1 /*
2 * Identifier access and function closure handling.
3 *
4 * Provides the primitives for slow path identifier accesses: GETVAR,
5 * PUTVAR, DELVAR, etc. The fast path, direct register accesses, should
6 * be used for most identifier accesses. Consequently, these slow path
7 * primitives should be optimized for maximum compactness.
8 *
9 * Ecmascript environment records (declarative and object) are represented
10 * as internal objects with control keys. Environment records have a
11 * parent record ("outer environment reference") which is represented by
12 * the implicit prototype for technical reasons (in other words, it is a
13 * convenient field). The prototype chain is not followed in the ordinary
14 * sense for variable lookups.
15 *
16 * See identifier-handling.rst for more details on the identifier algorithms
17 * and the internal representation. See function-objects.rst for details on
18 * what function templates and instances are expected to look like.
19 *
20 * Care must be taken to avoid duk_tval pointer invalidation caused by
21 * e.g. value stack or object resizing.
22 *
23 * TODO: properties for function instances could be initialized much more
24 * efficiently by creating a property allocation for a certain size and
25 * filling in keys and values directly (and INCREFing both with "bulk incref"
26 * primitives.
27 *
28 * XXX: duk_hobject_getprop() and duk_hobject_putprop() calls are a bit
29 * awkward (especially because they follow the prototype chain); rework
30 * if "raw" own property helpers are added.
31 */
32
33 #include "duk_internal.h"
34
35 /*
36 * Local result type for duk__get_identifier_reference() lookup.
37 */
38
39 typedef struct {
40 duk_hobject *holder; /* for object-bound identifiers */
41 duk_tval *value; /* for register-bound and declarative env identifiers */
42 duk_int_t attrs; /* property attributes for identifier (relevant if value != NULL) */
43 duk_tval *this_binding;
44 duk_hobject *env;
45 } duk__id_lookup_result;
46
47 /*
48 * Create a new function object based on a "template function" which contains
49 * compiled bytecode, constants, etc, but lacks a lexical environment.
50 *
51 * Ecmascript requires that each created closure is a separate object, with
52 * its own set of editable properties. However, structured property values
53 * (such as the formal arguments list and the variable map) are shared.
54 * Also the bytecode, constants, and inner functions are shared.
55 *
56 * See E5 Section 13.2 for detailed requirements on the function objects;
57 * there are no similar requirements for function "templates" which are an
58 * implementation dependent internal feature. Also see function-objects.rst
59 * for a discussion on the function instance properties provided by this
60 * implementation.
61 *
62 * Notes:
63 *
64 * * Order of internal properties should match frequency of use, since the
65 * properties will be linearly scanned on lookup (functions usually don't
66 * have enough properties to warrant a hash part).
67 *
68 * * The created closure is independent of its template; they do share the
69 * same 'data' buffer object, but the template object itself can be freed
70 * even if the closure object remains reachable.
71 */
72
duk__inc_data_inner_refcounts(duk_hthread * thr,duk_hcompiledfunction * f)73 DUK_LOCAL void duk__inc_data_inner_refcounts(duk_hthread *thr, duk_hcompiledfunction *f) {
74 duk_tval *tv, *tv_end;
75 duk_hobject **funcs, **funcs_end;
76
77 /* If function creation fails due to out-of-memory, the data buffer
78 * pointer may be NULL in some cases. That's actually possible for
79 * GC code, but shouldn't be possible here because the incomplete
80 * function will be unwound from the value stack and never instantiated.
81 */
82 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, f) != NULL);
83 DUK_UNREF(thr);
84
85 tv = DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(thr->heap, f);
86 tv_end = DUK_HCOMPILEDFUNCTION_GET_CONSTS_END(thr->heap, f);
87 while (tv < tv_end) {
88 DUK_TVAL_INCREF(thr, tv);
89 tv++;
90 }
91
92 funcs = DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, f);
93 funcs_end = DUK_HCOMPILEDFUNCTION_GET_FUNCS_END(thr->heap, f);
94 while (funcs < funcs_end) {
95 DUK_HEAPHDR_INCREF(thr, (duk_heaphdr *) *funcs);
96 funcs++;
97 }
98 }
99
100 /* Push a new closure on the stack.
101 *
102 * Note: if fun_temp has NEWENV, i.e. a new lexical and variable declaration
103 * is created when the function is called, only outer_lex_env matters
104 * (outer_var_env is ignored and may or may not be same as outer_lex_env).
105 */
106
107 DUK_LOCAL const duk_uint16_t duk__closure_copy_proplist[] = {
108 /* order: most frequent to least frequent */
109 DUK_STRIDX_INT_VARMAP,
110 DUK_STRIDX_INT_FORMALS,
111 DUK_STRIDX_NAME,
112 DUK_STRIDX_INT_PC2LINE,
113 DUK_STRIDX_FILE_NAME,
114 DUK_STRIDX_INT_SOURCE
115 };
116
117 DUK_INTERNAL
duk_js_push_closure(duk_hthread * thr,duk_hcompiledfunction * fun_temp,duk_hobject * outer_var_env,duk_hobject * outer_lex_env,duk_bool_t add_auto_proto)118 void duk_js_push_closure(duk_hthread *thr,
119 duk_hcompiledfunction *fun_temp,
120 duk_hobject *outer_var_env,
121 duk_hobject *outer_lex_env,
122 duk_bool_t add_auto_proto) {
123 duk_context *ctx = (duk_context *) thr;
124 duk_hcompiledfunction *fun_clos;
125 duk_small_uint_t i;
126 duk_uint_t len_value;
127
128 DUK_ASSERT(fun_temp != NULL);
129 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, fun_temp) != NULL);
130 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_FUNCS(thr->heap, fun_temp) != NULL);
131 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_BYTECODE(thr->heap, fun_temp) != NULL);
132 DUK_ASSERT(outer_var_env != NULL);
133 DUK_ASSERT(outer_lex_env != NULL);
134 DUK_UNREF(len_value);
135
136 duk_push_compiledfunction(ctx);
137 duk_push_hobject(ctx, &fun_temp->obj); /* -> [ ... closure template ] */
138
139 fun_clos = (duk_hcompiledfunction *) duk_get_hcompiledfunction(ctx, -2);
140 DUK_ASSERT(fun_clos != NULL);
141 DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION((duk_hobject *) fun_clos));
142 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, fun_clos) == NULL);
143 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_FUNCS(thr->heap, fun_clos) == NULL);
144 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_BYTECODE(thr->heap, fun_clos) == NULL);
145
146 DUK_HCOMPILEDFUNCTION_SET_DATA(thr->heap, fun_clos, DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, fun_temp));
147 DUK_HCOMPILEDFUNCTION_SET_FUNCS(thr->heap, fun_clos, DUK_HCOMPILEDFUNCTION_GET_FUNCS(thr->heap, fun_temp));
148 DUK_HCOMPILEDFUNCTION_SET_BYTECODE(thr->heap, fun_clos, DUK_HCOMPILEDFUNCTION_GET_BYTECODE(thr->heap, fun_temp));
149
150 /* Note: all references inside 'data' need to get their refcounts
151 * upped too. This is the case because refcounts are decreased
152 * through every function referencing 'data' independently.
153 */
154
155 DUK_HBUFFER_INCREF(thr, DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, fun_clos));
156 duk__inc_data_inner_refcounts(thr, fun_temp);
157
158 fun_clos->nregs = fun_temp->nregs;
159 fun_clos->nargs = fun_temp->nargs;
160 #if defined(DUK_USE_DEBUGGER_SUPPORT)
161 fun_clos->start_line = fun_temp->start_line;
162 fun_clos->end_line = fun_temp->end_line;
163 #endif
164
165 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, fun_clos) != NULL);
166 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_FUNCS(thr->heap, fun_clos) != NULL);
167 DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_BYTECODE(thr->heap, fun_clos) != NULL);
168
169 /* XXX: could also copy from template, but there's no way to have any
170 * other value here now (used code has no access to the template).
171 */
172 DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, &fun_clos->obj, thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
173
174 /*
175 * Init/assert flags, copying them where appropriate. Some flags
176 * (like NEWENV) are processed separately below.
177 */
178
179 /* XXX: copy flags using a mask */
180
181 DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(&fun_clos->obj));
182 DUK_HOBJECT_SET_CONSTRUCTABLE(&fun_clos->obj); /* Note: not set in template (has no "prototype") */
183 DUK_ASSERT(DUK_HOBJECT_HAS_CONSTRUCTABLE(&fun_clos->obj));
184 DUK_ASSERT(!DUK_HOBJECT_HAS_BOUND(&fun_clos->obj));
185 DUK_ASSERT(DUK_HOBJECT_HAS_COMPILEDFUNCTION(&fun_clos->obj));
186 DUK_ASSERT(!DUK_HOBJECT_HAS_NATIVEFUNCTION(&fun_clos->obj));
187 DUK_ASSERT(!DUK_HOBJECT_HAS_THREAD(&fun_clos->obj));
188 /* DUK_HOBJECT_FLAG_ARRAY_PART: don't care */
189 if (DUK_HOBJECT_HAS_STRICT(&fun_temp->obj)) {
190 DUK_HOBJECT_SET_STRICT(&fun_clos->obj);
191 }
192 if (DUK_HOBJECT_HAS_NOTAIL(&fun_temp->obj)) {
193 DUK_HOBJECT_SET_NOTAIL(&fun_clos->obj);
194 }
195 /* DUK_HOBJECT_FLAG_NEWENV: handled below */
196 if (DUK_HOBJECT_HAS_NAMEBINDING(&fun_temp->obj)) {
197 /* Although NAMEBINDING is not directly needed for using
198 * function instances, it's needed by bytecode dump/load
199 * so copy it too.
200 */
201 DUK_HOBJECT_SET_NAMEBINDING(&fun_clos->obj);
202 }
203 if (DUK_HOBJECT_HAS_CREATEARGS(&fun_temp->obj)) {
204 DUK_HOBJECT_SET_CREATEARGS(&fun_clos->obj);
205 }
206 DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARRAY(&fun_clos->obj));
207 DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_STRINGOBJ(&fun_clos->obj));
208 DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARGUMENTS(&fun_clos->obj));
209
210 /*
211 * Setup environment record properties based on the template and
212 * its flags.
213 *
214 * If DUK_HOBJECT_HAS_NEWENV(fun_temp) is true, the environment
215 * records represent identifiers "outside" the function; the
216 * "inner" environment records are created on demand. Otherwise,
217 * the environment records are those that will be directly used
218 * (e.g. for declarations).
219 *
220 * _Lexenv is always set; _Varenv defaults to _Lexenv if missing,
221 * so _Varenv is only set if _Lexenv != _Varenv.
222 *
223 * This is relatively complex, see doc/identifier-handling.rst.
224 */
225
226 if (DUK_HOBJECT_HAS_NEWENV(&fun_temp->obj)) {
227 DUK_HOBJECT_SET_NEWENV(&fun_clos->obj);
228
229 if (DUK_HOBJECT_HAS_NAMEBINDING(&fun_temp->obj)) {
230 duk_hobject *proto;
231
232 /*
233 * Named function expression, name needs to be bound
234 * in an intermediate environment record. The "outer"
235 * lexical/variable environment will thus be:
236 *
237 * a) { funcname: <func>, __prototype: outer_lex_env }
238 * b) { funcname: <func>, __prototype: <globalenv> } (if outer_lex_env missing)
239 */
240
241 DUK_ASSERT(duk_has_prop_stridx(ctx, -1, DUK_STRIDX_NAME)); /* required if NAMEBINDING set */
242
243 if (outer_lex_env) {
244 proto = outer_lex_env;
245 } else {
246 proto = thr->builtins[DUK_BIDX_GLOBAL_ENV];
247 }
248
249 /* -> [ ... closure template env ] */
250 (void) duk_push_object_helper_proto(ctx,
251 DUK_HOBJECT_FLAG_EXTENSIBLE |
252 DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV),
253 proto);
254
255 /* It's important that duk_xdef_prop() is a 'raw define' so that any
256 * properties in an ancestor are never an issue (they should never be
257 * e.g. non-writable, but just in case).
258 */
259 duk_get_prop_stridx(ctx, -2, DUK_STRIDX_NAME); /* -> [ ... closure template env funcname ] */
260 duk_dup(ctx, -4); /* -> [ ... closure template env funcname closure ] */
261 duk_xdef_prop(ctx, -3, DUK_PROPDESC_FLAGS_NONE); /* -> [ ... closure template env ] */
262 /* env[funcname] = closure */
263
264 /* [ ... closure template env ] */
265
266 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_INT_LEXENV, DUK_PROPDESC_FLAGS_WC);
267 /* since closure has NEWENV, never define DUK_STRIDX_INT_VARENV, as it
268 * will be ignored anyway
269 */
270
271 /* [ ... closure template ] */
272 } else {
273 /*
274 * Other cases (function declaration, anonymous function expression,
275 * strict direct eval code). The "outer" environment will be whatever
276 * the caller gave us.
277 */
278
279 duk_push_hobject(ctx, outer_lex_env); /* -> [ ... closure template env ] */
280 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_INT_LEXENV, DUK_PROPDESC_FLAGS_WC);
281 /* since closure has NEWENV, never define DUK_STRIDX_INT_VARENV, as it
282 * will be ignored anyway
283 */
284
285 /* [ ... closure template ] */
286 }
287 } else {
288 /*
289 * Function gets no new environment when called. This is the
290 * case for global code, indirect eval code, and non-strict
291 * direct eval code. There is no direct correspondence to the
292 * E5 specification, as global/eval code is not exposed as a
293 * function.
294 */
295
296 DUK_ASSERT(!DUK_HOBJECT_HAS_NAMEBINDING(&fun_temp->obj));
297
298 duk_push_hobject(ctx, outer_lex_env); /* -> [ ... closure template env ] */
299 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_INT_LEXENV, DUK_PROPDESC_FLAGS_WC);
300
301 if (outer_var_env != outer_lex_env) {
302 duk_push_hobject(ctx, outer_var_env); /* -> [ ... closure template env ] */
303 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_INT_VARENV, DUK_PROPDESC_FLAGS_WC);
304 }
305 }
306 #ifdef DUK_USE_DDDPRINT
307 duk_get_prop_stridx(ctx, -2, DUK_STRIDX_INT_VARENV);
308 duk_get_prop_stridx(ctx, -3, DUK_STRIDX_INT_LEXENV);
309 DUK_DDD(DUK_DDDPRINT("closure varenv -> %!ipT, lexenv -> %!ipT",
310 (duk_tval *) duk_get_tval(ctx, -2),
311 (duk_tval *) duk_get_tval(ctx, -1)));
312 duk_pop_2(ctx);
313 #endif
314
315 /*
316 * Copy some internal properties directly
317 *
318 * The properties will be writable and configurable, but not enumerable.
319 */
320
321 /* [ ... closure template ] */
322
323 DUK_DDD(DUK_DDDPRINT("copying properties: closure=%!iT, template=%!iT",
324 (duk_tval *) duk_get_tval(ctx, -2),
325 (duk_tval *) duk_get_tval(ctx, -1)));
326
327 for (i = 0; i < (duk_small_uint_t) (sizeof(duk__closure_copy_proplist) / sizeof(duk_uint16_t)); i++) {
328 duk_small_int_t stridx = (duk_small_int_t) duk__closure_copy_proplist[i];
329 if (duk_get_prop_stridx(ctx, -1, stridx)) {
330 /* [ ... closure template val ] */
331 DUK_DDD(DUK_DDDPRINT("copying property, stridx=%ld -> found", (long) stridx));
332 duk_xdef_prop_stridx(ctx, -3, stridx, DUK_PROPDESC_FLAGS_WC);
333 } else {
334 DUK_DDD(DUK_DDDPRINT("copying property, stridx=%ld -> not found", (long) stridx));
335 duk_pop(ctx);
336 }
337 }
338
339 /*
340 * "length" maps to number of formals (E5 Section 13.2) for function
341 * declarations/expressions (non-bound functions). Note that 'nargs'
342 * is NOT necessarily equal to the number of arguments.
343 */
344
345 /* [ ... closure template ] */
346
347 len_value = 0;
348
349 /* XXX: use helper for size optimization */
350 if (duk_get_prop_stridx(ctx, -2, DUK_STRIDX_INT_FORMALS)) {
351 /* [ ... closure template formals ] */
352 DUK_ASSERT(duk_has_prop_stridx(ctx, -1, DUK_STRIDX_LENGTH));
353 DUK_ASSERT(duk_get_length(ctx, -1) <= DUK_UINT_MAX); /* formal arg limits */
354 len_value = (duk_uint_t) duk_get_length(ctx, -1);
355 } else {
356 /* XXX: what to do if _Formals is not empty but compiler has
357 * optimized it away -- read length from an explicit property
358 * then?
359 */
360 }
361 duk_pop(ctx);
362
363 duk_push_uint(ctx, len_value); /* [ ... closure template len_value ] */
364 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_LENGTH, DUK_PROPDESC_FLAGS_NONE);
365
366 /*
367 * "prototype" is, by default, a fresh object with the "constructor"
368 * property.
369 *
370 * Note that this creates a circular reference for every function
371 * instance (closure) which prevents refcount-based collection of
372 * function instances.
373 *
374 * XXX: Try to avoid creating the default prototype object, because
375 * many functions are not used as constructors and the default
376 * prototype is unnecessary. Perhaps it could be created on-demand
377 * when it is first accessed?
378 */
379
380 /* [ ... closure template ] */
381
382 if (add_auto_proto) {
383 duk_push_object(ctx); /* -> [ ... closure template newobj ] */
384 duk_dup(ctx, -3); /* -> [ ... closure template newobj closure ] */
385 duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_CONSTRUCTOR, DUK_PROPDESC_FLAGS_WC); /* -> [ ... closure template newobj ] */
386 duk_compact(ctx, -1); /* compact the prototype */
387 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_PROTOTYPE, DUK_PROPDESC_FLAGS_W); /* -> [ ... closure template ] */
388 }
389
390 /*
391 * "arguments" and "caller" must be mapped to throwers for strict
392 * mode and bound functions (E5 Section 15.3.5).
393 *
394 * XXX: This is expensive to have for every strict function instance.
395 * Try to implement as virtual properties or on-demand created properties.
396 */
397
398 /* [ ... closure template ] */
399
400 if (DUK_HOBJECT_HAS_STRICT(&fun_clos->obj)) {
401 duk_xdef_prop_stridx_thrower(ctx, -2, DUK_STRIDX_CALLER, DUK_PROPDESC_FLAGS_NONE);
402 duk_xdef_prop_stridx_thrower(ctx, -2, DUK_STRIDX_LC_ARGUMENTS, DUK_PROPDESC_FLAGS_NONE);
403 } else {
404 #ifdef DUK_USE_NONSTD_FUNC_CALLER_PROPERTY
405 DUK_DDD(DUK_DDDPRINT("function is non-strict and non-standard 'caller' property in use, add initial 'null' value"));
406 duk_push_null(ctx);
407 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_CALLER, DUK_PROPDESC_FLAGS_NONE);
408 #else
409 DUK_DDD(DUK_DDDPRINT("function is non-strict and non-standard 'caller' property not used"));
410 #endif
411 }
412
413 /*
414 * "name" is a non-standard property found in at least V8, Rhino, smjs.
415 * For Rhino and smjs it is non-writable, non-enumerable, and non-configurable;
416 * for V8 it is writable, non-enumerable, non-configurable. It is also defined
417 * for an anonymous function expression in which case the value is an empty string.
418 * We could also leave name 'undefined' for anonymous functions but that would
419 * differ from behavior of other engines, so use an empty string.
420 *
421 * XXX: make optional? costs something per function.
422 */
423
424 /* [ ... closure template ] */
425
426 if (duk_get_prop_stridx(ctx, -1, DUK_STRIDX_NAME)) {
427 /* [ ... closure template name ] */
428 DUK_ASSERT(duk_is_string(ctx, -1));
429 } else {
430 /* [ ... closure template undefined ] */
431 duk_pop(ctx);
432 duk_push_hstring_stridx(ctx, DUK_STRIDX_EMPTY_STRING);
433 }
434 duk_xdef_prop_stridx(ctx, -3, DUK_STRIDX_NAME, DUK_PROPDESC_FLAGS_NONE); /* -> [ ... closure template ] */
435
436 /*
437 * Compact the closure, in most cases no properties will be added later.
438 * Also, without this the closures end up having unused property slots
439 * (e.g. in Duktape 0.9.0, 8 slots would be allocated and only 7 used).
440 * A better future solution would be to allocate the closure directly
441 * to correct size (and setup the properties directly without going
442 * through the API).
443 */
444
445 duk_compact(ctx, -2);
446
447 /*
448 * Some assertions (E5 Section 13.2).
449 */
450
451 DUK_ASSERT(DUK_HOBJECT_GET_CLASS_NUMBER(&fun_clos->obj) == DUK_HOBJECT_CLASS_FUNCTION);
452 DUK_ASSERT(DUK_HOBJECT_GET_PROTOTYPE(thr->heap, &fun_clos->obj) == thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
453 DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(&fun_clos->obj));
454 DUK_ASSERT(duk_has_prop_stridx(ctx, -2, DUK_STRIDX_LENGTH) != 0);
455 DUK_ASSERT(add_auto_proto == 0 || duk_has_prop_stridx(ctx, -2, DUK_STRIDX_PROTOTYPE) != 0);
456 DUK_ASSERT(duk_has_prop_stridx(ctx, -2, DUK_STRIDX_NAME) != 0); /* non-standard */
457 DUK_ASSERT(!DUK_HOBJECT_HAS_STRICT(&fun_clos->obj) ||
458 duk_has_prop_stridx(ctx, -2, DUK_STRIDX_CALLER) != 0);
459 DUK_ASSERT(!DUK_HOBJECT_HAS_STRICT(&fun_clos->obj) ||
460 duk_has_prop_stridx(ctx, -2, DUK_STRIDX_LC_ARGUMENTS) != 0);
461
462 /*
463 * Finish
464 */
465
466 /* [ ... closure template ] */
467
468 DUK_DDD(DUK_DDDPRINT("created function instance: template=%!iT -> closure=%!iT",
469 (duk_tval *) duk_get_tval(ctx, -1),
470 (duk_tval *) duk_get_tval(ctx, -2)));
471
472 duk_pop(ctx);
473
474 /* [ ... closure ] */
475 }
476
477 /*
478 * Delayed activation environment record initialization (for functions
479 * with NEWENV).
480 *
481 * The non-delayed initialization is handled by duk_handle_call().
482 */
483
484 /* shared helper */
485 DUK_INTERNAL
duk_create_activation_environment_record(duk_hthread * thr,duk_hobject * func,duk_size_t idx_bottom)486 duk_hobject *duk_create_activation_environment_record(duk_hthread *thr,
487 duk_hobject *func,
488 duk_size_t idx_bottom) {
489 duk_context *ctx = (duk_context *) thr;
490 duk_hobject *env;
491 duk_hobject *parent;
492 duk_tval *tv;
493
494 DUK_ASSERT(thr != NULL);
495 DUK_ASSERT(func != NULL);
496
497 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, func, DUK_HTHREAD_STRING_INT_LEXENV(thr));
498 if (tv) {
499 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
500 DUK_ASSERT(DUK_HOBJECT_IS_ENV(DUK_TVAL_GET_OBJECT(tv)));
501 parent = DUK_TVAL_GET_OBJECT(tv);
502 } else {
503 parent = thr->builtins[DUK_BIDX_GLOBAL_ENV];
504 }
505
506 (void) duk_push_object_helper(ctx,
507 DUK_HOBJECT_FLAG_EXTENSIBLE |
508 DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV),
509 -1); /* no prototype, updated below */
510 env = duk_require_hobject(ctx, -1);
511 DUK_ASSERT(env != NULL);
512 DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, env, parent); /* parent env is the prototype */
513
514 /* open scope information, for compiled functions only */
515
516 if (DUK_HOBJECT_IS_COMPILEDFUNCTION(func)) {
517 duk_push_hthread(ctx, thr);
518 duk_xdef_prop_stridx_wec(ctx, -2, DUK_STRIDX_INT_THREAD);
519 duk_push_hobject(ctx, func);
520 duk_xdef_prop_stridx_wec(ctx, -2, DUK_STRIDX_INT_CALLEE);
521 duk_push_size_t(ctx, idx_bottom);
522 duk_xdef_prop_stridx_wec(ctx, -2, DUK_STRIDX_INT_REGBASE);
523 }
524
525 return env;
526 }
527
528 DUK_INTERNAL
duk_js_init_activation_environment_records_delayed(duk_hthread * thr,duk_activation * act)529 void duk_js_init_activation_environment_records_delayed(duk_hthread *thr,
530 duk_activation *act) {
531 duk_context *ctx = (duk_context *) thr;
532 duk_hobject *func;
533 duk_hobject *env;
534
535 func = DUK_ACT_GET_FUNC(act);
536 DUK_ASSERT(func != NULL);
537 DUK_ASSERT(!DUK_HOBJECT_HAS_BOUND(func)); /* bound functions are never in act 'func' */
538
539 /*
540 * Delayed initialization only occurs for 'NEWENV' functions.
541 */
542
543 DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV(func));
544 DUK_ASSERT(act->lex_env == NULL);
545 DUK_ASSERT(act->var_env == NULL);
546
547 env = duk_create_activation_environment_record(thr, func, act->idx_bottom);
548 DUK_ASSERT(env != NULL);
549
550 DUK_DDD(DUK_DDDPRINT("created delayed fresh env: %!ipO", (duk_heaphdr *) env));
551 #ifdef DUK_USE_DDDPRINT
552 {
553 duk_hobject *p = env;
554 while (p) {
555 DUK_DDD(DUK_DDDPRINT(" -> %!ipO", (duk_heaphdr *) p));
556 p = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, p);
557 }
558 }
559 #endif
560
561 act->lex_env = env;
562 act->var_env = env;
563 DUK_HOBJECT_INCREF(thr, env); /* XXX: incref by count (here 2 times) */
564 DUK_HOBJECT_INCREF(thr, env);
565
566 duk_pop(ctx);
567 }
568
569 /*
570 * Closing environment records.
571 *
572 * The environment record MUST be closed with the thread where its activation
573 * is. In other words (if 'env' is open):
574 *
575 * - 'thr' must match _env.thread
576 * - 'func' must match _env.callee
577 * - 'regbase' must match _env.regbase
578 *
579 * These are not looked up from the env to minimize code size.
580 *
581 * XXX: should access the own properties directly instead of using the API
582 */
583
duk_js_close_environment_record(duk_hthread * thr,duk_hobject * env,duk_hobject * func,duk_size_t regbase)584 DUK_INTERNAL void duk_js_close_environment_record(duk_hthread *thr, duk_hobject *env, duk_hobject *func, duk_size_t regbase) {
585 duk_context *ctx = (duk_context *) thr;
586 duk_uint_fast32_t i;
587
588 DUK_ASSERT(thr != NULL);
589 DUK_ASSERT(env != NULL);
590 /* func is NULL for lightfuncs */
591
592 if (!DUK_HOBJECT_IS_DECENV(env) || DUK_HOBJECT_HAS_ENVRECCLOSED(env)) {
593 DUK_DDD(DUK_DDDPRINT("environment record not a declarative record, "
594 "or already closed: %!iO",
595 (duk_heaphdr *) env));
596 return;
597 }
598
599 DUK_DDD(DUK_DDDPRINT("closing environment record: %!iO, func: %!iO, regbase: %ld",
600 (duk_heaphdr *) env, (duk_heaphdr *) func, (long) regbase));
601
602 duk_push_hobject(ctx, env);
603
604 /* assertions: env must be closed in the same thread as where it runs */
605 #ifdef DUK_USE_ASSERTIONS
606 {
607 /* [... env] */
608
609 if (duk_get_prop_stridx(ctx, -1, DUK_STRIDX_INT_CALLEE)) {
610 DUK_ASSERT(duk_is_object(ctx, -1));
611 DUK_ASSERT(duk_get_hobject(ctx, -1) == (duk_hobject *) func);
612 }
613 duk_pop(ctx);
614
615 if (duk_get_prop_stridx(ctx, -1, DUK_STRIDX_INT_THREAD)) {
616 DUK_ASSERT(duk_is_object(ctx, -1));
617 DUK_ASSERT(duk_get_hobject(ctx, -1) == (duk_hobject *) thr);
618 }
619 duk_pop(ctx);
620
621 if (duk_get_prop_stridx(ctx, -1, DUK_STRIDX_INT_REGBASE)) {
622 DUK_ASSERT(duk_is_number(ctx, -1));
623 DUK_ASSERT(duk_get_number(ctx, -1) == (double) regbase);
624 }
625 duk_pop(ctx);
626
627 /* [... env] */
628 }
629 #endif
630
631 if (func != NULL && DUK_HOBJECT_IS_COMPILEDFUNCTION(func)) {
632 duk_hobject *varmap;
633 duk_hstring *key;
634 duk_tval *tv;
635 duk_uint_t regnum;
636
637 /* XXX: additional conditions when to close variables? we don't want to do it
638 * unless the environment may have "escaped" (referenced in a function closure).
639 * With delayed environments, the existence is probably good enough of a check.
640 */
641
642 /* XXX: any way to detect faster whether something needs to be closed?
643 * We now look up _Callee and then skip the rest.
644 */
645
646 /* Note: we rely on the _Varmap having a bunch of nice properties, like:
647 * - being compacted and unmodified during this process
648 * - not containing an array part
649 * - having correct value types
650 */
651
652 /* [... env] */
653
654 if (!duk_get_prop_stridx(ctx, -1, DUK_STRIDX_INT_CALLEE)) {
655 DUK_DDD(DUK_DDDPRINT("env has no callee property, nothing to close; re-delete the control properties just in case"));
656 duk_pop(ctx);
657 goto skip_varmap;
658 }
659
660 /* [... env callee] */
661
662 if (!duk_get_prop_stridx(ctx, -1, DUK_STRIDX_INT_VARMAP)) {
663 DUK_DDD(DUK_DDDPRINT("callee has no varmap property, nothing to close; delete the control properties"));
664 duk_pop_2(ctx);
665 goto skip_varmap;
666 }
667 varmap = duk_require_hobject(ctx, -1);
668 DUK_ASSERT(varmap != NULL);
669
670 DUK_DDD(DUK_DDDPRINT("varmap: %!O", (duk_heaphdr *) varmap));
671
672 /* [... env callee varmap] */
673
674 DUK_DDD(DUK_DDDPRINT("copying bound register values, %ld bound regs", (long) DUK_HOBJECT_GET_ENEXT(varmap)));
675
676 for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ENEXT(varmap); i++) {
677 key = DUK_HOBJECT_E_GET_KEY(thr->heap, varmap, i);
678 DUK_ASSERT(key != NULL); /* assume keys are compacted */
679
680 DUK_ASSERT(!DUK_HOBJECT_E_SLOT_IS_ACCESSOR(thr->heap, varmap, i)); /* assume plain values */
681
682 tv = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, varmap, i);
683 DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv)); /* assume value is a number */
684 regnum = (duk_uint_t) DUK_TVAL_GET_NUMBER(tv);
685 DUK_ASSERT_DISABLE(regnum >= 0); /* unsigned */
686 DUK_ASSERT(regnum < ((duk_hcompiledfunction *) func)->nregs); /* regnum is sane */
687 DUK_ASSERT(thr->valstack + regbase + regnum >= thr->valstack);
688 DUK_ASSERT(thr->valstack + regbase + regnum < thr->valstack_top);
689
690 /* XXX: slightly awkward */
691 duk_push_hstring(ctx, key);
692 duk_push_tval(ctx, thr->valstack + regbase + regnum);
693 DUK_DDD(DUK_DDDPRINT("closing identifier '%s' -> reg %ld, value %!T",
694 (const char *) duk_require_string(ctx, -2),
695 (long) regnum,
696 (duk_tval *) duk_get_tval(ctx, -1)));
697
698 /* [... env callee varmap key val] */
699
700 /* if property already exists, overwrites silently */
701 duk_xdef_prop(ctx, -5, DUK_PROPDESC_FLAGS_WE); /* writable but not deletable */
702 }
703
704 duk_pop_2(ctx);
705
706 /* [... env] */
707 }
708
709 skip_varmap:
710
711 /* [... env] */
712
713 duk_del_prop_stridx(ctx, -1, DUK_STRIDX_INT_CALLEE);
714 duk_del_prop_stridx(ctx, -1, DUK_STRIDX_INT_THREAD);
715 duk_del_prop_stridx(ctx, -1, DUK_STRIDX_INT_REGBASE);
716
717 duk_pop(ctx);
718
719 DUK_HOBJECT_SET_ENVRECCLOSED(env);
720
721 DUK_DDD(DUK_DDDPRINT("environment record after being closed: %!O",
722 (duk_heaphdr *) env));
723 }
724
725 /*
726 * GETIDREF: a GetIdentifierReference-like helper.
727 *
728 * Provides a parent traversing lookup and a single level lookup
729 * (for HasBinding).
730 *
731 * Instead of returning the value, returns a bunch of values allowing
732 * the caller to read, write, or delete the binding. Value pointers
733 * are duk_tval pointers which can be mutated directly as long as
734 * refcounts are properly updated. Note that any operation which may
735 * reallocate valstacks or compact objects may invalidate the returned
736 * duk_tval (but not object) pointers, so caller must be very careful.
737 *
738 * If starting environment record 'env' is given, 'act' is ignored.
739 * However, if 'env' is NULL, the caller may identify, in 'act', an
740 * activation which hasn't had its declarative environment initialized
741 * yet. The activation registers are then looked up, and its parent
742 * traversed normally.
743 *
744 * The 'out' structure values are only valid if the function returns
745 * success (non-zero).
746 */
747
748 /* lookup name from an open declarative record's registers */
749 DUK_LOCAL
duk__getid_open_decl_env_regs(duk_hthread * thr,duk_hstring * name,duk_hobject * env,duk__id_lookup_result * out)750 duk_bool_t duk__getid_open_decl_env_regs(duk_hthread *thr,
751 duk_hstring *name,
752 duk_hobject *env,
753 duk__id_lookup_result *out) {
754 duk_hthread *env_thr;
755 duk_hobject *env_func;
756 duk_size_t env_regbase;
757 duk_hobject *varmap;
758 duk_tval *tv;
759 duk_size_t reg_rel;
760 duk_size_t idx;
761
762 DUK_ASSERT(thr != NULL);
763 DUK_ASSERT(name != NULL);
764 DUK_ASSERT(env != NULL);
765 DUK_ASSERT(out != NULL);
766
767 DUK_ASSERT(DUK_HOBJECT_IS_DECENV(env));
768
769 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_CALLEE(thr));
770 if (!tv) {
771 /* env is closed, should be missing _Callee, _Thread, _Regbase */
772 DUK_ASSERT(duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL);
773 DUK_ASSERT(duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL);
774 DUK_ASSERT(duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL);
775 return 0;
776 }
777
778 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
779 DUK_ASSERT(DUK_TVAL_GET_OBJECT(tv) != NULL);
780 DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_TVAL_GET_OBJECT(tv)));
781 env_func = DUK_TVAL_GET_OBJECT(tv);
782 DUK_ASSERT(env_func != NULL);
783
784 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env_func, DUK_HTHREAD_STRING_INT_VARMAP(thr));
785 if (!tv) {
786 return 0;
787 }
788 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
789 varmap = DUK_TVAL_GET_OBJECT(tv);
790 DUK_ASSERT(varmap != NULL);
791
792 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, varmap, name);
793 if (!tv) {
794 return 0;
795 }
796 DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
797 reg_rel = (duk_size_t) DUK_TVAL_GET_NUMBER(tv);
798 DUK_ASSERT_DISABLE(reg_rel >= 0); /* unsigned */
799 DUK_ASSERT(reg_rel < ((duk_hcompiledfunction *) env_func)->nregs);
800
801 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_THREAD(thr));
802 DUK_ASSERT(tv != NULL);
803 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
804 DUK_ASSERT(DUK_TVAL_GET_OBJECT(tv) != NULL);
805 DUK_ASSERT(DUK_HOBJECT_IS_THREAD(DUK_TVAL_GET_OBJECT(tv)));
806 env_thr = (duk_hthread *) DUK_TVAL_GET_OBJECT(tv);
807 DUK_ASSERT(env_thr != NULL);
808
809 /* Note: env_thr != thr is quite possible and normal, so careful
810 * with what thread is used for valstack lookup.
811 */
812
813 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_REGBASE(thr));
814 DUK_ASSERT(tv != NULL);
815 DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
816 env_regbase = (duk_size_t) DUK_TVAL_GET_NUMBER(tv);
817
818 idx = env_regbase + reg_rel;
819 tv = env_thr->valstack + idx;
820 DUK_ASSERT(tv >= env_thr->valstack && tv < env_thr->valstack_end); /* XXX: more accurate? */
821
822 out->value = tv;
823 out->attrs = DUK_PROPDESC_FLAGS_W; /* registers are mutable, non-deletable */
824 out->this_binding = NULL; /* implicit this value always undefined for
825 * declarative environment records.
826 */
827 out->env = env;
828 out->holder = NULL;
829
830 return 1;
831 }
832
833 /* lookup name from current activation record's functions' registers */
834 DUK_LOCAL
duk__getid_activation_regs(duk_hthread * thr,duk_hstring * name,duk_activation * act,duk__id_lookup_result * out)835 duk_bool_t duk__getid_activation_regs(duk_hthread *thr,
836 duk_hstring *name,
837 duk_activation *act,
838 duk__id_lookup_result *out) {
839 duk_tval *tv;
840 duk_hobject *func;
841 duk_hobject *varmap;
842 duk_size_t reg_rel;
843 duk_size_t idx;
844
845 DUK_ASSERT(thr != NULL);
846 DUK_ASSERT(name != NULL);
847 DUK_ASSERT(act != NULL);
848 DUK_ASSERT(out != NULL);
849
850 func = DUK_ACT_GET_FUNC(act);
851 DUK_ASSERT(func != NULL);
852 DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV(func));
853
854 if (!DUK_HOBJECT_IS_COMPILEDFUNCTION(func)) {
855 return 0;
856 }
857
858 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, func, DUK_HTHREAD_STRING_INT_VARMAP(thr));
859 if (!tv) {
860 return 0;
861 }
862 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
863 varmap = DUK_TVAL_GET_OBJECT(tv);
864 DUK_ASSERT(varmap != NULL);
865
866 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, varmap, name);
867 if (!tv) {
868 return 0;
869 }
870 DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
871 reg_rel = (duk_size_t) DUK_TVAL_GET_NUMBER(tv);
872 DUK_ASSERT_DISABLE(reg_rel >= 0);
873 DUK_ASSERT(reg_rel < ((duk_hcompiledfunction *) func)->nregs);
874
875 idx = act->idx_bottom + reg_rel;
876 DUK_ASSERT(idx >= act->idx_bottom);
877 tv = thr->valstack + idx;
878
879 out->value = tv;
880 out->attrs = DUK_PROPDESC_FLAGS_W; /* registers are mutable, non-deletable */
881 out->this_binding = NULL; /* implicit this value always undefined for
882 * declarative environment records.
883 */
884 out->env = NULL;
885 out->holder = NULL;
886
887 return 1;
888 }
889
890 DUK_LOCAL
duk__get_identifier_reference(duk_hthread * thr,duk_hobject * env,duk_hstring * name,duk_activation * act,duk_bool_t parents,duk__id_lookup_result * out)891 duk_bool_t duk__get_identifier_reference(duk_hthread *thr,
892 duk_hobject *env,
893 duk_hstring *name,
894 duk_activation *act,
895 duk_bool_t parents,
896 duk__id_lookup_result *out) {
897 duk_tval *tv;
898 duk_tval *tv_target;
899 duk_tval tv_name;
900 duk_uint_t sanity;
901
902 DUK_ASSERT(thr != NULL);
903 DUK_ASSERT(env != NULL || act != NULL);
904 DUK_ASSERT(name != NULL);
905 DUK_ASSERT(out != NULL);
906
907 DUK_ASSERT(!env || DUK_HOBJECT_IS_ENV(env));
908 DUK_ASSERT(!env || !DUK_HOBJECT_HAS_ARRAY_PART(env));
909
910 /*
911 * Conceptually, we look for the identifier binding by starting from
912 * 'env' and following to chain of environment records (represented
913 * by the prototype chain).
914 *
915 * If 'env' is NULL, the current activation does not yet have an
916 * allocated declarative environment record; this should be treated
917 * exactly as if the environment record existed but had no bindings
918 * other than register bindings.
919 *
920 * Note: we assume that with the DUK_HOBJECT_FLAG_NEWENV cleared
921 * the environment will always be initialized immediately; hence
922 * a NULL 'env' should only happen with the flag set. This is the
923 * case for: (1) function calls, and (2) strict, direct eval calls.
924 */
925
926 if (env == NULL && act != NULL) {
927 duk_hobject *func;
928
929 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference: env is NULL, activation is non-NULL -> "
930 "delayed env case, look up activation regs first"));
931
932 /*
933 * Try registers
934 */
935
936 if (duk__getid_activation_regs(thr, name, act, out)) {
937 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
938 "name=%!O -> value=%!T, attrs=%ld, this=%!T, env=%!O, holder=%!O "
939 "(found from register bindings when env=NULL)",
940 (duk_heaphdr *) name, (duk_tval *) out->value,
941 (long) out->attrs, (duk_tval *) out->this_binding,
942 (duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
943 return 1;
944 }
945
946 DUK_DDD(DUK_DDDPRINT("not found in current activation regs"));
947
948 /*
949 * Not found in registers, proceed to the parent record.
950 * Here we need to determine what the parent would be,
951 * if 'env' was not NULL (i.e. same logic as when initializing
952 * the record).
953 *
954 * Note that environment initialization is only deferred when
955 * DUK_HOBJECT_HAS_NEWENV is set, and this only happens for:
956 * - Function code
957 * - Strict eval code
958 *
959 * We only need to check _Lexenv here; _Varenv exists only if it
960 * differs from _Lexenv (and thus _Lexenv will also be present).
961 */
962
963 if (!parents) {
964 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference failed, no parent traversal "
965 "(not found from register bindings when env=NULL)"));
966 goto fail_not_found;
967 }
968
969 func = DUK_ACT_GET_FUNC(act);
970 DUK_ASSERT(func != NULL);
971 DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV(func));
972
973 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, func, DUK_HTHREAD_STRING_INT_LEXENV(thr));
974 if (tv) {
975 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
976 env = DUK_TVAL_GET_OBJECT(tv);
977 } else {
978 DUK_ASSERT(duk_hobject_find_existing_entry_tval_ptr(thr->heap, func, DUK_HTHREAD_STRING_INT_VARENV(thr)) == NULL);
979 env = thr->builtins[DUK_BIDX_GLOBAL_ENV];
980 }
981
982 DUK_DDD(DUK_DDDPRINT("continue lookup from env: %!iO",
983 (duk_heaphdr *) env));
984 }
985
986 /*
987 * Prototype walking starting from 'env'.
988 *
989 * ('act' is not needed anywhere here.)
990 */
991
992 sanity = DUK_HOBJECT_PROTOTYPE_CHAIN_SANITY;
993 while (env != NULL) {
994 duk_small_int_t cl;
995 duk_int_t attrs;
996
997 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference, name=%!O, considering env=%p -> %!iO",
998 (duk_heaphdr *) name,
999 (void *) env,
1000 (duk_heaphdr *) env));
1001
1002 DUK_ASSERT(env != NULL);
1003 DUK_ASSERT(DUK_HOBJECT_IS_ENV(env));
1004 DUK_ASSERT(!DUK_HOBJECT_HAS_ARRAY_PART(env));
1005
1006 cl = DUK_HOBJECT_GET_CLASS_NUMBER(env);
1007 DUK_ASSERT(cl == DUK_HOBJECT_CLASS_OBJENV || cl == DUK_HOBJECT_CLASS_DECENV);
1008 if (cl == DUK_HOBJECT_CLASS_DECENV) {
1009 /*
1010 * Declarative environment record.
1011 *
1012 * Identifiers can never be stored in ancestors and are
1013 * always plain values, so we can use an internal helper
1014 * and access the value directly with an duk_tval ptr.
1015 *
1016 * A closed environment is only indicated by it missing
1017 * the "book-keeping" properties required for accessing
1018 * register-bound variables.
1019 */
1020
1021 if (DUK_HOBJECT_HAS_ENVRECCLOSED(env)) {
1022 /* already closed */
1023 goto skip_regs;
1024 }
1025
1026 if (duk__getid_open_decl_env_regs(thr, name, env, out)) {
1027 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
1028 "name=%!O -> value=%!T, attrs=%ld, this=%!T, env=%!O, holder=%!O "
1029 "(declarative environment record, scope open, found in regs)",
1030 (duk_heaphdr *) name, (duk_tval *) out->value,
1031 (long) out->attrs, (duk_tval *) out->this_binding,
1032 (duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
1033 return 1;
1034 }
1035 skip_regs:
1036
1037 tv = duk_hobject_find_existing_entry_tval_ptr_and_attrs(thr->heap, env, name, &attrs);
1038 if (tv) {
1039 out->value = tv;
1040 out->attrs = attrs;
1041 out->this_binding = NULL; /* implicit this value always undefined for
1042 * declarative environment records.
1043 */
1044 out->env = env;
1045 out->holder = env;
1046
1047 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
1048 "name=%!O -> value=%!T, attrs=%ld, this=%!T, env=%!O, holder=%!O "
1049 "(declarative environment record, found in properties)",
1050 (duk_heaphdr *) name, (duk_tval *) out->value,
1051 (long) out->attrs, (duk_tval *) out->this_binding,
1052 (duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
1053 return 1;
1054 }
1055 } else {
1056 /*
1057 * Object environment record.
1058 *
1059 * Binding (target) object is an external, uncontrolled object.
1060 * Identifier may be bound in an ancestor property, and may be
1061 * an accessor. Target can also be a Proxy which we must support
1062 * here.
1063 */
1064
1065 /* XXX: we could save space by using _Target OR _This. If _Target, assume
1066 * this binding is undefined. If _This, assumes this binding is _This, and
1067 * target is also _This. One property would then be enough.
1068 */
1069
1070 duk_hobject *target;
1071 duk_bool_t found;
1072
1073 DUK_ASSERT(cl == DUK_HOBJECT_CLASS_OBJENV);
1074
1075 tv_target = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_TARGET(thr));
1076 DUK_ASSERT(tv_target != NULL);
1077 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv_target));
1078 target = DUK_TVAL_GET_OBJECT(tv_target);
1079 DUK_ASSERT(target != NULL);
1080
1081 /* Target may be a Proxy or property may be an accessor, so we must
1082 * use an actual, Proxy-aware hasprop check here.
1083 *
1084 * out->holder is NOT set to the actual duk_hobject where the
1085 * property is found, but rather the object binding target object.
1086 */
1087
1088 if (DUK_HOBJECT_HAS_EXOTIC_PROXYOBJ(target)) {
1089 DUK_ASSERT(name != NULL);
1090 DUK_TVAL_SET_STRING(&tv_name, name);
1091
1092 found = duk_hobject_hasprop(thr, tv_target, &tv_name);
1093 } else {
1094 /* XXX: duk_hobject_hasprop() would be correct for
1095 * non-Proxy objects too, but it is about ~20-25%
1096 * slower at present so separate code paths for
1097 * Proxy and non-Proxy now.
1098 */
1099 found = duk_hobject_hasprop_raw(thr, target, name);
1100 }
1101
1102 if (found) {
1103 out->value = NULL; /* can't get value, may be accessor */
1104 out->attrs = 0; /* irrelevant when out->value == NULL */
1105 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_THIS(thr));
1106 out->this_binding = tv; /* may be NULL */
1107 out->env = env;
1108 out->holder = target;
1109
1110 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
1111 "name=%!O -> value=%!T, attrs=%ld, this=%!T, env=%!O, holder=%!O "
1112 "(object environment record)",
1113 (duk_heaphdr *) name, (duk_tval *) out->value,
1114 (long) out->attrs, (duk_tval *) out->this_binding,
1115 (duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
1116 return 1;
1117 }
1118 }
1119
1120 if (!parents) {
1121 DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference failed, no parent traversal "
1122 "(not found from first traversed env)"));
1123 goto fail_not_found;
1124 }
1125
1126 if (sanity-- == 0) {
1127 DUK_ERROR_RANGE(thr, DUK_STR_PROTOTYPE_CHAIN_LIMIT);
1128 }
1129 env = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, env);
1130 };
1131
1132 /*
1133 * Not found (even in global object)
1134 */
1135
1136 fail_not_found:
1137 return 0;
1138 }
1139
1140 /*
1141 * HASVAR: check identifier binding from a given environment record
1142 * without traversing its parents.
1143 *
1144 * This primitive is not exposed to user code as such, but is used
1145 * internally for e.g. declaration binding instantiation.
1146 *
1147 * See E5 Sections:
1148 * 10.2.1.1.1 HasBinding(N)
1149 * 10.2.1.2.1 HasBinding(N)
1150 *
1151 * Note: strictness has no bearing on this check. Hence we don't take
1152 * a 'strict' parameter.
1153 */
1154
1155 #if 0 /*unused*/
1156 DUK_INTERNAL
1157 duk_bool_t duk_js_hasvar_envrec(duk_hthread *thr,
1158 duk_hobject *env,
1159 duk_hstring *name) {
1160 duk__id_lookup_result ref;
1161 duk_bool_t parents;
1162
1163 DUK_DDD(DUK_DDDPRINT("hasvar: thr=%p, env=%p, name=%!O "
1164 "(env -> %!dO)",
1165 (void *) thr, (void *) env, (duk_heaphdr *) name,
1166 (duk_heaphdr *) env));
1167
1168 DUK_ASSERT(thr != NULL);
1169 DUK_ASSERT(env != NULL);
1170 DUK_ASSERT(name != NULL);
1171
1172 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
1173 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
1174
1175 DUK_ASSERT(DUK_HOBJECT_IS_ENV(env));
1176 DUK_ASSERT(!DUK_HOBJECT_HAS_ARRAY_PART(env));
1177
1178 /* lookup results is ignored */
1179 parents = 0;
1180 return duk__get_identifier_reference(thr, env, name, NULL, parents, &ref);
1181 }
1182 #endif
1183
1184 /*
1185 * GETVAR
1186 *
1187 * See E5 Sections:
1188 * 11.1.2 Identifier Reference
1189 * 10.3.1 Identifier Resolution
1190 * 11.13.1 Simple Assignment [example of where the Reference is GetValue'd]
1191 * 8.7.1 GetValue (V)
1192 * 8.12.1 [[GetOwnProperty]] (P)
1193 * 8.12.2 [[GetProperty]] (P)
1194 * 8.12.3 [[Get]] (P)
1195 *
1196 * If 'throw' is true, always leaves two values on top of stack: [val this].
1197 *
1198 * If 'throw' is false, returns 0 if identifier cannot be resolved, and the
1199 * stack will be unaffected in this case. If identifier is resolved, returns
1200 * 1 and leaves [val this] on top of stack.
1201 *
1202 * Note: the 'strict' flag of a reference returned by GetIdentifierReference
1203 * is ignored by GetValue. Hence we don't take a 'strict' parameter.
1204 *
1205 * The 'throw' flag is needed for implementing 'typeof' for an unreferenced
1206 * identifier. An unreference identifier in other contexts generates a
1207 * ReferenceError.
1208 */
1209
1210 DUK_LOCAL
duk__getvar_helper(duk_hthread * thr,duk_hobject * env,duk_activation * act,duk_hstring * name,duk_bool_t throw_flag)1211 duk_bool_t duk__getvar_helper(duk_hthread *thr,
1212 duk_hobject *env,
1213 duk_activation *act,
1214 duk_hstring *name,
1215 duk_bool_t throw_flag) {
1216 duk_context *ctx = (duk_context *) thr;
1217 duk__id_lookup_result ref;
1218 duk_tval tv_tmp_obj;
1219 duk_tval tv_tmp_key;
1220 duk_bool_t parents;
1221
1222 DUK_DDD(DUK_DDDPRINT("getvar: thr=%p, env=%p, act=%p, name=%!O "
1223 "(env -> %!dO)",
1224 (void *) thr, (void *) env, (void *) act,
1225 (duk_heaphdr *) name, (duk_heaphdr *) env));
1226
1227 DUK_ASSERT(thr != NULL);
1228 DUK_ASSERT(name != NULL);
1229 /* env and act may be NULL */
1230
1231 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
1232 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
1233
1234 parents = 1; /* follow parent chain */
1235 if (duk__get_identifier_reference(thr, env, name, act, parents, &ref)) {
1236 if (ref.value) {
1237 DUK_ASSERT(ref.this_binding == NULL); /* always for register bindings */
1238 duk_push_tval(ctx, ref.value);
1239 duk_push_undefined(ctx);
1240 } else {
1241 DUK_ASSERT(ref.holder != NULL);
1242
1243 /* Note: getprop may invoke any getter and invalidate any
1244 * duk_tval pointers, so this must be done first.
1245 */
1246
1247 if (ref.this_binding) {
1248 duk_push_tval(ctx, ref.this_binding);
1249 } else {
1250 duk_push_undefined(ctx);
1251 }
1252
1253 DUK_TVAL_SET_OBJECT(&tv_tmp_obj, ref.holder);
1254 DUK_TVAL_SET_STRING(&tv_tmp_key, name);
1255 (void) duk_hobject_getprop(thr, &tv_tmp_obj, &tv_tmp_key); /* [this value] */
1256
1257 /* ref.value, ref.this.binding invalidated here by getprop call */
1258
1259 duk_insert(ctx, -2); /* [this value] -> [value this] */
1260 }
1261
1262 return 1;
1263 } else {
1264 if (throw_flag) {
1265 DUK_ERROR_FMT1(thr, DUK_ERR_REFERENCE_ERROR,
1266 "identifier '%s' undefined",
1267 (const char *) DUK_HSTRING_GET_DATA(name));
1268 }
1269
1270 return 0;
1271 }
1272 }
1273
1274 DUK_INTERNAL
duk_js_getvar_envrec(duk_hthread * thr,duk_hobject * env,duk_hstring * name,duk_bool_t throw_flag)1275 duk_bool_t duk_js_getvar_envrec(duk_hthread *thr,
1276 duk_hobject *env,
1277 duk_hstring *name,
1278 duk_bool_t throw_flag) {
1279 return duk__getvar_helper(thr, env, NULL, name, throw_flag);
1280 }
1281
1282 DUK_INTERNAL
duk_js_getvar_activation(duk_hthread * thr,duk_activation * act,duk_hstring * name,duk_bool_t throw_flag)1283 duk_bool_t duk_js_getvar_activation(duk_hthread *thr,
1284 duk_activation *act,
1285 duk_hstring *name,
1286 duk_bool_t throw_flag) {
1287 DUK_ASSERT(act != NULL);
1288 return duk__getvar_helper(thr, act->lex_env, act, name, throw_flag);
1289 }
1290
1291 /*
1292 * PUTVAR
1293 *
1294 * See E5 Sections:
1295 * 11.1.2 Identifier Reference
1296 * 10.3.1 Identifier Resolution
1297 * 11.13.1 Simple Assignment [example of where the Reference is PutValue'd]
1298 * 8.7.2 PutValue (V,W) [see especially step 3.b, undefined -> automatic global in non-strict mode]
1299 * 8.12.4 [[CanPut]] (P)
1300 * 8.12.5 [[Put]] (P)
1301 *
1302 * Note: may invalidate any valstack (or object) duk_tval pointers because
1303 * putting a value may reallocate any object or any valstack. Caller beware.
1304 */
1305
1306 DUK_LOCAL
duk__putvar_helper(duk_hthread * thr,duk_hobject * env,duk_activation * act,duk_hstring * name,duk_tval * val,duk_bool_t strict)1307 void duk__putvar_helper(duk_hthread *thr,
1308 duk_hobject *env,
1309 duk_activation *act,
1310 duk_hstring *name,
1311 duk_tval *val,
1312 duk_bool_t strict) {
1313 duk__id_lookup_result ref;
1314 duk_tval tv_tmp_obj;
1315 duk_tval tv_tmp_key;
1316 duk_bool_t parents;
1317
1318 DUK_DDD(DUK_DDDPRINT("putvar: thr=%p, env=%p, act=%p, name=%!O, val=%p, strict=%ld "
1319 "(env -> %!dO, val -> %!T)",
1320 (void *) thr, (void *) env, (void *) act,
1321 (duk_heaphdr *) name, (void *) val, (long) strict,
1322 (duk_heaphdr *) env, (duk_tval *) val));
1323
1324 DUK_ASSERT(thr != NULL);
1325 DUK_ASSERT(name != NULL);
1326 DUK_ASSERT(val != NULL);
1327 /* env and act may be NULL */
1328
1329 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
1330 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
1331 DUK_ASSERT_REFCOUNT_NONZERO_TVAL(val);
1332
1333 /*
1334 * In strict mode E5 protects 'eval' and 'arguments' from being
1335 * assigned to (or even declared anywhere). Attempt to do so
1336 * should result in a compile time SyntaxError. See the internal
1337 * design documentation for details.
1338 *
1339 * Thus, we should never come here, run-time, for strict code,
1340 * and name 'eval' or 'arguments'.
1341 */
1342
1343 DUK_ASSERT(!strict ||
1344 (name != DUK_HTHREAD_STRING_EVAL(thr) &&
1345 name != DUK_HTHREAD_STRING_LC_ARGUMENTS(thr)));
1346
1347 /*
1348 * Lookup variable and update in-place if found.
1349 */
1350
1351 parents = 1; /* follow parent chain */
1352
1353 if (duk__get_identifier_reference(thr, env, name, act, parents, &ref)) {
1354 if (ref.value && (ref.attrs & DUK_PROPDESC_FLAG_WRITABLE)) {
1355 /* Update duk_tval in-place if pointer provided and the
1356 * property is writable. If the property is not writable
1357 * (immutable binding), use duk_hobject_putprop() which
1358 * will respect mutability.
1359 */
1360 duk_tval *tv_val;
1361
1362 DUK_ASSERT(ref.this_binding == NULL); /* always for register bindings */
1363
1364 tv_val = ref.value;
1365 DUK_ASSERT(tv_val != NULL);
1366 DUK_TVAL_SET_TVAL_UPDREF(thr, tv_val, val); /* side effects */
1367
1368 /* ref.value and ref.this_binding invalidated here */
1369 } else {
1370 DUK_ASSERT(ref.holder != NULL);
1371
1372 DUK_TVAL_SET_OBJECT(&tv_tmp_obj, ref.holder);
1373 DUK_TVAL_SET_STRING(&tv_tmp_key, name);
1374 (void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, val, strict);
1375
1376 /* ref.value and ref.this_binding invalidated here */
1377 }
1378
1379 return;
1380 }
1381
1382 /*
1383 * Not found: write to global object (non-strict) or ReferenceError
1384 * (strict); see E5 Section 8.7.2, step 3.
1385 */
1386
1387 if (strict) {
1388 DUK_DDD(DUK_DDDPRINT("identifier binding not found, strict => reference error"));
1389 DUK_ERROR(thr, DUK_ERR_REFERENCE_ERROR, "identifier not defined");
1390 }
1391
1392 DUK_DDD(DUK_DDDPRINT("identifier binding not found, not strict => set to global"));
1393
1394 DUK_TVAL_SET_OBJECT(&tv_tmp_obj, thr->builtins[DUK_BIDX_GLOBAL]);
1395 DUK_TVAL_SET_STRING(&tv_tmp_key, name);
1396 (void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, val, 0); /* 0 = no throw */
1397
1398 /* NB: 'val' may be invalidated here because put_value may realloc valstack,
1399 * caller beware.
1400 */
1401 }
1402
1403 DUK_INTERNAL
duk_js_putvar_envrec(duk_hthread * thr,duk_hobject * env,duk_hstring * name,duk_tval * val,duk_bool_t strict)1404 void duk_js_putvar_envrec(duk_hthread *thr,
1405 duk_hobject *env,
1406 duk_hstring *name,
1407 duk_tval *val,
1408 duk_bool_t strict) {
1409 duk__putvar_helper(thr, env, NULL, name, val, strict);
1410 }
1411
1412 DUK_INTERNAL
duk_js_putvar_activation(duk_hthread * thr,duk_activation * act,duk_hstring * name,duk_tval * val,duk_bool_t strict)1413 void duk_js_putvar_activation(duk_hthread *thr,
1414 duk_activation *act,
1415 duk_hstring *name,
1416 duk_tval *val,
1417 duk_bool_t strict) {
1418 DUK_ASSERT(act != NULL);
1419 duk__putvar_helper(thr, act->lex_env, act, name, val, strict);
1420 }
1421
1422 /*
1423 * DELVAR
1424 *
1425 * See E5 Sections:
1426 * 11.4.1 The delete operator
1427 * 10.2.1.1.5 DeleteBinding (N) [declarative environment record]
1428 * 10.2.1.2.5 DeleteBinding (N) [object environment record]
1429 *
1430 * Variable bindings established inside eval() are deletable (configurable),
1431 * other bindings are not, including variables declared in global level.
1432 * Registers are always non-deletable, and the deletion of other bindings
1433 * is controlled by the configurable flag.
1434 *
1435 * For strict mode code, the 'delete' operator should fail with a compile
1436 * time SyntaxError if applied to identifiers. Hence, no strict mode
1437 * run-time deletion of identifiers should ever happen. This function
1438 * should never be called from strict mode code!
1439 */
1440
1441 DUK_LOCAL
duk__delvar_helper(duk_hthread * thr,duk_hobject * env,duk_activation * act,duk_hstring * name)1442 duk_bool_t duk__delvar_helper(duk_hthread *thr,
1443 duk_hobject *env,
1444 duk_activation *act,
1445 duk_hstring *name) {
1446 duk__id_lookup_result ref;
1447 duk_bool_t parents;
1448
1449 DUK_DDD(DUK_DDDPRINT("delvar: thr=%p, env=%p, act=%p, name=%!O "
1450 "(env -> %!dO)",
1451 (void *) thr, (void *) env, (void *) act,
1452 (duk_heaphdr *) name, (duk_heaphdr *) env));
1453
1454 DUK_ASSERT(thr != NULL);
1455 DUK_ASSERT(name != NULL);
1456 /* env and act may be NULL */
1457
1458 DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
1459
1460 parents = 1; /* follow parent chain */
1461
1462 if (duk__get_identifier_reference(thr, env, name, act, parents, &ref)) {
1463 if (ref.value && !(ref.attrs & DUK_PROPDESC_FLAG_CONFIGURABLE)) {
1464 /* Identifier found in registers (always non-deletable)
1465 * or declarative environment record and non-configurable.
1466 */
1467 return 0;
1468 }
1469 DUK_ASSERT(ref.holder != NULL);
1470
1471 return duk_hobject_delprop_raw(thr, ref.holder, name, 0);
1472 }
1473
1474 /*
1475 * Not found (even in global object).
1476 *
1477 * In non-strict mode this is a silent SUCCESS (!), see E5 Section 11.4.1,
1478 * step 3.b. In strict mode this case is a compile time SyntaxError so
1479 * we should not come here.
1480 */
1481
1482 DUK_DDD(DUK_DDDPRINT("identifier to be deleted not found: name=%!O "
1483 "(treated as silent success)",
1484 (duk_heaphdr *) name));
1485 return 1;
1486 }
1487
1488 #if 0 /*unused*/
1489 DUK_INTERNAL
1490 duk_bool_t duk_js_delvar_envrec(duk_hthread *thr,
1491 duk_hobject *env,
1492 duk_hstring *name) {
1493 return duk__delvar_helper(thr, env, NULL, name);
1494 }
1495 #endif
1496
1497 DUK_INTERNAL
duk_js_delvar_activation(duk_hthread * thr,duk_activation * act,duk_hstring * name)1498 duk_bool_t duk_js_delvar_activation(duk_hthread *thr,
1499 duk_activation *act,
1500 duk_hstring *name) {
1501 DUK_ASSERT(act != NULL);
1502 return duk__delvar_helper(thr, act->lex_env, act, name);
1503 }
1504
1505 /*
1506 * DECLVAR
1507 *
1508 * See E5 Sections:
1509 * 10.4.3 Entering Function Code
1510 * 10.5 Declaration Binding Instantion
1511 * 12.2 Variable Statement
1512 * 11.1.2 Identifier Reference
1513 * 10.3.1 Identifier Resolution
1514 *
1515 * Variable declaration behavior is mainly discussed in Section 10.5,
1516 * and is not discussed in the execution semantics (Sections 11-13).
1517 *
1518 * Conceptually declarations happen when code (global, eval, function)
1519 * is entered, before any user code is executed. In practice, register-
1520 * bound identifiers are 'declared' automatically (by virtue of being
1521 * allocated to registers with the initial value 'undefined'). Other
1522 * identifiers are declared in the function prologue with this primitive.
1523 *
1524 * Since non-register bindings eventually back to an internal object's
1525 * properties, the 'prop_flags' argument is used to specify binding
1526 * type:
1527 *
1528 * - Immutable binding: set DUK_PROPDESC_FLAG_WRITABLE to false
1529 * - Non-deletable binding: set DUK_PROPDESC_FLAG_CONFIGURABLE to false
1530 * - The flag DUK_PROPDESC_FLAG_ENUMERABLE should be set, although it
1531 * doesn't really matter for internal objects
1532 *
1533 * All bindings are non-deletable mutable bindings except:
1534 *
1535 * - Declarations in eval code (mutable, deletable)
1536 * - 'arguments' binding in strict function code (immutable)
1537 * - Function name binding of a function expression (immutable)
1538 *
1539 * Declarations may go to declarative environment records (always
1540 * so for functions), but may also go to object environment records
1541 * (e.g. global code). The global object environment has special
1542 * behavior when re-declaring a function (but not a variable); see
1543 * E5.1 specification, Section 10.5, step 5.e.
1544 *
1545 * Declarations always go to the 'top-most' environment record, i.e.
1546 * we never check the record chain. It's not an error even if a
1547 * property (even an immutable or non-deletable one) of the same name
1548 * already exists.
1549 *
1550 * If a declared variable already exists, its value needs to be updated
1551 * (if possible). Returns 1 if a PUTVAR needs to be done by the caller;
1552 * otherwise returns 0.
1553 */
1554
1555 DUK_LOCAL
duk__declvar_helper(duk_hthread * thr,duk_hobject * env,duk_hstring * name,duk_tval * val,duk_small_int_t prop_flags,duk_bool_t is_func_decl)1556 duk_bool_t duk__declvar_helper(duk_hthread *thr,
1557 duk_hobject *env,
1558 duk_hstring *name,
1559 duk_tval *val,
1560 duk_small_int_t prop_flags,
1561 duk_bool_t is_func_decl) {
1562 duk_context *ctx = (duk_context *) thr;
1563 duk_hobject *holder;
1564 duk_bool_t parents;
1565 duk__id_lookup_result ref;
1566 duk_tval *tv;
1567
1568 DUK_DDD(DUK_DDDPRINT("declvar: thr=%p, env=%p, name=%!O, val=%!T, prop_flags=0x%08lx, is_func_decl=%ld "
1569 "(env -> %!iO)",
1570 (void *) thr, (void *) env, (duk_heaphdr *) name,
1571 (duk_tval *) val, (unsigned long) prop_flags,
1572 (unsigned int) is_func_decl, (duk_heaphdr *) env));
1573
1574 DUK_ASSERT(thr != NULL);
1575 DUK_ASSERT(env != NULL);
1576 DUK_ASSERT(name != NULL);
1577 DUK_ASSERT(val != NULL);
1578
1579 /* Note: in strict mode the compiler should reject explicit
1580 * declaration of 'eval' or 'arguments'. However, internal
1581 * bytecode may declare 'arguments' in the function prologue.
1582 * We don't bother checking (or asserting) for these now.
1583 */
1584
1585 /* Note: val is a stable duk_tval pointer. The caller makes
1586 * a value copy into its stack frame, so 'tv_val' is not subject
1587 * to side effects here.
1588 */
1589
1590 /*
1591 * Check whether already declared.
1592 *
1593 * We need to check whether the binding exists in the environment
1594 * without walking its parents. However, we still need to check
1595 * register-bound identifiers and the prototype chain of an object
1596 * environment target object.
1597 */
1598
1599 parents = 0; /* just check 'env' */
1600 if (duk__get_identifier_reference(thr, env, name, NULL, parents, &ref)) {
1601 duk_int_t e_idx;
1602 duk_int_t h_idx;
1603 duk_small_int_t flags;
1604
1605 /*
1606 * Variable already declared, ignore re-declaration.
1607 * The only exception is the updated behavior of E5.1 for
1608 * global function declarations, E5.1 Section 10.5, step 5.e.
1609 * This behavior does not apply to global variable declarations.
1610 */
1611
1612 if (!(is_func_decl && env == thr->builtins[DUK_BIDX_GLOBAL_ENV])) {
1613 DUK_DDD(DUK_DDDPRINT("re-declare a binding, ignoring"));
1614 return 1; /* 1 -> needs a PUTVAR */
1615 }
1616
1617 /*
1618 * Special behavior in E5.1.
1619 *
1620 * Note that even though parents == 0, the conflicting property
1621 * may be an inherited property (currently our global object's
1622 * prototype is Object.prototype). Step 5.e first operates on
1623 * the existing property (which is potentially in an ancestor)
1624 * and then defines a new property in the global object (and
1625 * never modifies the ancestor).
1626 *
1627 * Also note that this logic would become even more complicated
1628 * if the conflicting property might be a virtual one. Object
1629 * prototype has no virtual properties, though.
1630 *
1631 * XXX: this is now very awkward, rework.
1632 */
1633
1634 DUK_DDD(DUK_DDDPRINT("re-declare a function binding in global object, "
1635 "updated E5.1 processing"));
1636
1637 DUK_ASSERT(ref.holder != NULL);
1638 holder = ref.holder;
1639
1640 /* holder will be set to the target object, not the actual object
1641 * where the property was found (see duk__get_identifier_reference()).
1642 */
1643 DUK_ASSERT(DUK_HOBJECT_GET_CLASS_NUMBER(holder) == DUK_HOBJECT_CLASS_GLOBAL);
1644 DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARRAY(holder)); /* global object doesn't have array part */
1645
1646 /* XXX: use a helper for prototype traversal; no loop check here */
1647 /* must be found: was found earlier, and cannot be inherited */
1648 for (;;) {
1649 DUK_ASSERT(holder != NULL);
1650 duk_hobject_find_existing_entry(thr->heap, holder, name, &e_idx, &h_idx);
1651 if (e_idx >= 0) {
1652 break;
1653 }
1654 /* SCANBUILD: NULL pointer dereference, doesn't actually trigger,
1655 * asserted above.
1656 */
1657 holder = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, holder);
1658 }
1659 DUK_ASSERT(holder != NULL);
1660 DUK_ASSERT(e_idx >= 0);
1661 /* SCANBUILD: scan-build produces a NULL pointer dereference warning
1662 * below; it never actually triggers because holder is actually never
1663 * NULL.
1664 */
1665
1666 /* ref.holder is global object, holder is the object with the
1667 * conflicting property.
1668 */
1669
1670 flags = DUK_HOBJECT_E_GET_FLAGS(thr->heap, holder, e_idx);
1671 if (!(flags & DUK_PROPDESC_FLAG_CONFIGURABLE)) {
1672 if (flags & DUK_PROPDESC_FLAG_ACCESSOR) {
1673 DUK_DDD(DUK_DDDPRINT("existing property is a non-configurable "
1674 "accessor -> reject"));
1675 goto fail_existing_attributes;
1676 }
1677 if (!((flags & DUK_PROPDESC_FLAG_WRITABLE) &&
1678 (flags & DUK_PROPDESC_FLAG_ENUMERABLE))) {
1679 DUK_DDD(DUK_DDDPRINT("existing property is a non-configurable "
1680 "plain property which is not writable and "
1681 "enumerable -> reject"));
1682 goto fail_existing_attributes;
1683 }
1684
1685 DUK_DDD(DUK_DDDPRINT("existing property is not configurable but "
1686 "is plain, enumerable, and writable -> "
1687 "allow redeclaration"));
1688 }
1689
1690 if (holder == ref.holder) {
1691 /* XXX: if duk_hobject_define_property_internal() was updated
1692 * to handle a pre-existing accessor property, this would be
1693 * a simple call (like for the ancestor case).
1694 */
1695 DUK_DDD(DUK_DDDPRINT("redefine, offending property in global object itself"));
1696
1697 if (flags & DUK_PROPDESC_FLAG_ACCESSOR) {
1698 duk_hobject *tmp;
1699
1700 tmp = DUK_HOBJECT_E_GET_VALUE_GETTER(thr->heap, holder, e_idx);
1701 DUK_HOBJECT_E_SET_VALUE_GETTER(thr->heap, holder, e_idx, NULL);
1702 DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
1703 DUK_UNREF(tmp);
1704 tmp = DUK_HOBJECT_E_GET_VALUE_SETTER(thr->heap, holder, e_idx);
1705 DUK_HOBJECT_E_SET_VALUE_SETTER(thr->heap, holder, e_idx, NULL);
1706 DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
1707 DUK_UNREF(tmp);
1708 } else {
1709 tv = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, holder, e_idx);
1710 DUK_TVAL_SET_UNDEFINED_UPDREF(thr, tv);
1711 }
1712
1713 /* Here val would be potentially invalid if we didn't make
1714 * a value copy at the caller.
1715 */
1716
1717 tv = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, holder, e_idx);
1718 DUK_TVAL_SET_TVAL(tv, val);
1719 DUK_TVAL_INCREF(thr, tv);
1720 DUK_HOBJECT_E_SET_FLAGS(thr->heap, holder, e_idx, prop_flags);
1721
1722 DUK_DDD(DUK_DDDPRINT("updated global binding, final result: "
1723 "value -> %!T, prop_flags=0x%08lx",
1724 (duk_tval *) DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, holder, e_idx),
1725 (unsigned long) prop_flags));
1726 } else {
1727 DUK_DDD(DUK_DDDPRINT("redefine, offending property in ancestor"));
1728
1729 DUK_ASSERT(ref.holder == thr->builtins[DUK_BIDX_GLOBAL]);
1730 duk_push_tval(ctx, val);
1731 duk_hobject_define_property_internal(thr, ref.holder, name, prop_flags);
1732 }
1733
1734 return 0;
1735 }
1736
1737 /*
1738 * Not found (in registers or record objects). Declare
1739 * to current variable environment.
1740 */
1741
1742 /*
1743 * Get holder object
1744 */
1745
1746 if (DUK_HOBJECT_IS_DECENV(env)) {
1747 holder = env;
1748 } else {
1749 DUK_ASSERT(DUK_HOBJECT_IS_OBJENV(env));
1750
1751 tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, env, DUK_HTHREAD_STRING_INT_TARGET(thr));
1752 DUK_ASSERT(tv != NULL);
1753 DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
1754 holder = DUK_TVAL_GET_OBJECT(tv);
1755 DUK_ASSERT(holder != NULL);
1756 }
1757
1758 /*
1759 * Define new property
1760 *
1761 * Note: this may fail if the holder is not extensible.
1762 */
1763
1764 /* XXX: this is awkward as we use an internal method which doesn't handle
1765 * extensibility etc correctly. Basically we'd want to do a [[DefineOwnProperty]]
1766 * or Object.defineProperty() here.
1767 */
1768
1769 if (!DUK_HOBJECT_HAS_EXTENSIBLE(holder)) {
1770 goto fail_not_extensible;
1771 }
1772
1773 duk_push_hobject(ctx, holder);
1774 duk_push_hstring(ctx, name);
1775 duk_push_tval(ctx, val);
1776 duk_xdef_prop(ctx, -3, prop_flags); /* [holder name val] -> [holder] */
1777 duk_pop(ctx);
1778
1779 return 0;
1780
1781 fail_existing_attributes:
1782 fail_not_extensible:
1783 DUK_ERROR_TYPE(thr, "declaration failed");
1784 return 0;
1785 }
1786
1787 DUK_INTERNAL
duk_js_declvar_activation(duk_hthread * thr,duk_activation * act,duk_hstring * name,duk_tval * val,duk_small_int_t prop_flags,duk_bool_t is_func_decl)1788 duk_bool_t duk_js_declvar_activation(duk_hthread *thr,
1789 duk_activation *act,
1790 duk_hstring *name,
1791 duk_tval *val,
1792 duk_small_int_t prop_flags,
1793 duk_bool_t is_func_decl) {
1794 duk_hobject *env;
1795 duk_tval tv_val_copy;
1796
1797 /*
1798 * Make a value copy of the input val. This ensures that
1799 * side effects cannot invalidate the pointer.
1800 */
1801
1802 DUK_TVAL_SET_TVAL(&tv_val_copy, val);
1803 val = &tv_val_copy;
1804
1805 /*
1806 * Delayed env creation check
1807 */
1808
1809 if (!act->var_env) {
1810 DUK_ASSERT(act->lex_env == NULL);
1811 duk_js_init_activation_environment_records_delayed(thr, act);
1812 }
1813 DUK_ASSERT(act->lex_env != NULL);
1814 DUK_ASSERT(act->var_env != NULL);
1815
1816 env = act->var_env;
1817 DUK_ASSERT(env != NULL);
1818 DUK_ASSERT(DUK_HOBJECT_IS_ENV(env));
1819
1820 return duk__declvar_helper(thr, env, name, val, prop_flags, is_func_decl);
1821 }
1822
