variable.c

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/*-------------------------------------------------------------------------
 *
 * variable.c
 *		Routines for handling specialized SET variables.
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.114.2.2 2006/02/12 22:32:56 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <ctype.h>

#include "access/xact.h"
#include "catalog/pg_authid.h"
#include "commands/variable.h"
#include "miscadmin.h"
#include "parser/scansup.h"
#include "pgtime.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/syscache.h"
#include "utils/tqual.h"
#include "mb/pg_wchar.h"

/*
 * DATESTYLE
 */

/*
 * assign_datestyle: GUC assign_hook for datestyle
 */
const char *
assign_datestyle(const char *value, bool doit, GucSource source)
{
	int			newDateStyle = DateStyle;
	int			newDateOrder = DateOrder;
	bool		have_style = false;
	bool		have_order = false;
	bool		ok = true;
	char	   *rawstring;
	char	   *result;
	List	   *elemlist;
	ListCell   *l;

	/* Need a modifiable copy of string */
	rawstring = pstrdup(value);

	/* Parse string into list of identifiers */
	if (!SplitIdentifierString(rawstring, ',', &elemlist))
	{
		/* syntax error in list */
		pfree(rawstring);
		list_free(elemlist);
		if (source >= PGC_S_INTERACTIVE)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("invalid list syntax for parameter \"datestyle\"")));
		return NULL;
	}

	foreach(l, elemlist)
	{
		char	   *tok = (char *) lfirst(l);

		/* Ugh. Somebody ought to write a table driven version -- mjl */

		if (pg_strcasecmp(tok, "ISO") == 0)
		{
			if (have_style && newDateStyle != USE_ISO_DATES)
				ok = false;		/* conflicting styles */
			newDateStyle = USE_ISO_DATES;
			have_style = true;
		}
		else if (pg_strcasecmp(tok, "SQL") == 0)
		{
			if (have_style && newDateStyle != USE_SQL_DATES)
				ok = false;		/* conflicting styles */
			newDateStyle = USE_SQL_DATES;
			have_style = true;
		}
		else if (pg_strncasecmp(tok, "POSTGRES", 8) == 0)
		{
			if (have_style && newDateStyle != USE_POSTGRES_DATES)
				ok = false;		/* conflicting styles */
			newDateStyle = USE_POSTGRES_DATES;
			have_style = true;
		}
		else if (pg_strcasecmp(tok, "GERMAN") == 0)
		{
			if (have_style && newDateStyle != USE_GERMAN_DATES)
				ok = false;		/* conflicting styles */
			newDateStyle = USE_GERMAN_DATES;
			have_style = true;
			/* GERMAN also sets DMY, unless explicitly overridden */
			if (!have_order)
				newDateOrder = DATEORDER_DMY;
		}
		else if (pg_strcasecmp(tok, "YMD") == 0)
		{
			if (have_order && newDateOrder != DATEORDER_YMD)
				ok = false;		/* conflicting orders */
			newDateOrder = DATEORDER_YMD;
			have_order = true;
		}
		else if (pg_strcasecmp(tok, "DMY") == 0 ||
				 pg_strncasecmp(tok, "EURO", 4) == 0)
		{
			if (have_order && newDateOrder != DATEORDER_DMY)
				ok = false;		/* conflicting orders */
			newDateOrder = DATEORDER_DMY;
			have_order = true;
		}
		else if (pg_strcasecmp(tok, "MDY") == 0 ||
				 pg_strcasecmp(tok, "US") == 0 ||
				 pg_strncasecmp(tok, "NONEURO", 7) == 0)
		{
			if (have_order && newDateOrder != DATEORDER_MDY)
				ok = false;		/* conflicting orders */
			newDateOrder = DATEORDER_MDY;
			have_order = true;
		}
		else if (pg_strcasecmp(tok, "DEFAULT") == 0)
		{
			/*
			 * Easiest way to get the current DEFAULT state is to fetch the
			 * DEFAULT string from guc.c and recursively parse it.
			 *
			 * We can't simply "return assign_datestyle(...)" because we need
			 * to handle constructs like "DEFAULT, ISO".
			 */
			int			saveDateStyle = DateStyle;
			int			saveDateOrder = DateOrder;
			const char *subval;

			subval = assign_datestyle(GetConfigOptionResetString("datestyle"),
									  true, source);
			if (!have_style)
				newDateStyle = DateStyle;
			if (!have_order)
				newDateOrder = DateOrder;
			DateStyle = saveDateStyle;
			DateOrder = saveDateOrder;
			if (!subval)
			{
				ok = false;
				break;
			}
			/* Here we know that our own return value is always malloc'd */
			/* when doit is true */
			free((char *) subval);
		}
		else
		{
			if (source >= PGC_S_INTERACTIVE)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("unrecognized \"datestyle\" key word: \"%s\"",
								tok)));
			ok = false;
			break;
		}
	}

	pfree(rawstring);
	list_free(elemlist);

	if (!ok)
	{
		if (source >= PGC_S_INTERACTIVE)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("conflicting \"datestyle\" specifications")));
		return NULL;
	}

	/*
	 * If we aren't going to do the assignment, just return OK indicator.
	 */
	if (!doit)
		return value;

	/*
	 * Prepare the canonical string to return.	GUC wants it malloc'd.
	 */
	result = (char *) malloc(32);
	if (!result)
		return NULL;

	switch (newDateStyle)
	{
		case USE_ISO_DATES:
			strcpy(result, "ISO");
			break;
		case USE_SQL_DATES:
			strcpy(result, "SQL");
			break;
		case USE_GERMAN_DATES:
			strcpy(result, "German");
			break;
		default:
			strcpy(result, "Postgres");
			break;
	}
	switch (newDateOrder)
	{
		case DATEORDER_YMD:
			strcat(result, ", YMD");
			break;
		case DATEORDER_DMY:
			strcat(result, ", DMY");
			break;
		default:
			strcat(result, ", MDY");
			break;
	}

	/*
	 * Finally, it's safe to assign to the global variables; the assignment
	 * cannot fail now.
	 */
	DateStyle = newDateStyle;
	DateOrder = newDateOrder;

	return result;
}


/*
 * TIMEZONE
 */

/*
 * assign_timezone: GUC assign_hook for timezone
 */
const char *
assign_timezone(const char *value, bool doit, GucSource source)
{
	char	   *result;
	char	   *endptr;
	double		hours;

	/*
	 * Check for INTERVAL 'foo'
	 */
	if (pg_strncasecmp(value, "interval", 8) == 0)
	{
		const char *valueptr = value;
		char	   *val;
		Interval   *interval;

		valueptr += 8;
		while (isspace((unsigned char) *valueptr))
			valueptr++;
		if (*valueptr++ != '\'')
			return NULL;
		val = pstrdup(valueptr);
		/* Check and remove trailing quote */
		endptr = strchr(val, '\'');
		if (!endptr || endptr[1] != '\0')
		{
			pfree(val);
			return NULL;
		}
		*endptr = '\0';

		/*
		 * Try to parse it.  XXX an invalid interval format will result in
		 * ereport, which is not desirable for GUC.  We did what we could to
		 * guard against this in flatten_set_variable_args, but a string
		 * coming in from postgresql.conf might contain anything.
		 */
		interval = DatumGetIntervalP(DirectFunctionCall3(interval_in,
														 CStringGetDatum(val),
												ObjectIdGetDatum(InvalidOid),
														 Int32GetDatum(-1)));

		pfree(val);
		if (interval->month != 0)
		{
			if (source >= PGC_S_INTERACTIVE)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("invalid interval value for time zone: month not allowed")));
			pfree(interval);
			return NULL;
		}
		if (interval->day != 0)
		{
			if (source >= PGC_S_INTERACTIVE)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("invalid interval value for time zone: day not allowed")));
			pfree(interval);
			return NULL;
		}
		if (doit)
		{
			/* Here we change from SQL to Unix sign convention */
#ifdef HAVE_INT64_TIMESTAMP
			CTimeZone = -(interval->time / USECS_PER_SEC);
#else
			CTimeZone = -interval->time;
#endif

			HasCTZSet = true;
		}
		pfree(interval);
	}
	else
	{
		/*
		 * Try it as a numeric number of hours (possibly fractional).
		 */
		hours = strtod(value, &endptr);
		if (endptr != value && *endptr == '\0')
		{
			if (doit)
			{
				/* Here we change from SQL to Unix sign convention */
				CTimeZone = -hours * SECS_PER_HOUR;
				HasCTZSet = true;
			}
		}
		else if (pg_strcasecmp(value, "UNKNOWN") == 0)
		{
			/*
			 * UNKNOWN is the value shown as the "default" for TimeZone in
			 * guc.c.  We interpret it as being a complete no-op; we don't
			 * change the timezone setting.  Note that if there is a known
			 * timezone setting, we will return that name rather than UNKNOWN
			 * as the canonical spelling.
			 *
			 * During GUC initialization, since the timezone library isn't set
			 * up yet, pg_get_timezone_name will return NULL and we will leave
			 * the setting as UNKNOWN.	If this isn't overridden from the
			 * config file then pg_timezone_initialize() will eventually
			 * select a default value from the environment.
			 */
			if (doit)
			{
				const char *curzone = pg_get_timezone_name(global_timezone);

				if (curzone)
					value = curzone;
			}
		}
		else
		{
			/*
			 * Otherwise assume it is a timezone name, and try to load it.
			 */
			pg_tz	   *new_tz;

			new_tz = pg_tzset(value);

			if (!new_tz)
			{
				ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("unrecognized time zone name: \"%s\"",
								value)));
				return NULL;
			}

			if (!tz_acceptable(new_tz))
			{
				ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					   errmsg("time zone \"%s\" appears to use leap seconds",
							  value),
					errdetail("PostgreSQL does not support leap seconds.")));
				return NULL;
			}

			if (doit)
			{
				/* Save the changed TZ */
				global_timezone = new_tz;
				HasCTZSet = false;
			}
		}
	}

	/*
	 * If we aren't going to do the assignment, just return OK indicator.
	 */
	if (!doit)
		return value;

	/*
	 * Prepare the canonical string to return.	GUC wants it malloc'd.
	 */
	if (HasCTZSet)
	{
		result = (char *) malloc(64);
		if (!result)
			return NULL;
		snprintf(result, 64, "%.5f",
				 (double) (-CTimeZone) / (double) SECS_PER_HOUR);
	}
	else
		result = strdup(value);

	return result;
}