variable.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 832 行 · 第 1/2 页

		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 (interactive)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("invalid interval value for time zone: month not allowed")));
			pfree(interval);
			return NULL;
		}
		if (doit)
		{
			/* Here we change from SQL to Unix sign convention */
			CTimeZone = -interval->time;
			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 * 3600;
				HasCTZSet = true;
			}
		}
		else if (strcasecmp(value, "UNKNOWN") == 0)
		{
			/*
			 * UNKNOWN is the value shown as the "default" for TimeZone in
			 * guc.c.  We interpret it as meaning the original TZ
			 * inherited from the environment.	Note that if there is an
			 * original TZ setting, we will return that rather than
			 * UNKNOWN as the canonical spelling.
			 */
			if (doit)
			{
				bool		ok;

				/* Revert to original setting of TZ, whatever it was */
				if (orig_tzbuf[0])
				{
					set_tz(orig_tzbuf);
					ok = tzset_succeeded(orig_tzbuf) && tz_acceptable();
				}
				else
				{
					clear_tz();
					ok = tz_acceptable();
				}

				if (ok)
					HasCTZSet = false;
				else
				{
					/* Bogus, so force UTC (equivalent to INTERVAL 0) */
					CTimeZone = 0;
					HasCTZSet = true;
				}
			}
		}
		else
		{
			/*
			 * Otherwise assume it is a timezone name.
			 *
			 * We have to actually apply the change before we can have any
			 * hope of checking it.  So, save the old value in case we
			 * have to back out.  Note that it's possible the old setting
			 * is in tzbuf, so we'd better copy it.
			 */
			char		save_tzbuf[TZBUF_LEN];
			char	   *save_tz;
			bool		known,
						acceptable;

			save_tz = getenv("TZ");
			if (save_tz)
				StrNCpy(save_tzbuf, save_tz, sizeof(save_tzbuf));

			set_tz(value);

			known = tzset_succeeded(value);
			acceptable = tz_acceptable();

			if (doit && known && acceptable)
			{
				/* Keep the changed TZ */
				HasCTZSet = false;
			}
			else
			{
				/*
				 * Revert to prior TZ setting; note we haven't changed
				 * HasCTZSet in this path, so if we were previously using
				 * a fixed offset, we still are.
				 */
				if (save_tz)
					set_tz(save_tzbuf);
				else
					clear_tz();
				/* Complain if it was bad */
				if (!known)
				{
					ereport(interactive ? ERROR : LOG,
							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
							 errmsg("unrecognized time zone name: \"%s\"",
									value)));
					return NULL;
				}
				if (!acceptable)
				{
					ereport(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 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(sizeof(tzbuf));
	if (!result)
		return NULL;

	if (HasCTZSet)
		snprintf(result, sizeof(tzbuf), "%.5f",
				 (double) (-CTimeZone) / 3600.0);
	else if (tzbuf[0] == 'T')
		strcpy(result, tzbuf + 3);
	else
		strcpy(result, "UNKNOWN");

	return result;
}

/*
 * show_timezone: GUC show_hook for timezone
 */
const char *
show_timezone(void)
{
	char	   *tzn;

	if (HasCTZSet)
	{
		Interval	interval;

		interval.month = 0;
		interval.time = -CTimeZone;

		tzn = DatumGetCString(DirectFunctionCall1(interval_out,
										  IntervalPGetDatum(&interval)));
	}
	else
		tzn = getenv("TZ");

	if (tzn != NULL)
		return tzn;

	return "unknown";
}


/*
 * SET TRANSACTION ISOLATION LEVEL
 */

const char *
assign_XactIsoLevel(const char *value, bool doit, bool interactive)
{
	if (doit && interactive && SerializableSnapshot != NULL)
		ereport(ERROR,
				(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
				 errmsg("SET TRANSACTION ISOLATION LEVEL must be called before any query")));

	if (strcmp(value, "serializable") == 0)
	{
		if (doit)
			XactIsoLevel = XACT_SERIALIZABLE;
	}
	else if (strcmp(value, "read committed") == 0)
	{
		if (doit)
			XactIsoLevel = XACT_READ_COMMITTED;
	}
	else if (strcmp(value, "default") == 0)
	{
		if (doit)
			XactIsoLevel = DefaultXactIsoLevel;
	}
	else
		return NULL;

	return value;
}

const char *
show_XactIsoLevel(void)
{
	if (XactIsoLevel == XACT_SERIALIZABLE)
		return "serializable";
	else
		return "read committed";
}


/*
 * Random number seed
 */

bool
assign_random_seed(double value, bool doit, bool interactive)
{
	/* Can't really roll back on error, so ignore non-interactive setting */
	if (doit && interactive)
		DirectFunctionCall1(setseed, Float8GetDatum(value));
	return true;
}

const char *
show_random_seed(void)
{
	return "unavailable";
}


/*
 * encoding handling functions
 */

const char *
assign_client_encoding(const char *value, bool doit, bool interactive)
{
	int			encoding;

	encoding = pg_valid_client_encoding(value);
	if (encoding < 0)
		return NULL;

	/*
	 * Note: if we are in startup phase then SetClientEncoding may not be
	 * able to really set the encoding.  In this case we will assume that
	 * the encoding is okay, and InitializeClientEncoding() will fix
	 * things once initialization is complete.
	 */
	if (SetClientEncoding(encoding, doit) < 0)
	{
		if (interactive)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				  errmsg("conversion between %s and %s is not supported",
						 value, GetDatabaseEncodingName())));
		return NULL;
	}
	return value;
}


/*
 * SET SESSION AUTHORIZATION
 *
 * When resetting session auth after an error, we can't expect to do catalog
 * lookups.  Hence, the stored form of the value must provide a numeric userid
 * that can be re-used directly.  We store the string in the form of
 * NAMEDATALEN 'x's, followed by T or F to indicate superuserness, followed
 * by the numeric userid, followed by a comma, followed by the user name.
 * This cannot be confused with a plain user name because of the NAMEDATALEN
 * limit on names, so we can tell whether we're being passed an initial
 * username or a saved/restored value.
 */
extern char *session_authorization_string; /* in guc.c */

const char *
assign_session_authorization(const char *value, bool doit, bool interactive)
{
	AclId		usesysid = 0;
	bool		is_superuser = false;
	const char *actual_username = NULL;
	char	   *result;

	if (strspn(value, "x") == NAMEDATALEN &&
		(value[NAMEDATALEN] == 'T' || value[NAMEDATALEN] == 'F'))
	{
		/* might be a saved userid string */
		AclId		savedsysid;
		char	   *endptr;

		savedsysid = (AclId) strtoul(value + NAMEDATALEN + 1, &endptr, 10);

		if (endptr != value + NAMEDATALEN + 1 && *endptr == ',')
		{
			/* syntactically valid, so break out the data */
			usesysid = savedsysid;
			is_superuser = (value[NAMEDATALEN] == 'T');
			actual_username = endptr + 1;
		}
	}

	if (usesysid == 0)
	{
		/* not a saved ID, so look it up */
		HeapTuple	userTup;

		if (!IsTransactionState())
		{
			/*
			 * Can't do catalog lookups, so fail.  The upshot of this is
			 * that session_authorization cannot be set in
			 * postgresql.conf, which seems like a good thing anyway.
			 */
			return NULL;
		}

		userTup = SearchSysCache(SHADOWNAME,
								 PointerGetDatum(value),
								 0, 0, 0);
		if (!HeapTupleIsValid(userTup))
		{
			if (interactive)
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_OBJECT),
						 errmsg("user \"%s\" does not exist", value)));
			return NULL;
		}

		usesysid = ((Form_pg_shadow) GETSTRUCT(userTup))->usesysid;
		is_superuser = ((Form_pg_shadow) GETSTRUCT(userTup))->usesuper;
		actual_username = value;

		ReleaseSysCache(userTup);
	}

	if (doit)
		SetSessionAuthorization(usesysid, is_superuser);

	result = (char *) malloc(NAMEDATALEN + 32 + strlen(actual_username));
	if (!result)
		return NULL;

	memset(result, 'x', NAMEDATALEN);

	sprintf(result + NAMEDATALEN, "%c%lu,%s",
			is_superuser ? 'T' : 'F',
			(unsigned long) usesysid,
			actual_username);

	return result;
}

const char *
show_session_authorization(void)
{
	/*
	 * Extract the user name from the stored string; see
	 * assign_session_authorization
	 */
	const char *value = session_authorization_string;
	AclId		savedsysid;
	char	   *endptr;

	Assert(strspn(value, "x") == NAMEDATALEN &&
		   (value[NAMEDATALEN] == 'T' || value[NAMEDATALEN] == 'F'));

	savedsysid = (AclId) strtoul(value + NAMEDATALEN + 1, &endptr, 10);

	Assert(endptr != value + NAMEDATALEN + 1 && *endptr == ',');

	return endptr + 1;
}