pg_proc.c

来自「PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统」· C语言 代码 · 共 814 行 · 第 1/2 页

/*
 * Validator for internal functions
 *
 * Check that the given internal function name (the "prosrc" value) is
 * a known builtin function.
 */
Datum
fmgr_internal_validator(PG_FUNCTION_ARGS)
{
	Oid			funcoid = PG_GETARG_OID(0);
	HeapTuple	tuple;
	Form_pg_proc proc;
	bool		isnull;
	Datum		tmp;
	char	   *prosrc;

	/*
	 * We do not honor check_function_bodies since it's unlikely the function
	 * name will be found later if it isn't there now.
	 */

	tuple = SearchSysCache(PROCOID,
						   ObjectIdGetDatum(funcoid),
						   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for function %u", funcoid);
	proc = (Form_pg_proc) GETSTRUCT(tuple);

	tmp = SysCacheGetAttr(PROCOID, tuple, Anum_pg_proc_prosrc, &isnull);
	if (isnull)
		elog(ERROR, "null prosrc");
	prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));

	if (fmgr_internal_function(prosrc) == InvalidOid)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("there is no built-in function named \"%s\"",
						prosrc)));

	ReleaseSysCache(tuple);

	PG_RETURN_VOID();
}



/*
 * Validator for C language functions
 *
 * Make sure that the library file exists, is loadable, and contains
 * the specified link symbol. Also check for a valid function
 * information record.
 */
Datum
fmgr_c_validator(PG_FUNCTION_ARGS)
{
	Oid			funcoid = PG_GETARG_OID(0);
	void	   *libraryhandle;
	HeapTuple	tuple;
	Form_pg_proc proc;
	bool		isnull;
	Datum		tmp;
	char	   *prosrc;
	char	   *probin;

	/*
	 * It'd be most consistent to skip the check if !check_function_bodies,
	 * but the purpose of that switch is to be helpful for pg_dump loading,
	 * and for pg_dump loading it's much better if we *do* check.
	 */

	tuple = SearchSysCache(PROCOID,
						   ObjectIdGetDatum(funcoid),
						   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for function %u", funcoid);
	proc = (Form_pg_proc) GETSTRUCT(tuple);

	tmp = SysCacheGetAttr(PROCOID, tuple, Anum_pg_proc_prosrc, &isnull);
	if (isnull)
		elog(ERROR, "null prosrc");
	prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));

	tmp = SysCacheGetAttr(PROCOID, tuple, Anum_pg_proc_probin, &isnull);
	if (isnull)
		elog(ERROR, "null probin");
	probin = DatumGetCString(DirectFunctionCall1(textout, tmp));

	(void) load_external_function(probin, prosrc, true, &libraryhandle);
	(void) fetch_finfo_record(libraryhandle, prosrc);

	ReleaseSysCache(tuple);

	PG_RETURN_VOID();
}


/*
 * Validator for SQL language functions
 *
 * Parse it here in order to be sure that it contains no syntax errors.
 */
Datum
fmgr_sql_validator(PG_FUNCTION_ARGS)
{
	Oid			funcoid = PG_GETARG_OID(0);
	HeapTuple	tuple;
	Form_pg_proc proc;
	List	   *querytree_list;
	bool		isnull;
	Datum		tmp;
	char	   *prosrc;
	ErrorContextCallback sqlerrcontext;
	bool		haspolyarg;
	int			i;

	tuple = SearchSysCache(PROCOID,
						   ObjectIdGetDatum(funcoid),
						   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for function %u", funcoid);
	proc = (Form_pg_proc) GETSTRUCT(tuple);

	/* Disallow pseudotype result */
	/* except for RECORD, VOID, ANYARRAY, or ANYELEMENT */
	if (get_typtype(proc->prorettype) == 'p' &&
		proc->prorettype != RECORDOID &&
		proc->prorettype != VOIDOID &&
		proc->prorettype != ANYARRAYOID &&
		proc->prorettype != ANYELEMENTOID)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
				 errmsg("SQL functions cannot return type %s",
						format_type_be(proc->prorettype))));

	/* Disallow pseudotypes in arguments */
	/* except for ANYARRAY or ANYELEMENT */
	haspolyarg = false;
	for (i = 0; i < proc->pronargs; i++)
	{
		if (get_typtype(proc->proargtypes.values[i]) == 'p')
		{
			if (proc->proargtypes.values[i] == ANYARRAYOID ||
				proc->proargtypes.values[i] == ANYELEMENTOID)
				haspolyarg = true;
			else
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
					 errmsg("SQL functions cannot have arguments of type %s",
							format_type_be(proc->proargtypes.values[i]))));
		}
	}

	/* Postpone body checks if !check_function_bodies */
	if (check_function_bodies)
	{
		tmp = SysCacheGetAttr(PROCOID, tuple, Anum_pg_proc_prosrc, &isnull);
		if (isnull)
			elog(ERROR, "null prosrc");

		prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));

		/*
		 * Setup error traceback support for ereport().
		 */
		sqlerrcontext.callback = sql_function_parse_error_callback;
		sqlerrcontext.arg = tuple;
		sqlerrcontext.previous = error_context_stack;
		error_context_stack = &sqlerrcontext;

		/*
		 * We can't do full prechecking of the function definition if there
		 * are any polymorphic input types, because actual datatypes of
		 * expression results will be unresolvable.  The check will be done at
		 * runtime instead.
		 *
		 * We can run the text through the raw parser though; this will at
		 * least catch silly syntactic errors.
		 */
		if (!haspolyarg)
		{
			querytree_list = pg_parse_and_rewrite(prosrc,
												  proc->proargtypes.values,
												  proc->pronargs);
			(void) check_sql_fn_retval(funcoid, proc->prorettype,
									   querytree_list, NULL);
		}
		else
			querytree_list = pg_parse_query(prosrc);

		error_context_stack = sqlerrcontext.previous;
	}

	ReleaseSysCache(tuple);

	PG_RETURN_VOID();
}

/*
 * Error context callback for handling errors in SQL function definitions
 */
static void
sql_function_parse_error_callback(void *arg)
{
	HeapTuple	tuple = (HeapTuple) arg;
	Form_pg_proc proc = (Form_pg_proc) GETSTRUCT(tuple);
	bool		isnull;
	Datum		tmp;
	char	   *prosrc;

	/* See if it's a syntax error; if so, transpose to CREATE FUNCTION */
	tmp = SysCacheGetAttr(PROCOID, tuple, Anum_pg_proc_prosrc, &isnull);
	if (isnull)
		elog(ERROR, "null prosrc");
	prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));

	if (!function_parse_error_transpose(prosrc))
	{
		/* If it's not a syntax error, push info onto context stack */
		errcontext("SQL function \"%s\"", NameStr(proc->proname));
	}

	pfree(prosrc);
}

/*
 * Adjust a syntax error occurring inside the function body of a CREATE
 * FUNCTION command.  This can be used by any function validator, not only
 * for SQL-language functions.	It is assumed that the syntax error position
 * is initially relative to the function body string (as passed in).  If
 * possible, we adjust the position to reference the original CREATE command;
 * if we can't manage that, we set up an "internal query" syntax error instead.
 *
 * Returns true if a syntax error was processed, false if not.
 */
bool
function_parse_error_transpose(const char *prosrc)
{
	int			origerrposition;
	int			newerrposition;
	const char *queryText;

	/*
	 * Nothing to do unless we are dealing with a syntax error that has a
	 * cursor position.
	 *
	 * Some PLs may prefer to report the error position as an internal error
	 * to begin with, so check that too.
	 */
	origerrposition = geterrposition();
	if (origerrposition <= 0)
	{
		origerrposition = getinternalerrposition();
		if (origerrposition <= 0)
			return false;
	}

	/* We can get the original query text from the active portal (hack...) */
	Assert(ActivePortal && ActivePortal->status == PORTAL_ACTIVE);
	queryText = ActivePortal->sourceText;

	/* Try to locate the prosrc in the original text */
	newerrposition = match_prosrc_to_query(prosrc, queryText, origerrposition);

	if (newerrposition > 0)
	{
		/* Successful, so fix error position to reference original query */
		errposition(newerrposition);
		/* Get rid of any report of the error as an "internal query" */
		internalerrposition(0);
		internalerrquery(NULL);
	}
	else
	{
		/*
		 * If unsuccessful, convert the position to an internal position
		 * marker and give the function text as the internal query.
		 */
		errposition(0);
		internalerrposition(origerrposition);
		internalerrquery(prosrc);
	}

	return true;
}

/*
 * Try to locate the string literal containing the function body in the
 * given text of the CREATE FUNCTION command.  If successful, return the
 * character (not byte) index within the command corresponding to the
 * given character index within the literal.  If not successful, return 0.
 */
static int
match_prosrc_to_query(const char *prosrc, const char *queryText,
					  int cursorpos)
{
	/*
	 * Rather than fully parsing the CREATE FUNCTION command, we just scan the
	 * command looking for $prosrc$ or 'prosrc'.  This could be fooled (though
	 * not in any very probable scenarios), so fail if we find more than one
	 * match.
	 */
	int			prosrclen = strlen(prosrc);
	int			querylen = strlen(queryText);
	int			matchpos = 0;
	int			curpos;
	int			newcursorpos;

	for (curpos = 0; curpos < querylen - prosrclen; curpos++)
	{
		if (queryText[curpos] == '$' &&
			strncmp(prosrc, &queryText[curpos + 1], prosrclen) == 0 &&
			queryText[curpos + 1 + prosrclen] == '$')
		{
			/*
			 * Found a $foo$ match.  Since there are no embedded quoting
			 * characters in a dollar-quoted literal, we don't have to do any
			 * fancy arithmetic; just offset by the starting position.
			 */
			if (matchpos)
				return 0;		/* multiple matches, fail */
			matchpos = pg_mbstrlen_with_len(queryText, curpos + 1)
				+ cursorpos;
		}
		else if (queryText[curpos] == '\'' &&
				 match_prosrc_to_literal(prosrc, &queryText[curpos + 1],
										 cursorpos, &newcursorpos))
		{
			/*
			 * Found a 'foo' match.  match_prosrc_to_literal() has adjusted
			 * for any quotes or backslashes embedded in the literal.
			 */
			if (matchpos)
				return 0;		/* multiple matches, fail */
			matchpos = pg_mbstrlen_with_len(queryText, curpos + 1)
				+ newcursorpos;
		}
	}

	return matchpos;
}

/*
 * Try to match the given source text to a single-quoted literal.
 * If successful, adjust newcursorpos to correspond to the character
 * (not byte) index corresponding to cursorpos in the source text.
 *
 * At entry, literal points just past a ' character.  We must check for the
 * trailing quote.
 */
static bool
match_prosrc_to_literal(const char *prosrc, const char *literal,
						int cursorpos, int *newcursorpos)
{
	int			newcp = cursorpos;
	int			chlen;

	/*
	 * This implementation handles backslashes and doubled quotes in the
	 * string literal.	It does not handle the SQL syntax for literals
	 * continued across line boundaries.
	 *
	 * We do the comparison a character at a time, not a byte at a time, so
	 * that we can do the correct cursorpos math.
	 */
	while (*prosrc)
	{
		cursorpos--;			/* characters left before cursor */

		/*
		 * Check for backslashes and doubled quotes in the literal; adjust
		 * newcp when one is found before the cursor.
		 */
		if (*literal == '\\')
		{
			literal++;
			if (cursorpos > 0)
				newcp++;
		}
		else if (*literal == '\'')
		{
			if (literal[1] != '\'')
				goto fail;
			literal++;
			if (cursorpos > 0)
				newcp++;
		}
		chlen = pg_mblen(prosrc);
		if (strncmp(prosrc, literal, chlen) != 0)
			goto fail;
		prosrc += chlen;
		literal += chlen;
	}

	if (*literal == '\'' && literal[1] != '\'')
	{
		/* success */
		*newcursorpos = newcp;
		return true;
	}

fail:
	/* Must set *newcursorpos to suppress compiler warning */
	*newcursorpos = newcp;
	return false;
}