/*-------------------------------------------------------------------------
 *
 * expr_walk.c
 *
 *			  set of Query/Expr walkers
 *
 * by Pavel Stehule 2013-2026
 *
 *-------------------------------------------------------------------------
 */

#include "plpgsql_check.h"

#include "nodes/nodeFuncs.h"

#include "catalog/pg_class.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "nodes/nodeFuncs.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"

typedef struct check_funcexpr_walker_params
{
	PLpgSQL_checkstate *cstate;
	PLpgSQL_expr *expr;
	char	   *query_str;
} check_funcexpr_walker_params;

static int	check_fmt_string(const char *fmt,
							 List *args,
							 int location,
							 check_funcexpr_walker_params *wp,
							 bool *is_error,
							 int *unsafe_expr_location,
							 bool no_error);

/*
 * Send to ouput all not yet displayed relations, operators and functions.
 */
static bool
detect_dependency_walker(Node *node, void *context)
{
	PLpgSQL_checkstate *cstate = (PLpgSQL_checkstate *) context;
	plpgsql_check_result_info *ri = cstate->result_info;

	if (node == NULL)
		return false;

	if (IsA(node, Query))
	{
		Query	   *query = (Query *) node;
		ListCell   *lc;

		foreach(lc, query->rtable)
		{
			RangeTblEntry *rt = (RangeTblEntry *) lfirst(lc);

			if (rt->rtekind == RTE_RELATION)
			{
				if (!bms_is_member(rt->relid, cstate->rel_oids))
				{
					plpgsql_check_put_dependency(ri,
												 "RELATION",
												 rt->relid,
												 get_namespace_name(get_rel_namespace(rt->relid)),
												 get_rel_name(rt->relid),
												 NULL);

					cstate->rel_oids = bms_add_member(cstate->rel_oids, rt->relid);
				}
			}
		}

		if (query->utilityStmt && IsA(query->utilityStmt, CallStmt))
		{
			CallStmt   *callstmt = (CallStmt *) query->utilityStmt;

			detect_dependency_walker((Node *) callstmt->funcexpr, context);
		}

		return query_tree_walker((Query *) node,
								 detect_dependency_walker,
								 context, 0);
	}

	if (IsA(node, FuncExpr))
	{
		FuncExpr   *fexpr = (FuncExpr *) node;

		if (get_func_namespace(fexpr->funcid) != PG_CATALOG_NAMESPACE)
		{
			if (!bms_is_member(fexpr->funcid, cstate->func_oids))
			{
				StringInfoData str;
				ListCell   *lc;
				bool		is_first = true;
				char		prokind = get_func_prokind(fexpr->funcid);

				initStringInfo(&str);
				appendStringInfoChar(&str, '(');
				foreach(lc, fexpr->args)
				{
					Node	   *expr = (Node *) lfirst(lc);

					if (!is_first)
						appendStringInfoChar(&str, ',');
					else
						is_first = false;

					appendStringInfoString(&str, format_type_be(exprType(expr)));
				}
				appendStringInfoChar(&str, ')');

				plpgsql_check_put_dependency(ri,
											 prokind == PROKIND_PROCEDURE ? "PROCEDURE" : "FUNCTION",
											 fexpr->funcid,
											 get_namespace_name(get_func_namespace(fexpr->funcid)),
											 get_func_name(fexpr->funcid),
											 str.data);

				pfree(str.data);

				cstate->func_oids = bms_add_member(cstate->func_oids, fexpr->funcid);
			}
		}
	}

	if (IsA(node, OpExpr))
	{
		OpExpr	   *opexpr = (OpExpr *) node;

		if (plpgsql_check_get_op_namespace(opexpr->opno) != PG_CATALOG_NAMESPACE)
		{
			StringInfoData str;
			Oid			lefttype;
			Oid			righttype;

			op_input_types(opexpr->opno, &lefttype, &righttype);

			initStringInfo(&str);
			appendStringInfoChar(&str, '(');
			if (lefttype != InvalidOid)
				appendStringInfoString(&str, format_type_be(lefttype));
			else
				appendStringInfoChar(&str, '-');
			appendStringInfoChar(&str, ',');
			if (righttype != InvalidOid)
				appendStringInfoString(&str, format_type_be(righttype));
			else
				appendStringInfoChar(&str, '-');
			appendStringInfoChar(&str, ')');

			plpgsql_check_put_dependency(ri,
										 "OPERATOR",
										 opexpr->opno,
										 get_namespace_name(plpgsql_check_get_op_namespace(opexpr->opno)),
										 get_opname(opexpr->opno),
										 str.data);
			pfree(str.data);
		}
	}

	return expression_tree_walker(node, detect_dependency_walker, context);
}

void
plpgsql_check_detect_dependency(PLpgSQL_checkstate *cstate, Query *query)
{
	if (cstate->result_info->format != PLPGSQL_SHOW_DEPENDENCY_FORMAT_TABULAR)
		return;

	detect_dependency_walker((Node *) query, cstate);
}

/*
 * When sequence related functions has constant oid parameter, then ensure, so
 * this oid is related to some sequnce object.
 *
 */
static bool
check_funcexpr_walker(Node *node, void *context)
{
	if (node == NULL)
		return false;

	if (IsA(node, Query))
	{
		return query_tree_walker((Query *) node,
								 check_funcexpr_walker,
								 context, 0);
	}
	if (IsA(node, FuncExpr))
	{
		FuncExpr   *fexpr = (FuncExpr *) node;

		switch (fexpr->funcid)
		{
			case NEXTVAL_OID:
			case CURRVAL_OID:
			case SETVAL_OID:
			case SETVAL2_OID:
				{
					Node	   *first_arg = linitial(fexpr->args);
					int			location = fexpr->location;

					if (first_arg && IsA(first_arg, Const))
					{
						Const	   *c = (Const *) first_arg;

						if (c->consttype == REGCLASSOID && !c->constisnull)
						{
							Oid			classid;

							if (c->location != -1)
								location = c->location;

							classid = DatumGetObjectId(c->constvalue);

							if (get_rel_relkind(classid) != RELKIND_SEQUENCE)
							{
								char		message[1024];
								check_funcexpr_walker_params *wp;

								wp = (check_funcexpr_walker_params *) context;

								snprintf(message, sizeof(message), "\"%s\" is not a sequence", get_rel_name(classid));

								plpgsql_check_put_error(wp->cstate,
														ERRCODE_WRONG_OBJECT_TYPE, 0,
														message,
														NULL, NULL,
														PLPGSQL_CHECK_ERROR,
														location,
														wp->query_str, NULL);
							}
						}
					}
				}
				break;

			case FORMAT_0PARAM_OID:
			case FORMAT_NPARAM_OID:
				{
					/* We can do check only when first argument is constant */
					Node	   *first_arg = linitial(fexpr->args);

					if (first_arg && IsA(first_arg, Const))
					{
						Const	   *c = (Const *) first_arg;

						if (c->consttype == TEXTOID && !c->constisnull)
						{
							char	   *fmt = TextDatumGetCString(c->constvalue);
							check_funcexpr_walker_params *wp;
							int			required_nargs;
							bool		is_error;

							wp = (check_funcexpr_walker_params *) context;

							required_nargs = check_fmt_string(fmt, fexpr->args, c->location, wp, &is_error, NULL, false);
							if (!is_error && required_nargs != -1)
							{
								if (required_nargs + 1 != list_length(fexpr->args))
									plpgsql_check_put_error(wp->cstate,
															0, 0,
															"unused parameters of function \"format\"",
															NULL, NULL,
															PLPGSQL_CHECK_WARNING_OTHERS,
															c->location,
															wp->query_str, NULL);
							}
						}
					}
				}
		}
	}

	return expression_tree_walker(node, check_funcexpr_walker, context);
}

void
plpgsql_check_funcexpr(PLpgSQL_checkstate *cstate, Query *query, char *query_str)
{
	check_funcexpr_walker_params wp;

	wp.cstate = cstate;
	wp.query_str = query_str;
	wp.expr = NULL;

	check_funcexpr_walker((Node *) query, &wp);
}

/*
 * Aux functions for checking format string of function format
 */

/*
 * Support macros for text_format()
 */
#define ADVANCE_PARSE_POINTER(ptr,end_ptr) \
	do { \
		if (++(ptr) >= (end_ptr)) \
		{ \
			if (wp) \
				plpgsql_check_put_error(wp->cstate, \
										ERRCODE_INVALID_PARAMETER_VALUE, 0, \
										"unterminated format() type specifier", \
										NULL, \
										"For a single \"%%\" use \"%%%%\".", \
										PLPGSQL_CHECK_ERROR, \
										location, \
										wp->query_str, NULL); \
			*is_error = true; \
		} \
	} while (0)

/*
 * Parse contiguous digits as a decimal number.
 *
 * Returns true if some digits could be parsed.
 * The value is returned into *value, and *ptr is advanced to the next
 * character to be parsed.
 */
static bool
text_format_parse_digits(const char **ptr,
						 const char *end_ptr,
						 int *value,
						 int location,
						 check_funcexpr_walker_params *wp,
						 bool *is_error)
{
	bool		found = false;
	const char *cp = *ptr;
	int			val = 0;

	*is_error = false;

	while (*cp >= '0' && *cp <= '9')
	{
		int			newval = val * 10 + (*cp - '0');

		if (newval / 10 != val) /* overflow? */
		{
			if (wp)
				plpgsql_check_put_error(wp->cstate,
										ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE, 0,
										"number is out of range",
										NULL,
										NULL,
										PLPGSQL_CHECK_ERROR,
										location,
										wp->query_str, NULL);
			*is_error = true;
			return false;
		}
		val = newval;

		ADVANCE_PARSE_POINTER(cp, end_ptr);
		if (*is_error)
			return false;

		found = true;
	}

	*ptr = cp;
	*value = val;

	return found;
}

/*
 * reduced code from varlena.c
 */
static const char *
text_format_parse_format(const char *start_ptr,
						 const char *end_ptr,
						 int *argpos,
						 int *widthpos,
						 int location,
						 check_funcexpr_walker_params *wp,
						 bool *is_error)
{
	const char *cp = start_ptr;
	int			n;
	bool		found;

	/* set defaults for output parameters */
	*argpos = -1;
	*widthpos = -1;
	*is_error = false;

	/* try to identify first number */
	found = text_format_parse_digits(&cp, end_ptr, &n, location, wp, is_error);
	if (*is_error)
		return NULL;

	if (found)
	{
		if (*cp != '$')
		{
			/* Must be just a width and a type, so we're done */
			return cp;
		}
		/* The number was argument position */
		*argpos = n;
		/* Explicit 0 for argument index is immediately refused */
		if (n == 0)
		{
			if (wp)
				plpgsql_check_put_error(wp->cstate,
										ERRCODE_INVALID_PARAMETER_VALUE, 0,
										"format specifies argument 0, but arguments are numbered from 1",
										NULL,
										NULL,
										PLPGSQL_CHECK_ERROR,
										location,
										wp->query_str, NULL);
			*is_error = true;
			return NULL;
		}

		ADVANCE_PARSE_POINTER(cp, end_ptr);
		if (*is_error)
			return NULL;
	}

	/* Handle flags (only minus is supported now) */
	while (*cp == '-')
	{
		ADVANCE_PARSE_POINTER(cp, end_ptr);
		if (*is_error)
			return NULL;
	}

	if (*cp == '*')
	{
		/* Handle indirect width */
		ADVANCE_PARSE_POINTER(cp, end_ptr);
		if (*is_error)
			return NULL;

		found = text_format_parse_digits(&cp, end_ptr, &n, location, wp, is_error);
		if (*is_error)
			return NULL;

		if (found)
		{
			/* number in this position must be closed by $ */
			if (*cp != '$')
			{
				if (wp)
					plpgsql_check_put_error(wp->cstate,
											ERRCODE_INVALID_PARAMETER_VALUE, 0,
											"width argument position must be ended by \"$\"",
											NULL,
											NULL,
											PLPGSQL_CHECK_ERROR,
											location,
											wp->query_str, NULL);
				*is_error = true;
				return NULL;
			}

			/* The number was width argument position */
			*widthpos = n;
			/* Explicit 0 for argument index is immediately refused */
			if (n == 0)
			{
				if (wp)
					plpgsql_check_put_error(wp->cstate,
											ERRCODE_INVALID_PARAMETER_VALUE, 0,
											"format specifies argument 0, but arguments are numbered from 1",
											NULL,
											NULL,
											PLPGSQL_CHECK_ERROR,
											location,
											wp->query_str, NULL);
				*is_error = true;
				return NULL;
			}

			ADVANCE_PARSE_POINTER(cp, end_ptr);
			if (*is_error)
				return NULL;
		}
		else
			*widthpos = 0;		/* width's argument position is unspecified */
	}
	else
	{
		/* Check for direct width specification */
		(void) text_format_parse_digits(&cp, end_ptr, &n, location, wp, is_error);
		if (*is_error)
			return NULL;
	}

	/* cp should now be pointing at type character */
	return cp;
}

#define TOO_FEW_ARGUMENTS_CHECK(arg, nargs) \
	if ((arg) > (nargs)) \
	{ \
		if (wp) \
			plpgsql_check_put_error(wp->cstate, \
									ERRCODE_INVALID_PARAMETER_VALUE, 0, \
									"too few arguments for format()", \
									NULL, \
									NULL, \
									PLPGSQL_CHECK_ERROR, \
									location, \
									wp->query_str, NULL); \
		*is_error = true; \
		return -1; \
	}

/*
 * Returns string based on expected result of "format" function.
 * Try to use traced constant, when are available.
 */
char *
plpgsql_check_get_formatted_string(PLpgSQL_checkstate *cstate,
								   const char *fmt,
								   List *args,
								   bool *found_ident_placeholder,
								   bool *found_literal_placeholder,
								   bool *expr_is_const)
{
	StringInfoData sinfo;
	const char *cp;
	const char *end_ptr = fmt + strlen(fmt);
	int			nargs = list_length(args);
	int			arg = 1;
	int			_arg;
	bool		is_error;

	*found_ident_placeholder = false;
	*found_literal_placeholder = false;
	*expr_is_const = true;

	initStringInfo(&sinfo);

	/* Scan format string, looking for conversion specifiers. */
	for (cp = fmt; cp < end_ptr; cp++)
	{
		int			argpos;
		int			widthpos;

		if (*cp != '%')
		{
			appendStringInfoChar(&sinfo, *cp);
			continue;
		}

		if (++cp >= end_ptr)
		{
			pfree(sinfo.data);
			return NULL;
		}

		if (*cp == '%')
		{
			appendStringInfoChar(&sinfo, '%');
			continue;
		}

		/* Parse the optional portions of the format specifier */
		cp = text_format_parse_format(cp, end_ptr,
									  &argpos, &widthpos,
									  -1, NULL, &is_error);

		if (is_error || strchr("sIL", *cp) == NULL)
		{
			pfree(sinfo.data);
			return NULL;
		}

		if (widthpos >= 0)
		{
			if (widthpos > 0)
			{
				if (widthpos > nargs)
				{
					pfree(sinfo.data);
					return NULL;
				}
			}
			else
			{
				if (++arg > nargs)
				{
					pfree(sinfo.data);
					return NULL;
				}
			}
		}

		_arg = argpos >= 1 ? argpos + 1 : arg + 1;
		if (_arg <= nargs)
		{
			char	   *str;

			str = plpgsql_check_get_const_string(cstate, list_nth(args, _arg - 1), NULL);

			if (*cp == 'I')
			{
				if (!str)
				{
					appendStringInfoString(&sinfo, "\"%I\"");
					*found_ident_placeholder = true;
					*expr_is_const = false;
				}
				else
					appendStringInfoString(&sinfo, quote_identifier(str));
			}
			else if (*cp == 'L')
			{
				if (!str)
				{
					/*
					 * Original idea was used external parameter, but external
					 * parameters requires known type, so most safe value is
					 * NULL instead.
					 */
					appendStringInfoString(&sinfo, " null ");
					*found_literal_placeholder = true;
					*expr_is_const = false;
				}
				else
				{
					char	   *qstr = quote_literal_cstr(str);

					appendStringInfoString(&sinfo, qstr);
					pfree(qstr);
				}
			}
			else
			{
				if (!str)
				{
					pfree(sinfo.data);
					*expr_is_const = false;
					return NULL;
				}
				else
					appendStringInfoString(&sinfo, str);
			}
		}

		if (argpos >= 1)
		{
			if (argpos > nargs)
			{
				pfree(sinfo.data);
				return NULL;
			}
		}
		else
		{
			if (++arg > nargs)
			{
				pfree(sinfo.data);
				return NULL;
			}
		}
	}

	return sinfo.data;
}

/*
 * Returns number of rquired arguments or -1 when we cannot detect this number.
 * When no_error is true, then this function doesn't raise a error or warning.
 */
static int
check_fmt_string(const char *fmt,
				 List *args,
				 int location,
				 check_funcexpr_walker_params *wp,
				 bool *is_error,
				 int *unsafe_expr_location,
				 bool no_error)
{
	const char *cp;
	const char *end_ptr = fmt + strlen(fmt);
	int			nargs = list_length(args);
	int			required_nargs = 0;
	int			arg = 1;

	/* Scan format string, looking for conversion specifiers. */
	for (cp = fmt; cp < end_ptr; cp++)
	{
		int			argpos;
		int			widthpos;

		if (*cp != '%')
			continue;

		ADVANCE_PARSE_POINTER(cp, end_ptr);

		if (*cp == '%')
			continue;

		/* Parse the optional portions of the format specifier */
		cp = text_format_parse_format(cp, end_ptr,
									  &argpos, &widthpos,
									  location, wp, is_error);

		if (*is_error)
			return -1;

		/*
		 * Next we should see the main conversion specifier.  Whether or not
		 * an argument position was present, it's known that at least one
		 * character remains in the string at this point.  Experience suggests
		 * that it's worth checking that that character is one of the expected
		 * ones before we try to fetch arguments, so as to produce the least
		 * confusing response to a mis-formatted specifier.
		 */
		if (strchr("sIL", *cp) == NULL)
		{
			StringInfoData sinfo;

			initStringInfo(&sinfo);

			appendStringInfo(&sinfo,
							 "unrecognized format() type specifier \"%c\"", *cp);

			if (!no_error)
				plpgsql_check_put_error(wp->cstate,
										ERRCODE_INVALID_PARAMETER_VALUE, 0,
										sinfo.data,
										NULL,
										NULL,
										PLPGSQL_CHECK_ERROR,
										location,
										wp->query_str, NULL);

			pfree(sinfo.data);

			*is_error = true;
			return -1;
		}

		if (widthpos >= 0)
		{
			if (widthpos > 0)
			{
				TOO_FEW_ARGUMENTS_CHECK(widthpos, nargs);
				required_nargs = -1;
			}
			else
			{
				TOO_FEW_ARGUMENTS_CHECK(++arg, nargs);
				if (required_nargs != -1)
					required_nargs += 1;
			}
		}

		/* Check safety of argument againt SQL injection when it is required */
		if (unsafe_expr_location)
		{
			if (*cp == 's')
			{
				int			argn = argpos >= 1 ? argpos : arg + 1;

				/*
				 * this is usually called after format check, but better be
				 * safe
				 */
				if (argn <= nargs)
				{
					if (plpgsql_check_is_sql_injection_vulnerable(wp->cstate,
																  wp->expr,
																  list_nth(args, argn - 1),
																  unsafe_expr_location))
					{
						/* found vulnerability, stop */
						*is_error = false;
						return -1;
					}
				}
			}
		}

		if (argpos >= 1)
		{
			TOO_FEW_ARGUMENTS_CHECK(argpos, nargs);
			required_nargs = -1;
		}
		else
		{
			TOO_FEW_ARGUMENTS_CHECK(++arg, nargs);
			if (required_nargs != -1)
				required_nargs += 1;
		}
	}

	return required_nargs;
}

/*
 * Try to detect relations in query
 */
static bool
has_rtable_walker(Node *node, void *context)
{
	if (node == NULL)
		return false;

	if (IsA(node, Query))
	{
		Query	   *query = (Query *) node;
		bool		has_relation = false;
		ListCell   *lc;

		foreach(lc, query->rtable)
		{
			RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);

			if (rte->rtekind == RTE_RELATION)
			{
				has_relation = true;
				break;
			}
		}

		if (has_relation)
		{
			return true;
		}
		else
			return query_tree_walker(query, has_rtable_walker, context, 0);
	}
	return expression_tree_walker(node, has_rtable_walker, context);
}

/*
 * Returns true, if query use any relation
 */
bool
plpgsql_check_has_rtable(Query *query)
{
	return has_rtable_walker((Node *) query, NULL);
}

/*
 * Try to identify constraint where variable from one side is implicitly casted to
 * parameter type of second side. It can symptom of parameter wrong type.
 *
 */
static bool
contain_fishy_cast_walker(Node *node, void *context)
{
	if (node == NULL)
		return false;

	if (IsA(node, OpExpr))
	{
		OpExpr	   *opexpr = (OpExpr *) node;

		if (!opexpr->opretset && opexpr->opresulttype == BOOLOID
			&& list_length(opexpr->args) == 2)
		{
			Node	   *l1 = linitial(opexpr->args);
			Node	   *l2 = lsecond(opexpr->args);
			Param	   *param = NULL;
			FuncExpr   *fexpr = NULL;

			if (IsA(l1, Param))
				param = (Param *) l1;
			else if (IsA(l1, FuncExpr))
				fexpr = (FuncExpr *) l1;

			if (IsA(l2, Param))
				param = (Param *) l2;
			else if (IsA(l2, FuncExpr))
				fexpr = (FuncExpr *) l2;

			if (param != NULL && fexpr != NULL)
			{
				if (param->paramkind != PARAM_EXTERN)
					return false;

				if (fexpr->funcformat != COERCE_IMPLICIT_CAST ||
					fexpr->funcretset ||
					list_length(fexpr->args) != 1 ||
					param->paramtype != fexpr->funcresulttype)
					return false;

				if (!IsA(linitial(fexpr->args), Var))
					return false;

				*((Param **) context) = param;

				return true;
			}
		}
	}

	return expression_tree_walker(node, contain_fishy_cast_walker, context);
}

bool
plpgsql_check_qual_has_fishy_cast(PlannedStmt *plannedstmt, Plan *plan, Param **param)
{
	ListCell   *lc;

	if (plan == NULL)
		return false;

	if (contain_fishy_cast_walker((Node *) plan->qual, param))
		return true;

	if (plpgsql_check_qual_has_fishy_cast(plannedstmt, innerPlan(plan), param))
		return true;
	if (plpgsql_check_qual_has_fishy_cast(plannedstmt, outerPlan(plan), param))
		return true;

	foreach(lc, plan->initPlan)
	{
		SubPlan    *subplan = (SubPlan *) lfirst(lc);
		Plan	   *s_plan = exec_subplan_get_plan(plannedstmt, subplan);

		if (plpgsql_check_qual_has_fishy_cast(plannedstmt, s_plan, param))
			return true;
	}

	return false;
}

#define QUOTE_IDENT_OID			1282
#define QUOTE_LITERAL_OID		1283
#define QUOTE_NULLABLE_OID		1289

/*
 * Recursive iterate to deep and search extern params with typcategory "S", and check
 * if this value is sanitized. Flag is_safe is true, when result is safe.
 */
bool
plpgsql_check_is_sql_injection_vulnerable(PLpgSQL_checkstate *cstate,
										  PLpgSQL_expr *expr,
										  Node *node,
										  int *location)
{
	if (IsA(node, FuncExpr))
	{
		FuncExpr   *fexpr = (FuncExpr *) node;
		bool		is_vulnerable = false;
		ListCell   *lc;

		foreach(lc, fexpr->args)
		{
			Node	   *arg = lfirst(lc);

			if (plpgsql_check_is_sql_injection_vulnerable(cstate, expr, arg, location))
			{
				is_vulnerable = true;
				break;
			}
		}

		if (is_vulnerable)
		{
			bool		typispreferred;
			char		typcategory;

			get_type_category_preferred(fexpr->funcresulttype,
										&typcategory,
										&typispreferred);

			if (typcategory == 'S')
			{
				switch (fexpr->funcid)
				{
					case QUOTE_IDENT_OID:
					case QUOTE_LITERAL_OID:
					case QUOTE_NULLABLE_OID:
						return false;

					case FORMAT_0PARAM_OID:
					case FORMAT_NPARAM_OID:
						{
							/*
							 * We can do check only when first argument is
							 * constant
							 */
							char	   *fmt;
							int			loc;

							fmt = plpgsql_check_get_const_string(cstate, linitial(fexpr->args), &loc);

							if (fmt)
							{
								check_funcexpr_walker_params wp;
								bool		is_error;

								wp.cstate = cstate;
								wp.expr = expr;
								wp.query_str = expr->query;

								*location = -1;
								check_fmt_string(fmt, fexpr->args, loc, &wp, &is_error, location, true);

								/*
								 * only in this case, "format" function
								 * obviously sanitize parameters
								 */
								if (!is_error)
									return *location != -1;
							}
						}
						break;
					default:
						/* do nothing */
						;
				}

				return true;
			}
		}

		return false;
	}
	else if (IsA(node, OpExpr))
	{
		OpExpr	   *op = (OpExpr *) node;
		bool		is_vulnerable = false;
		ListCell   *lc;

		foreach(lc, op->args)
		{
			Node	   *arg = lfirst(lc);

			if (plpgsql_check_is_sql_injection_vulnerable(cstate, expr, arg, location))
			{
				is_vulnerable = true;
				break;
			}
		}

		if (is_vulnerable)
		{
			bool		typispreferred;
			char		typcategory;

			get_type_category_preferred(op->opresulttype,
										&typcategory,
										&typispreferred);
			if (typcategory == 'S')
			{
				char	   *opname = get_opname(op->opno);
				bool		result = false;

				if (opname)
				{
					result = strcmp(opname, "||") == 0;

					pfree(opname);
				}

				return result;
			}
		}

		return false;
	}
	else if (IsA(node, NamedArgExpr))
	{
		return plpgsql_check_is_sql_injection_vulnerable(cstate, expr, (Node *) ((NamedArgExpr *) node)->arg, location);
	}
	else if (IsA(node, RelabelType))
	{
		return plpgsql_check_is_sql_injection_vulnerable(cstate, expr, (Node *) ((RelabelType *) node)->arg, location);
	}
	else if (IsA(node, Param))
	{
		Param	   *p = (Param *) node;

		if (p->paramkind == PARAM_EXTERN || p->paramkind == PARAM_EXEC)
		{
			bool		typispreferred;
			char		typcategory;

			get_type_category_preferred(p->paramtype, &typcategory, &typispreferred);
			if (typcategory == 'S')
			{
				if (p->paramkind == PARAM_EXTERN && p->paramid > 0 && p->location != -1)
				{
					int			dno = p->paramid - 1;

					/*
					 * When paramid looks well and related datum is variable
					 * with same type, then we can check, if this variable has
					 * sanitized content already.
					 */
					if (expr && bms_is_member(dno, expr->paramnos))
					{
						PLpgSQL_var *var = (PLpgSQL_var *) cstate->estate->datums[dno];

						if (var->dtype == PLPGSQL_DTYPE_VAR)
						{
							if (var->datatype->typoid == p->paramtype)
							{
								if (bms_is_member(dno, cstate->safe_variables))
									return false;
							}
						}
					}
				}

				*location = p->location;
				return true;
			}
		}

		return false;
	}
	else
		return false;
}

/*
 * These checker function returns volatility or immutability of any function.
 * Special case is plpgsql_check_pragma function. This function is vollatile,
 * but we should to fake flags to be immutable - becase we would not to change
 * result of analyzes and we know so this function has not any negative side
 * effect.
 */
static bool
contain_volatile_functions_checker(Oid func_id, void *context)
{
	PLpgSQL_checkstate *cstate = (PLpgSQL_checkstate *) context;

	if (func_id == cstate->pragma_foid)
		return false;

	return (func_volatile(func_id) == PROVOLATILE_VOLATILE);
}

static bool
contain_mutable_functions_checker(Oid func_id, void *context)
{
	PLpgSQL_checkstate *cstate = (PLpgSQL_checkstate *) context;

	if (func_id == cstate->pragma_foid)
		return false;

	return (func_volatile(func_id) != PROVOLATILE_IMMUTABLE);
}

static bool
contain_volatile_functions_walker(Node *node, void *context)
{
	if (node == NULL)
		return false;

	/* Check for volatile functions in node itself */
	if (check_functions_in_node(node, contain_volatile_functions_checker,
								context))
		return true;

	if (IsA(node, NextValueExpr))
	{
		/* NextValueExpr is volatile */
		return true;
	}

	/*
	 * See notes in contain_mutable_functions_walker about why we treat
	 * MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
	 * SQLValueFunction is stable.  Hence, none of them are of interest here.
	 */

	/* Recurse to check arguments */
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		return query_tree_walker((Query *) node,
								 contain_volatile_functions_walker,
								 context, 0);
	}
	return expression_tree_walker(node, contain_volatile_functions_walker,
								  context);
}

static bool
contain_mutable_functions_walker(Node *node, void *context)
{
	if (node == NULL)
		return false;

	/* Check for mutable functions in node itself */
	if (check_functions_in_node(node, contain_mutable_functions_checker,
								context))
		return true;

	if (IsA(node, SQLValueFunction))
	{
		/* all variants of SQLValueFunction are stable */
		return true;
	}

	if (IsA(node, NextValueExpr))
	{
		/* NextValueExpr is volatile */
		return true;
	}

	/*
	 * It should be safe to treat MinMaxExpr as immutable, because it will
	 * depend on a non-cross-type btree comparison function, and those should
	 * always be immutable.  Treating XmlExpr as immutable is more dubious,
	 * and treating CoerceToDomain as immutable is outright dangerous.  But we
	 * have done so historically, and changing this would probably cause more
	 * problems than it would fix.  In practice, if you have a non-immutable
	 * domain constraint you are in for pain anyhow.
	 */

	/* Recurse to check arguments */
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		return query_tree_walker((Query *) node,
								 contain_mutable_functions_walker,
								 context, 0);
	}
	return expression_tree_walker(node, contain_mutable_functions_walker,
								  context);
}

/*
 * This is same like Postgres buildin function, but it ignores used
 * plpgsql_check pragma function
 */
bool
plpgsql_check_contain_volatile_functions(Node *clause, PLpgSQL_checkstate *cstate)
{
	return contain_volatile_functions_walker(clause, cstate);
}


bool
plpgsql_check_contain_mutable_functions(Node *clause, PLpgSQL_checkstate *cstate)
{
	return contain_mutable_functions_walker(clause, cstate);
}

static bool
has_external_param_with_paramid(Node *node, void *context)
{
	if (node == NULL)
		return false;

	if (IsA(node, Param))
	{
		Param	   *p = (Param *) node;

		if (p->paramkind == PARAM_EXTERN &&
			p->paramid > 0 && p->location != -1)
		{
			int			dno = p->paramid - 1;

			if (dno == *((int *) context))
				return true;
		}
	}

	return expression_tree_walker(node, has_external_param_with_paramid, context);
}

/*
 * This walker is used for checking usage target_param elsewhere than top subscripting
 * node.
 */
bool
plpgsql_check_vardno_is_used_for_reading(Node *node, int dno)
{
	if (node == NULL)
		return false;

	if (IsA(node, SubscriptingRef))
		node = (Node *) ((SubscriptingRef *) node)->refassgnexpr;

	return has_external_param_with_paramid(node, (void *) &dno);
}
