1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "gpos.h"
6
7 #include <limits>
8 #include <vector>
9
10 #include "gdef.h"
11 #include "gsub.h"
12 #include "layout.h"
13 #include "maxp.h"
14
15 // GPOS - The Glyph Positioning Table
16 // http://www.microsoft.com/typography/otspec/gpos.htm
17
18 namespace {
19
20 enum GPOS_TYPE {
21 GPOS_TYPE_SINGLE_ADJUSTMENT = 1,
22 GPOS_TYPE_PAIR_ADJUSTMENT = 2,
23 GPOS_TYPE_CURSIVE_ATTACHMENT = 3,
24 GPOS_TYPE_MARK_TO_BASE_ATTACHMENT = 4,
25 GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT = 5,
26 GPOS_TYPE_MARK_TO_MARK_ATTACHMENT = 6,
27 GPOS_TYPE_CONTEXT_POSITIONING = 7,
28 GPOS_TYPE_CHAINED_CONTEXT_POSITIONING = 8,
29 GPOS_TYPE_EXTENSION_POSITIONING = 9,
30 GPOS_TYPE_RESERVED = 10
31 };
32
33 // The size of gpos header.
34 const unsigned kGposHeaderSize = 10;
35 // The maximum format number for anchor tables.
36 const uint16_t kMaxAnchorFormat = 3;
37 // The maximum number of class value.
38 const uint16_t kMaxClassDefValue = 0xFFFF;
39
40 // Lookup type parsers.
41 bool ParseSingleAdjustment(const ots::OpenTypeFile *file,
42 const uint8_t *data, const size_t length);
43 bool ParsePairAdjustment(const ots::OpenTypeFile *file,
44 const uint8_t *data, const size_t length);
45 bool ParseCursiveAttachment(const ots::OpenTypeFile *file,
46 const uint8_t *data, const size_t length);
47 bool ParseMarkToBaseAttachment(const ots::OpenTypeFile *file,
48 const uint8_t *data, const size_t length);
49 bool ParseMarkToLigatureAttachment(const ots::OpenTypeFile *file,
50 const uint8_t *data, const size_t length);
51 bool ParseMarkToMarkAttachment(const ots::OpenTypeFile *file,
52 const uint8_t *data, const size_t length);
53 bool ParseContextPositioning(const ots::OpenTypeFile *file,
54 const uint8_t *data, const size_t length);
55 bool ParseChainedContextPositioning(const ots::OpenTypeFile *file,
56 const uint8_t *data, const size_t length);
57 bool ParseExtensionPositioning(const ots::OpenTypeFile *file,
58 const uint8_t *data, const size_t length);
59
60 const ots::LookupSubtableParser::TypeParser kGposTypeParsers[] = {
61 {GPOS_TYPE_SINGLE_ADJUSTMENT, ParseSingleAdjustment},
62 {GPOS_TYPE_PAIR_ADJUSTMENT, ParsePairAdjustment},
63 {GPOS_TYPE_CURSIVE_ATTACHMENT, ParseCursiveAttachment},
64 {GPOS_TYPE_MARK_TO_BASE_ATTACHMENT, ParseMarkToBaseAttachment},
65 {GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT, ParseMarkToLigatureAttachment},
66 {GPOS_TYPE_MARK_TO_MARK_ATTACHMENT, ParseMarkToMarkAttachment},
67 {GPOS_TYPE_CONTEXT_POSITIONING, ParseContextPositioning},
68 {GPOS_TYPE_CHAINED_CONTEXT_POSITIONING, ParseChainedContextPositioning},
69 {GPOS_TYPE_EXTENSION_POSITIONING, ParseExtensionPositioning}
70 };
71
72 const ots::LookupSubtableParser kGposLookupSubtableParser = {
73 arraysize(kGposTypeParsers),
74 GPOS_TYPE_EXTENSION_POSITIONING, kGposTypeParsers
75 };
76
77 // Shared Tables: ValueRecord, Anchor Table, and MarkArray
78
ParseValueRecord(ots::Buffer * subtable,const uint8_t * data,const size_t length,const uint16_t value_format)79 bool ParseValueRecord(ots::Buffer* subtable, const uint8_t *data,
80 const size_t length, const uint16_t value_format) {
81 // Check existence of adjustment fields.
82 for (unsigned i = 0; i < 4; ++i) {
83 if ((value_format >> i) & 0x1) {
84 // Just read the field since these fileds could take an arbitrary values.
85 if (!subtable->Skip(2)) {
86 return OTS_FAILURE();
87 }
88 }
89 }
90
91 // Check existence of offsets to device table.
92 for (unsigned i = 0; i < 4; ++i) {
93 if ((value_format >> (i + 4)) & 0x1) {
94 uint16_t offset = 0;
95 if (!subtable->ReadU16(&offset)) {
96 return OTS_FAILURE();
97 }
98 if (offset) {
99 // TODO(bashi): Is it possible that device tables locate before
100 // this record? No fonts contain such offset AKAIF.
101 if (offset >= length) {
102 return OTS_FAILURE();
103 }
104 if (!ots::ParseDeviceTable(data + offset, length - offset)) {
105 return OTS_FAILURE();
106 }
107 }
108 }
109 }
110 return true;
111 }
112
ParseAnchorTable(const uint8_t * data,const size_t length)113 bool ParseAnchorTable(const uint8_t *data, const size_t length) {
114 ots::Buffer subtable(data, length);
115
116 uint16_t format = 0;
117 // Read format and skip 2 2-byte fields that could be arbitrary values.
118 if (!subtable.ReadU16(&format) ||
119 !subtable.Skip(4)) {
120 return OTS_FAILURE();
121 }
122
123 if (format == 0 || format > kMaxAnchorFormat) {
124 return OTS_FAILURE();
125 }
126
127 // Format 2 and 3 has additional fields.
128 if (format == 2) {
129 // Format 2 provides an index to a glyph contour point, which will take
130 // arbitrary value.
131 uint16_t anchor_point = 0;
132 if (!subtable.ReadU16(&anchor_point)) {
133 return OTS_FAILURE();
134 }
135 } else if (format == 3) {
136 uint16_t offset_x_device = 0;
137 uint16_t offset_y_device = 0;
138 if (!subtable.ReadU16(&offset_x_device) ||
139 !subtable.ReadU16(&offset_y_device)) {
140 return OTS_FAILURE();
141 }
142 const unsigned format_end = static_cast<unsigned>(10);
143 if (offset_x_device) {
144 if (offset_x_device < format_end || offset_x_device >= length) {
145 return OTS_FAILURE();
146 }
147 if (!ots::ParseDeviceTable(data + offset_x_device,
148 length - offset_x_device)) {
149 return OTS_FAILURE();
150 }
151 }
152 if (offset_y_device) {
153 if (offset_y_device < format_end || offset_y_device >= length) {
154 return OTS_FAILURE();
155 }
156 if (!ots::ParseDeviceTable(data + offset_y_device,
157 length - offset_y_device)) {
158 return OTS_FAILURE();
159 }
160 }
161 }
162 return true;
163 }
164
ParseMarkArrayTable(const uint8_t * data,const size_t length,const uint16_t class_count)165 bool ParseMarkArrayTable(const uint8_t *data, const size_t length,
166 const uint16_t class_count) {
167 ots::Buffer subtable(data, length);
168
169 uint16_t mark_count = 0;
170 if (!subtable.ReadU16(&mark_count)) {
171 return OTS_FAILURE();
172 }
173
174 // MarkRecord consists of 4-bytes.
175 const unsigned mark_records_end = 4 * static_cast<unsigned>(mark_count) + 2;
176 if (mark_records_end > std::numeric_limits<uint16_t>::max()) {
177 return OTS_FAILURE();
178 }
179 for (unsigned i = 0; i < mark_count; ++i) {
180 uint16_t class_value = 0;
181 uint16_t offset_mark_anchor = 0;
182 if (!subtable.ReadU16(&class_value) ||
183 !subtable.ReadU16(&offset_mark_anchor)) {
184 return OTS_FAILURE();
185 }
186 // |class_value| may take arbitrary values including 0 here so we don't
187 // check the value.
188 if (offset_mark_anchor < mark_records_end ||
189 offset_mark_anchor >= length) {
190 return OTS_FAILURE();
191 }
192 if (!ParseAnchorTable(data + offset_mark_anchor,
193 length - offset_mark_anchor)) {
194 return OTS_FAILURE();
195 }
196 }
197
198 return true;
199 }
200
201 // Lookup Type 1:
202 // Single Adjustment Positioning Subtable
ParseSingleAdjustment(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)203 bool ParseSingleAdjustment(const ots::OpenTypeFile *file, const uint8_t *data,
204 const size_t length) {
205 ots::Buffer subtable(data, length);
206
207 uint16_t format = 0;
208 uint16_t offset_coverage = 0;
209 uint16_t value_format = 0;
210 if (!subtable.ReadU16(&format) ||
211 !subtable.ReadU16(&offset_coverage) ||
212 !subtable.ReadU16(&value_format)) {
213 return OTS_FAILURE();
214 }
215
216 if (format == 1) {
217 // Format 1 exactly one value record.
218 if (!ParseValueRecord(&subtable, data, length, value_format)) {
219 return OTS_FAILURE();
220 }
221 } else if (format == 2) {
222 uint16_t value_count = 0;
223 if (!subtable.ReadU16(&value_count)) {
224 return OTS_FAILURE();
225 }
226 for (unsigned i = 0; i < value_count; ++i) {
227 if (!ParseValueRecord(&subtable, data, length, value_format)) {
228 return OTS_FAILURE();
229 }
230 }
231 } else {
232 return OTS_FAILURE();
233 }
234
235 if (offset_coverage < subtable.offset() || offset_coverage >= length) {
236 return OTS_FAILURE();
237 }
238
239 if (!ots::ParseCoverageTable(data + offset_coverage,
240 length - offset_coverage,
241 file->maxp->num_glyphs)) {
242 return OTS_FAILURE();
243 }
244
245 return true;
246 }
247
ParsePairSetTable(const uint8_t * data,const size_t length,const uint16_t value_format1,const uint16_t value_format2,const uint16_t num_glyphs)248 bool ParsePairSetTable(const uint8_t *data, const size_t length,
249 const uint16_t value_format1,
250 const uint16_t value_format2,
251 const uint16_t num_glyphs) {
252 ots::Buffer subtable(data, length);
253
254 uint16_t value_count = 0;
255 if (!subtable.ReadU16(&value_count)) {
256 return OTS_FAILURE();
257 }
258 for (unsigned i = 0; i < value_count; ++i) {
259 // Check pair value record.
260 uint16_t glyph_id = 0;
261 if (!subtable.ReadU16(&glyph_id)) {
262 return OTS_FAILURE();
263 }
264 if (glyph_id >= num_glyphs) {
265 return OTS_FAILURE();
266 }
267 if (!ParseValueRecord(&subtable, data, length, value_format1)) {
268 return OTS_FAILURE();
269 }
270 if (!ParseValueRecord(&subtable, data, length, value_format2)) {
271 return OTS_FAILURE();
272 }
273 }
274 return true;
275 }
276
ParsePairPosFormat1(const uint8_t * data,const size_t length,const uint16_t value_format1,const uint16_t value_format2,const uint16_t num_glyphs)277 bool ParsePairPosFormat1(const uint8_t *data, const size_t length,
278 const uint16_t value_format1,
279 const uint16_t value_format2,
280 const uint16_t num_glyphs) {
281 ots::Buffer subtable(data, length);
282
283 // Skip 8 bytes that are already read before.
284 if (!subtable.Skip(8)) {
285 return OTS_FAILURE();
286 }
287
288 uint16_t pair_set_count = 0;
289 if (!subtable.ReadU16(&pair_set_count)) {
290 return OTS_FAILURE();
291 }
292
293 const unsigned pair_pos_end = 2 * static_cast<unsigned>(pair_set_count) + 10;
294 if (pair_pos_end > std::numeric_limits<uint16_t>::max()) {
295 return OTS_FAILURE();
296 }
297 for (unsigned i = 0; i < pair_set_count; ++i) {
298 uint16_t pair_set_offset = 0;
299 if (!subtable.ReadU16(&pair_set_offset)) {
300 return OTS_FAILURE();
301 }
302 if (pair_set_offset < pair_pos_end || pair_set_offset >= length) {
303 return OTS_FAILURE();
304 }
305 // Check pair set tables
306 if (!ParsePairSetTable(data + pair_set_offset, length - pair_set_offset,
307 value_format1, value_format2,
308 num_glyphs)) {
309 return OTS_FAILURE();
310 }
311 }
312
313 return true;
314 }
315
ParsePairPosFormat2(const uint8_t * data,const size_t length,const uint16_t value_format1,const uint16_t value_format2,const uint16_t num_glyphs)316 bool ParsePairPosFormat2(const uint8_t *data, const size_t length,
317 const uint16_t value_format1,
318 const uint16_t value_format2,
319 const uint16_t num_glyphs) {
320 ots::Buffer subtable(data, length);
321
322 // Skip 8 bytes that are already read before.
323 if (!subtable.Skip(8)) {
324 return OTS_FAILURE();
325 }
326
327 uint16_t offset_class_def1 = 0;
328 uint16_t offset_class_def2 = 0;
329 uint16_t class1_count = 0;
330 uint16_t class2_count = 0;
331 if (!subtable.ReadU16(&offset_class_def1) ||
332 !subtable.ReadU16(&offset_class_def2) ||
333 !subtable.ReadU16(&class1_count) ||
334 !subtable.ReadU16(&class2_count)) {
335 return OTS_FAILURE();
336 }
337
338 // Check class 1 records.
339 for (unsigned i = 0; i < class1_count; ++i) {
340 // Check class 2 records.
341 for (unsigned j = 0; j < class2_count; ++j) {
342 if (value_format1 && !ParseValueRecord(&subtable, data, length,
343 value_format1)) {
344 return OTS_FAILURE();
345 }
346 if (value_format2 && !ParseValueRecord(&subtable, data, length,
347 value_format2)) {
348 return OTS_FAILURE();
349 }
350 }
351 }
352
353 // Check class definition tables.
354 if (offset_class_def1 < subtable.offset() || offset_class_def1 >= length ||
355 offset_class_def2 < subtable.offset() || offset_class_def2 >= length) {
356 return OTS_FAILURE();
357 }
358 if (!ots::ParseClassDefTable(data + offset_class_def1,
359 length - offset_class_def1,
360 num_glyphs, kMaxClassDefValue)) {
361 return OTS_FAILURE();
362 }
363 if (!ots::ParseClassDefTable(data + offset_class_def2,
364 length - offset_class_def2,
365 num_glyphs, kMaxClassDefValue)) {
366 return OTS_FAILURE();
367 }
368
369 return true;
370 }
371
372 // Lookup Type 2:
373 // Pair Adjustment Positioning Subtable
ParsePairAdjustment(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)374 bool ParsePairAdjustment(const ots::OpenTypeFile *file, const uint8_t *data,
375 const size_t length) {
376 ots::Buffer subtable(data, length);
377
378 uint16_t format = 0;
379 uint16_t offset_coverage = 0;
380 uint16_t value_format1 = 0;
381 uint16_t value_format2 = 0;
382 if (!subtable.ReadU16(&format) ||
383 !subtable.ReadU16(&offset_coverage) ||
384 !subtable.ReadU16(&value_format1) ||
385 !subtable.ReadU16(&value_format2)) {
386 return OTS_FAILURE();
387 }
388
389 if (format == 1) {
390 if (!ParsePairPosFormat1(data, length, value_format1, value_format2,
391 file->maxp->num_glyphs)) {
392 return OTS_FAILURE();
393 }
394 } else if (format == 2) {
395 if (!ParsePairPosFormat2(data, length, value_format1, value_format2,
396 file->maxp->num_glyphs)) {
397 return OTS_FAILURE();
398 }
399 } else {
400 return OTS_FAILURE();
401 }
402
403 if (offset_coverage < subtable.offset() || offset_coverage >= length) {
404 return OTS_FAILURE();
405 }
406 if (!ots::ParseCoverageTable(data + offset_coverage,
407 length - offset_coverage,
408 file->maxp->num_glyphs)) {
409 return OTS_FAILURE();
410 }
411
412 return true;
413 }
414
415 // Lookup Type 3
416 // Cursive Attachment Positioning Subtable
ParseCursiveAttachment(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)417 bool ParseCursiveAttachment(const ots::OpenTypeFile *file, const uint8_t *data,
418 const size_t length) {
419 ots::Buffer subtable(data, length);
420
421 uint16_t format = 0;
422 uint16_t offset_coverage = 0;
423 uint16_t entry_exit_count = 0;
424 if (!subtable.ReadU16(&format) ||
425 !subtable.ReadU16(&offset_coverage) ||
426 !subtable.ReadU16(&entry_exit_count)) {
427 return OTS_FAILURE();
428 }
429
430 if (format != 1) {
431 return OTS_FAILURE();
432 }
433
434 // Check entry exit records.
435 const unsigned entry_exit_records_end =
436 2 * static_cast<unsigned>(entry_exit_count) + 6;
437 if (entry_exit_records_end > std::numeric_limits<uint16_t>::max()) {
438 return OTS_FAILURE();
439 }
440 for (unsigned i = 0; i < entry_exit_count; ++i) {
441 uint16_t offset_entry_anchor = 0;
442 uint16_t offset_exit_anchor = 0;
443 if (!subtable.ReadU16(&offset_entry_anchor) ||
444 !subtable.ReadU16(&offset_exit_anchor)) {
445 return OTS_FAILURE();
446 }
447 // These offsets could be NULL.
448 if (offset_entry_anchor) {
449 if (offset_entry_anchor < entry_exit_records_end ||
450 offset_entry_anchor >= length) {
451 return OTS_FAILURE();
452 }
453 if (!ParseAnchorTable(data + offset_entry_anchor,
454 length - offset_entry_anchor)) {
455 return OTS_FAILURE();
456 }
457 }
458 if (offset_exit_anchor) {
459 if (offset_exit_anchor < entry_exit_records_end ||
460 offset_exit_anchor >= length) {
461 return OTS_FAILURE();
462 }
463 if (!ParseAnchorTable(data + offset_exit_anchor,
464 length - offset_exit_anchor)) {
465 return OTS_FAILURE();
466 }
467 }
468 }
469
470 if (offset_coverage < subtable.offset() || offset_coverage >= length) {
471 return OTS_FAILURE();
472 }
473 if (!ots::ParseCoverageTable(data + offset_coverage,
474 length - offset_coverage,
475 file->maxp->num_glyphs)) {
476 return OTS_FAILURE();
477 }
478
479 return true;
480 }
481
ParseAnchorArrayTable(const uint8_t * data,const size_t length,const uint16_t class_count)482 bool ParseAnchorArrayTable(const uint8_t *data, const size_t length,
483 const uint16_t class_count) {
484 ots::Buffer subtable(data, length);
485
486 uint16_t record_count = 0;
487 if (!subtable.ReadU16(&record_count)) {
488 return OTS_FAILURE();
489 }
490
491 const unsigned anchor_array_end = 2 * static_cast<unsigned>(record_count) *
492 static_cast<unsigned>(class_count) + 2;
493 if (anchor_array_end > std::numeric_limits<uint16_t>::max()) {
494 return OTS_FAILURE();
495 }
496 for (unsigned i = 0; i < record_count; ++i) {
497 for (unsigned j = 0; j < class_count; ++j) {
498 uint16_t offset_record = 0;
499 if (!subtable.ReadU16(&offset_record)) {
500 return OTS_FAILURE();
501 }
502 // |offset_record| could be NULL.
503 if (offset_record) {
504 if (offset_record < anchor_array_end || offset_record >= length) {
505 return OTS_FAILURE();
506 }
507 if (!ParseAnchorTable(data + offset_record,
508 length - offset_record)) {
509 return OTS_FAILURE();
510 }
511 }
512 }
513 }
514 return true;
515 }
516
ParseLigatureArrayTable(const uint8_t * data,const size_t length,const uint16_t class_count)517 bool ParseLigatureArrayTable(const uint8_t *data, const size_t length,
518 const uint16_t class_count) {
519 ots::Buffer subtable(data, length);
520
521 uint16_t ligature_count = 0;
522 if (!subtable.ReadU16(&ligature_count)) {
523 return OTS_FAILURE();
524 }
525 for (unsigned i = 0; i < ligature_count; ++i) {
526 uint16_t offset_ligature_attach = 0;
527 if (!subtable.ReadU16(&offset_ligature_attach)) {
528 return OTS_FAILURE();
529 }
530 if (offset_ligature_attach < 2 || offset_ligature_attach >= length) {
531 return OTS_FAILURE();
532 }
533 if (!ParseAnchorArrayTable(data + offset_ligature_attach,
534 length - offset_ligature_attach, class_count)) {
535 return OTS_FAILURE();
536 }
537 }
538 return true;
539 }
540
541 // Common parser for Lookup Type 4, 5 and 6.
ParseMarkToAttachmentSubtables(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length,const GPOS_TYPE type)542 bool ParseMarkToAttachmentSubtables(const ots::OpenTypeFile *file,
543 const uint8_t *data, const size_t length,
544 const GPOS_TYPE type) {
545 ots::Buffer subtable(data, length);
546
547 uint16_t format = 0;
548 uint16_t offset_coverage1 = 0;
549 uint16_t offset_coverage2 = 0;
550 uint16_t class_count = 0;
551 uint16_t offset_mark_array = 0;
552 uint16_t offset_type_specific_array = 0;
553 if (!subtable.ReadU16(&format) ||
554 !subtable.ReadU16(&offset_coverage1) ||
555 !subtable.ReadU16(&offset_coverage2) ||
556 !subtable.ReadU16(&class_count) ||
557 !subtable.ReadU16(&offset_mark_array) ||
558 !subtable.ReadU16(&offset_type_specific_array)) {
559 return OTS_FAILURE();
560 }
561
562 if (format != 1) {
563 return OTS_FAILURE();
564 }
565
566 const unsigned header_end = static_cast<unsigned>(subtable.offset());
567 if (header_end > std::numeric_limits<uint16_t>::max()) {
568 return OTS_FAILURE();
569 }
570 if (offset_coverage1 < header_end || offset_coverage1 >= length) {
571 return OTS_FAILURE();
572 }
573 if (!ots::ParseCoverageTable(data + offset_coverage1,
574 length - offset_coverage1,
575 file->maxp->num_glyphs)) {
576 return OTS_FAILURE();
577 }
578 if (offset_coverage2 < header_end || offset_coverage2 >= length) {
579 return OTS_FAILURE();
580 }
581 if (!ots::ParseCoverageTable(data + offset_coverage2,
582 length - offset_coverage2,
583 file->maxp->num_glyphs)) {
584 return OTS_FAILURE();
585 }
586
587 if (offset_mark_array < header_end || offset_mark_array >= length) {
588 return OTS_FAILURE();
589 }
590 if (!ParseMarkArrayTable(data + offset_mark_array,
591 length - offset_mark_array, class_count)) {
592 return OTS_FAILURE();
593 }
594
595 if (offset_type_specific_array < header_end ||
596 offset_type_specific_array >= length) {
597 return OTS_FAILURE();
598 }
599 if (type == GPOS_TYPE_MARK_TO_BASE_ATTACHMENT ||
600 type == GPOS_TYPE_MARK_TO_MARK_ATTACHMENT) {
601 if (!ParseAnchorArrayTable(data + offset_type_specific_array,
602 length - offset_type_specific_array,
603 class_count)) {
604 return OTS_FAILURE();
605 }
606 } else if (type == GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT) {
607 if (!ParseLigatureArrayTable(data + offset_type_specific_array,
608 length - offset_type_specific_array,
609 class_count)) {
610 return OTS_FAILURE();
611 }
612 } else {
613 return OTS_FAILURE();
614 }
615
616 return true;
617 }
618
619 // Lookup Type 4:
620 // MarkToBase Attachment Positioning Subtable
ParseMarkToBaseAttachment(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)621 bool ParseMarkToBaseAttachment(const ots::OpenTypeFile *file,
622 const uint8_t *data, const size_t length) {
623 return ParseMarkToAttachmentSubtables(file, data, length,
624 GPOS_TYPE_MARK_TO_BASE_ATTACHMENT);
625 }
626
627 // Lookup Type 5:
628 // MarkToLigature Attachment Positioning Subtable
ParseMarkToLigatureAttachment(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)629 bool ParseMarkToLigatureAttachment(const ots::OpenTypeFile *file,
630 const uint8_t *data, const size_t length) {
631 return ParseMarkToAttachmentSubtables(file, data, length,
632 GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT);
633 }
634
635 // Lookup Type 6:
636 // MarkToMark Attachment Positioning Subtable
ParseMarkToMarkAttachment(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)637 bool ParseMarkToMarkAttachment(const ots::OpenTypeFile *file,
638 const uint8_t *data, const size_t length) {
639 return ParseMarkToAttachmentSubtables(file, data, length,
640 GPOS_TYPE_MARK_TO_MARK_ATTACHMENT);
641 }
642
643 // Lookup Type 7:
644 // Contextual Positioning Subtables
ParseContextPositioning(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)645 bool ParseContextPositioning(const ots::OpenTypeFile *file,
646 const uint8_t *data, const size_t length) {
647 return ots::ParseContextSubtable(data, length, file->maxp->num_glyphs,
648 file->gpos->num_lookups);
649 }
650
651 // Lookup Type 8:
652 // Chaining Contexual Positioning Subtable
ParseChainedContextPositioning(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)653 bool ParseChainedContextPositioning(const ots::OpenTypeFile *file,
654 const uint8_t *data, const size_t length) {
655 return ots::ParseChainingContextSubtable(data, length,
656 file->maxp->num_glyphs,
657 file->gpos->num_lookups);
658 }
659
660 // Lookup Type 9:
661 // Extension Positioning
ParseExtensionPositioning(const ots::OpenTypeFile * file,const uint8_t * data,const size_t length)662 bool ParseExtensionPositioning(const ots::OpenTypeFile *file,
663 const uint8_t *data, const size_t length) {
664 return ots::ParseExtensionSubtable(file, data, length,
665 &kGposLookupSubtableParser);
666 }
667
668 } // namespace
669
670 #define DROP_THIS_TABLE \
671 do { file->gpos->data = 0; file->gpos->length = 0; } while (0)
672
673 namespace ots {
674
675 // As far as I checked, following fonts contain invalid GPOS table and
676 // OTS will drop their GPOS table.
677 //
678 // # invalid delta format in device table
679 // samanata.ttf
680 //
681 // # bad size range in device table
682 // Sarai_07.ttf
683 //
684 // # bad offset to PairSetTable
685 // chandas1-2.ttf
686 //
687 // # bad offset to FeatureTable
688 // glrso12.ttf
689 // gllr12.ttf
690 // glbo12.ttf
691 // glb12.ttf
692 // glro12.ttf
693 // glbso12.ttf
694 // glrc12.ttf
695 // glrsc12.ttf
696 // glbs12.ttf
697 // glrs12.ttf
698 // glr12.ttf
699 //
700 // # ScriptRecords aren't sorted by tag
701 // Garogier_unhinted.otf
702 //
703 // # bad start coverage index in CoverageFormat2
704 // AndBasR.ttf
705 // CharisSILB.ttf
706 // CharisSILBI.ttf
707 // CharisSILI.ttf
708 // CharisSILR.ttf
709 // DoulosSILR.ttf
710 // GenBasBI.ttf
711 // GenBasI.ttf
712 // GenBkBasI.ttf
713 // GenBkBasB.ttf
714 // GenBkBasR.ttf
715 // Padauk-Bold.ttf
716 // Padauk.ttf
717 //
718 // # Contour point indexes aren't sorted
719 // Arial Unicode.ttf
720
ots_gpos_parse(OpenTypeFile * file,const uint8_t * data,size_t length)721 bool ots_gpos_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
722 // Parsing GPOS table requires num_glyphs which is contained in maxp table.
723 if (!file->maxp) {
724 return OTS_FAILURE();
725 }
726
727 Buffer table(data, length);
728
729 OpenTypeGPOS *gpos = new OpenTypeGPOS;
730 file->gpos = gpos;
731
732 uint32_t version = 0;
733 uint16_t offset_script_list = 0;
734 uint16_t offset_feature_list = 0;
735 uint16_t offset_lookup_list = 0;
736 if (!table.ReadU32(&version) ||
737 !table.ReadU16(&offset_script_list) ||
738 !table.ReadU16(&offset_feature_list) ||
739 !table.ReadU16(&offset_lookup_list)) {
740 return OTS_FAILURE();
741 }
742
743 if (version != 0x00010000) {
744 OTS_WARNING("bad GPOS version");
745 DROP_THIS_TABLE;
746 return true;
747 }
748 if ((offset_script_list < kGposHeaderSize ||
749 offset_script_list >= length) ||
750 (offset_feature_list < kGposHeaderSize ||
751 offset_feature_list >= length) ||
752 (offset_lookup_list < kGposHeaderSize ||
753 offset_lookup_list >= length)) {
754 OTS_WARNING("bad offset in GPOS header");
755 DROP_THIS_TABLE;
756 return true;
757 }
758
759 if (!ParseLookupListTable(file, data + offset_lookup_list,
760 length - offset_lookup_list,
761 &kGposLookupSubtableParser,
762 &gpos->num_lookups)) {
763 OTS_WARNING("faild to parse lookup list table");
764 DROP_THIS_TABLE;
765 return true;
766 }
767
768 uint16_t num_features = 0;
769 if (!ParseFeatureListTable(data + offset_feature_list,
770 length - offset_feature_list, gpos->num_lookups,
771 &num_features)) {
772 OTS_WARNING("faild to parse feature list table");
773 DROP_THIS_TABLE;
774 return true;
775 }
776
777 if (!ParseScriptListTable(data + offset_script_list,
778 length - offset_script_list, num_features)) {
779 OTS_WARNING("faild to parse script list table");
780 DROP_THIS_TABLE;
781 return true;
782 }
783
784 gpos->data = data;
785 gpos->length = length;
786 return true;
787 }
788
ots_gpos_should_serialise(OpenTypeFile * file)789 bool ots_gpos_should_serialise(OpenTypeFile *file) {
790 const bool needed_tables_dropped =
791 (file->gdef && file->gdef->data == NULL) ||
792 (file->gsub && file->gsub->data == NULL);
793 return file->gpos != NULL && file->gpos->data != NULL &&
794 !needed_tables_dropped;
795 }
796
ots_gpos_serialise(OTSStream * out,OpenTypeFile * file)797 bool ots_gpos_serialise(OTSStream *out, OpenTypeFile *file) {
798 if (!out->Write(file->gpos->data, file->gpos->length)) {
799 return OTS_FAILURE();
800 }
801
802 return true;
803 }
804
ots_gpos_free(OpenTypeFile * file)805 void ots_gpos_free(OpenTypeFile *file) {
806 delete file->gpos;
807 }
808
809 } // namespace ots
810
811