_started;
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	MemoryContext oldcontext;
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	List	   *parsetree_list,
			   *parsetree_item;
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	debug_query_string = query_string;	/* used by pgmonitor */

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	/*
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	 * Start up a transaction command.	All queries generated by the
	 * query_string will be in this same command block, *unless* we find a
	 * BEGIN/COMMIT/ABORT statement; we have to force a new xact command
	 * after one of those, else bad things will happen in xact.c. (Note
	 * that this will possibly change current memory context.)
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	 */
	start_xact_command();
	xact_started = true;

	/*
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	 * parse_context *must* be different from the execution memory
	 * context, else the context reset at the bottom of the loop will
	 * destroy the parsetree list.	(We really ought to check that
	 * parse_context isn't a child of CurrentMemoryContext either, but
	 * that would take more cycles than it's likely to be worth.)
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	 */
	Assert(parse_context != CurrentMemoryContext);

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	/*
	 * Switch to appropriate context for constructing parsetrees.
	 */
	oldcontext = MemoryContextSwitchTo(parse_context);
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	/*
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	 * Do basic parsing of the query or queries (this should be safe even
	 * if we are in aborted transaction state!)
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	 */
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	parsetree_list = pg_parse_query(query_string, NULL, 0);
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	/*
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	 * Switch back to execution context to enter the loop.
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	 */
	MemoryContextSwitchTo(oldcontext);

	/*
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	 * Run through the parsetree(s) and process each one.
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	 */
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	foreach(parsetree_item, parsetree_list)
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	{
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		Node	   *parsetree = (Node *) lfirst(parsetree_item);
		bool		isTransactionStmt;
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		const char *commandTag;
		char		completionTag[COMPLETION_TAG_BUFSIZE];
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		List	   *querytree_list,
				   *querytree_item;
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		/* Transaction control statements need some special handling */
		isTransactionStmt = IsA(parsetree, TransactionStmt);
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		/*
		 * First we set the command-completion tag to the main query
		 * (as opposed to each of the others that may be generated by
		 * analyze and rewrite).  Also set ps_status and do any special
		 * start-of-SQL-command processing needed by the destination.
		 */
		commandTag = CreateCommandTag(parsetree);

		set_ps_display(commandTag);

		BeginCommand(commandTag, dest);

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		/*
		 * If we are in an aborted transaction, ignore all commands except
		 * COMMIT/ABORT.  It is important that this test occur before we
		 * try to do parse analysis, rewrite, or planning, since all those
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		 * phases try to do database accesses, which may fail in abort
		 * state. (It might be safe to allow some additional utility
		 * commands in this state, but not many...)
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		 */
		if (IsAbortedTransactionBlockState())
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		{
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			bool		allowit = false;
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			if (isTransactionStmt)
			{
				TransactionStmt *stmt = (TransactionStmt *) parsetree;

				switch (stmt->command)
				{
					case COMMIT:
					case ROLLBACK:
						allowit = true;
						break;
					default:
						break;
				}
			}
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			if (!allowit)
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			{
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				elog(NOTICE, "current transaction is aborted, "
					 "queries ignored until end of transaction block");

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				/*
				 * We need to emit a command-complete report to the client,
				 * even though we didn't process the query.
				 * - cim 6/1/90
				 */
				commandTag = "*ABORT STATE*";

				EndCommand(commandTag, dest);
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				/*
				 * We continue in the loop, on the off chance that there
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				 * is a COMMIT or ROLLBACK utility command later in the
				 * query string.
				 */
				continue;
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			}
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		}
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		/* Make sure we are in a transaction command */
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		if (!xact_started)
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		{
			start_xact_command();
			xact_started = true;
		}
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717
		/* If we got a cancel signal in parsing or prior command, quit */
718
		CHECK_FOR_INTERRUPTS();
719 720 721

		/*
		 * OK to analyze and rewrite this query.
722
		 *
723 724
		 * Switch to appropriate context for constructing querytrees (again,
		 * these must outlive the execution context).
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		 */
		oldcontext = MemoryContextSwitchTo(parse_context);
727

728
		querytree_list = pg_analyze_and_rewrite(parsetree);
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		/*
		 * Switch back to execution context for planning and execution.
		 */
		MemoryContextSwitchTo(oldcontext);

		/*
		 * Inner loop handles the individual queries generated from a
		 * single parsetree by analysis and rewrite.
		 */
		foreach(querytree_item, querytree_list)
		{
			Query	   *querytree = (Query *) lfirst(querytree_item);
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743
			/* Make sure we are in a transaction command */
744
			if (!xact_started)
745
			{
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				start_xact_command();
				xact_started = true;
			}

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			/*
			 * If we got a cancel signal in analysis or prior command,
			 * quit
			 */
754
			CHECK_FOR_INTERRUPTS();
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			if (querytree->commandType == CMD_UTILITY)
			{
758 759
				/*
				 * process utility functions (create, destroy, etc..)
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				 */
				if (Debug_print_query)
					elog(DEBUG, "ProcessUtility: %s", query_string);
				else if (DebugLvl > 1)
					elog(DEBUG, "ProcessUtility");

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				if (querytree->originalQuery)
				{
					/* utility statement can override default tag string */
					ProcessUtility(querytree->utilityStmt, dest,
								   completionTag);
					if (completionTag[0])
						commandTag = completionTag;
				}
				else
				{
					/* utility added by rewrite cannot override tag */
					ProcessUtility(querytree->utilityStmt, dest, NULL);
				}
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			}
			else
			{
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				/*
				 * process a plannable query.
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				 */
				Plan	   *plan;

				plan = pg_plan_query(querytree);

				/* if we got a cancel signal whilst planning, quit */
790
				CHECK_FOR_INTERRUPTS();
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				/* Initialize snapshot state for query */
				SetQuerySnapshot();

				/*
				 * execute the plan
				 */
				if (Show_executor_stats)
					ResetUsage();

				if (dontExecute)
				{
					/* don't execute it, just show the query plan */
					print_plan(plan, querytree);
				}
				else
				{
					if (DebugLvl > 1)
						elog(DEBUG, "ProcessQuery");
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					if (querytree->originalQuery)
					{
						/* original stmt can override default tag string */
						ProcessQuery(querytree, plan, dest, completionTag);
						commandTag = completionTag;
					}
					else
					{
						/* stmt added by rewrite cannot override tag */
						ProcessQuery(querytree, plan, dest, NULL);
					}
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				}

				if (Show_executor_stats)
825
					ShowUsage("EXECUTOR STATISTICS");
826
			}
827

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			/*
			 * In a query block, we want to increment the command counter
			 * between queries so that the effects of early queries are
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			 * visible to subsequent ones.	In particular we'd better do
			 * so before checking constraints.
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			 */
			if (!isTransactionStmt)
				CommandCounterIncrement();

			/*
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			 * Clear the execution context to recover temporary memory
			 * used by the query.  NOTE: if query string contains
840
			 * BEGIN/COMMIT transaction commands, execution context may
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			 * now be different from what we were originally passed; so be
			 * careful to clear current context not "oldcontext".
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			 */
			Assert(parse_context != CurrentMemoryContext);

			MemoryContextResetAndDeleteChildren(CurrentMemoryContext);

			/*
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			 * If this was a transaction control statement, commit it and
			 * arrange to start a new xact command for the next command
			 * (if any).
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			 */
			if (isTransactionStmt)
854
			{
855 856
				finish_xact_command();
				xact_started = false;
857 858
			}

859 860
		}						/* end loop over queries generated from a
								 * parsetree */
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		/*
		 * It is possible that the original query was removed due to
		 * a DO INSTEAD rewrite rule.  In that case we will still have
		 * the default completion tag, which is fine for most purposes,
		 * but it may confuse clients if it's INSERT/UPDATE/DELETE.
		 * Clients expect those tags to have counts after them (cf.
		 * ProcessQuery).
		 */
		if (strcmp(commandTag, "INSERT") == 0)
			commandTag = "INSERT 0 0";
		else if (strcmp(commandTag, "UPDATE") == 0)
			commandTag = "UPDATE 0";
		else if (strcmp(commandTag, "DELETE") == 0)
			commandTag = "DELETE 0";

		/*
		 * Tell client that we're done with this query.  Note we emit
		 * exactly one EndCommand report for each raw parsetree, thus
		 * one for each SQL command the client sent, regardless of
		 * rewriting.
		 */
		EndCommand(commandTag, dest);
884
	}							/* end loop over parsetrees */
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	/*
	 * Close down transaction statement, if one is open.
	 */
	if (xact_started)
		finish_xact_command();
891

892
	debug_query_string = NULL;	/* used by pgmonitor */
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}

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/*
 * Convenience routines for starting/committing a single command.
 */
static void
start_xact_command(void)
{
	if (DebugLvl >= 1)
		elog(DEBUG, "StartTransactionCommand");
	StartTransactionCommand();
}

static void
finish_xact_command(void)
{
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	/* Invoke IMMEDIATE constraint triggers */
	DeferredTriggerEndQuery();

	/* Now commit the command */
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	if (DebugLvl >= 1)
		elog(DEBUG, "CommitTransactionCommand");
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916
	CommitTransactionCommand();
917

918
#ifdef SHOW_MEMORY_STATS
919
	/* Print mem stats at each commit for leak tracking */
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	if (ShowStats)
		MemoryContextStats(TopMemoryContext);
#endif
}


926
/* --------------------------------
927
 *		signal handler routines used in PostgresMain()
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 * --------------------------------
 */

931
/*
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 * quickdie() occurs when signalled SIGQUIT by the postmaster.
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 *
 * Some backend has bought the farm,
 * so we need to stop what we're doing and exit.
 */
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void
938
quickdie(SIGNAL_ARGS)
939
{
940
	PG_SETMASK(&BlockSig);
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	elog(NOTICE, "Message from PostgreSQL backend:"
942
		 "\n\tThe Postmaster has informed me that some other backend"
943
		 "\n\tdied abnormally and possibly corrupted shared memory."
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		 "\n\tI have rolled back the current transaction and am"
945
	   "\n\tgoing to terminate your database system connection and exit."
946
	"\n\tPlease reconnect to the database system and repeat your query.");
947

948
	/*
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	 * DO NOT proc_exit() -- we're here because shared memory may be
	 * corrupted, so we don't want to try to clean up our transaction.
	 * Just nail the windows shut and get out of town.
	 *
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	 * Note we do exit(1) not exit(0).	This is to force the postmaster into
	 * a system reset cycle if some idiot DBA sends a manual SIGQUIT to a
	 * random backend.	This is necessary precisely because we don't clean
	 * up our shared memory state.
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	 */

959
	exit(1);
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}

962
/*
963 964
 * Shutdown signal from postmaster: abort transaction and exit
 * at soonest convenient time
965
 */
966
void
967
die(SIGNAL_ARGS)
968
{
969 970 971
	int			save_errno = errno;

	/* Don't joggle the elbow of proc_exit */
972
	if (!proc_exit_inprogress)
973
	{
974
		InterruptPending = true;
975
		ProcDiePending = true;
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977
		/*
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		 * If it's safe to interrupt, and we're waiting for input or a
		 * lock, service the interrupt immediately
980
		 */
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		if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
			CritSectionCount == 0)
983
		{
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			/* bump holdoff count to make ProcessInterrupts() a no-op */
			/* until we are done getting ready for it */
			InterruptHoldoffCount++;
987
			DisableNotifyInterrupt();
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			/* Make sure HandleDeadLock won't run while shutting down... */
			LockWaitCancel();
990
			InterruptHoldoffCount--;
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			ProcessInterrupts();
		}
993
	}
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	errno = save_errno;
996 997
}

998
/*
999
 * Timeout or shutdown signal from postmaster during client authentication.
1000
 * Simply exit(0).
1001 1002 1003
 *
 * XXX: possible future improvement: try to send a message indicating
 * why we are disconnecting.  Problem is to be sure we don't block while
1004
 * doing so, nor mess up the authentication message exchange.
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 */
void
authdie(SIGNAL_ARGS)
{
	exit(0);
}

1012
/*
1013 1014
 * Query-cancel signal from postmaster: abort current transaction
 * at soonest convenient time
1015
 */
1016
static void
1017
QueryCancelHandler(SIGNAL_ARGS)
1018
{
1019 1020
	int			save_errno = errno;

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	/*
	 * Don't joggle the elbow of proc_exit, nor an already-in-progress
	 * abort
	 */
1025
	if (!proc_exit_inprogress && !InError)
1026
	{
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		InterruptPending = true;
		QueryCancelPending = true;
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1030
		/*
1031
		 * If it's safe to interrupt, and we're waiting for a lock,
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		 * service the interrupt immediately.  No point in interrupting if
		 * we're waiting for input, however.
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		 */
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		if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
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			CritSectionCount == 0)
1037
		{
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			/* bump holdoff count to make ProcessInterrupts() a no-op */
			/* until we are done getting ready for it */
			InterruptHoldoffCount++;
			if (LockWaitCancel())
			{
				DisableNotifyInterrupt();
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				InterruptHoldoffCount--;
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				ProcessInterrupts();
			}
			else
				InterruptHoldoffCount--;
1049
		}
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	}

1052
	errno = save_errno;
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}

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/* signal handler for floating point exception */
static void
FloatExceptionHandler(SIGNAL_ARGS)
{
	elog(ERROR, "floating point exception!"
		 " The last floating point operation either exceeded legal ranges"
		 " or was a divide by zero");
}

1064
/* SIGHUP: set flag to re-read config file at next convenient time */
1065
static void
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SigHupHandler(SIGNAL_ARGS)
1067
{
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	got_SIGHUP = true;
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}

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/*
 * ProcessInterrupts: out-of-line portion of CHECK_FOR_INTERRUPTS() macro
 *
 * If an interrupt condition is pending, and it's safe to service it,
 * then clear the flag and accept the interrupt.  Called only when
 * InterruptPending is true.
 */
void
ProcessInterrupts(void)
{
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	/* OK to accept interrupt now? */
	if (InterruptHoldoffCount != 0 || CritSectionCount != 0)
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		return;
	InterruptPending = false;
	if (ProcDiePending)
	{
		ProcDiePending = false;
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		QueryCancelPending = false;		/* ProcDie trumps QueryCancel */
		ImmediateInterruptOK = false;	/* not idle anymore */
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		elog(FATAL, "This connection has been terminated by the administrator.");
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	}
	if (QueryCancelPending)
	{
		QueryCancelPending = false;
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		ImmediateInterruptOK = false;	/* not idle anymore */
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		elog(ERROR, "Query was cancelled.");
	}
	/* If we get here, do nothing (probably, QueryCancelPending was reset) */
}

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1103 1104
static void
usage(char *progname)
1105
{
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	printf("%s is the PostgreSQL stand-alone backend.  It is not\nintended to be used by normal users.\n\n", progname);

	printf("Usage:\n  %s [options...] [dbname]\n\n", progname);
	printf("Options:\n");
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#ifdef USE_ASSERT_CHECKING
1111
	printf("  -A 1|0          enable/disable run-time assert checking\n");
1112
#endif
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	printf("  -B NBUFFERS     number of shared buffers (default %d)\n", DEF_NBUFFERS);
	printf("  -c NAME=VALUE   set run-time parameter\n");
	printf("  -d 1-5          debugging level\n");
	printf("  -D DATADIR      database directory\n");
	printf("  -e              use European date format\n");
	printf("  -E              echo query before execution\n");
	printf("  -F              turn fsync off\n");
	printf("  -N              do not use newline as interactive query delimiter\n");
	printf("  -o FILENAME     send stdout and stderr to given file\n");
1122
	printf("  -P              disable system indexes\n");
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	printf("  -s              show statistics after each query\n");
	printf("  -S SORT-MEM     set amount of memory for sorts (in kbytes)\n");
	printf("Developer options:\n");
	printf("  -f [s|i|n|m|h]  forbid use of some plan types\n");
	printf("  -i              do not execute queries\n");
	printf("  -O              allow system table structure changes\n");
	printf("  -t [pa|pl|ex]   show timings after each query\n");
	printf("  -W NUM          wait NUM seconds to allow attach from a debugger\n");
	printf("\nReport bugs to <pgsql-bugs@postgresql.org>.\n");
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}

1134 1135


1136
/* ----------------------------------------------------------------
1137
 * PostgresMain
1138
 *	   postgres main loop -- all backends, interactive or otherwise start here
1139
 *
1140 1141 1142 1143
 * argc/argv are the command line arguments to be used.  (When being forked
 * by the postmaster, these are not the original argv array of the process.)
 * username is the (possibly authenticated) PostgreSQL user name to be used
 * for the session.
1144 1145 1146
 * ----------------------------------------------------------------
 */
int
1147
PostgresMain(int argc, char *argv[], const char *username)
1148
{
1149
	int			flag;
1150

1151
	const char *DBName = NULL;
1152
	bool		secure;
1153
	int			errs = 0;
1154
	GucContext	ctx;
1155
	GucSource	gucsource;
1156
	char	   *tmp;
1157

1158
	int			firstchar;
1159
	StringInfo	parser_input;
1160

1161
	char	   *potential_DataDir = NULL;
1162

1163
	/*
1164 1165
	 * Catch standard options before doing much else.  This even works on
	 * systems without getopt_long.
1166 1167 1168
	 */
	if (!IsUnderPostmaster && argc > 1)
	{
1169
		if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
1170 1171 1172 1173
		{
			usage(argv[0]);
			exit(0);
		}
1174
		if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
1175 1176 1177 1178
		{
			puts("postgres (PostgreSQL) " PG_VERSION);
			exit(0);
		}
1179
	}
1180

1181 1182 1183 1184 1185
	/*
	 * Fire up essential subsystems: error and memory management
	 *
	 * If we are running under the postmaster, this is done already.
	 */
1186
	if (!IsUnderPostmaster)
1187 1188 1189 1190 1191
	{
		EnableExceptionHandling(true);
		MemoryContextInit();
	}

1192 1193
	set_ps_display("startup");

1194 1195
	SetProcessingMode(InitProcessing);

1196
	/*
1197
	 * Set default values for command-line options.
1198
	 */
1199 1200
	Noversion = false;
	EchoQuery = false;
1201 1202 1203

	if (!IsUnderPostmaster)
	{
1204
		ResetAllOptions(true);
1205
		potential_DataDir = getenv("PGDATA");
1206
	}
1207

1208 1209
	/* Check for PGDATESTYLE environment variable */
	set_default_datestyle();
1210

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	/* ----------------
	 *	parse command line arguments
	 *
	 *	There are now two styles of command line layout for the backend:
	 *
	 *	For interactive use (not started from postmaster) the format is
	 *		postgres [switches] [databasename]
	 *	If the databasename is omitted it is taken to be the user name.
	 *
	 *	When started from the postmaster, the format is
	 *		postgres [secure switches] -p databasename [insecure switches]
	 *	Switches appearing after -p came from the client (via "options"
	 *	field of connection request).  For security reasons we restrict
	 *	what these switches can do.
	 * ----------------
	 */

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	/* all options are allowed until '-p' */
	secure = true;
	ctx = PGC_POSTMASTER;
1231
	gucsource = PGC_S_ARGV;		/* initial switches came from command line */
1232

1233
	while ((flag = getopt(argc, argv, "A:B:c:CD:d:Eef:FiNOPo:p:S:st:v:W:x:-:")) != -1)
1234 1235
		switch (flag)
		{
1236 1237
			case 'A':
#ifdef USE_ASSERT_CHECKING
1238
				SetConfigOption("debug_assertions", optarg, ctx, gucsource);
1239
#else
1240
				elog(NOTICE, "Assert checking is not compiled in");
1241 1242
#endif
				break;
1243

1244
			case 'B':
1245 1246 1247

				/*
				 * specify the size of buffer pool
1248
				 */
1249
				SetConfigOption("shared_buffers", optarg, ctx, gucsource);
1250
				break;
1251

1252
			case 'C':
1253 1254 1255

				/*
				 * don't print version string
1256
				 */
1257
				Noversion = true;
1258
				break;
1259

1260
			case 'D':			/* PGDATA directory */
1261
				if (secure)
1262
					potential_DataDir = optarg;
1263
				break;
1264

1265
			case 'd':			/* debug level */
1266
				SetConfigOption("debug_level", optarg, ctx, gucsource);
1267
				if (DebugLvl >= 1)
1268
					SetConfigOption("log_connections", "true", ctx, gucsource);
1269
				if (DebugLvl >= 2)
1270
					SetConfigOption("debug_print_query", "true", ctx, gucsource);
1271
				if (DebugLvl >= 3)
1272
					SetConfigOption("debug_print_parse", "true", ctx, gucsource);
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				if (DebugLvl >= 4)
1274
					SetConfigOption("debug_print_plan", "true", ctx, gucsource);
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				if (DebugLvl >= 5)
1276
					SetConfigOption("debug_print_rewritten", "true", ctx, gucsource);
1277
				break;
1278 1279

			case 'E':
1280 1281 1282

				/*
				 * E - echo the query the user entered
1283
				 */
1284
				EchoQuery = true;
1285
				break;
1286 1287

			case 'e':
1288 1289

				/*
1290 1291
				 * Use european date formats.
				 */
1292
				EuroDates = true;
1293
				break;
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			case 'F':
1296 1297 1298

				/*
				 * turn off fsync
1299
				 */
1300
				SetConfigOption("fsync", "false", ctx, gucsource);
1301
				break;
1302 1303

			case 'f':
1304 1305 1306

				/*
				 * f - forbid generation of certain plans
1307
				 */
1308
				tmp = NULL;
1309 1310 1311
				switch (optarg[0])
				{
					case 's':	/* seqscan */
1312
						tmp = "enable_seqscan";
1313 1314
						break;
					case 'i':	/* indexscan */
1315
						tmp = "enable_indexscan";
1316 1317
						break;
					case 't':	/* tidscan */
1318
						tmp = "enable_tidscan";
1319 1320
						break;
					case 'n':	/* nestloop */
1321
						tmp = "enable_nestloop";
1322 1323
						break;
					case 'm':	/* mergejoin */
1324
						tmp = "enable_mergejoin";
1325 1326
						break;
					case 'h':	/* hashjoin */
1327
						tmp = "enable_hashjoin";
1328 1329 1330 1331
						break;
					default:
						errs++;
				}
1332
				if (tmp)
1333
					SetConfigOption(tmp, "false", ctx, gucsource);
1334 1335
				break;

1336
			case 'i':
1337
				dontExecute = true;
1338
				break;
1339

1340
			case 'N':
1341 1342 1343

				/*
				 * N - Don't use newline as a query delimiter
1344 1345 1346
				 */
				UseNewLine = 0;
				break;
1347

1348
			case 'O':
1349 1350 1351

				/*
				 * allow system table structure modifications
1352
				 */
1353 1354
				if (secure)		/* XXX safe to allow from client??? */
					allowSystemTableMods = true;
1355 1356
				break;

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			case 'P':
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				/*
				 * ignore system indexes
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				 */
				if (secure)		/* XXX safe to allow from client??? */
					IgnoreSystemIndexes(true);
				break;

1366
			case 'o':
1367 1368 1369

				/*
				 * o - send output (stdout and stderr) to the given file
1370
				 */
1371 1372
				if (secure)
					StrNCpy(OutputFileName, optarg, MAXPGPATH);
1373 1374
				break;

1375
			case 'p':
1376 1377 1378 1379

				/*
				 * p - special flag passed if backend was forked by a
				 * postmaster.
1380
				 */
1381 1382
				if (secure)
				{
1383
					DBName = strdup(optarg);
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					secure = false;		/* subsequent switches are NOT
										 * secure */
1386
					ctx = PGC_BACKEND;
1387
					gucsource = PGC_S_CLIENT;
1388
				}
1389
				break;
1390

1391
			case 'S':
1392 1393 1394

				/*
				 * S - amount of sort memory to use in 1k bytes
1395
				 */
1396
				SetConfigOption("sort_mem", optarg, ctx, gucsource);
1397
				break;
1398 1399

			case 's':
1400 1401 1402

				/*
				 * s - report usage statistics (timings) after each query
1403
				 */
1404
				SetConfigOption("show_query_stats", "true", ctx, gucsource);
1405 1406
				break;

1407
			case 't':
1408
				/* ---------------
1409 1410 1411 1412 1413 1414 1415 1416 1417
				 *	tell postgres to report usage statistics (timings) for
				 *	each query
				 *
				 *	-tpa[rser] = print stats for parser time of each query
				 *	-tpl[anner] = print stats for planner time of each query
				 *	-te[xecutor] = print stats for executor time of each query
				 *	caution: -s can not be used together with -t.
				 * ----------------
				 */
1418
				tmp = NULL;
1419 1420 1421 1422
				switch (optarg[0])
				{
					case 'p':
						if (optarg[1] == 'a')
1423
							tmp = "show_parser_stats";
1424
						else if (optarg[1] == 'l')
1425
							tmp = "show_planner_stats";
1426 1427 1428 1429
						else
							errs++;
						break;
					case 'e':
1430
						tmp = "show_executor_stats";
1431 1432 1433 1434 1435
						break;
					default:
						errs++;
						break;
				}
1436
				if (tmp)
1437
					SetConfigOption(tmp, "true", ctx, gucsource);
1438 1439
				break;

1440
			case 'v':
1441 1442
				if (secure)
					FrontendProtocol = (ProtocolVersion) atoi(optarg);
1443 1444
				break;

1445
			case 'W':
1446 1447 1448

				/*
				 * wait N seconds to allow attach from a debugger
1449 1450 1451 1452
				 */
				sleep(atoi(optarg));
				break;

1453
			case 'x':
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1454
#ifdef NOT_USED					/* planner/xfunc.h */
1455 1456 1457 1458 1459 1460 1461

				/*
				 * control joey hellerstein's expensive function
				 * optimization
				 */
				if (XfuncMode != 0)
				{
1462
					elog(NOTICE, "only one -x flag is allowed");
1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479
					errs++;
					break;
				}
				if (strcmp(optarg, "off") == 0)
					XfuncMode = XFUNC_OFF;
				else if (strcmp(optarg, "nor") == 0)
					XfuncMode = XFUNC_NOR;
				else if (strcmp(optarg, "nopull") == 0)
					XfuncMode = XFUNC_NOPULL;
				else if (strcmp(optarg, "nopm") == 0)
					XfuncMode = XFUNC_NOPM;
				else if (strcmp(optarg, "pullall") == 0)
					XfuncMode = XFUNC_PULLALL;
				else if (strcmp(optarg, "wait") == 0)
					XfuncMode = XFUNC_WAIT;
				else
				{
1480
					elog(NOTICE, "use -x {off,nor,nopull,nopm,pullall,wait}");
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					errs++;
				}
1483
#endif
1484
				break;
1485

1486
			case 'c':
1487
			case '-':
1488
				{
1489 1490
					char	   *name,
							   *value;
1491

1492 1493 1494 1495 1496 1497 1498 1499 1500
					ParseLongOption(optarg, &name, &value);
					if (!value)
					{
						if (flag == '-')
							elog(ERROR, "--%s requires argument", optarg);
						else
							elog(ERROR, "-c %s requires argument", optarg);
					}

1501
					SetConfigOption(name, value, ctx, gucsource);
1502 1503 1504 1505 1506
					free(name);
					if (value)
						free(value);
					break;
				}
1507

1508 1509
			default:
				errs++;
1510
				break;
1511 1512
		}

1513 1514 1515
	/*
	 * Post-processing for command line options.
	 */
1516 1517
	if (Show_query_stats &&
		(Show_parser_stats || Show_planner_stats || Show_executor_stats))
1518
	{
1519
		elog(NOTICE, "Query statistics are disabled because parser, planner, or executor statistics are on.");
1520
		SetConfigOption("show_query_stats", "false", ctx, gucsource);
1521 1522
	}

1523
	if (!IsUnderPostmaster)
1524
	{
1525 1526 1527
		if (!potential_DataDir)
		{
			fprintf(stderr, "%s does not know where to find the database system "
1528 1529 1530
			   "data.  You must specify the directory that contains the "
				"database system either by specifying the -D invocation "
			 "option or by setting the PGDATA environment variable.\n\n",
1531 1532 1533 1534
					argv[0]);
			proc_exit(1);
		}
		SetDataDir(potential_DataDir);
1535
	}
1536
	Assert(DataDir);
1537 1538

	/*
1539
	 * Set up signal handlers and masks.
1540
	 *
1541
	 * Note that postmaster blocked all signals before forking child process,
1542 1543
	 * so there is no race condition whereby we might receive a signal
	 * before we have set up the handler.
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1544 1545
	 *
	 * Also note: it's best not to use any signals that are SIG_IGNored in
1546
	 * the postmaster.	If such a signal arrives before we are able to
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	 * change the handler to non-SIG_IGN, it'll get dropped.  Instead,
	 * make a dummy handler in the postmaster to reserve the signal.
	 * (Of course, this isn't an issue for signals that are locally generated,
	 * such as SIGALRM and SIGPIPE.)
1551
	 */
1552

1553
	pqsignal(SIGHUP, SigHupHandler);	/* set flag to read config file */
1554
	pqsignal(SIGINT, QueryCancelHandler);		/* cancel current query */
1555
	pqsignal(SIGTERM, die);		/* cancel current query and exit */
1556
	pqsignal(SIGQUIT, quickdie);	/* hard crash time */
1557 1558
	pqsignal(SIGALRM, HandleDeadLock);	/* check for deadlock after
										 * timeout */
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	/*
	 * Ignore failure to write to frontend. Note: if frontend closes
	 * connection, we will notice it and exit cleanly when control next
	 * returns to outer loop.  This seems safer than forcing exit in the
1564 1565 1566
	 * midst of output during who-knows-what operation...
	 */
	pqsignal(SIGPIPE, SIG_IGN);
1567
	pqsignal(SIGUSR1, SIG_IGN); /* this signal available for use */
1568

1569
	pqsignal(SIGUSR2, Async_NotifyHandler);		/* flush also sinval cache */
1570
	pqsignal(SIGFPE, FloatExceptionHandler);
1571 1572

	/*
1573 1574
	 * Reset some signals that are accepted by postmaster but not by
	 * backend
1575
	 */
1576 1577
	pqsignal(SIGCHLD, SIG_DFL); /* system() requires this on some
								 * platforms */
1578

1579 1580
	pqinitmask();

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1581
	/* We allow SIGQUIT (quickdie) at all times */
1582
#ifdef HAVE_SIGPROCMASK
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1583
	sigdelset(&BlockSig, SIGQUIT);
1584
#else
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1585
	BlockSig &= ~(sigmask(SIGQUIT));
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#endif

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1588
	PG_SETMASK(&BlockSig);		/* block everything except SIGQUIT */
1589

1590

1591
	if (IsUnderPostmaster)
1592
	{
1593 1594 1595
		/* noninteractive case: nothing should be left after switches */
		if (errs || argc != optind || DBName == NULL)
		{
1596 1597
			elog(NOTICE, "%s: invalid command line arguments\nTry -? for help.",
				 argv[0]);
1598 1599
			proc_exit(0);		/* not 1, that causes system-wide
								 * restart... */
1600
		}
1601
		BaseInit();
1602
	}
1603
	else
1604
	{
1605 1606 1607
		/* interactive case: database name can be last arg on command line */
		if (errs || argc - optind > 1)
		{
1608 1609
			elog(NOTICE, "%s: invalid command line arguments\nTry -? for help.",
				 argv[0]);
1610
			proc_exit(1);
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		}
		else if (argc - optind == 1)
			DBName = argv[optind];
1614
		else if ((DBName = username) == NULL)
1615
		{
1616 1617
			elog(NOTICE, "%s: user name undefined and no database specified\n",
				 argv[0]);
1618
			proc_exit(1);
1619
		}
1620

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		/*
		 * On some systems our dynloader code needs the executable's
		 * pathname.  (If under postmaster, this was done already.)
		 */
		if (FindExec(pg_pathname, argv[0], "postgres") < 0)
			elog(FATAL, "%s: could not locate executable, bailing out...",
				 argv[0]);

1629
		/*
1630 1631
		 * Validate we have been given a reasonable-looking DataDir (if
		 * under postmaster, assume postmaster did this already).
1632 1633 1634
		 */
		ValidatePgVersion(DataDir);

1635
		/*
1636
		 * Create lockfile for data directory.
1637
		 */
1638
		if (!CreateDataDirLockFile(DataDir, false))
1639
			proc_exit(1);
1640

1641
		XLOGPathInit();
1642
		BaseInit();
1643 1644 1645 1646 1647

		/*
		 * Start up xlog for standalone backend, and register to have it
		 * closed down at exit.
		 */
1648
		StartupXLOG();
1649
		on_shmem_exit(ShutdownXLOG, 0);
1650 1651
	}

1652 1653 1654 1655 1656 1657 1658 1659
	/*
	 * Set up additional info.
	 */

#ifdef CYR_RECODE
	SetCharSet();
#endif

1660
	/*
1661 1662 1663 1664 1665
	 * General initialization.
	 *
	 * NOTE: if you are tempted to add code in this vicinity, consider
	 * putting it inside InitPostgres() instead.  In particular, anything
	 * that involves database access should be there, not here.
1666
	 */
1667 1668
	if (DebugLvl > 1)
		elog(DEBUG, "InitPostgres");
1669
	InitPostgres(DBName, username);
1670

1671
	SetProcessingMode(NormalProcessing);
1672

1673 1674
	/*
	 * Send this backend's cancellation info to the frontend.
1675
	 */
1676 1677 1678
	if (whereToSendOutput == Remote &&
		PG_PROTOCOL_MAJOR(FrontendProtocol) >= 2)
	{
1679
		StringInfoData buf;
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1681 1682 1683 1684 1685
		pq_beginmessage(&buf);
		pq_sendbyte(&buf, 'K');
		pq_sendint(&buf, (int32) MyProcPid, sizeof(int32));
		pq_sendint(&buf, (int32) MyCancelKey, sizeof(int32));
		pq_endmessage(&buf);
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		/* Need not flush since ReadyForQuery will do it. */
	}

1689 1690 1691
	if (!IsUnderPostmaster)
	{
		puts("\nPOSTGRES backend interactive interface ");
1692
		puts("$Revision: 1.249 $ $Date: 2002/02/27 19:35:12 $\n");
1693 1694
	}

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	/*
	 * Create the memory context we will use in the main loop.
	 *
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	 * QueryContext is reset once per iteration of the main loop, ie, upon
	 * completion of processing of each supplied query string. It can
	 * therefore be used for any data that should live just as long as the
	 * query string --- parse trees, for example.
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	 */
	QueryContext = AllocSetContextCreate(TopMemoryContext,
										 "QueryContext",
										 ALLOCSET_DEFAULT_MINSIZE,
										 ALLOCSET_DEFAULT_INITSIZE,
										 ALLOCSET_DEFAULT_MAXSIZE);

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	/* ----------
	 * Tell the statistics collector that we're alive and
	 * to which database we belong.
	 * ----------
	 */
	pgstat_bestart();

1716 1717
	/*
	 * POSTGRES main processing loop begins here
1718
	 *
1719 1720
	 * If an exception is encountered, processing resumes here so we abort
	 * the current transaction and start a new one.
1721 1722 1723 1724
	 */

	if (sigsetjmp(Warn_restart, 1) != 0)
	{
1725
		/*
1726
		 * NOTE: if you are tempted to add more code in this if-block,
1727 1728
		 * consider the probability that it should be in
		 * AbortTransaction() instead.
1729
		 *
1730 1731
		 * Make sure we're not interrupted while cleaning up.  Also forget
		 * any pending QueryCancel request, since we're aborting anyway.
1732 1733
		 * Force InterruptHoldoffCount to a known state in case we elog'd
		 * from inside a holdoff section.
1734 1735 1736
		 */
		ImmediateInterruptOK = false;
		QueryCancelPending = false;
1737 1738
		InterruptHoldoffCount = 1;
		CritSectionCount = 0;	/* should be unnecessary, but... */
1739
		debug_query_string = NULL;		/* used by pgmonitor */
1740 1741

		/*
1742 1743 1744 1745 1746 1747
		 * Make sure we are in a valid memory context during recovery.
		 *
		 * We use ErrorContext in hopes that it will have some free space
		 * even if we're otherwise up against it...
		 */
		MemoryContextSwitchTo(ErrorContext);
1748

1749
		/* Do the recovery */
1750 1751
		if (DebugLvl >= 1)
			elog(DEBUG, "AbortCurrentTransaction");
1752
		AbortCurrentTransaction();
1753 1754

		/*
1755 1756
		 * Now return to normal top-level context and clear ErrorContext
		 * for next time.
1757 1758 1759
		 */
		MemoryContextSwitchTo(TopMemoryContext);
		MemoryContextResetAndDeleteChildren(ErrorContext);
1760 1761 1762 1763 1764

		/*
		 * Clear flag to indicate that we got out of error recovery mode
		 * successfully.  (Flag was set in elog.c before longjmp().)
		 */
1765
		InError = false;
1766 1767

		/*
1768
		 * Exit interrupt holdoff section we implicitly established above.
1769
		 */
1770
		RESUME_INTERRUPTS();
1771
	}
1772

1773 1774
	Warn_restart_ready = true;	/* we can now handle elog(ERROR) */

1775
	PG_SETMASK(&UnBlockSig);
1776

1777 1778
	/*
	 * Non-error queries loop here.
1779 1780 1781 1782
	 */

	for (;;)
	{
1783
		/*
1784 1785
		 * Release storage left over from prior query cycle, and create a
		 * new query input buffer in the cleared QueryContext.
1786 1787 1788 1789 1790
		 */
		MemoryContextSwitchTo(QueryContext);
		MemoryContextResetAndDeleteChildren(QueryContext);

		parser_input = makeStringInfo();
1791

1792 1793
		/*
		 * (1) tell the frontend we're ready for a new query.
1794
		 *
1795
		 * Note: this includes fflush()'ing the last of the prior output.
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1796
		 */
1797
		ReadyForQuery(whereToSendOutput);
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1799 1800 1801 1802 1803 1804 1805
		/* ----------
		 * Tell the statistics collector what we've collected
		 * so far.
		 * ----------
		 */
		pgstat_report_tabstat();

1806
		if (IsTransactionBlock())
1807
		{
1808
			set_ps_display("idle in transaction");
1809 1810
			pgstat_report_activity("<IDLE> in transaction");
		}
1811
		else
1812
		{
1813
			set_ps_display("idle");
1814 1815
			pgstat_report_activity("<IDLE>");
		}
1816

1817 1818 1819 1820
		/*
		 * (2) deal with pending asynchronous NOTIFY from other backends,
		 * and enable async.c's signal handler to execute NOTIFY directly.
		 * Then set up other stuff needed before blocking for input.
1821
		 */
1822 1823
		QueryCancelPending = false;		/* forget any earlier CANCEL
										 * signal */
1824 1825 1826

		EnableNotifyInterrupt();

1827 1828 1829 1830 1831 1832
		/* Allow "die" interrupt to be processed while waiting */
		ImmediateInterruptOK = true;
		/* and don't forget to detect one that already arrived */
		QueryCancelPending = false;
		CHECK_FOR_INTERRUPTS();

1833 1834
		/*
		 * (3) read a command (loop blocks here)
1835
		 */
1836
		firstchar = ReadCommand(parser_input);
1837

1838 1839
		/*
		 * (4) disable async signal conditions again.
1840
		 */
1841
		ImmediateInterruptOK = false;
1842
		QueryCancelPending = false;		/* forget any CANCEL signal */
1843

1844 1845
		DisableNotifyInterrupt();

1846 1847 1848
		/*
		 * (5) check for any other interesting events that happened while
		 * we slept.
1849 1850 1851 1852 1853 1854 1855
		 */
		if (got_SIGHUP)
		{
			got_SIGHUP = false;
			ProcessConfigFile(PGC_SIGHUP);
		}

1856 1857
		/*
		 * (6) process the command.
1858
		 */
1859 1860
		switch (firstchar)
		{
1861 1862
				/*
				 * 'F' indicates a fastpath call.
1863
				 */
1864
			case 'F':
1865 1866 1867 1868 1869 1870
				/* ----------
				 * Tell the collector what we're doing
				 * ----------
				 */
				pgstat_report_activity("<FASTPATH> function call");

1871
				/* start an xact for this function invocation */
1872
				start_xact_command();
1873

1874 1875 1876
				if (HandleFunctionRequest() == EOF)
				{
					/* lost frontend connection during F message input */
1877
					proc_exit(0);
1878
				}
1879 1880 1881

				/* commit the function-invocation transaction */
				finish_xact_command();
1882
				break;
1883

1884 1885
				/*
				 * 'Q' indicates a user query
1886 1887
				 */
			case 'Q':
1888
				if (strspn(parser_input->data, " \t\r\n") == parser_input->len)
1889
				{
1890 1891 1892 1893
					/*
					 * if there is nothing in the input buffer, don't
					 * bother trying to parse and execute anything; just
					 * send back a quick NullCommand response.
1894
					 */
1895 1896
					if (IsUnderPostmaster)
						NullCommand(Remote);
1897 1898 1899
				}
				else
				{
1900 1901
					/*
					 * otherwise, process the input string.
1902
					 *
1903 1904
					 * Note: transaction command start/end is now done within
					 * pg_exec_query_string(), not here.
1905
					 */
1906
					if (Show_query_stats)
1907 1908
						ResetUsage();

1909 1910
					pgstat_report_activity(parser_input->data);

1911 1912 1913
					pg_exec_query_string(parser_input->data,
										 whereToSendOutput,
										 QueryContext);
1914

1915
					if (Show_query_stats)
1916
						ShowUsage("QUERY STATISTICS");
1917 1918 1919 1920
				}
				break;

				/* ----------------
1921 1922 1923
				 *	'X' means that the frontend is closing down the socket.
				 *	EOF means unexpected loss of frontend connection.
				 *	Either way, perform normal shutdown.
1924 1925 1926
				 * ----------------
				 */
			case 'X':
1927
			case EOF:
1928

1929 1930
				/*
				 * NOTE: if you are tempted to add more code here, DON'T!
1931 1932
				 * Whatever you had in mind to do should be set up as an
				 * on_proc_exit or on_shmem_exit callback, instead.
1933 1934 1935 1936
				 * Otherwise it will fail to be called during other
				 * backend-shutdown scenarios.
				 */
				proc_exit(0);
1937 1938

			default:
1939
				elog(ERROR, "unknown frontend message was received");
1940 1941
		}

1942
#ifdef MEMORY_CONTEXT_CHECKING
1943

1944
		/*
1945 1946
		 * Check all memory after each backend loop.  This is a rather
		 * weird place to do it, perhaps.
1947
		 */
1948
		MemoryContextCheck(TopMemoryContext);
1949
#endif
1950
	}							/* end of input-reading loop */
1951

1952 1953
	/* can't get here because the above loop never exits */
	Assert(false);
1954

1955
	return 1;					/* keep compiler quiet */
1956 1957
}

1958
#ifndef HAVE_GETRUSAGE
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1959 1960
#include "rusagestub.h"
#else
1961
#include <sys/resource.h>
1962
#endif   /* HAVE_GETRUSAGE */
1963

1964 1965
struct rusage Save_r;
struct timeval Save_t;
1966 1967

void
1968
ResetUsage(void)
1969
{
1970 1971 1972 1973 1974 1975
	struct timezone tz;

	getrusage(RUSAGE_SELF, &Save_r);
	gettimeofday(&Save_t, &tz);
	ResetBufferUsage();
/*	  ResetTupleCount(); */
1976 1977 1978
}

void
1979
ShowUsage(const char *title)
1980
{
1981
	StringInfoData str;
1982 1983 1984
	struct timeval user,
				sys;
	struct timeval elapse_t;
1985
	struct timezone tz;
1986
	struct rusage r;
1987
	char *bufusage;
1988 1989 1990

	getrusage(RUSAGE_SELF, &r);
	gettimeofday(&elapse_t, &tz);
1991 1992
	memcpy((char *) &user, (char *) &r.ru_utime, sizeof(user));
	memcpy((char *) &sys, (char *) &r.ru_stime, sizeof(sys));
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
	if (elapse_t.tv_usec < Save_t.tv_usec)
	{
		elapse_t.tv_sec--;
		elapse_t.tv_usec += 1000000;
	}
	if (r.ru_utime.tv_usec < Save_r.ru_utime.tv_usec)
	{
		r.ru_utime.tv_sec--;
		r.ru_utime.tv_usec += 1000000;
	}
	if (r.ru_stime.tv_usec < Save_r.ru_stime.tv_usec)
	{
		r.ru_stime.tv_sec--;
		r.ru_stime.tv_usec += 1000000;
	}

	/*
	 * the only stats we don't show here are for memory usage -- i can't
	 * figure out how to interpret the relevant fields in the rusage
	 * struct, and they change names across o/s platforms, anyway. if you
	 * can figure out what the entries mean, you can somehow extract
	 * resident set size, shared text size, and unshared data and stack
	 * sizes.
	 */
2017
	initStringInfo(&str);
2018

2019 2020
	appendStringInfo(&str, "! system usage stats:\n");
	appendStringInfo(&str,
2021 2022 2023 2024 2025 2026 2027
			"!\t%ld.%06ld elapsed %ld.%06ld user %ld.%06ld system sec\n",
			(long int) elapse_t.tv_sec - Save_t.tv_sec,
			(long int) elapse_t.tv_usec - Save_t.tv_usec,
			(long int) r.ru_utime.tv_sec - Save_r.ru_utime.tv_sec,
			(long int) r.ru_utime.tv_usec - Save_r.ru_utime.tv_usec,
			(long int) r.ru_stime.tv_sec - Save_r.ru_stime.tv_sec,
			(long int) r.ru_stime.tv_usec - Save_r.ru_stime.tv_usec);
2028
	appendStringInfo(&str,
2029 2030 2031 2032 2033
			"!\t[%ld.%06ld user %ld.%06ld sys total]\n",
			(long int) user.tv_sec,
			(long int) user.tv_usec,
			(long int) sys.tv_sec,
			(long int) sys.tv_usec);
2034
/* BeOS has rusage but only has some fields, and not these... */
2035
#if defined(HAVE_GETRUSAGE)
2036
	appendStringInfo(&str,
2037 2038 2039 2040 2041
			"!\t%ld/%ld [%ld/%ld] filesystem blocks in/out\n",
			r.ru_inblock - Save_r.ru_inblock,
	/* they only drink coffee at dec */
			r.ru_oublock - Save_r.ru_oublock,
			r.ru_inblock, r.ru_oublock);
2042
	appendStringInfo(&str,
2043 2044 2045 2046 2047 2048
		  "!\t%ld/%ld [%ld/%ld] page faults/reclaims, %ld [%ld] swaps\n",
			r.ru_majflt - Save_r.ru_majflt,
			r.ru_minflt - Save_r.ru_minflt,
			r.ru_majflt, r.ru_minflt,
			r.ru_nswap - Save_r.ru_nswap,
			r.ru_nswap);
2049
	appendStringInfo(&str,
2050 2051 2052 2053 2054 2055
	 "!\t%ld [%ld] signals rcvd, %ld/%ld [%ld/%ld] messages rcvd/sent\n",
			r.ru_nsignals - Save_r.ru_nsignals,
			r.ru_nsignals,
			r.ru_msgrcv - Save_r.ru_msgrcv,
			r.ru_msgsnd - Save_r.ru_msgsnd,
			r.ru_msgrcv, r.ru_msgsnd);
2056
	appendStringInfo(&str,
2057 2058 2059 2060
		 "!\t%ld/%ld [%ld/%ld] voluntary/involuntary context switches\n",
			r.ru_nvcsw - Save_r.ru_nvcsw,
			r.ru_nivcsw - Save_r.ru_nivcsw,
			r.ru_nvcsw, r.ru_nivcsw);
2061
#endif   /* HAVE_GETRUSAGE */
2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073

	bufusage = ShowBufferUsage();
	appendStringInfo(&str, "! postgres usage stats:\n%s", bufusage);
	pfree(bufusage);

	/* remove trailing newline */
	if (str.data[str.len-1] == '\n')
		str.data[--str.len] = '\0';

	elog(DEBUG, "%s\n%s", title, str.data);

	pfree(str.data);
2074
}
2075

2076 2077
#ifdef NOT_USED
static int
2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089
assertEnable(int val)
{
	assert_enabled = val;
	return val;
}

#ifdef ASSERT_CHECKING_TEST
int
assertTest(int val)
{
	Assert(val == 0);

2090 2091
	if (assert_enabled)
	{
2092 2093 2094
		/* val != 0 should be trapped by previous Assert */
		elog(NOTICE, "Assert test successfull (val = %d)", val);
	}
2095 2096
	else
		elog(NOTICE, "Assert checking is disabled (val = %d)", val);
2097 2098 2099 2100

	return val;
}
#endif
2101

2102
#endif
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/* ----------------------------------------------------------------
 *		CreateCommandTag
 *
 *		utility to get a string representation of the
 *		command operation.
 * ----------------------------------------------------------------
 */
static const char *
CreateCommandTag(Node *parsetree)
{
	const char   *tag;

	switch (nodeTag(parsetree))
	{
		case T_InsertStmt:
			tag = "INSERT";
			break;

		case T_DeleteStmt:
			tag = "DELETE";
			break;

		case T_UpdateStmt:
			tag = "UPDATE";
			break;

		case T_SelectStmt:
			tag = "SELECT";
			break;

		case T_TransactionStmt:
			{
				TransactionStmt *stmt = (TransactionStmt *) parsetree;

				switch (stmt->command)
				{
					case BEGIN_TRANS:
						tag = "BEGIN";
						break;

					case COMMIT:
						tag = "COMMIT";
						break;

					case ROLLBACK:
						tag = "ROLLBACK";
						break;

					default:
						tag = "???";
						break;
				}
			}
			break;

		case T_ClosePortalStmt:
			tag = "CLOSE";
			break;

		case T_FetchStmt:
			{
				FetchStmt  *stmt = (FetchStmt *) parsetree;
				tag = (stmt->ismove) ? "MOVE" : "FETCH";
			}
			break;

		case T_CreateStmt:
			tag = "CREATE";
			break;

		case T_DropStmt:
			tag = "DROP";
			break;

		case T_TruncateStmt:
			tag = "TRUNCATE";
			break;

		case T_CommentStmt:
			tag = "COMMENT";
			break;

		case T_CopyStmt:
			tag = "COPY";
			break;

		case T_RenameStmt:
			tag = "ALTER";
			break;

		case T_AlterTableStmt:
			tag = "ALTER";
			break;

		case T_GrantStmt:
			{
				GrantStmt  *stmt = (GrantStmt *) parsetree;
				tag = (stmt->is_grant) ? "GRANT" : "REVOKE";
			}
			break;

		case T_DefineStmt:
			tag = "CREATE";
			break;

		case T_ViewStmt:		/* CREATE VIEW */
			tag = "CREATE";
			break;

		case T_ProcedureStmt:	/* CREATE FUNCTION */
			tag = "CREATE";
			break;

		case T_IndexStmt:		/* CREATE INDEX */
			tag = "CREATE";
			break;

		case T_RuleStmt:		/* CREATE RULE */
			tag = "CREATE";
			break;

		case T_CreateSeqStmt:
			tag = "CREATE";
			break;

		case T_RemoveAggrStmt:
			tag = "DROP";
			break;

		case T_RemoveFuncStmt:
			tag = "DROP";
			break;

		case T_RemoveOperStmt:
			tag = "DROP";
			break;

		case T_VersionStmt:
			tag = "CREATE VERSION";
			break;

		case T_CreatedbStmt:
			tag = "CREATE DATABASE";
			break;

		case T_DropdbStmt:
			tag = "DROP DATABASE";
			break;

		case T_NotifyStmt:
			tag = "NOTIFY";
			break;

		case T_ListenStmt:
			tag = "LISTEN";
			break;

		case T_UnlistenStmt:
			tag = "UNLISTEN";
			break;

		case T_LoadStmt:
			tag = "LOAD";
			break;

		case T_ClusterStmt:
			tag = "CLUSTER";
			break;

		case T_VacuumStmt:
			if (((VacuumStmt *) parsetree)->vacuum)
				tag = "VACUUM";
			else
				tag = "ANALYZE";
			break;

		case T_ExplainStmt:
			tag = "EXPLAIN";
			break;

#ifdef NOT_USED
		case T_RecipeStmt:
			tag = "EXECUTE RECIPE";
			break;
#endif

		case T_VariableSetStmt:
			tag = "SET VARIABLE";
			break;

		case T_VariableShowStmt:
			tag = "SHOW VARIABLE";
			break;

		case T_VariableResetStmt:
			tag = "RESET VARIABLE";
			break;

		case T_CreateTrigStmt:
			tag = "CREATE";
			break;

		case T_DropTrigStmt:
			tag = "DROP";
			break;

		case T_CreatePLangStmt:
			tag = "CREATE";
			break;

		case T_DropPLangStmt:
			tag = "DROP";
			break;

		case T_CreateUserStmt:
			tag = "CREATE USER";
			break;

		case T_AlterUserStmt:
			tag = "ALTER USER";
			break;

		case T_DropUserStmt:
			tag = "DROP USER";
			break;

		case T_LockStmt:
			tag = "LOCK TABLE";
			break;

		case T_ConstraintsSetStmt:
			tag = "SET CONSTRAINTS";
			break;

		case T_CreateGroupStmt:
			tag = "CREATE GROUP";
			break;

		case T_AlterGroupStmt:
			tag = "ALTER GROUP";
			break;

		case T_DropGroupStmt:
			tag = "DROP GROUP";
			break;

		case T_CheckPointStmt:
			tag = "CHECKPOINT";
			break;

		case T_ReindexStmt:
			tag = "REINDEX";
			break;

		default:
			elog(DEBUG, "CreateCommandTag: unknown parse node type %d",
				 nodeTag(parsetree));
			tag = "???";
			break;
	}

	return tag;
}