michael@0: // Copyright (c) 2011 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #include "gpos.h"
michael@0: 
michael@0: #include <limits>
michael@0: #include <vector>
michael@0: 
michael@0: #include "layout.h"
michael@0: #include "maxp.h"
michael@0: 
michael@0: // GPOS - The Glyph Positioning Table
michael@0: // http://www.microsoft.com/typography/otspec/gpos.htm
michael@0: 
michael@0: #define TABLE_NAME "GPOS"
michael@0: 
michael@0: namespace {
michael@0: 
michael@0: enum GPOS_TYPE {
michael@0:   GPOS_TYPE_SINGLE_ADJUSTMENT = 1,
michael@0:   GPOS_TYPE_PAIR_ADJUSTMENT = 2,
michael@0:   GPOS_TYPE_CURSIVE_ATTACHMENT = 3,
michael@0:   GPOS_TYPE_MARK_TO_BASE_ATTACHMENT = 4,
michael@0:   GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT = 5,
michael@0:   GPOS_TYPE_MARK_TO_MARK_ATTACHMENT = 6,
michael@0:   GPOS_TYPE_CONTEXT_POSITIONING = 7,
michael@0:   GPOS_TYPE_CHAINED_CONTEXT_POSITIONING = 8,
michael@0:   GPOS_TYPE_EXTENSION_POSITIONING = 9,
michael@0:   GPOS_TYPE_RESERVED = 10
michael@0: };
michael@0: 
michael@0: // The size of gpos header.
michael@0: const unsigned kGposHeaderSize = 10;
michael@0: // The maximum format number for anchor tables.
michael@0: const uint16_t kMaxAnchorFormat = 3;
michael@0: // The maximum number of class value.
michael@0: const uint16_t kMaxClassDefValue = 0xFFFF;
michael@0: 
michael@0: // Lookup type parsers.
michael@0: bool ParseSingleAdjustment(const ots::OpenTypeFile *file,
michael@0:                            const uint8_t *data, const size_t length);
michael@0: bool ParsePairAdjustment(const ots::OpenTypeFile *file,
michael@0:                          const uint8_t *data, const size_t length);
michael@0: bool ParseCursiveAttachment(const ots::OpenTypeFile *file,
michael@0:                             const uint8_t *data, const size_t length);
michael@0: bool ParseMarkToBaseAttachment(const ots::OpenTypeFile *file,
michael@0:                                const uint8_t *data, const size_t length);
michael@0: bool ParseMarkToLigatureAttachment(const ots::OpenTypeFile *file,
michael@0:                                    const uint8_t *data, const size_t length);
michael@0: bool ParseMarkToMarkAttachment(const ots::OpenTypeFile *file,
michael@0:                                const uint8_t *data, const size_t length);
michael@0: bool ParseContextPositioning(const ots::OpenTypeFile *file,
michael@0:                              const uint8_t *data, const size_t length);
michael@0: bool ParseChainedContextPositioning(const ots::OpenTypeFile *file,
michael@0:                                     const uint8_t *data, const size_t length);
michael@0: bool ParseExtensionPositioning(const ots::OpenTypeFile *file,
michael@0:                                const uint8_t *data, const size_t length);
michael@0: 
michael@0: const ots::LookupSubtableParser::TypeParser kGposTypeParsers[] = {
michael@0:   {GPOS_TYPE_SINGLE_ADJUSTMENT, ParseSingleAdjustment},
michael@0:   {GPOS_TYPE_PAIR_ADJUSTMENT, ParsePairAdjustment},
michael@0:   {GPOS_TYPE_CURSIVE_ATTACHMENT, ParseCursiveAttachment},
michael@0:   {GPOS_TYPE_MARK_TO_BASE_ATTACHMENT, ParseMarkToBaseAttachment},
michael@0:   {GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT, ParseMarkToLigatureAttachment},
michael@0:   {GPOS_TYPE_MARK_TO_MARK_ATTACHMENT, ParseMarkToMarkAttachment},
michael@0:   {GPOS_TYPE_CONTEXT_POSITIONING, ParseContextPositioning},
michael@0:   {GPOS_TYPE_CHAINED_CONTEXT_POSITIONING, ParseChainedContextPositioning},
michael@0:   {GPOS_TYPE_EXTENSION_POSITIONING, ParseExtensionPositioning}
michael@0: };
michael@0: 
michael@0: const ots::LookupSubtableParser kGposLookupSubtableParser = {
michael@0:   arraysize(kGposTypeParsers),
michael@0:   GPOS_TYPE_EXTENSION_POSITIONING, kGposTypeParsers
michael@0: };
michael@0: 
michael@0: // Shared Tables: ValueRecord, Anchor Table, and MarkArray
michael@0: 
michael@0: bool ParseValueRecord(const ots::OpenTypeFile *file,
michael@0:                       ots::Buffer* subtable, const uint8_t *data,
michael@0:                       const size_t length, const uint16_t value_format) {
michael@0:   // Check existence of adjustment fields.
michael@0:   for (unsigned i = 0; i < 4; ++i) {
michael@0:     if ((value_format >> i) & 0x1) {
michael@0:       // Just read the field since these fileds could take an arbitrary values.
michael@0:       if (!subtable->Skip(2)) {
michael@0:         return OTS_FAILURE_MSG("Failed to read value reacord component");
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   // Check existence of offsets to device table.
michael@0:   for (unsigned i = 0; i < 4; ++i) {
michael@0:     if ((value_format >> (i + 4)) & 0x1) {
michael@0:       uint16_t offset = 0;
michael@0:       if (!subtable->ReadU16(&offset)) {
michael@0:         return OTS_FAILURE_MSG("Failed to read value record offset");
michael@0:       }
michael@0:       if (offset) {
michael@0:         // TODO(bashi): Is it possible that device tables locate before
michael@0:         // this record? No fonts contain such offset AKAIF.
michael@0:         if (offset >= length) {
michael@0:           return OTS_FAILURE_MSG("Value record offset too high %d >= %ld", offset, length);
michael@0:         }
michael@0:         if (!ots::ParseDeviceTable(file, data + offset, length - offset)) {
michael@0:           return OTS_FAILURE_MSG("Failed to parse device table in value record");
michael@0:         }
michael@0:       }
michael@0:     }
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParseAnchorTable(const ots::OpenTypeFile *file,
michael@0:                       const uint8_t *data, const size_t length) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t format = 0;
michael@0:   // Read format and skip 2 2-byte fields that could be arbitrary values.
michael@0:   if (!subtable.ReadU16(&format) ||
michael@0:       !subtable.Skip(4)) {
michael@0:     return OTS_FAILURE_MSG("Faled to read anchor table");
michael@0:   }
michael@0: 
michael@0:   if (format == 0 || format > kMaxAnchorFormat) {
michael@0:     return OTS_FAILURE_MSG("Bad Anchor table format %d", format);
michael@0:   }
michael@0: 
michael@0:   // Format 2 and 3 has additional fields.
michael@0:   if (format == 2) {
michael@0:     // Format 2 provides an index to a glyph contour point, which will take
michael@0:     // arbitrary value.
michael@0:     uint16_t anchor_point = 0;
michael@0:     if (!subtable.ReadU16(&anchor_point)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read anchor point in format 2 Anchor Table");
michael@0:     }
michael@0:   } else if (format == 3) {
michael@0:     uint16_t offset_x_device = 0;
michael@0:     uint16_t offset_y_device = 0;
michael@0:     if (!subtable.ReadU16(&offset_x_device) ||
michael@0:         !subtable.ReadU16(&offset_y_device)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read device table offsets in format 3 anchor table");
michael@0:     }
michael@0:     const unsigned format_end = static_cast<unsigned>(10);
michael@0:     if (offset_x_device) {
michael@0:       if (offset_x_device < format_end || offset_x_device >= length) {
michael@0:         return OTS_FAILURE_MSG("Bad x device table offset %d", offset_x_device);
michael@0:       }
michael@0:       if (!ots::ParseDeviceTable(file, data + offset_x_device,
michael@0:                                  length - offset_x_device)) {
michael@0:         return OTS_FAILURE_MSG("Failed to parse device table in anchor table");
michael@0:       }
michael@0:     }
michael@0:     if (offset_y_device) {
michael@0:       if (offset_y_device < format_end || offset_y_device >= length) {
michael@0:         return OTS_FAILURE_MSG("Bad y device table offset %d", offset_y_device);
michael@0:       }
michael@0:       if (!ots::ParseDeviceTable(file, data + offset_y_device,
michael@0:                                  length - offset_y_device)) {
michael@0:         return OTS_FAILURE_MSG("Failed to parse device table in anchor table");
michael@0:       }
michael@0:     }
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParseMarkArrayTable(const ots::OpenTypeFile *file,
michael@0:                          const uint8_t *data, const size_t length,
michael@0:                          const uint16_t class_count) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t mark_count = 0;
michael@0:   if (!subtable.ReadU16(&mark_count)) {
michael@0:     return OTS_FAILURE_MSG("Can't read mark table length");
michael@0:   }
michael@0: 
michael@0:   // MarkRecord consists of 4-bytes.
michael@0:   const unsigned mark_records_end = 4 * static_cast<unsigned>(mark_count) + 2;
michael@0:   if (mark_records_end > std::numeric_limits<uint16_t>::max()) {
michael@0:     return OTS_FAILURE_MSG("Bad mark table length");
michael@0:   }
michael@0:   for (unsigned i = 0; i < mark_count; ++i) {
michael@0:     uint16_t class_value = 0;
michael@0:     uint16_t offset_mark_anchor = 0;
michael@0:     if (!subtable.ReadU16(&class_value) ||
michael@0:         !subtable.ReadU16(&offset_mark_anchor)) {
michael@0:       return OTS_FAILURE_MSG("Can't read mark table %d", i);
michael@0:     }
michael@0:     // |class_value| may take arbitrary values including 0 here so we don't
michael@0:     // check the value.
michael@0:     if (offset_mark_anchor < mark_records_end ||
michael@0:         offset_mark_anchor >= length) {
michael@0:       return OTS_FAILURE_MSG("Bad mark anchor offset %d for mark table %d", offset_mark_anchor, i);
michael@0:     }
michael@0:     if (!ParseAnchorTable(file, data + offset_mark_anchor,
michael@0:                           length - offset_mark_anchor)) {
michael@0:       return OTS_FAILURE_MSG("Faled to parse anchor table for mark table %d", i);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // Lookup Type 1:
michael@0: // Single Adjustment Positioning Subtable
michael@0: bool ParseSingleAdjustment(const ots::OpenTypeFile *file, const uint8_t *data,
michael@0:                            const size_t length) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t format = 0;
michael@0:   uint16_t offset_coverage = 0;
michael@0:   uint16_t value_format = 0;
michael@0:   if (!subtable.ReadU16(&format) ||
michael@0:       !subtable.ReadU16(&offset_coverage) ||
michael@0:       !subtable.ReadU16(&value_format)) {
michael@0:     return OTS_FAILURE_MSG("Can't read single adjustment information");
michael@0:   }
michael@0: 
michael@0:   if (format == 1) {
michael@0:     // Format 1 exactly one value record.
michael@0:     if (!ParseValueRecord(file, &subtable, data, length, value_format)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse format 1 single adjustment table");
michael@0:     }
michael@0:   } else if (format == 2) {
michael@0:     uint16_t value_count = 0;
michael@0:     if (!subtable.ReadU16(&value_count)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse format 2 single adjustment table");
michael@0:     }
michael@0:     for (unsigned i = 0; i < value_count; ++i) {
michael@0:       if (!ParseValueRecord(file, &subtable, data, length, value_format)) {
michael@0:         return OTS_FAILURE_MSG("Failed to parse value record %d in format 2 single adjustment table", i);
michael@0:       }
michael@0:     }
michael@0:   } else {
michael@0:     return OTS_FAILURE_MSG("Bad format %d in single adjustment table", format);
michael@0:   }
michael@0: 
michael@0:   if (offset_coverage < subtable.offset() || offset_coverage >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad coverage offset %d in single adjustment table", offset_coverage);
michael@0:   }
michael@0: 
michael@0:   if (!ots::ParseCoverageTable(file, data + offset_coverage,
michael@0:                                length - offset_coverage,
michael@0:                                file->maxp->num_glyphs)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse coverage table in single adjustment table");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParsePairSetTable(const ots::OpenTypeFile *file,
michael@0:                        const uint8_t *data, const size_t length,
michael@0:                        const uint16_t value_format1,
michael@0:                        const uint16_t value_format2,
michael@0:                        const uint16_t num_glyphs) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t value_count = 0;
michael@0:   if (!subtable.ReadU16(&value_count)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pair set table structure");
michael@0:   }
michael@0:   for (unsigned i = 0; i < value_count; ++i) {
michael@0:     // Check pair value record.
michael@0:     uint16_t glyph_id = 0;
michael@0:     if (!subtable.ReadU16(&glyph_id)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read glyph in pair value record %d", i);
michael@0:     }
michael@0:     if (glyph_id >= num_glyphs) {
michael@0:       return OTS_FAILURE_MSG("glyph id %d too high >= %d", glyph_id, num_glyphs);
michael@0:     }
michael@0:     if (!ParseValueRecord(file, &subtable, data, length, value_format1)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse value record in format 1 pair set table");
michael@0:     }
michael@0:     if (!ParseValueRecord(file, &subtable, data, length, value_format2)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse value record in format 2 pair set table");
michael@0:     }
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParsePairPosFormat1(const ots::OpenTypeFile *file,
michael@0:                          const uint8_t *data, const size_t length,
michael@0:                          const uint16_t value_format1,
michael@0:                          const uint16_t value_format2,
michael@0:                          const uint16_t num_glyphs) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   // Skip 8 bytes that are already read before.
michael@0:   if (!subtable.Skip(8)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pair pos table structure");
michael@0:   }
michael@0: 
michael@0:   uint16_t pair_set_count = 0;
michael@0:   if (!subtable.ReadU16(&pair_set_count)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pair pos set count");
michael@0:   }
michael@0: 
michael@0:   const unsigned pair_pos_end = 2 * static_cast<unsigned>(pair_set_count) + 10;
michael@0:   if (pair_pos_end > std::numeric_limits<uint16_t>::max()) {
michael@0:     return OTS_FAILURE_MSG("Bad pair set length %d", pair_pos_end);
michael@0:   }
michael@0:   for (unsigned i = 0; i < pair_set_count; ++i) {
michael@0:     uint16_t pair_set_offset = 0;
michael@0:     if (!subtable.ReadU16(&pair_set_offset)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read pair set offset for pair set %d", i);
michael@0:     }
michael@0:     if (pair_set_offset < pair_pos_end || pair_set_offset >= length) {
michael@0:       return OTS_FAILURE_MSG("Bad pair set offset %d for pair set %d", pair_set_offset, i);
michael@0:     }
michael@0:     // Check pair set tables
michael@0:     if (!ParsePairSetTable(file, data + pair_set_offset, length - pair_set_offset,
michael@0:                            value_format1, value_format2,
michael@0:                            num_glyphs)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse pair set table %d", i);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParsePairPosFormat2(const ots::OpenTypeFile *file,
michael@0:                          const uint8_t *data, const size_t length,
michael@0:                          const uint16_t value_format1,
michael@0:                          const uint16_t value_format2,
michael@0:                          const uint16_t num_glyphs) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   // Skip 8 bytes that are already read before.
michael@0:   if (!subtable.Skip(8)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pair pos format 2 structure");
michael@0:   }
michael@0: 
michael@0:   uint16_t offset_class_def1 = 0;
michael@0:   uint16_t offset_class_def2 = 0;
michael@0:   uint16_t class1_count = 0;
michael@0:   uint16_t class2_count = 0;
michael@0:   if (!subtable.ReadU16(&offset_class_def1) ||
michael@0:       !subtable.ReadU16(&offset_class_def2) ||
michael@0:       !subtable.ReadU16(&class1_count) ||
michael@0:       !subtable.ReadU16(&class2_count)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pair pos format 2 data");
michael@0:   }
michael@0: 
michael@0:   // Check class 1 records.
michael@0:   for (unsigned i = 0; i < class1_count; ++i) {
michael@0:     // Check class 2 records.
michael@0:     for (unsigned j = 0; j < class2_count; ++j) {
michael@0:       if (value_format1 && !ParseValueRecord(file, &subtable, data, length,
michael@0:                                              value_format1)) {
michael@0:         return OTS_FAILURE_MSG("Failed to parse value record 1 %d and %d", j, i);
michael@0:       }
michael@0:       if (value_format2 && !ParseValueRecord(file, &subtable, data, length,
michael@0:                                              value_format2)) {
michael@0:         return OTS_FAILURE_MSG("Falied to parse value record 2 %d and %d", j, i);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   // Check class definition tables.
michael@0:   if (offset_class_def1 < subtable.offset() || offset_class_def1 >= length ||
michael@0:       offset_class_def2 < subtable.offset() || offset_class_def2 >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad class definition table offsets %d or %d", offset_class_def1, offset_class_def2);
michael@0:   }
michael@0:   if (!ots::ParseClassDefTable(file, data + offset_class_def1,
michael@0:                                length - offset_class_def1,
michael@0:                                num_glyphs, kMaxClassDefValue)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse class definition table 1");
michael@0:   }
michael@0:   if (!ots::ParseClassDefTable(file, data + offset_class_def2,
michael@0:                                length - offset_class_def2,
michael@0:                                num_glyphs, kMaxClassDefValue)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse class definition table 2");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // Lookup Type 2:
michael@0: // Pair Adjustment Positioning Subtable
michael@0: bool ParsePairAdjustment(const ots::OpenTypeFile *file, const uint8_t *data,
michael@0:                          const size_t length) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t format = 0;
michael@0:   uint16_t offset_coverage = 0;
michael@0:   uint16_t value_format1 = 0;
michael@0:   uint16_t value_format2 = 0;
michael@0:   if (!subtable.ReadU16(&format) ||
michael@0:       !subtable.ReadU16(&offset_coverage) ||
michael@0:       !subtable.ReadU16(&value_format1) ||
michael@0:       !subtable.ReadU16(&value_format2)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pair adjustment structure");
michael@0:   }
michael@0: 
michael@0:   if (format == 1) {
michael@0:     if (!ParsePairPosFormat1(file, data, length, value_format1, value_format2,
michael@0:                              file->maxp->num_glyphs)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse pair pos format 1");
michael@0:     }
michael@0:   } else if (format == 2) {
michael@0:     if (!ParsePairPosFormat2(file, data, length, value_format1, value_format2,
michael@0:                              file->maxp->num_glyphs)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse pair format 2");
michael@0:     }
michael@0:   } else {
michael@0:     return OTS_FAILURE_MSG("Bad pos pair format %d", format);
michael@0:   }
michael@0: 
michael@0:   if (offset_coverage < subtable.offset() || offset_coverage >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad pair pos offset coverage %d", offset_coverage);
michael@0:   }
michael@0:   if (!ots::ParseCoverageTable(file, data + offset_coverage,
michael@0:                                length - offset_coverage,
michael@0:                                file->maxp->num_glyphs)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse coverage table");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // Lookup Type 3
michael@0: // Cursive Attachment Positioning Subtable
michael@0: bool ParseCursiveAttachment(const ots::OpenTypeFile *file, const uint8_t *data,
michael@0:                             const size_t length) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t format = 0;
michael@0:   uint16_t offset_coverage = 0;
michael@0:   uint16_t entry_exit_count = 0;
michael@0:   if (!subtable.ReadU16(&format) ||
michael@0:       !subtable.ReadU16(&offset_coverage) ||
michael@0:       !subtable.ReadU16(&entry_exit_count)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read cursive attachment structure");
michael@0:   }
michael@0: 
michael@0:   if (format != 1) {
michael@0:     return OTS_FAILURE_MSG("Bad cursive attachment format %d", format);
michael@0:   }
michael@0: 
michael@0:   // Check entry exit records.
michael@0:   const unsigned entry_exit_records_end =
michael@0:       2 * static_cast<unsigned>(entry_exit_count) + 6;
michael@0:   if (entry_exit_records_end > std::numeric_limits<uint16_t>::max()) {
michael@0:     return OTS_FAILURE_MSG("Bad entry exit record end %d", entry_exit_records_end);
michael@0:   }
michael@0:   for (unsigned i = 0; i < entry_exit_count; ++i) {
michael@0:     uint16_t offset_entry_anchor = 0;
michael@0:     uint16_t offset_exit_anchor = 0;
michael@0:     if (!subtable.ReadU16(&offset_entry_anchor) ||
michael@0:         !subtable.ReadU16(&offset_exit_anchor)) {
michael@0:       return OTS_FAILURE_MSG("Can't read entry exit record %d", i);
michael@0:     }
michael@0:     // These offsets could be NULL.
michael@0:     if (offset_entry_anchor) {
michael@0:       if (offset_entry_anchor < entry_exit_records_end ||
michael@0:           offset_entry_anchor >= length) {
michael@0:         return OTS_FAILURE_MSG("Bad entry anchor offset %d in entry exit record %d", offset_entry_anchor, i);
michael@0:       }
michael@0:       if (!ParseAnchorTable(file, data + offset_entry_anchor,
michael@0:                             length - offset_entry_anchor)) {
michael@0:         return OTS_FAILURE_MSG("Failed to parse entry anchor table in entry exit record %d", i);
michael@0:       }
michael@0:     }
michael@0:     if (offset_exit_anchor) {
michael@0:       if (offset_exit_anchor < entry_exit_records_end ||
michael@0:          offset_exit_anchor >= length) {
michael@0:         return OTS_FAILURE_MSG("Bad exit anchor offset %d in entry exit record %d", offset_exit_anchor, i);
michael@0:       }
michael@0:       if (!ParseAnchorTable(file, data + offset_exit_anchor,
michael@0:                             length - offset_exit_anchor)) {
michael@0:         return OTS_FAILURE_MSG("Failed to parse exit anchor table in entry exit record %d", i);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   if (offset_coverage < subtable.offset() || offset_coverage >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad coverage offset in cursive attachment %d", offset_coverage);
michael@0:   }
michael@0:   if (!ots::ParseCoverageTable(file, data + offset_coverage,
michael@0:                                length - offset_coverage,
michael@0:                                file->maxp->num_glyphs)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse coverage table in cursive attachment");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParseAnchorArrayTable(const ots::OpenTypeFile *file,
michael@0:                            const uint8_t *data, const size_t length,
michael@0:                            const uint16_t class_count) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t record_count = 0;
michael@0:   if (!subtable.ReadU16(&record_count)) {
michael@0:     return OTS_FAILURE_MSG("Can't read anchor array length");
michael@0:   }
michael@0: 
michael@0:   const unsigned anchor_array_end = 2 * static_cast<unsigned>(record_count) *
michael@0:       static_cast<unsigned>(class_count) + 2;
michael@0:   if (anchor_array_end > std::numeric_limits<uint16_t>::max()) {
michael@0:     return OTS_FAILURE_MSG("Bad end of anchor array %d", anchor_array_end);
michael@0:   }
michael@0:   for (unsigned i = 0; i < record_count; ++i) {
michael@0:     for (unsigned j = 0; j < class_count; ++j) {
michael@0:       uint16_t offset_record = 0;
michael@0:       if (!subtable.ReadU16(&offset_record)) {
michael@0:         return OTS_FAILURE_MSG("Can't read anchor array record offset for class %d and record %d", j, i);
michael@0:       }
michael@0:       // |offset_record| could be NULL.
michael@0:       if (offset_record) {
michael@0:         if (offset_record < anchor_array_end || offset_record >= length) {
michael@0:           return OTS_FAILURE_MSG("Bad record offset %d in class %d, record %d", offset_record, j, i);
michael@0:         }
michael@0:         if (!ParseAnchorTable(file, data + offset_record,
michael@0:                               length - offset_record)) {
michael@0:           return OTS_FAILURE_MSG("Failed to parse anchor table for class %d, record %d", j, i);
michael@0:         }
michael@0:       }
michael@0:     }
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ParseLigatureArrayTable(const ots::OpenTypeFile *file,
michael@0:                              const uint8_t *data, const size_t length,
michael@0:                              const uint16_t class_count) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t ligature_count = 0;
michael@0:   if (!subtable.ReadU16(&ligature_count)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read ligature count");
michael@0:   }
michael@0:   for (unsigned i = 0; i < ligature_count; ++i) {
michael@0:     uint16_t offset_ligature_attach = 0;
michael@0:     if (!subtable.ReadU16(&offset_ligature_attach)) {
michael@0:       return OTS_FAILURE_MSG("Can't read ligature offset %d", i);
michael@0:     }
michael@0:     if (offset_ligature_attach < 2 || offset_ligature_attach >= length) {
michael@0:       return OTS_FAILURE_MSG("Bad ligature attachment offset %d in ligature %d", offset_ligature_attach, i);
michael@0:     }
michael@0:     if (!ParseAnchorArrayTable(file, data + offset_ligature_attach,
michael@0:                                length - offset_ligature_attach, class_count)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse anchor table for ligature %d", i);
michael@0:     }
michael@0:   }
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // Common parser for Lookup Type 4, 5 and 6.
michael@0: bool ParseMarkToAttachmentSubtables(const ots::OpenTypeFile *file,
michael@0:                                     const uint8_t *data, const size_t length,
michael@0:                                     const GPOS_TYPE type) {
michael@0:   ots::Buffer subtable(data, length);
michael@0: 
michael@0:   uint16_t format = 0;
michael@0:   uint16_t offset_coverage1 = 0;
michael@0:   uint16_t offset_coverage2 = 0;
michael@0:   uint16_t class_count = 0;
michael@0:   uint16_t offset_mark_array = 0;
michael@0:   uint16_t offset_type_specific_array = 0;
michael@0:   if (!subtable.ReadU16(&format) ||
michael@0:       !subtable.ReadU16(&offset_coverage1) ||
michael@0:       !subtable.ReadU16(&offset_coverage2) ||
michael@0:       !subtable.ReadU16(&class_count) ||
michael@0:       !subtable.ReadU16(&offset_mark_array) ||
michael@0:       !subtable.ReadU16(&offset_type_specific_array)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read mark attachment subtable header");
michael@0:   }
michael@0: 
michael@0:   if (format != 1) {
michael@0:     return OTS_FAILURE_MSG("bad mark attachment subtable format %d", format);
michael@0:   }
michael@0: 
michael@0:   const unsigned header_end = static_cast<unsigned>(subtable.offset());
michael@0:   if (header_end > std::numeric_limits<uint16_t>::max()) {
michael@0:     return OTS_FAILURE_MSG("Bad mark attachment subtable size ending at %d", header_end);
michael@0:   }
michael@0:   if (offset_coverage1 < header_end || offset_coverage1 >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad coverage 1 offset %d", offset_coverage1);
michael@0:   }
michael@0:   if (!ots::ParseCoverageTable(file, data + offset_coverage1,
michael@0:                                length - offset_coverage1,
michael@0:                                file->maxp->num_glyphs)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse converge 1 table");
michael@0:   }
michael@0:   if (offset_coverage2 < header_end || offset_coverage2 >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad coverage 2 offset %d", offset_coverage2);
michael@0:   }
michael@0:   if (!ots::ParseCoverageTable(file, data + offset_coverage2,
michael@0:                                length - offset_coverage2,
michael@0:                                file->maxp->num_glyphs)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse coverage table 2");
michael@0:   }
michael@0: 
michael@0:   if (offset_mark_array < header_end || offset_mark_array >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad mark array offset %d", offset_mark_array);
michael@0:   }
michael@0:   if (!ParseMarkArrayTable(file, data + offset_mark_array,
michael@0:                            length - offset_mark_array, class_count)) {
michael@0:     return OTS_FAILURE_MSG("Failed to parse mark array");
michael@0:   }
michael@0: 
michael@0:   if (offset_type_specific_array < header_end ||
michael@0:       offset_type_specific_array >= length) {
michael@0:     return OTS_FAILURE_MSG("Bad type specific array offset %d", offset_type_specific_array);
michael@0:   }
michael@0:   if (type == GPOS_TYPE_MARK_TO_BASE_ATTACHMENT ||
michael@0:       type == GPOS_TYPE_MARK_TO_MARK_ATTACHMENT) {
michael@0:     if (!ParseAnchorArrayTable(file, data + offset_type_specific_array,
michael@0:                                length - offset_type_specific_array,
michael@0:                                class_count)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse anchor array");
michael@0:     }
michael@0:   } else if (type == GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT) {
michael@0:     if (!ParseLigatureArrayTable(file, data + offset_type_specific_array,
michael@0:                                  length - offset_type_specific_array,
michael@0:                                  class_count)) {
michael@0:       return OTS_FAILURE_MSG("Failed to parse ligature array");
michael@0:     }
michael@0:   } else {
michael@0:     return OTS_FAILURE_MSG("Bad attachment type %d", type);
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // Lookup Type 4:
michael@0: // MarkToBase Attachment Positioning Subtable
michael@0: bool ParseMarkToBaseAttachment(const ots::OpenTypeFile *file,
michael@0:                                const uint8_t *data, const size_t length) {
michael@0:   return ParseMarkToAttachmentSubtables(file, data, length,
michael@0:                                         GPOS_TYPE_MARK_TO_BASE_ATTACHMENT);
michael@0: }
michael@0: 
michael@0: // Lookup Type 5:
michael@0: // MarkToLigature Attachment Positioning Subtable
michael@0: bool ParseMarkToLigatureAttachment(const ots::OpenTypeFile *file,
michael@0:                                    const uint8_t *data, const size_t length) {
michael@0:   return ParseMarkToAttachmentSubtables(file, data, length,
michael@0:                                         GPOS_TYPE_MARK_TO_LIGATURE_ATTACHMENT);
michael@0: }
michael@0: 
michael@0: // Lookup Type 6:
michael@0: // MarkToMark Attachment Positioning Subtable
michael@0: bool ParseMarkToMarkAttachment(const ots::OpenTypeFile *file,
michael@0:                                const uint8_t *data, const size_t length) {
michael@0:   return ParseMarkToAttachmentSubtables(file, data, length,
michael@0:                                         GPOS_TYPE_MARK_TO_MARK_ATTACHMENT);
michael@0: }
michael@0: 
michael@0: // Lookup Type 7:
michael@0: // Contextual Positioning Subtables
michael@0: bool ParseContextPositioning(const ots::OpenTypeFile *file,
michael@0:                              const uint8_t *data, const size_t length) {
michael@0:   return ots::ParseContextSubtable(file, data, length, file->maxp->num_glyphs,
michael@0:                                    file->gpos->num_lookups);
michael@0: }
michael@0: 
michael@0: // Lookup Type 8:
michael@0: // Chaining Contexual Positioning Subtable
michael@0: bool ParseChainedContextPositioning(const ots::OpenTypeFile *file,
michael@0:                                     const uint8_t *data, const size_t length) {
michael@0:   return ots::ParseChainingContextSubtable(file, data, length,
michael@0:                                            file->maxp->num_glyphs,
michael@0:                                            file->gpos->num_lookups);
michael@0: }
michael@0: 
michael@0: // Lookup Type 9:
michael@0: // Extension Positioning
michael@0: bool ParseExtensionPositioning(const ots::OpenTypeFile *file,
michael@0:                                const uint8_t *data, const size_t length) {
michael@0:   return ots::ParseExtensionSubtable(file, data, length,
michael@0:                                      &kGposLookupSubtableParser);
michael@0: }
michael@0: 
michael@0: }  // namespace
michael@0: 
michael@0: #define DROP_THIS_TABLE(msg_) \
michael@0:   do { \
michael@0:     file->gpos->data = 0; \
michael@0:     file->gpos->length = 0; \
michael@0:     OTS_FAILURE_MSG(msg_ ", table discarded"); \
michael@0:   } while (0)
michael@0: 
michael@0: namespace ots {
michael@0: 
michael@0: // As far as I checked, following fonts contain invalid GPOS table and
michael@0: // OTS will drop their GPOS table.
michael@0: //
michael@0: // # invalid delta format in device table
michael@0: // samanata.ttf
michael@0: //
michael@0: // # bad size range in device table
michael@0: // Sarai_07.ttf
michael@0: //
michael@0: // # bad offset to PairSetTable
michael@0: // chandas1-2.ttf
michael@0: //
michael@0: // # bad offset to FeatureTable
michael@0: // glrso12.ttf
michael@0: // gllr12.ttf
michael@0: // glbo12.ttf
michael@0: // glb12.ttf
michael@0: // glro12.ttf
michael@0: // glbso12.ttf
michael@0: // glrc12.ttf
michael@0: // glrsc12.ttf
michael@0: // glbs12.ttf
michael@0: // glrs12.ttf
michael@0: // glr12.ttf
michael@0: //
michael@0: // # ScriptRecords aren't sorted by tag
michael@0: // Garogier_unhinted.otf
michael@0: //
michael@0: // # bad start coverage index in CoverageFormat2
michael@0: // AndBasR.ttf
michael@0: // CharisSILB.ttf
michael@0: // CharisSILBI.ttf
michael@0: // CharisSILI.ttf
michael@0: // CharisSILR.ttf
michael@0: // DoulosSILR.ttf
michael@0: // GenBasBI.ttf
michael@0: // GenBasI.ttf
michael@0: // GenBkBasI.ttf
michael@0: // GenBkBasB.ttf
michael@0: // GenBkBasR.ttf
michael@0: // Padauk-Bold.ttf
michael@0: // Padauk.ttf
michael@0: //
michael@0: // # Contour point indexes aren't sorted
michael@0: // Arial Unicode.ttf
michael@0: 
michael@0: bool ots_gpos_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
michael@0:   // Parsing GPOS table requires num_glyphs which is contained in maxp table.
michael@0:   if (!file->maxp) {
michael@0:     return OTS_FAILURE_MSG("missing maxp table needed in GPOS");
michael@0:   }
michael@0: 
michael@0:   Buffer table(data, length);
michael@0: 
michael@0:   OpenTypeGPOS *gpos = new OpenTypeGPOS;
michael@0:   file->gpos = gpos;
michael@0: 
michael@0:   uint32_t version = 0;
michael@0:   uint16_t offset_script_list = 0;
michael@0:   uint16_t offset_feature_list = 0;
michael@0:   uint16_t offset_lookup_list = 0;
michael@0:   if (!table.ReadU32(&version) ||
michael@0:       !table.ReadU16(&offset_script_list) ||
michael@0:       !table.ReadU16(&offset_feature_list) ||
michael@0:       !table.ReadU16(&offset_lookup_list)) {
michael@0:     DROP_THIS_TABLE("Incomplete table");
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   if (version != 0x00010000) {
michael@0:     DROP_THIS_TABLE("Bad version");
michael@0:     return true;
michael@0:   }
michael@0:   if ((offset_script_list < kGposHeaderSize ||
michael@0:        offset_script_list >= length) ||
michael@0:       (offset_feature_list < kGposHeaderSize ||
michael@0:        offset_feature_list >= length) ||
michael@0:       (offset_lookup_list < kGposHeaderSize ||
michael@0:        offset_lookup_list >= length)) {
michael@0:     DROP_THIS_TABLE("Bad offset in table header");
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   if (!ParseLookupListTable(file, data + offset_lookup_list,
michael@0:                             length - offset_lookup_list,
michael@0:                             &kGposLookupSubtableParser,
michael@0:                             &gpos->num_lookups)) {
michael@0:     DROP_THIS_TABLE("Failed to parse lookup list table");
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   uint16_t num_features = 0;
michael@0:   if (!ParseFeatureListTable(file, data + offset_feature_list,
michael@0:                              length - offset_feature_list, gpos->num_lookups,
michael@0:                              &num_features)) {
michael@0:     DROP_THIS_TABLE("Failed to parse feature list table");
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   if (!ParseScriptListTable(file, data + offset_script_list,
michael@0:                             length - offset_script_list, num_features)) {
michael@0:     DROP_THIS_TABLE("Failed to parse script list table");
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   gpos->data = data;
michael@0:   gpos->length = length;
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ots_gpos_should_serialise(OpenTypeFile *file) {
michael@0:   return file->gpos != NULL && file->gpos->data != NULL;
michael@0: }
michael@0: 
michael@0: bool ots_gpos_serialise(OTSStream *out, OpenTypeFile *file) {
michael@0:   if (!out->Write(file->gpos->data, file->gpos->length)) {
michael@0:     return OTS_FAILURE_MSG("Failed to write GPOS table");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: void ots_gpos_free(OpenTypeFile *file) {
michael@0:   delete file->gpos;
michael@0: }
michael@0: 
michael@0: }  // namespace ots
michael@0: