zeek/src/Var.cc

// See the file "COPYING" in the main distribution directory for copyright.

#include "zeek/Var.h"

#include "zeek/zeek-config.h"

#include <memory>

#include "zeek/EventRegistry.h"
#include "zeek/Expr.h"
#include "zeek/Func.h"
#include "zeek/ID.h"
#include "zeek/IntrusivePtr.h"
#include "zeek/Reporter.h"
#include "zeek/Scope.h"
#include "zeek/Stmt.h"
#include "zeek/Traverse.h"
#include "zeek/Val.h"
#include "zeek/module_util.h"
#include "zeek/script_opt/ScriptOpt.h"
#include "zeek/script_opt/StmtOptInfo.h"

namespace zeek::detail
	{

static bool add_prototype(const IDPtr& id, Type* t, std::vector<AttrPtr>* attrs,
                          const ExprPtr& init)
	{
	if ( ! IsFunc(id->GetType()->Tag()) )
		return false;

	if ( ! IsFunc(t->Tag()) )
		{
		t->Error("type incompatible with previous definition", id.get());
		return false;
		}

	auto canon_ft = id->GetType()->AsFuncType();
	auto alt_ft = t->AsFuncType();

	if ( canon_ft->Flavor() != alt_ft->Flavor() )
		{
		alt_ft->Error("incompatible function flavor", canon_ft);
		return false;
		}

	if ( canon_ft->Flavor() == FUNC_FLAVOR_FUNCTION )
		{
		alt_ft->Error("redeclaration of function", canon_ft);
		return false;
		}

	if ( init )
		{
		init->Error("initialization not allowed during event/hook alternate prototype declaration");
		return false;
		}

	const auto& canon_args = canon_ft->Params();
	const auto& alt_args = alt_ft->Params();

	if ( auto p = canon_ft->FindPrototype(*alt_args); p )
		{
		alt_ft->Error("alternate function prototype already exists", p->args.get());
		return false;
		}

	std::map<int, int> offsets;

	for ( auto i = 0; i < alt_args->NumFields(); ++i )
		{
		auto field = alt_args->FieldName(i);

		if ( alt_args->FieldDecl(i)->attrs )
			{
			alt_ft->Error(
				util::fmt(
					"alternate function prototype arguments may not have attributes: arg '%s'",
					field),
				canon_ft);
			return false;
			}

		auto o = canon_args->FieldOffset(field);

		if ( o < 0 )
			{
			alt_ft->Error(
				util::fmt("alternate function prototype arg '%s' not found in canonical prototype",
			              field),
				canon_ft);
			return false;
			}

		offsets[o] = i;
		}

	auto deprecated = false;
	std::string depr_msg;

	if ( attrs )
		for ( const auto& a : *attrs )
			if ( a->Tag() == ATTR_DEPRECATED )
				{
				deprecated = true;
				depr_msg = a->DeprecationMessage();
				break;
				}

	FuncType::Prototype p;
	p.deprecated = deprecated;
	p.deprecation_msg = std::move(depr_msg);
	p.args = alt_args;
	p.offsets = std::move(offsets);

	canon_ft->AddPrototype(std::move(p));
	return true;
	}

static void initialize_var(const IDPtr& id, InitClass c, ExprPtr init)
	{
	if ( ! id->HasVal() )
		{
		if ( c == INIT_REMOVE )
			return;

		bool no_init = ! init;

		if ( ! no_init && init->Tag() == EXPR_LIST )
			no_init = init->AsListExpr()->Exprs().empty();

		if ( no_init )
			{
			auto& t = id->GetType();

			if ( ! IsAggr(t) )
				return;

			ValPtr init_val;

			if ( t->Tag() == TYPE_RECORD )
				{
				try
					{
					init_val = make_intrusive<RecordVal>(cast_intrusive<RecordType>(t));
					}
				catch ( InterpreterException& )
					{
					id->Error("initialization failed");
					return;
					}
				}

			else if ( t->Tag() == TYPE_TABLE )
				init_val = make_intrusive<TableVal>(cast_intrusive<TableType>(t), id->GetAttrs());

			else if ( t->Tag() == TYPE_VECTOR )
				init_val = make_intrusive<VectorVal>(cast_intrusive<VectorType>(t));

			id->SetVal(init_val);
			return;
			}

		if ( c == INIT_EXTRA )
			c = INIT_FULL;
		}

	bool is_const = id->IsConst() || id->IsOption();
	auto lhs = make_intrusive<NameExpr>(id, is_const);
	ExprPtr assignment;

	if ( c == INIT_FULL )
		assignment = make_intrusive<AssignExpr>(lhs, init, false);
	else if ( c == INIT_EXTRA )
		assignment = make_intrusive<AddToExpr>(lhs, init);
	else if ( c == INIT_REMOVE )
		assignment = make_intrusive<RemoveFromExpr>(lhs, init);
	else
		reporter->InternalError("bad InitClass in initialize_var");

	if ( assignment->IsError() )
		return;

	try
		{
		(void)assignment->Eval(nullptr);
		}
	catch ( InterpreterException& )
		{
		id->Error("initialization failed");
		}
	}

static void make_var(const IDPtr& id, TypePtr t, InitClass c, ExprPtr init,
                     std::unique_ptr<std::vector<AttrPtr>> attr, DeclType dt, bool do_init)
	{
	if ( c == INIT_NONE && init )
		{
		// This can happen because the grammar allows any "init_class",
		// including none, to be followed by an expression.
		init->Warn("initialization not preceded by =/+=/-= is deprecated");

		// The historical instances of these, such as the
		// language/redef-same-prefixtable-idx.zeek btest, treat
		// this as += rather than =, and with the initializer
		// implicitly inside a list.
		init = make_intrusive<ListExpr>(init);
		c = INIT_EXTRA;
		}

	if ( init && init->Tag() == EXPR_LIST )
		{
		auto& init_t = t ? t : id->GetType();
		init = expand_op(cast_intrusive<ListExpr>(init), init_t);
		}

	if ( id->GetType() )
		{
		if ( id->IsRedefinable() || (! init && attr && ! IsFunc(id->GetType()->Tag())) )
			{
			Obj* redef_obj = init ? (Obj*)init.get() : (Obj*)t.get();
			if ( dt != VAR_REDEF )
				id->Warn("redefinition requires \"redef\"", redef_obj, true);
			}

		else if ( dt != VAR_REDEF || init || ! attr )
			{
			if ( IsFunc(id->GetType()->Tag()) )
				add_prototype(id, t.get(), attr.get(), init);
			else
				id->Error("already defined", init.get());

			return;
			}
		}

	if ( dt == VAR_REDEF )
		{
		if ( ! id->GetType() )
			{
			id->Error("\"redef\" used but not previously defined");
			return;
			}

		if ( ! t )
			t = id->GetType();
		}

	if ( id->GetType() && id->GetType()->Tag() != TYPE_ERROR )
		{
		if ( dt != VAR_REDEF && (! init || ! do_init || (! t && ! (t = init_type(init)))) )
			{
			id->Error("already defined", init.get());
			return;
			}

		// Allow redeclaration in order to initialize.
		if ( ! same_type(t, id->GetType()) )
			{
			id->Error("redefinition changes type", init.get());
			return;
			}
		}

	if ( t && t->IsSet() )
		{ // Check for set with explicit elements.
		SetType* st = t->AsTableType()->AsSetType();
		const auto& elements = st->Elements();

		if ( elements )
			{
			if ( init )
				{
				id->Error("double initialization", init.get());
				return;
				}

			init = elements;
			}
		}

	if ( ! t )
		{ // Take type from initialization.
		if ( ! init )
			{
			id->Error("no type given");
			return;
			}

		t = init_type(init);
		if ( ! t )
			{
			id->SetType(error_type());
			return;
			}
		}

	id->SetType(t);

	if ( attr )
		id->AddAttrs(make_intrusive<Attributes>(std::move(*attr), t, false, id->IsGlobal()),
		             dt == VAR_REDEF);

	if ( init )
		{
		switch ( init->Tag() )
			{
			case EXPR_TABLE_CONSTRUCTOR:
				{
				auto* ctor = static_cast<TableConstructorExpr*>(init.get());
				if ( ctor->GetAttrs() )
					id->AddAttrs(ctor->GetAttrs());
				else
					ctor->SetAttrs(id->GetAttrs());
				}
				break;

			case EXPR_SET_CONSTRUCTOR:
				{
				auto* ctor = static_cast<SetConstructorExpr*>(init.get());
				if ( ctor->GetAttrs() )
					id->AddAttrs(ctor->GetAttrs());
				else
					ctor->SetAttrs(id->GetAttrs());
				}
				break;

			default:
				break;
			}
		}

	if ( do_init )
		{
		if ( c == INIT_NONE && dt == VAR_REDEF && t->IsTable() && init &&
		     init->Tag() == EXPR_ASSIGN )
			// e.g. 'redef foo["x"] = 1' is missing an init class, but the
			// intention clearly isn't to overwrite entire existing table val.
			c = INIT_EXTRA;

		if ( init && ((c == INIT_EXTRA && id->GetAttr(ATTR_ADD_FUNC)) ||
		              (c == INIT_REMOVE && id->GetAttr(ATTR_DEL_FUNC))) )
			// Just apply the function.
			id->SetVal(init, c);

		else if ( dt != VAR_REDEF || init || ! attr )
			initialize_var(id, c, init);
		}

	if ( dt == VAR_CONST )
		{
		if ( ! init && ! id->IsRedefinable() )
			id->Error("const variable must be initialized");

		id->SetConst();
		}

	if ( dt == VAR_OPTION )
		{
		if ( ! init )
			id->Error("option variable must be initialized");

		id->SetOption();
		}

	id->UpdateValAttrs();

	if ( t && t->Tag() == TYPE_FUNC &&
	     (t->AsFuncType()->Flavor() == FUNC_FLAVOR_EVENT ||
	      t->AsFuncType()->Flavor() == FUNC_FLAVOR_HOOK) )
		{
		// For events, add a function value (without any body) here so that
		// we can later access the ID even if no implementations have been
		// defined.
		std::vector<IDPtr> inits;
		auto f = make_intrusive<ScriptFunc>(id, nullptr, inits, 0, 0);
		id->SetVal(make_intrusive<FuncVal>(std::move(f)));
		}
	}

void add_global(const IDPtr& id, TypePtr t, InitClass c, ExprPtr init,
                std::unique_ptr<std::vector<AttrPtr>> attr, DeclType dt)
	{
	make_var(id, std::move(t), c, std::move(init), std::move(attr), dt, true);
	}

StmtPtr add_local(IDPtr id, TypePtr t, InitClass c, ExprPtr init,
                  std::unique_ptr<std::vector<AttrPtr>> attr, DeclType dt)
	{
	make_var(id, std::move(t), c, init, std::move(attr), dt, false);

	if ( init )
		{
		if ( c != INIT_FULL )
			id->Error("can't use += / -= for initializations of local variables");

		// copy Location to the stack, because AssignExpr may free "init"
		const Location location = init->GetLocationInfo() ? *init->GetLocationInfo() : no_location;

		auto name_expr = make_intrusive<NameExpr>(id, dt == VAR_CONST);
		auto assign_expr = make_intrusive<AssignExpr>(std::move(name_expr), std::move(init), 0,
		                                              nullptr, id->GetAttrs());
		auto stmt = make_intrusive<ExprStmt>(std::move(assign_expr));
		stmt->SetLocationInfo(&location);
		return stmt;
		}

	else
		{
		current_scope()->AddInit(std::move(id));
		return make_intrusive<NullStmt>();
		}
	}

extern ExprPtr add_and_assign_local(IDPtr id, ExprPtr init, ValPtr val)
	{
	make_var(id, nullptr, INIT_FULL, init, nullptr, VAR_REGULAR, false);
	auto name_expr = make_intrusive<NameExpr>(std::move(id));
	return make_intrusive<AssignExpr>(std::move(name_expr), std::move(init), false, std::move(val));
	}

void add_type(ID* id, TypePtr t, std::unique_ptr<std::vector<AttrPtr>> attr)
	{
	std::string new_type_name = id->Name();
	std::string old_type_name = t->GetName();
	TypePtr tnew;

	if ( (t->Tag() == TYPE_RECORD || t->Tag() == TYPE_ENUM) && old_type_name.empty() )
		// An extensible type (record/enum) being declared for first time.
		tnew = std::move(t);
	else
		// Clone the type to preserve type name aliasing.
		tnew = t->ShallowClone();

	Type::RegisterAlias(new_type_name, tnew);

	if ( new_type_name != old_type_name && ! old_type_name.empty() )
		Type::RegisterAlias(old_type_name, tnew);

	tnew->SetName(id->Name());

	id->SetType(tnew);
	id->MakeType();

	if ( attr )
		id->SetAttrs(make_intrusive<Attributes>(std::move(*attr), tnew, false, false));
	}

static void transfer_arg_defaults(RecordType* args, RecordType* recv)
	{
	for ( int i = 0; i < args->NumFields(); ++i )
		{
		TypeDecl* args_i = args->FieldDecl(i);
		TypeDecl* recv_i = recv->FieldDecl(i);

		const auto& def = args_i->attrs ? args_i->attrs->Find(ATTR_DEFAULT) : nullptr;

		if ( ! def )
			continue;

		if ( ! recv_i->attrs )
			{
			std::vector<AttrPtr> a{def};
			recv_i->attrs = make_intrusive<Attributes>(std::move(a), recv_i->type, true, false);
			}

		else if ( ! recv_i->attrs->Find(ATTR_DEFAULT) )
			recv_i->attrs->AddAttr(def);
		}
	}

static Attr* find_attr(const std::vector<AttrPtr>* al, AttrTag tag)
	{
	if ( ! al )
		return nullptr;

	for ( size_t i = 0; i < al->size(); ++i )
		if ( (*al)[i]->Tag() == tag )
			return (*al)[i].get();

	return nullptr;
	}

static std::optional<FuncType::Prototype> func_type_check(const FuncType* decl,
                                                          const FuncType* impl)
	{
	if ( decl->Flavor() != impl->Flavor() )
		{
		impl->Error("incompatible function flavor", decl);
		return {};
		}

	if ( impl->Flavor() == FUNC_FLAVOR_FUNCTION )
		{
		if ( same_type(decl, impl) )
			return decl->Prototypes()[0];

		impl->Error("incompatible function types", decl);
		return {};
		}

	auto rval = decl->FindPrototype(*impl->Params());

	if ( rval )
		for ( auto i = 0; i < rval->args->NumFields(); ++i )
			if ( auto ad = rval->args->FieldDecl(i)->GetAttr(ATTR_DEPRECATED) )
				{
				auto msg = ad->DeprecationMessage();

				if ( msg.empty() )
					impl->Warn(
						util::fmt("use of deprecated parameter '%s'", rval->args->FieldName(i)),
						decl, true);
				else
					impl->Warn(util::fmt("use of deprecated parameter '%s': %s",
					                     rval->args->FieldName(i), msg.data()),
					           decl, true);
				}

	return rval;
	}

static bool canonical_arg_types_match(const FuncType* decl, const FuncType* impl)
	{
	const auto& canon_args = decl->Params();
	const auto& impl_args = impl->Params();

	if ( canon_args->NumFields() != impl_args->NumFields() )
		return false;

	for ( auto i = 0; i < canon_args->NumFields(); ++i )
		if ( ! same_type(canon_args->GetFieldType(i), impl_args->GetFieldType(i)) )
			return false;

	return true;
	}

static auto get_prototype(IDPtr id, FuncTypePtr t)
	{
	auto decl = id->GetType()->AsFuncType();
	auto prototype = func_type_check(decl, t.get());

	if ( prototype )
		{
		if ( decl->Flavor() == FUNC_FLAVOR_FUNCTION )
			{
			// If a previous declaration of the function had
			// &default params, automatically transfer any that
			// are missing (convenience so that implementations
			// don't need to specify the &default expression again).
			transfer_arg_defaults(prototype->args.get(), t->Params().get());
			}
		else
			{
			// Warn for trying to use &default parameters in
			// hook/event handler body when it already has a
			// declaration since only &default in the declaration
			// has any effect.
			const auto& args = t->Params();

			for ( int i = 0; i < args->NumFields(); ++i )
				{
				auto f = args->FieldDecl(i);

				if ( f->attrs && f->attrs->Find(ATTR_DEFAULT) )
					{
					reporter->PushLocation(args->GetLocationInfo());
					reporter->Warning(
						"&default on parameter '%s' has no effect (not a %s declaration)",
						args->FieldName(i), t->FlavorString().data());
					reporter->PopLocation();
					}
				}
			}

		if ( prototype->deprecated )
			{
			if ( prototype->deprecation_msg.empty() )
				t->Warn(util::fmt("use of deprecated '%s' prototype", id->Name()),
				        prototype->args.get(), true);
			else
				t->Warn(util::fmt("use of deprecated '%s' prototype: %s", id->Name(),
				                  prototype->deprecation_msg.data()),
				        prototype->args.get(), true);
			}
		}

	else
		{
		// Allow renaming arguments, but only for the canonical
		// prototypes of hooks/events.
		if ( canonical_arg_types_match(decl, t.get()) )
			prototype = decl->Prototypes()[0];
		else
			t->Error("use of undeclared alternate prototype", id.get());
		}

	return prototype;
	}

static bool check_params(int i, std::optional<FuncType::Prototype> prototype,
                         const RecordTypePtr& args, const RecordTypePtr& canon_args,
                         const char* module_name)
	{
	TypeDecl* arg_i;
	bool hide = false;

	if ( prototype )
		{
		auto it = prototype->offsets.find(i);

		if ( it == prototype->offsets.end() )
			{
			// Alternate prototype hides this param
			hide = true;
			arg_i = canon_args->FieldDecl(i);
			}
		else
			{
			// Alternate prototype maps this param to another index
			arg_i = args->FieldDecl(it->second);
			}
		}
	else
		{
		if ( i < args->NumFields() )
			arg_i = args->FieldDecl(i);
		else
			return false;
		}

	auto arg_id = lookup_ID(arg_i->id, module_name);

	if ( arg_id && ! arg_id->IsGlobal() )
		arg_id->Error("argument name used twice");

	const char* local_name = arg_i->id;

	if ( hide )
		// Note the illegal '-' in hidden name implies we haven't
		// clobbered any local variable names.
		local_name = util::fmt("%s-hidden", local_name);

	arg_id = install_ID(local_name, module_name, false, false);
	arg_id->SetType(arg_i->type);

	return true;
	}

void begin_func(IDPtr id, const char* module_name, FunctionFlavor flavor, bool is_redef,
                FuncTypePtr t, std::unique_ptr<std::vector<AttrPtr>> attrs)
	{
	if ( flavor == FUNC_FLAVOR_EVENT )
		{
		const auto& yt = t->Yield();

		if ( yt && yt->Tag() != TYPE_VOID )
			id->Error("event cannot yield a value", t.get());

		t->ClearYieldType(flavor);
		}

	std::optional<FuncType::Prototype> prototype;

	if ( id->GetType() )
		{
		if ( id->GetType()->Tag() != TYPE_FUNC )
			{
			id->Error("Function clash with previous definition with incompatible type", t.get());
			reporter->FatalError("invalid definition of '%s' (see previous errors)", id->Name());
			}
		prototype = get_prototype(id, t);
		}
	else if ( is_redef )
		id->Error("redef of not-previously-declared value");

	if ( id->HasVal() )
		{
		FunctionFlavor id_flavor = id->GetVal()->AsFunc()->Flavor();

		if ( id_flavor != flavor )
			id->Error("inconsistent function flavor", t.get());

		switch ( id_flavor )
			{

			case FUNC_FLAVOR_EVENT:
			case FUNC_FLAVOR_HOOK:
				if ( is_redef )
					// Clear out value so it will be replaced.
					id->SetVal(nullptr);
				break;

			case FUNC_FLAVOR_FUNCTION:
				if ( ! id->IsRedefinable() )
					id->Error("already defined", t.get());
				break;

			default:
				reporter->InternalError("invalid function flavor");
				break;
			}
		}
	else
		id->SetType(t);

	if ( IsErrorType(id->GetType()->Tag()) )
		reporter->FatalError("invalid definition of '%s' (see previous errors)", id->Name());

	const auto& args = t->Params();
	const auto& canon_args = id->GetType()->AsFuncType()->Params();

	push_scope(std::move(id), std::move(attrs));

	for ( int i = 0; i < canon_args->NumFields(); ++i )
		if ( ! check_params(i, prototype, args, canon_args, module_name) )
			break;

	if ( Attr* depr_attr = find_attr(current_scope()->Attrs().get(), ATTR_DEPRECATED) )
		current_scope()->GetID()->MakeDeprecated(depr_attr->GetExpr());
	}

class OuterIDBindingFinder : public TraversalCallback
	{
public:
	OuterIDBindingFinder(ScopePtr s) { scopes.emplace_back(s); }

	TraversalCode PreStmt(const Stmt*) override;
	TraversalCode PreExpr(const Expr*) override;
	TraversalCode PostExpr(const Expr*) override;

	std::vector<ScopePtr> scopes;
	std::unordered_set<ID*> outer_id_references;
	};

TraversalCode OuterIDBindingFinder::PreStmt(const Stmt* stmt)
	{
	if ( stmt->Tag() != STMT_WHEN )
		return TC_CONTINUE;

	auto ws = static_cast<const WhenStmt*>(stmt);
	auto lambda = ws->Info()->Lambda();

	if ( ! lambda )
		// Old-style semantics.
		return TC_CONTINUE;

	// The semantics of identifiers for the "when" statement are those
	// of the lambda it's transformed into.
	lambda->Traverse(this);
	return TC_ABORTSTMT;
	}

TraversalCode OuterIDBindingFinder::PreExpr(const Expr* expr)
	{
	if ( expr->Tag() == EXPR_LAMBDA )
		{
		auto le = static_cast<const LambdaExpr*>(expr);
		scopes.emplace_back(le->GetScope());
		return TC_CONTINUE;
		}

	if ( expr->Tag() != EXPR_NAME )
		return TC_CONTINUE;

	auto* e = static_cast<const NameExpr*>(expr);

	if ( e->Id()->IsGlobal() )
		return TC_CONTINUE;

	for ( const auto& scope : scopes )
		if ( scope->Find(e->Id()->Name()) )
			// Shadowing is not allowed, so if it's found at inner scope, it's
			// not something we have to worry about also being at outer scope.
			return TC_CONTINUE;

	outer_id_references.insert(e->Id());
	return TC_CONTINUE;
	}

TraversalCode OuterIDBindingFinder::PostExpr(const Expr* expr)
	{
	if ( expr->Tag() == EXPR_LAMBDA )
		scopes.pop_back();

	return TC_CONTINUE;
	}

// The following is only used for debugging AST duplication.  If activated,
// each AST is replaced with its duplicate.  In the absence of a duplication
// error, this shouldn't change any semantics, so running the test suite
// with this variable set can find flaws in the duplication machinery.
static bool duplicate_ASTs = getenv("ZEEK_DUPLICATE_ASTS");

void end_func(StmtPtr body, bool free_of_conditionals)
	{
	if ( duplicate_ASTs && reporter->Errors() == 0 )
		// Only try duplication in the absence of errors.  If errors
		// have occurred, they can be re-generated during the
		// duplication process, leading to regression failures due
		// to duplicated error messages.
		//
		// We duplicate twice to make sure that the AST produced
		// by duplicating can itself be correctly duplicated.
		body = body->Duplicate()->Duplicate();

	body->GetOptInfo()->is_free_of_conditionals = free_of_conditionals;

	auto ingredients = std::make_unique<function_ingredients>(pop_scope(), std::move(body));

	if ( ingredients->id->HasVal() )
		ingredients->id->GetVal()->AsFunc()->AddBody(
			ingredients->body, ingredients->inits, ingredients->frame_size, ingredients->priority);
	else
		{
		auto f = make_intrusive<ScriptFunc>(ingredients->id, ingredients->body, ingredients->inits,
		                                    ingredients->frame_size, ingredients->priority);

		ingredients->id->SetVal(make_intrusive<FuncVal>(std::move(f)));
		ingredients->id->SetConst();
		}

	auto func_ptr = cast_intrusive<FuncVal>(ingredients->id->GetVal())->AsFuncPtr();
	auto func = cast_intrusive<ScriptFunc>(func_ptr);
	func->SetScope(ingredients->scope);

	analyze_func(std::move(func));

	// Note: ideally, something would take ownership of this memory until the
	// end of script execution, but that's essentially the same as the
	// lifetime of the process at the moment, so ok to "leak" it.
	ingredients.release();
	}

IDPList gather_outer_ids(ScopePtr scope, StmtPtr body)
	{
	OuterIDBindingFinder cb(scope);
	body->Traverse(&cb);

	IDPList idl;

	for ( auto id : cb.outer_id_references )
		idl.append(id);

	return idl;
	}

	} // namespace zeek::detail