1 /* 2 * Copyright 2007,2008,2009,2010 Red Hat, Inc. 3 * Copyright 2012,2018 Google, Inc. 4 * 5 * This is part of HarfBuzz, a text shaping library. 6 * 7 * Permission is hereby granted, without written agreement and without 8 * license or royalty fees, to use, copy, modify, and distribute this 9 * software and its documentation for any purpose, provided that the 10 * above copyright notice and the following two paragraphs appear in 11 * all copies of this software. 12 * 13 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR 14 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES 15 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN 16 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH 17 * DAMAGE. 18 * 19 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, 20 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 21 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS 22 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO 23 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. 24 * 25 * Red Hat Author(s): Behdad Esfahbod 26 * Google Author(s): Behdad Esfahbod 27 */ 28 29 #ifndef HB_MACHINERY_HH 30 #define HB_MACHINERY_HH 31 32 #include "hb.hh" 33 #include "hb-blob.hh" 34 35 #include "hb-array.hh" 36 #include "hb-vector.hh" 37 38 39 /* 40 * Casts 41 */ 42 43 /* Cast to struct T, reference to reference */ 44 template<typename Type, typename TObject> 45 static inline const Type& CastR(const TObject &X) 46 { return reinterpret_cast<const Type&> (X); } 47 template<typename Type, typename TObject> 48 static inline Type& CastR(TObject &X) 49 { return reinterpret_cast<Type&> (X); } 50 51 /* Cast to struct T, pointer to pointer */ 52 template<typename Type, typename TObject> 53 static inline const Type* CastP(const TObject *X) 54 { return reinterpret_cast<const Type*> (X); } 55 template<typename Type, typename TObject> 56 static inline Type* CastP(TObject *X) 57 { return reinterpret_cast<Type*> (X); } 58 59 /* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory 60 * location pointed to by P plus Ofs bytes. */ 61 template<typename Type> 62 static inline const Type& StructAtOffset(const void *P, unsigned int offset) 63 { return * reinterpret_cast<const Type*> ((const char *) P + offset); } 64 template<typename Type> 65 static inline Type& StructAtOffset(void *P, unsigned int offset) 66 { return * reinterpret_cast<Type*> ((char *) P + offset); } 67 68 /* StructAfter<T>(X) returns the struct T& that is placed after X. 69 * Works with X of variable size also. X must implement get_size() */ 70 template<typename Type, typename TObject> 71 static inline const Type& StructAfter(const TObject &X) 72 { return StructAtOffset<Type>(&X, X.get_size()); } 73 template<typename Type, typename TObject> 74 static inline Type& StructAfter(TObject &X) 75 { return StructAtOffset<Type>(&X, X.get_size()); } 76 77 78 /* 79 * Size checking 80 */ 81 82 /* Check _assertion in a method environment */ 83 #define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \ 84 void _instance_assertion_on_line_##_line () const \ 85 { static_assert ((_assertion), ""); } 86 # define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion) 87 # define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion) 88 89 /* Check that _code compiles in a method environment */ 90 #define _DEFINE_COMPILES_ASSERTION1(_line, _code) \ 91 void _compiles_assertion_on_line_##_line () const \ 92 { _code; } 93 # define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code) 94 # define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code) 95 96 97 #define DEFINE_SIZE_STATIC(size) \ 98 DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \ 99 unsigned int get_size () const { return (size); } \ 100 enum { null_size = (size) }; \ 101 enum { min_size = (size) }; \ 102 enum { static_size = (size) } 103 104 #define DEFINE_SIZE_UNION(size, _member) \ 105 DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \ 106 DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \ 107 enum { null_size = (size) }; \ 108 enum { min_size = (size) } 109 110 #define DEFINE_SIZE_MIN(size) \ 111 DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \ 112 enum { null_size = (size) }; \ 113 enum { min_size = (size) } 114 115 #define DEFINE_SIZE_UNBOUNDED(size) \ 116 DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \ 117 enum { min_size = (size) } 118 119 #define DEFINE_SIZE_ARRAY(size, array) \ 120 DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \ 121 DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + VAR * sizeof ((array)[0])) \ 122 enum { null_size = (size) }; \ 123 enum { min_size = (size) } 124 125 #define DEFINE_SIZE_ARRAY_SIZED(size, array) \ 126 unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \ 127 DEFINE_SIZE_ARRAY(size, array) 128 129 130 /* 131 * Dispatch 132 */ 133 134 template <typename Context, typename Return, unsigned int MaxDebugDepth> 135 struct hb_dispatch_context_t 136 { 137 enum { max_debug_depth = MaxDebugDepth }; 138 typedef Return return_t; 139 template <typename T, typename F> 140 bool may_dispatch (const T *obj HB_UNUSED, const F *format HB_UNUSED) { return true; } 141 static return_t no_dispatch_return_value () { return Context::default_return_value (); } 142 static bool stop_sublookup_iteration (const return_t r HB_UNUSED) { return false; } 143 }; 144 145 146 /* 147 * Sanitize 148 * 149 * 150 * === Introduction === 151 * 152 * The sanitize machinery is at the core of our zero-cost font loading. We 153 * mmap() font file into memory and create a blob out of it. Font subtables 154 * are returned as a readonly sub-blob of the main font blob. These table 155 * blobs are then sanitized before use, to ensure invalid memory access does 156 * not happen. The toplevel sanitize API use is like, eg. to load the 'head' 157 * table: 158 * 159 * hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table<OT::head> (face); 160 * 161 * The blob then can be converted to a head table struct with: 162 * 163 * const head *head_table = head_blob->as<head> (); 164 * 165 * What the reference_table does is, to call hb_face_reference_table() to load 166 * the table blob, sanitize it and return either the sanitized blob, or empty 167 * blob if sanitization failed. The blob->as() function returns the null 168 * object of its template type argument if the blob is empty. Otherwise, it 169 * just casts the blob contents to the desired type. 170 * 171 * Sanitizing a blob of data with a type T works as follows (with minor 172 * simplification): 173 * 174 * - Cast blob content to T*, call sanitize() method of it, 175 * - If sanitize succeeded, return blob. 176 * - Otherwise, if blob is not writable, try making it writable, 177 * or copy if cannot be made writable in-place, 178 * - Call sanitize() again. Return blob if sanitize succeeded. 179 * - Return empty blob otherwise. 180 * 181 * 182 * === The sanitize() contract === 183 * 184 * The sanitize() method of each object type shall return true if it's safe to 185 * call other methods of the object, and false otherwise. 186 * 187 * Note that what sanitize() checks for might align with what the specification 188 * describes as valid table data, but does not have to be. In particular, we 189 * do NOT want to be pedantic and concern ourselves with validity checks that 190 * are irrelevant to our use of the table. On the contrary, we want to be 191 * lenient with error handling and accept invalid data to the extent that it 192 * does not impose extra burden on us. 193 * 194 * Based on the sanitize contract, one can see that what we check for depends 195 * on how we use the data in other table methods. Ie. if other table methods 196 * assume that offsets do NOT point out of the table data block, then that's 197 * something sanitize() must check for (GSUB/GPOS/GDEF/etc work this way). On 198 * the other hand, if other methods do such checks themselves, then sanitize() 199 * does not have to bother with them (glyf/local work this way). The choice 200 * depends on the table structure and sanitize() performance. For example, to 201 * check glyf/loca offsets in sanitize() would cost O(num-glyphs). We try hard 202 * to avoid such costs during font loading. By postponing such checks to the 203 * actual glyph loading, we reduce the sanitize cost to O(1) and total runtime 204 * cost to O(used-glyphs). As such, this is preferred. 205 * 206 * The same argument can be made re GSUB/GPOS/GDEF, but there, the table 207 * structure is so complicated that by checking all offsets at sanitize() time, 208 * we make the code much simpler in other methods, as offsets and referenced 209 * objects do not need to be validated at each use site. 210 */ 211 212 /* This limits sanitizing time on really broken fonts. */ 213 #ifndef HB_SANITIZE_MAX_EDITS 214 #define HB_SANITIZE_MAX_EDITS 32 215 #endif 216 #ifndef HB_SANITIZE_MAX_OPS_FACTOR 217 #define HB_SANITIZE_MAX_OPS_FACTOR 8 218 #endif 219 #ifndef HB_SANITIZE_MAX_OPS_MIN 220 #define HB_SANITIZE_MAX_OPS_MIN 16384 221 #endif 222 #ifndef HB_SANITIZE_MAX_OPS_MAX 223 #define HB_SANITIZE_MAX_OPS_MAX 0x3FFFFFFF 224 #endif 225 226 struct hb_sanitize_context_t : 227 hb_dispatch_context_t<hb_sanitize_context_t, bool, HB_DEBUG_SANITIZE> 228 { 229 hb_sanitize_context_t () : 230 debug_depth (0), 231 start (nullptr), end (nullptr), 232 max_ops (0), 233 writable (false), edit_count (0), 234 blob (nullptr), 235 num_glyphs (65536), 236 num_glyphs_set (false) {} 237 238 const char *get_name () { return "SANITIZE"; } 239 template <typename T, typename F> 240 bool may_dispatch (const T *obj HB_UNUSED, const F *format) 241 { return format->sanitize (this); } 242 template <typename T> 243 return_t dispatch (const T &obj) { return obj.sanitize (this); } 244 static return_t default_return_value () { return true; } 245 static return_t no_dispatch_return_value () { return false; } 246 bool stop_sublookup_iteration (const return_t r) const { return !r; } 247 248 void init (hb_blob_t *b) 249 { 250 this->blob = hb_blob_reference (b); 251 this->writable = false; 252 } 253 254 void set_num_glyphs (unsigned int num_glyphs_) 255 { 256 num_glyphs = num_glyphs_; 257 num_glyphs_set = true; 258 } 259 unsigned int get_num_glyphs () { return num_glyphs; } 260 261 void set_max_ops (int max_ops_) { max_ops = max_ops_; } 262 263 template <typename T> 264 void set_object (const T *obj) 265 { 266 reset_object (); 267 268 if (!obj) return; 269 270 const char *obj_start = (const char *) obj; 271 const char *obj_end = (const char *) obj + obj->get_size (); 272 assert (obj_start <= obj_end); /* Must not overflow. */ 273 274 if (unlikely (obj_end < this->start || this->end < obj_start)) 275 this->start = this->end = nullptr; 276 else 277 { 278 this->start = MAX (this->start, obj_start); 279 this->end = MIN (this->end , obj_end ); 280 } 281 } 282 283 void reset_object () 284 { 285 this->start = this->blob->data; 286 this->end = this->start + this->blob->length; 287 assert (this->start <= this->end); /* Must not overflow. */ 288 } 289 290 void start_processing () 291 { 292 reset_object (); 293 this->max_ops = MAX ((unsigned int) (this->end - this->start) * HB_SANITIZE_MAX_OPS_FACTOR, 294 (unsigned) HB_SANITIZE_MAX_OPS_MIN); 295 this->edit_count = 0; 296 this->debug_depth = 0; 297 298 DEBUG_MSG_LEVEL (SANITIZE, start, 0, +1, 299 "start [%p..%p] (%lu bytes)", 300 this->start, this->end, 301 (unsigned long) (this->end - this->start)); 302 } 303 304 void end_processing () 305 { 306 DEBUG_MSG_LEVEL (SANITIZE, this->start, 0, -1, 307 "end [%p..%p] %u edit requests", 308 this->start, this->end, this->edit_count); 309 310 hb_blob_destroy (this->blob); 311 this->blob = nullptr; 312 this->start = this->end = nullptr; 313 } 314 315 bool check_range (const void *base, 316 unsigned int len) const 317 { 318 const char *p = (const char *) base; 319 bool ok = this->start <= p && 320 p <= this->end && 321 (unsigned int) (this->end - p) >= len && 322 this->max_ops-- > 0; 323 324 DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0, 325 "check_range [%p..%p] (%d bytes) in [%p..%p] -> %s", 326 p, p + len, len, 327 this->start, this->end, 328 ok ? "OK" : "OUT-OF-RANGE"); 329 330 return likely (ok); 331 } 332 333 template <typename T> 334 bool check_range (const T *base, 335 unsigned int a, 336 unsigned int b) const 337 { 338 return !hb_unsigned_mul_overflows (a, b) && 339 this->check_range (base, a * b); 340 } 341 342 template <typename T> 343 bool check_range (const T *base, 344 unsigned int a, 345 unsigned int b, 346 unsigned int c) const 347 { 348 return !hb_unsigned_mul_overflows (a, b) && 349 this->check_range (base, a * b, c); 350 } 351 352 template <typename T> 353 bool check_array (const T *base, unsigned int len) const 354 { 355 return this->check_range (base, len, hb_static_size (T)); 356 } 357 358 template <typename T> 359 bool check_array (const T *base, 360 unsigned int a, 361 unsigned int b) const 362 { 363 return this->check_range (base, a, b, hb_static_size (T)); 364 } 365 366 template <typename Type> 367 bool check_struct (const Type *obj) const 368 { return likely (this->check_range (obj, obj->min_size)); } 369 370 bool may_edit (const void *base, unsigned int len) 371 { 372 if (this->edit_count >= HB_SANITIZE_MAX_EDITS) 373 return false; 374 375 const char *p = (const char *) base; 376 this->edit_count++; 377 378 DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0, 379 "may_edit(%u) [%p..%p] (%d bytes) in [%p..%p] -> %s", 380 this->edit_count, 381 p, p + len, len, 382 this->start, this->end, 383 this->writable ? "GRANTED" : "DENIED"); 384 385 return this->writable; 386 } 387 388 template <typename Type, typename ValueType> 389 bool try_set (const Type *obj, const ValueType &v) 390 { 391 if (this->may_edit (obj, hb_static_size (Type))) 392 { 393 hb_assign (* const_cast<Type *> (obj), v); 394 return true; 395 } 396 return false; 397 } 398 399 template <typename Type> 400 hb_blob_t *sanitize_blob (hb_blob_t *blob) 401 { 402 bool sane; 403 404 init (blob); 405 406 retry: 407 DEBUG_MSG_FUNC (SANITIZE, start, "start"); 408 409 start_processing (); 410 411 if (unlikely (!start)) 412 { 413 end_processing (); 414 return blob; 415 } 416 417 Type *t = CastP<Type> (const_cast<char *> (start)); 418 419 sane = t->sanitize (this); 420 if (sane) 421 { 422 if (edit_count) 423 { 424 DEBUG_MSG_FUNC (SANITIZE, start, "passed first round with %d edits; going for second round", edit_count); 425 426 /* sanitize again to ensure no toe-stepping */ 427 edit_count = 0; 428 sane = t->sanitize (this); 429 if (edit_count) { 430 DEBUG_MSG_FUNC (SANITIZE, start, "requested %d edits in second round; FAILLING", edit_count); 431 sane = false; 432 } 433 } 434 } 435 else 436 { 437 if (edit_count && !writable) { 438 start = hb_blob_get_data_writable (blob, nullptr); 439 end = start + blob->length; 440 441 if (start) 442 { 443 writable = true; 444 /* ok, we made it writable by relocating. try again */ 445 DEBUG_MSG_FUNC (SANITIZE, start, "retry"); 446 goto retry; 447 } 448 } 449 } 450 451 end_processing (); 452 453 DEBUG_MSG_FUNC (SANITIZE, start, sane ? "PASSED" : "FAILED"); 454 if (sane) 455 { 456 hb_blob_make_immutable (blob); 457 return blob; 458 } 459 else 460 { 461 hb_blob_destroy (blob); 462 return hb_blob_get_empty (); 463 } 464 } 465 466 template <typename Type> 467 hb_blob_t *reference_table (const hb_face_t *face, hb_tag_t tableTag = Type::tableTag) 468 { 469 if (!num_glyphs_set) 470 set_num_glyphs (hb_face_get_glyph_count (face)); 471 return sanitize_blob<Type> (hb_face_reference_table (face, tableTag)); 472 } 473 474 mutable unsigned int debug_depth; 475 const char *start, *end; 476 mutable int max_ops; 477 private: 478 bool writable; 479 unsigned int edit_count; 480 hb_blob_t *blob; 481 unsigned int num_glyphs; 482 bool num_glyphs_set; 483 }; 484 485 struct hb_sanitize_with_object_t 486 { 487 template <typename T> 488 hb_sanitize_with_object_t (hb_sanitize_context_t *c, 489 const T& obj) : c (c) 490 { c->set_object (obj); } 491 ~hb_sanitize_with_object_t () 492 { c->reset_object (); } 493 494 private: 495 hb_sanitize_context_t *c; 496 }; 497 498 499 /* 500 * Serialize 501 */ 502 503 struct hb_serialize_context_t 504 { 505 hb_serialize_context_t (void *start_, unsigned int size) 506 { 507 this->start = (char *) start_; 508 this->end = this->start + size; 509 reset (); 510 } 511 512 bool in_error () const { return !this->successful; } 513 514 void reset () 515 { 516 this->successful = true; 517 this->head = this->start; 518 this->debug_depth = 0; 519 } 520 521 bool propagate_error (bool e) 522 { return this->successful = this->successful && e; } 523 template <typename T> bool propagate_error (const T &obj) 524 { return this->successful = this->successful && !obj.in_error (); } 525 template <typename T> bool propagate_error (const T *obj) 526 { return this->successful = this->successful && !obj->in_error (); } 527 template <typename T1, typename T2> bool propagate_error (T1 &o1, T2 &o2) 528 { return propagate_error (o1) && propagate_error (o2); } 529 template <typename T1, typename T2> bool propagate_error (T1 *o1, T2 *o2) 530 { return propagate_error (o1) && propagate_error (o2); } 531 template <typename T1, typename T2, typename T3> 532 bool propagate_error (T1 &o1, T2 &o2, T3 &o3) 533 { return propagate_error (o1) && propagate_error (o2, o3); } 534 template <typename T1, typename T2, typename T3> 535 bool propagate_error (T1 *o1, T2 *o2, T3 *o3) 536 { return propagate_error (o1) && propagate_error (o2, o3); } 537 538 /* To be called around main operation. */ 539 template <typename Type> 540 Type *start_serialize () 541 { 542 DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, +1, 543 "start [%p..%p] (%lu bytes)", 544 this->start, this->end, 545 (unsigned long) (this->end - this->start)); 546 547 return start_embed<Type> (); 548 } 549 void end_serialize () 550 { 551 DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, -1, 552 "end [%p..%p] serialized %d bytes; %s", 553 this->start, this->end, 554 (int) (this->head - this->start), 555 this->successful ? "successful" : "UNSUCCESSFUL"); 556 } 557 558 unsigned int length () const { return this->head - this->start; } 559 560 void align (unsigned int alignment) 561 { 562 unsigned int l = length () % alignment; 563 if (l) 564 allocate_size<void> (alignment - l); 565 } 566 567 template <typename Type> 568 Type *start_embed (const Type *_ HB_UNUSED = nullptr) const 569 { 570 Type *ret = reinterpret_cast<Type *> (this->head); 571 return ret; 572 } 573 574 template <typename Type> 575 Type *allocate_size (unsigned int size) 576 { 577 if (unlikely (!this->successful || this->end - this->head < ptrdiff_t (size))) { 578 this->successful = false; 579 return nullptr; 580 } 581 memset (this->head, 0, size); 582 char *ret = this->head; 583 this->head += size; 584 return reinterpret_cast<Type *> (ret); 585 } 586 587 template <typename Type> 588 Type *allocate_min () 589 { 590 return this->allocate_size<Type> (Type::min_size); 591 } 592 593 template <typename Type> 594 Type *embed (const Type &obj) 595 { 596 unsigned int size = obj.get_size (); 597 Type *ret = this->allocate_size<Type> (size); 598 if (unlikely (!ret)) return nullptr; 599 memcpy (ret, &obj, size); 600 return ret; 601 } 602 template <typename Type> 603 hb_serialize_context_t &operator << (const Type &obj) { embed (obj); return *this; } 604 605 template <typename Type> 606 Type *extend_size (Type &obj, unsigned int size) 607 { 608 assert (this->start <= (char *) &obj); 609 assert ((char *) &obj <= this->head); 610 assert ((char *) &obj + size >= this->head); 611 if (unlikely (!this->allocate_size<Type> (((char *) &obj) + size - this->head))) return nullptr; 612 return reinterpret_cast<Type *> (&obj); 613 } 614 615 template <typename Type> 616 Type *extend_min (Type &obj) { return extend_size (obj, obj.min_size); } 617 618 template <typename Type> 619 Type *extend (Type &obj) { return extend_size (obj, obj.get_size ()); } 620 621 /* Output routines. */ 622 template <typename Type> 623 Type *copy () const 624 { 625 assert (this->successful); 626 unsigned int len = this->head - this->start; 627 void *p = malloc (len); 628 if (p) 629 memcpy (p, this->start, len); 630 return reinterpret_cast<Type *> (p); 631 } 632 hb_bytes_t copy_bytes () const 633 { 634 assert (this->successful); 635 unsigned int len = this->head - this->start; 636 void *p = malloc (len); 637 if (p) 638 memcpy (p, this->start, len); 639 else 640 return hb_bytes_t (); 641 return hb_bytes_t ((char *) p, len); 642 } 643 hb_blob_t *copy_blob () const 644 { 645 assert (this->successful); 646 return hb_blob_create (this->start, 647 this->head - this->start, 648 HB_MEMORY_MODE_DUPLICATE, 649 nullptr, nullptr); 650 } 651 652 public: 653 unsigned int debug_depth; 654 char *start, *end, *head; 655 bool successful; 656 }; 657 658 659 660 /* 661 * Big-endian integers. 662 */ 663 664 template <typename Type, int Bytes> struct BEInt; 665 666 template <typename Type> 667 struct BEInt<Type, 1> 668 { 669 public: 670 typedef Type type; 671 void set (Type V) { v = V; } 672 operator Type () const { return v; } 673 private: uint8_t v; 674 }; 675 template <typename Type> 676 struct BEInt<Type, 2> 677 { 678 public: 679 typedef Type type; 680 void set (Type V) 681 { 682 v[0] = (V >> 8) & 0xFF; 683 v[1] = (V ) & 0xFF; 684 } 685 operator Type () const 686 { 687 #if ((defined(__GNUC__) && __GNUC__ >= 5) || defined(__clang__)) && \ 688 defined(__BYTE_ORDER) && \ 689 (__BYTE_ORDER == __LITTLE_ENDIAN || __BYTE_ORDER == __BIG_ENDIAN) 690 /* Spoon-feed the compiler a big-endian integer with alignment 1. 691 * https://github.com/harfbuzz/harfbuzz/pull/1398 */ 692 struct __attribute__((packed)) packed_uint16_t { uint16_t v; }; 693 #if __BYTE_ORDER == __LITTLE_ENDIAN 694 return __builtin_bswap16 (((packed_uint16_t *) this)->v); 695 #else /* __BYTE_ORDER == __BIG_ENDIAN */ 696 return ((packed_uint16_t *) this)->v; 697 #endif 698 #endif 699 return (v[0] << 8) 700 + (v[1] ); 701 } 702 private: uint8_t v[2]; 703 }; 704 template <typename Type> 705 struct BEInt<Type, 3> 706 { 707 public: 708 typedef Type type; 709 void set (Type V) 710 { 711 v[0] = (V >> 16) & 0xFF; 712 v[1] = (V >> 8) & 0xFF; 713 v[2] = (V ) & 0xFF; 714 } 715 operator Type () const 716 { 717 return (v[0] << 16) 718 + (v[1] << 8) 719 + (v[2] ); 720 } 721 private: uint8_t v[3]; 722 }; 723 template <typename Type> 724 struct BEInt<Type, 4> 725 { 726 public: 727 typedef Type type; 728 void set (Type V) 729 { 730 v[0] = (V >> 24) & 0xFF; 731 v[1] = (V >> 16) & 0xFF; 732 v[2] = (V >> 8) & 0xFF; 733 v[3] = (V ) & 0xFF; 734 } 735 operator Type () const 736 { 737 return (v[0] << 24) 738 + (v[1] << 16) 739 + (v[2] << 8) 740 + (v[3] ); 741 } 742 private: uint8_t v[4]; 743 }; 744 745 746 /* 747 * Lazy loaders. 748 */ 749 750 template <typename Data, unsigned int WheresData> 751 struct hb_data_wrapper_t 752 { 753 static_assert (WheresData > 0, ""); 754 755 Data * get_data () const 756 { return *(((Data **) (void *) this) - WheresData); } 757 758 bool is_inert () const { return !get_data (); } 759 760 template <typename Stored, typename Subclass> 761 Stored * call_create () const { return Subclass::create (get_data ()); } 762 }; 763 template <> 764 struct hb_data_wrapper_t<void, 0> 765 { 766 bool is_inert () const { return false; } 767 768 template <typename Stored, typename Funcs> 769 Stored * call_create () const { return Funcs::create (); } 770 }; 771 772 template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; }; 773 template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; }; 774 775 template <typename Returned, 776 typename Subclass = void, 777 typename Data = void, 778 unsigned int WheresData = 0, 779 typename Stored = Returned> 780 struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData> 781 { 782 typedef typename hb_non_void_t<Subclass, 783 hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored> 784 >::value Funcs; 785 786 void init0 () {} /* Init, when memory is already set to 0. No-op for us. */ 787 void init () { instance.set_relaxed (nullptr); } 788 void fini () { do_destroy (instance.get ()); } 789 790 void free_instance () 791 { 792 retry: 793 Stored *p = instance.get (); 794 if (unlikely (p && !cmpexch (p, nullptr))) 795 goto retry; 796 do_destroy (p); 797 } 798 799 static void do_destroy (Stored *p) 800 { 801 if (p && p != const_cast<Stored *> (Funcs::get_null ())) 802 Funcs::destroy (p); 803 } 804 805 const Returned * operator -> () const { return get (); } 806 const Returned & operator * () const { return *get (); } 807 explicit_operator bool () const 808 { return get_stored () != Funcs::get_null (); } 809 template <typename C> operator const C * () const { return get (); } 810 811 Stored * get_stored () const 812 { 813 retry: 814 Stored *p = this->instance.get (); 815 if (unlikely (!p)) 816 { 817 if (unlikely (this->is_inert ())) 818 return const_cast<Stored *> (Funcs::get_null ()); 819 820 p = this->template call_create<Stored, Funcs> (); 821 if (unlikely (!p)) 822 p = const_cast<Stored *> (Funcs::get_null ()); 823 824 if (unlikely (!cmpexch (nullptr, p))) 825 { 826 do_destroy (p); 827 goto retry; 828 } 829 } 830 return p; 831 } 832 Stored * get_stored_relaxed () const 833 { 834 return this->instance.get_relaxed (); 835 } 836 837 bool cmpexch (Stored *current, Stored *value) const 838 { 839 /* This *must* be called when there are no other threads accessing. */ 840 return this->instance.cmpexch (current, value); 841 } 842 843 const Returned * get () const { return Funcs::convert (get_stored ()); } 844 const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); } 845 Returned * get_unconst () const { return const_cast<Returned *> (Funcs::convert (get_stored ())); } 846 847 /* To be possibly overloaded by subclasses. */ 848 static Returned* convert (Stored *p) { return p; } 849 850 /* By default null/init/fini the object. */ 851 static const Stored* get_null () { return &Null(Stored); } 852 static Stored *create (Data *data) 853 { 854 Stored *p = (Stored *) calloc (1, sizeof (Stored)); 855 if (likely (p)) 856 p->init (data); 857 return p; 858 } 859 static Stored *create () 860 { 861 Stored *p = (Stored *) calloc (1, sizeof (Stored)); 862 if (likely (p)) 863 p->init (); 864 return p; 865 } 866 static void destroy (Stored *p) 867 { 868 p->fini (); 869 free (p); 870 } 871 872 // private: 873 /* Must only have one pointer. */ 874 hb_atomic_ptr_t<Stored *> instance; 875 }; 876 877 /* Specializations. */ 878 879 template <typename T, unsigned int WheresFace> 880 struct hb_face_lazy_loader_t : hb_lazy_loader_t<T, 881 hb_face_lazy_loader_t<T, WheresFace>, 882 hb_face_t, WheresFace> {}; 883 884 template <typename T, unsigned int WheresFace> 885 struct hb_table_lazy_loader_t : hb_lazy_loader_t<T, 886 hb_table_lazy_loader_t<T, WheresFace>, 887 hb_face_t, WheresFace, 888 hb_blob_t> 889 { 890 static hb_blob_t *create (hb_face_t *face) 891 { return hb_sanitize_context_t ().reference_table<T> (face); } 892 static void destroy (hb_blob_t *p) { hb_blob_destroy (p); } 893 894 static const hb_blob_t *get_null () 895 { return hb_blob_get_empty (); } 896 897 static const T* convert (const hb_blob_t *blob) 898 { return blob->as<T> (); } 899 900 hb_blob_t* get_blob () const { return this->get_stored (); } 901 }; 902 903 template <typename Subclass> 904 struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<hb_font_funcs_t, Subclass> 905 { 906 static void destroy (hb_font_funcs_t *p) 907 { hb_font_funcs_destroy (p); } 908 static const hb_font_funcs_t *get_null () 909 { return hb_font_funcs_get_empty (); } 910 }; 911 template <typename Subclass> 912 struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<hb_unicode_funcs_t, Subclass> 913 { 914 static void destroy (hb_unicode_funcs_t *p) 915 { hb_unicode_funcs_destroy (p); } 916 static const hb_unicode_funcs_t *get_null () 917 { return hb_unicode_funcs_get_empty (); } 918 }; 919 920 921 #endif /* HB_MACHINERY_HH */ 922
