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
18namespace {
19
20enum 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.
34const unsigned kGposHeaderSize = 10;
35// The maximum format number for anchor tables.
36const uint16_t kMaxAnchorFormat = 3;
37// The maximum number of class value.
38const uint16_t kMaxClassDefValue = 0xFFFF;
39
40// Lookup type parsers.
41bool ParseSingleAdjustment(const ots::OpenTypeFile *file,
42                           const uint8_t *data, const size_t length);
43bool ParsePairAdjustment(const ots::OpenTypeFile *file,
44                         const uint8_t *data, const size_t length);
45bool ParseCursiveAttachment(const ots::OpenTypeFile *file,
46                            const uint8_t *data, const size_t length);
47bool ParseMarkToBaseAttachment(const ots::OpenTypeFile *file,
48                               const uint8_t *data, const size_t length);
49bool ParseMarkToLigatureAttachment(const ots::OpenTypeFile *file,
50                                   const uint8_t *data, const size_t length);
51bool ParseMarkToMarkAttachment(const ots::OpenTypeFile *file,
52                               const uint8_t *data, const size_t length);
53bool ParseContextPositioning(const ots::OpenTypeFile *file,
54                             const uint8_t *data, const size_t length);
55bool ParseChainedContextPositioning(const ots::OpenTypeFile *file,
56                                    const uint8_t *data, const size_t length);
57bool ParseExtensionPositioning(const ots::OpenTypeFile *file,
58                               const uint8_t *data, const size_t length);
59
60const 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
72const ots::LookupSubtableParser kGposLookupSubtableParser = {
73  arraysize(kGposTypeParsers),
74  GPOS_TYPE_EXTENSION_POSITIONING, kGposTypeParsers
75};
76
77// Shared Tables: ValueRecord, Anchor Table, and MarkArray
78
79bool 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
113bool 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
165bool 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
203bool 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
248bool 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
277bool 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
316bool 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
374bool 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
417bool 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
482bool 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
517bool 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.
542bool 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
621bool 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
629bool 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
637bool 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
645bool 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
653bool 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
662bool 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
673namespace 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
721bool 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
789bool 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
797bool 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
805void ots_gpos_free(OpenTypeFile *file) {
806  delete file->gpos;
807}
808
809}  // namespace ots
810
811