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Diffstat (limited to 'gfx/ots/src/layout.cc')
| -rw-r--r-- | gfx/ots/src/layout.cc | 1521 |
1 files changed, 1521 insertions, 0 deletions
diff --git a/gfx/ots/src/layout.cc b/gfx/ots/src/layout.cc new file mode 100644 index 000000000..1d87b53d4 --- /dev/null +++ b/gfx/ots/src/layout.cc @@ -0,0 +1,1521 @@ +// Copyright (c) 2011 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#include "layout.h" + +#include <limits> +#include <vector> + +#include "gdef.h" + +// OpenType Layout Common Table Formats +// http://www.microsoft.com/typography/otspec/chapter2.htm + +#define TABLE_NAME "Layout" // XXX: use individual table names + +namespace { + +// The 'DFLT' tag of script table. +const uint32_t kScriptTableTagDflt = 0x44464c54; +// The value which represents there is no required feature index. +const uint16_t kNoRequiredFeatureIndexDefined = 0xFFFF; +// The lookup flag bit which indicates existence of MarkFilteringSet. +const uint16_t kUseMarkFilteringSetBit = 0x0010; +// The lookup flags which require GDEF table. +const uint16_t kGdefRequiredFlags = 0x0002 | 0x0004 | 0x0008; +// The mask for MarkAttachmentType. +const uint16_t kMarkAttachmentTypeMask = 0xFF00; +// The maximum type number of format for device tables. +const uint16_t kMaxDeltaFormatType = 3; +// The maximum number of class value. +const uint16_t kMaxClassDefValue = 0xFFFF; + +struct ScriptRecord { + uint32_t tag; + uint16_t offset; +}; + +struct LangSysRecord { + uint32_t tag; + uint16_t offset; +}; + +struct FeatureRecord { + uint32_t tag; + uint16_t offset; +}; + +bool ParseLangSysTable(const ots::Font *font, + ots::Buffer *subtable, const uint32_t tag, + const uint16_t num_features) { + uint16_t offset_lookup_order = 0; + uint16_t req_feature_index = 0; + uint16_t feature_count = 0; + if (!subtable->ReadU16(&offset_lookup_order) || + !subtable->ReadU16(&req_feature_index) || + !subtable->ReadU16(&feature_count)) { + return OTS_FAILURE_MSG("Failed to read langsys header for tag %c%c%c%c", OTS_UNTAG(tag)); + } + // |offset_lookup_order| is reserved and should be NULL. + if (offset_lookup_order != 0) { + return OTS_FAILURE_MSG("Bad lookup offset order %d for langsys tag %c%c%c%c", offset_lookup_order, OTS_UNTAG(tag)); + } + if (req_feature_index != kNoRequiredFeatureIndexDefined && + req_feature_index >= num_features) { + return OTS_FAILURE_MSG("Bad required features index %d for langsys tag %c%c%c%c", req_feature_index, OTS_UNTAG(tag)); + } + if (feature_count > num_features) { + return OTS_FAILURE_MSG("Bad feature count %d for langsys tag %c%c%c%c", feature_count, OTS_UNTAG(tag)); + } + + for (unsigned i = 0; i < feature_count; ++i) { + uint16_t feature_index = 0; + if (!subtable->ReadU16(&feature_index)) { + return OTS_FAILURE_MSG("Failed to read feature index %d for langsys tag %c%c%c%c", i, OTS_UNTAG(tag)); + } + if (feature_index >= num_features) { + return OTS_FAILURE_MSG("Bad feature index %d for feature %d for langsys tag %c%c%c%c", feature_index, i, OTS_UNTAG(tag)); + } + } + return true; +} + +bool ParseScriptTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint32_t tag, const uint16_t num_features) { + ots::Buffer subtable(data, length); + + uint16_t offset_default_lang_sys = 0; + uint16_t lang_sys_count = 0; + if (!subtable.ReadU16(&offset_default_lang_sys) || + !subtable.ReadU16(&lang_sys_count)) { + return OTS_FAILURE_MSG("Failed to read script header for script tag %c%c%c%c", OTS_UNTAG(tag)); + } + + // The spec requires a script table for 'DFLT' tag must contain non-NULL + // |offset_default_lang_sys| and |lang_sys_count| == 0 + // https://www.microsoft.com/typography/otspec/chapter2.htm + if (tag == kScriptTableTagDflt) { + if (offset_default_lang_sys == 0) { + return OTS_FAILURE_MSG("DFLT script doesn't satisfy the spec. DefaultLangSys is NULL"); + } + if (lang_sys_count != 0) { + return OTS_FAILURE_MSG("DFLT script doesn't satisfy the spec. LangSysCount is not zero: %d", lang_sys_count); + } + } + + const unsigned lang_sys_record_end = + 6 * static_cast<unsigned>(lang_sys_count) + 4; + if (lang_sys_record_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of langsys record %d for script tag %c%c%c%c", lang_sys_record_end, OTS_UNTAG(tag)); + } + + std::vector<LangSysRecord> lang_sys_records; + lang_sys_records.resize(lang_sys_count); + uint32_t last_tag = 0; + for (unsigned i = 0; i < lang_sys_count; ++i) { + if (!subtable.ReadU32(&lang_sys_records[i].tag) || + !subtable.ReadU16(&lang_sys_records[i].offset)) { + return OTS_FAILURE_MSG("Failed to read langsys record header %d for script tag %c%c%c%c", i, OTS_UNTAG(tag)); + } + // The record array must store the records alphabetically by tag + if (last_tag != 0 && last_tag > lang_sys_records[i].tag) { + return OTS_FAILURE_MSG("Bad last tag %d for langsys record %d for script tag %c%c%c%c", last_tag, i, OTS_UNTAG(tag)); + } + if (lang_sys_records[i].offset < lang_sys_record_end || + lang_sys_records[i].offset >= length) { + return OTS_FAILURE_MSG("bad offset to lang sys table: %x", + lang_sys_records[i].offset); + } + last_tag = lang_sys_records[i].tag; + } + + // Check lang sys tables + for (unsigned i = 0; i < lang_sys_count; ++i) { + subtable.set_offset(lang_sys_records[i].offset); + if (!ParseLangSysTable(font, &subtable, lang_sys_records[i].tag, num_features)) { + return OTS_FAILURE_MSG("Failed to parse langsys table %d (%c%c%c%c) for script tag %c%c%c%c", i, OTS_UNTAG(lang_sys_records[i].tag), OTS_UNTAG(tag)); + } + } + + return true; +} + +bool ParseFeatureTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t offset_feature_params = 0; + uint16_t lookup_count = 0; + if (!subtable.ReadU16(&offset_feature_params) || + !subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read feature table header"); + } + + const unsigned feature_table_end = + 2 * static_cast<unsigned>(lookup_count) + 4; + if (feature_table_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of feature table %d", feature_table_end); + } + // |offset_feature_params| is generally set to NULL. + if (offset_feature_params != 0 && + (offset_feature_params < feature_table_end || + offset_feature_params >= length)) { + return OTS_FAILURE_MSG("Bad feature params offset %d", offset_feature_params); + } + + for (unsigned i = 0; i < lookup_count; ++i) { + uint16_t lookup_index = 0; + if (!subtable.ReadU16(&lookup_index)) { + return OTS_FAILURE_MSG("Failed to read lookup index for lookup %d", i); + } + // lookup index starts with 0. + if (lookup_index >= num_lookups) { + return OTS_FAILURE_MSG("Bad lookup index %d for lookup %d", lookup_index, i); + } + } + return true; +} + +bool ParseLookupTable(ots::Font *font, const uint8_t *data, + const size_t length, + const ots::LookupSubtableParser* parser) { + ots::Buffer subtable(data, length); + + uint16_t lookup_type = 0; + uint16_t lookup_flag = 0; + uint16_t subtable_count = 0; + if (!subtable.ReadU16(&lookup_type) || + !subtable.ReadU16(&lookup_flag) || + !subtable.ReadU16(&subtable_count)) { + return OTS_FAILURE_MSG("Failed to read lookup table header"); + } + + if (lookup_type == 0 || lookup_type > parser->num_types) { + return OTS_FAILURE_MSG("Bad lookup type %d", lookup_type); + } + + // Check lookup flags. + if ((lookup_flag & kGdefRequiredFlags) && + (!font->gdef || !font->gdef->has_glyph_class_def)) { + return OTS_FAILURE_MSG("Lookup flags require GDEF table, " + "but none was found: %d", lookup_flag); + } + if ((lookup_flag & kMarkAttachmentTypeMask) && + (!font->gdef || !font->gdef->has_mark_attachment_class_def)) { + return OTS_FAILURE_MSG("Lookup flags ask for mark attachment, " + "but there is no GDEF table or it has no " + "mark attachment classes: %d", lookup_flag); + } + bool use_mark_filtering_set = false; + if (lookup_flag & kUseMarkFilteringSetBit) { + if (!font->gdef || !font->gdef->has_mark_glyph_sets_def) { + return OTS_FAILURE_MSG("Lookup flags ask for mark filtering, " + "but there is no GDEF table or it has no " + "mark filtering sets: %d", lookup_flag); + } + use_mark_filtering_set = true; + } + + std::vector<uint16_t> subtables; + subtables.reserve(subtable_count); + // If the |kUseMarkFilteringSetBit| of |lookup_flag| is set, + // extra 2 bytes will follow after subtable offset array. + const unsigned lookup_table_end = 2 * static_cast<unsigned>(subtable_count) + + (use_mark_filtering_set ? 8 : 6); + if (lookup_table_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of lookup %d", lookup_table_end); + } + for (unsigned i = 0; i < subtable_count; ++i) { + uint16_t offset_subtable = 0; + if (!subtable.ReadU16(&offset_subtable)) { + return OTS_FAILURE_MSG("Failed to read subtable offset %d", i); + } + if (offset_subtable < lookup_table_end || + offset_subtable >= length) { + return OTS_FAILURE_MSG("Bad subtable offset %d for subtable %d", offset_subtable, i); + } + subtables.push_back(offset_subtable); + } + if (subtables.size() != subtable_count) { + return OTS_FAILURE_MSG("Bad subtable size %ld", subtables.size()); + } + + if (use_mark_filtering_set) { + uint16_t mark_filtering_set = 0; + if (!subtable.ReadU16(&mark_filtering_set)) { + return OTS_FAILURE_MSG("Failed to read mark filtering set"); + } + if (font->gdef->num_mark_glyph_sets == 0 || + mark_filtering_set >= font->gdef->num_mark_glyph_sets) { + return OTS_FAILURE_MSG("Bad mark filtering set %d", mark_filtering_set); + } + } + + // Parse lookup subtables for this lookup type. + for (unsigned i = 0; i < subtable_count; ++i) { + if (!parser->Parse(font, data + subtables[i], length - subtables[i], + lookup_type)) { + return OTS_FAILURE_MSG("Failed to parse subtable %d", i); + } + } + return true; +} + +bool ParseClassDefFormat1(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs, + const uint16_t num_classes) { + ots::Buffer subtable(data, length); + + // Skip format field. + if (!subtable.Skip(2)) { + return OTS_FAILURE_MSG("Failed to skip class definition header"); + } + + uint16_t start_glyph = 0; + if (!subtable.ReadU16(&start_glyph)) { + return OTS_FAILURE_MSG("Failed to read starting glyph of class definition"); + } + if (start_glyph > num_glyphs) { + return OTS_FAILURE_MSG("Bad starting glyph %d in class definition", start_glyph); + } + + uint16_t glyph_count = 0; + if (!subtable.ReadU16(&glyph_count)) { + return OTS_FAILURE_MSG("Failed to read glyph count in class definition"); + } + if (glyph_count > num_glyphs) { + return OTS_FAILURE_MSG("bad glyph count: %u", glyph_count); + } + for (unsigned i = 0; i < glyph_count; ++i) { + uint16_t class_value = 0; + if (!subtable.ReadU16(&class_value)) { + return OTS_FAILURE_MSG("Failed to read class value for glyph %d in class definition", i); + } + if (class_value > num_classes) { + return OTS_FAILURE_MSG("Bad class value %d for glyph %d in class definition", class_value, i); + } + } + + return true; +} + +bool ParseClassDefFormat2(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs, + const uint16_t num_classes) { + ots::Buffer subtable(data, length); + + // Skip format field. + if (!subtable.Skip(2)) { + return OTS_FAILURE_MSG("Failed to skip format of class defintion header"); + } + + uint16_t range_count = 0; + if (!subtable.ReadU16(&range_count)) { + return OTS_FAILURE_MSG("Failed to read range count in class definition"); + } + if (range_count > num_glyphs) { + return OTS_FAILURE_MSG("bad range count: %u", range_count); + } + + uint16_t last_end = 0; + for (unsigned i = 0; i < range_count; ++i) { + uint16_t start = 0; + uint16_t end = 0; + uint16_t class_value = 0; + if (!subtable.ReadU16(&start) || + !subtable.ReadU16(&end) || + !subtable.ReadU16(&class_value)) { + return OTS_FAILURE_MSG("Failed to read class definition reange %d", i); + } + if (start > end || (last_end && start <= last_end)) { + return OTS_FAILURE_MSG("glyph range is overlapping.in range %d", i); + } + if (class_value > num_classes) { + return OTS_FAILURE_MSG("bad class value: %u", class_value); + } + last_end = end; + } + + return true; +} + +bool ParseCoverageFormat1(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs, + const uint16_t expected_num_glyphs) { + ots::Buffer subtable(data, length); + + // Skip format field. + if (!subtable.Skip(2)) { + return OTS_FAILURE_MSG("Failed to skip coverage format"); + } + + uint16_t glyph_count = 0; + if (!subtable.ReadU16(&glyph_count)) { + return OTS_FAILURE_MSG("Failed to read glyph count in coverage"); + } + if (glyph_count > num_glyphs) { + return OTS_FAILURE_MSG("bad glyph count: %u", glyph_count); + } + for (unsigned i = 0; i < glyph_count; ++i) { + uint16_t glyph = 0; + if (!subtable.ReadU16(&glyph)) { + return OTS_FAILURE_MSG("Failed to read glyph %d in coverage", i); + } + if (glyph > num_glyphs) { + return OTS_FAILURE_MSG("bad glyph ID: %u", glyph); + } + } + + if (expected_num_glyphs && expected_num_glyphs != glyph_count) { + return OTS_FAILURE_MSG("unexpected number of glyphs: %u", glyph_count); + } + + return true; +} + +bool ParseCoverageFormat2(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs, + const uint16_t expected_num_glyphs) { + ots::Buffer subtable(data, length); + + // Skip format field. + if (!subtable.Skip(2)) { + return OTS_FAILURE_MSG("Failed to skip format of coverage type 2"); + } + + uint16_t range_count = 0; + if (!subtable.ReadU16(&range_count)) { + return OTS_FAILURE_MSG("Failed to read range count in coverage"); + } + if (range_count > num_glyphs) { + return OTS_FAILURE_MSG("bad range count: %u", range_count); + } + uint16_t last_end = 0; + uint16_t last_start_coverage_index = 0; + for (unsigned i = 0; i < range_count; ++i) { + uint16_t start = 0; + uint16_t end = 0; + uint16_t start_coverage_index = 0; + if (!subtable.ReadU16(&start) || + !subtable.ReadU16(&end) || + !subtable.ReadU16(&start_coverage_index)) { + return OTS_FAILURE_MSG("Failed to read range %d in coverage", i); + } + + // Some of the Adobe Pro fonts have ranges that overlap by one element: the + // start of one range is equal to the end of the previous range. Therefore + // the < in the following condition should be <= were it not for this. + // See crbug.com/134135. + if (start > end || (last_end && start < last_end)) { + return OTS_FAILURE_MSG("glyph range is overlapping."); + } + if (start_coverage_index != last_start_coverage_index) { + return OTS_FAILURE_MSG("bad start coverage index."); + } + last_end = end; + last_start_coverage_index += end - start + 1; + } + + if (expected_num_glyphs && + expected_num_glyphs != last_start_coverage_index) { + return OTS_FAILURE_MSG("unexpected number of glyphs: %u", last_start_coverage_index); + } + + return true; +} + +// Parsers for Contextual subtables in GSUB/GPOS tables. + +bool ParseLookupRecord(const ots::Font *font, + ots::Buffer *subtable, const uint16_t num_glyphs, + const uint16_t num_lookups) { + uint16_t sequence_index = 0; + uint16_t lookup_list_index = 0; + if (!subtable->ReadU16(&sequence_index) || + !subtable->ReadU16(&lookup_list_index)) { + return OTS_FAILURE_MSG("Failed to read header for lookup record"); + } + if (sequence_index >= num_glyphs) { + return OTS_FAILURE_MSG("Bad sequence index %d in lookup record", sequence_index); + } + if (lookup_list_index >= num_lookups) { + return OTS_FAILURE_MSG("Bad lookup list index %d in lookup record", lookup_list_index); + } + return true; +} + +bool ParseRuleSubtable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t glyph_count = 0; + uint16_t lookup_count = 0; + if (!subtable.ReadU16(&glyph_count) || + !subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read rule subtable header"); + } + + if (glyph_count == 0 || glyph_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph count %d in rule subtable", glyph_count); + } + for (unsigned i = 0; i < glyph_count - static_cast<unsigned>(1); ++i) { + uint16_t glyph_id = 0; + if (!subtable.ReadU16(&glyph_id)) { + return OTS_FAILURE_MSG("Failed to read glyph %d", i); + } + if (glyph_id > num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph %d for entry %d", glyph_id, i); + } + } + + for (unsigned i = 0; i < lookup_count; ++i) { + if (!ParseLookupRecord(font, &subtable, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse lookup record %d", i); + } + } + return true; +} + +bool ParseRuleSetTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t rule_count = 0; + if (!subtable.ReadU16(&rule_count)) { + return OTS_FAILURE_MSG("Failed to read rule count in rule set"); + } + const unsigned rule_end = 2 * static_cast<unsigned>(rule_count) + 2; + if (rule_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of rule %d in rule set", rule_end); + } + + for (unsigned i = 0; i < rule_count; ++i) { + uint16_t offset_rule = 0; + if (!subtable.ReadU16(&offset_rule)) { + return OTS_FAILURE_MSG("Failed to read rule offset for rule set %d", i); + } + if (offset_rule < rule_end || offset_rule >= length) { + return OTS_FAILURE_MSG("Bad rule offset %d in set %d", offset_rule, i); + } + if (!ParseRuleSubtable(font, data + offset_rule, length - offset_rule, + num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse rule set %d", i); + } + } + + return true; +} + +bool ParseContextFormat1(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t offset_coverage = 0; + uint16_t rule_set_count = 0; + // Skip format field. + if (!subtable.Skip(2) || + !subtable.ReadU16(&offset_coverage) || + !subtable.ReadU16(&rule_set_count)) { + return OTS_FAILURE_MSG("Failed to read header of context format 1"); + } + + const unsigned rule_set_end = static_cast<unsigned>(6) + + rule_set_count * 2; + if (rule_set_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of rule set %d of context format 1", rule_set_end); + } + if (offset_coverage < rule_set_end || offset_coverage >= length) { + return OTS_FAILURE_MSG("Bad coverage offset %d in context format 1", offset_coverage); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse coverage table in context format 1"); + } + + for (unsigned i = 0; i < rule_set_count; ++i) { + uint16_t offset_rule = 0; + if (!subtable.ReadU16(&offset_rule)) { + return OTS_FAILURE_MSG("Failed to read rule offset %d in context format 1", i); + } + if (offset_rule < rule_set_end || offset_rule >= length) { + return OTS_FAILURE_MSG("Bad rule offset %d in rule %d in context format 1", offset_rule, i); + } + if (!ParseRuleSetTable(font, data + offset_rule, length - offset_rule, + num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse rule set %d in context format 1", i); + } + } + + return true; +} + +bool ParseClassRuleTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t glyph_count = 0; + uint16_t lookup_count = 0; + if (!subtable.ReadU16(&glyph_count) || + !subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read header of class rule table"); + } + + if (glyph_count == 0 || glyph_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph count %d in class rule table", glyph_count); + } + + // ClassRule table contains an array of classes. Each value of classes + // could take arbitrary values including zero so we don't check these value. + const unsigned num_classes = glyph_count - static_cast<unsigned>(1); + if (!subtable.Skip(2 * num_classes)) { + return OTS_FAILURE_MSG("Failed to skip classes in class rule table"); + } + + for (unsigned i = 0; i < lookup_count; ++i) { + if (!ParseLookupRecord(font, &subtable, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse lookup record %d in class rule table", i); + } + } + return true; +} + +bool ParseClassSetTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t class_rule_count = 0; + if (!subtable.ReadU16(&class_rule_count)) { + return OTS_FAILURE_MSG("Failed to read class rule count in class set table"); + } + const unsigned class_rule_end = + 2 * static_cast<unsigned>(class_rule_count) + 2; + if (class_rule_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("bad class rule end %d in class set table", class_rule_end); + } + for (unsigned i = 0; i < class_rule_count; ++i) { + uint16_t offset_class_rule = 0; + if (!subtable.ReadU16(&offset_class_rule)) { + return OTS_FAILURE_MSG("Failed to read class rule offset %d in class set table", i); + } + if (offset_class_rule < class_rule_end || offset_class_rule >= length) { + return OTS_FAILURE_MSG("Bad class rule offset %d in class %d", offset_class_rule, i); + } + if (!ParseClassRuleTable(font, data + offset_class_rule, + length - offset_class_rule, num_glyphs, + num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse class rule table %d", i); + } + } + + return true; +} + +bool ParseContextFormat2(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t offset_coverage = 0; + uint16_t offset_class_def = 0; + uint16_t class_set_cnt = 0; + // Skip format field. + if (!subtable.Skip(2) || + !subtable.ReadU16(&offset_coverage) || + !subtable.ReadU16(&offset_class_def) || + !subtable.ReadU16(&class_set_cnt)) { + return OTS_FAILURE_MSG("Failed to read header for context format 2"); + } + + const unsigned class_set_end = 2 * static_cast<unsigned>(class_set_cnt) + 8; + if (class_set_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of class set %d for context format 2", class_set_end); + } + if (offset_coverage < class_set_end || offset_coverage >= length) { + return OTS_FAILURE_MSG("Bad coverage offset %d in context format 2", offset_coverage); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse coverage table in context format 2"); + } + + if (offset_class_def < class_set_end || offset_class_def >= length) { + return OTS_FAILURE_MSG("bad class definition offset %d in context format 2", offset_class_def); + } + if (!ots::ParseClassDefTable(font, data + offset_class_def, + length - offset_class_def, + num_glyphs, kMaxClassDefValue)) { + return OTS_FAILURE_MSG("Failed to parse class definition table in context format 2"); + } + + for (unsigned i = 0; i < class_set_cnt; ++i) { + uint16_t offset_class_rule = 0; + if (!subtable.ReadU16(&offset_class_rule)) { + return OTS_FAILURE_MSG("Failed to read class rule offset %d in context format 2", i); + } + if (offset_class_rule) { + if (offset_class_rule < class_set_end || offset_class_rule >= length) { + return OTS_FAILURE_MSG("Bad class rule offset %d for rule %d in context format 2", offset_class_rule, i); + } + if (!ParseClassSetTable(font, data + offset_class_rule, + length - offset_class_rule, num_glyphs, + num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse class set %d in context format 2", i); + } + } + } + + return true; +} + +bool ParseContextFormat3(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t glyph_count = 0; + uint16_t lookup_count = 0; + // Skip format field. + if (!subtable.Skip(2) || + !subtable.ReadU16(&glyph_count) || + !subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read header in context format 3"); + } + + if (glyph_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph count %d in context format 3", glyph_count); + } + const unsigned lookup_record_end = 2 * static_cast<unsigned>(glyph_count) + + 4 * static_cast<unsigned>(lookup_count) + 6; + if (lookup_record_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of lookup %d in context format 3", lookup_record_end); + } + for (unsigned i = 0; i < glyph_count; ++i) { + uint16_t offset_coverage = 0; + if (!subtable.ReadU16(&offset_coverage)) { + return OTS_FAILURE_MSG("Failed to read coverage offset %d in conxtext format 3", i); + } + if (offset_coverage < lookup_record_end || offset_coverage >= length) { + return OTS_FAILURE_MSG("Bad coverage offset %d for glyph %d in context format 3", offset_coverage, i); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse coverage table for glyph %d in context format 3", i); + } + } + + for (unsigned i = 0; i < lookup_count; ++i) { + if (!ParseLookupRecord(font, &subtable, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse lookup record %d in context format 3", i); + } + } + + return true; +} + +// Parsers for Chaning Contextual subtables in GSUB/GPOS tables. + +bool ParseChainRuleSubtable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t backtrack_count = 0; + if (!subtable.ReadU16(&backtrack_count)) { + return OTS_FAILURE_MSG("Failed to read backtrack count in chain rule subtable"); + } + if (backtrack_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad backtrack count %d in chain rule subtable", backtrack_count); + } + for (unsigned i = 0; i < backtrack_count; ++i) { + uint16_t glyph_id = 0; + if (!subtable.ReadU16(&glyph_id)) { + return OTS_FAILURE_MSG("Failed to read backtrack glyph %d in chain rule subtable", i); + } + if (glyph_id > num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph id %d for bactrack glyph %d in chain rule subtable", glyph_id, i); + } + } + + uint16_t input_count = 0; + if (!subtable.ReadU16(&input_count)) { + return OTS_FAILURE_MSG("Failed to read input count in chain rule subtable"); + } + if (input_count == 0 || input_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad input count %d in chain rule subtable", input_count); + } + for (unsigned i = 0; i < input_count - static_cast<unsigned>(1); ++i) { + uint16_t glyph_id = 0; + if (!subtable.ReadU16(&glyph_id)) { + return OTS_FAILURE_MSG("Failed to read input glyph %d in chain rule subtable", i); + } + if (glyph_id > num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph id %d for input glyph %d in chain rule subtable", glyph_id, i); + } + } + + uint16_t lookahead_count = 0; + if (!subtable.ReadU16(&lookahead_count)) { + return OTS_FAILURE_MSG("Failed to read lookahead count in chain rule subtable"); + } + if (lookahead_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad lookahead count %d in chain rule subtable", lookahead_count); + } + for (unsigned i = 0; i < lookahead_count; ++i) { + uint16_t glyph_id = 0; + if (!subtable.ReadU16(&glyph_id)) { + return OTS_FAILURE_MSG("Failed to read lookahead glyph %d in chain rule subtable", i); + } + if (glyph_id > num_glyphs) { + return OTS_FAILURE_MSG("Bad glyph id %d for lookadhead glyph %d in chain rule subtable", glyph_id, i); + } + } + + uint16_t lookup_count = 0; + if (!subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read lookup count in chain rule subtable"); + } + for (unsigned i = 0; i < lookup_count; ++i) { + if (!ParseLookupRecord(font, &subtable, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse lookup record %d in chain rule subtable", i); + } + } + + return true; +} + +bool ParseChainRuleSetTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t chain_rule_count = 0; + if (!subtable.ReadU16(&chain_rule_count)) { + return OTS_FAILURE_MSG("Failed to read rule count in chain rule set"); + } + const unsigned chain_rule_end = + 2 * static_cast<unsigned>(chain_rule_count) + 2; + if (chain_rule_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of chain rule %d in chain rule set", chain_rule_end); + } + for (unsigned i = 0; i < chain_rule_count; ++i) { + uint16_t offset_chain_rule = 0; + if (!subtable.ReadU16(&offset_chain_rule)) { + return OTS_FAILURE_MSG("Failed to read chain rule offset %d in chain rule set", i); + } + if (offset_chain_rule < chain_rule_end || offset_chain_rule >= length) { + return OTS_FAILURE_MSG("Bad chain rule offset %d for chain rule %d in chain rule set", offset_chain_rule, i); + } + if (!ParseChainRuleSubtable(font, data + offset_chain_rule, + length - offset_chain_rule, + num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chain rule %d in chain rule set", i); + } + } + + return true; +} + +bool ParseChainContextFormat1(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t offset_coverage = 0; + uint16_t chain_rule_set_count = 0; + // Skip format field. + if (!subtable.Skip(2) || + !subtable.ReadU16(&offset_coverage) || + !subtable.ReadU16(&chain_rule_set_count)) { + return OTS_FAILURE_MSG("Failed to read header of chain context format 1"); + } + + const unsigned chain_rule_set_end = + 2 * static_cast<unsigned>(chain_rule_set_count) + 6; + if (chain_rule_set_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad chain rule end %d in chain context format 1", chain_rule_set_end); + } + if (offset_coverage < chain_rule_set_end || offset_coverage >= length) { + return OTS_FAILURE_MSG("Bad coverage offset %d in chain context format 1", chain_rule_set_end); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse coverage table for chain context format 1"); + } + + for (unsigned i = 0; i < chain_rule_set_count; ++i) { + uint16_t offset_chain_rule_set = 0; + if (!subtable.ReadU16(&offset_chain_rule_set)) { + return OTS_FAILURE_MSG("Failed to read chain rule offset %d in chain context format 1", i); + } + if (offset_chain_rule_set < chain_rule_set_end || + offset_chain_rule_set >= length) { + return OTS_FAILURE_MSG("Bad chain rule set offset %d for chain rule set %d in chain context format 1", offset_chain_rule_set, i); + } + if (!ParseChainRuleSetTable(font, data + offset_chain_rule_set, + length - offset_chain_rule_set, + num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chain rule set %d in chain context format 1", i); + } + } + + return true; +} + +bool ParseChainClassRuleSubtable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + // In this subtable, we don't check the value of classes for now since + // these could take arbitrary values. + + uint16_t backtrack_count = 0; + if (!subtable.ReadU16(&backtrack_count)) { + return OTS_FAILURE_MSG("Failed to read backtrack count in chain class rule subtable"); + } + if (backtrack_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad backtrack count %d in chain class rule subtable", backtrack_count); + } + if (!subtable.Skip(2 * backtrack_count)) { + return OTS_FAILURE_MSG("Failed to skip backtrack offsets in chain class rule subtable"); + } + + uint16_t input_count = 0; + if (!subtable.ReadU16(&input_count)) { + return OTS_FAILURE_MSG("Failed to read input count in chain class rule subtable"); + } + if (input_count == 0 || input_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad input count %d in chain class rule subtable", input_count); + } + if (!subtable.Skip(2 * (input_count - 1))) { + return OTS_FAILURE_MSG("Failed to skip input offsets in chain class rule subtable"); + } + + uint16_t lookahead_count = 0; + if (!subtable.ReadU16(&lookahead_count)) { + return OTS_FAILURE_MSG("Failed to read lookahead count in chain class rule subtable"); + } + if (lookahead_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad lookahead count %d in chain class rule subtable", lookahead_count); + } + if (!subtable.Skip(2 * lookahead_count)) { + return OTS_FAILURE_MSG("Failed to skip lookahead offsets in chain class rule subtable"); + } + + uint16_t lookup_count = 0; + if (!subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read lookup count in chain class rule subtable"); + } + for (unsigned i = 0; i < lookup_count; ++i) { + if (!ParseLookupRecord(font, &subtable, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse lookup record %d in chain class rule subtable", i); + } + } + + return true; +} + +bool ParseChainClassSetTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t chain_class_rule_count = 0; + if (!subtable.ReadU16(&chain_class_rule_count)) { + return OTS_FAILURE_MSG("Failed to read rule count in chain class set"); + } + const unsigned chain_class_rule_end = + 2 * static_cast<unsigned>(chain_class_rule_count) + 2; + if (chain_class_rule_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of chain class set %d in chain class set", chain_class_rule_end); + } + for (unsigned i = 0; i < chain_class_rule_count; ++i) { + uint16_t offset_chain_class_rule = 0; + if (!subtable.ReadU16(&offset_chain_class_rule)) { + return OTS_FAILURE_MSG("Failed to read chain class rule offset %d in chain class set", i); + } + if (offset_chain_class_rule < chain_class_rule_end || + offset_chain_class_rule >= length) { + return OTS_FAILURE_MSG("Bad chain class rule offset %d for chain class %d in chain class set", offset_chain_class_rule, i); + } + if (!ParseChainClassRuleSubtable(font, data + offset_chain_class_rule, + length - offset_chain_class_rule, + num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chain class rule %d in chain class set", i); + } + } + + return true; +} + +bool ParseChainContextFormat2(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t offset_coverage = 0; + uint16_t offset_backtrack_class_def = 0; + uint16_t offset_input_class_def = 0; + uint16_t offset_lookahead_class_def = 0; + uint16_t chain_class_set_count = 0; + // Skip format field. + if (!subtable.Skip(2) || + !subtable.ReadU16(&offset_coverage) || + !subtable.ReadU16(&offset_backtrack_class_def) || + !subtable.ReadU16(&offset_input_class_def) || + !subtable.ReadU16(&offset_lookahead_class_def) || + !subtable.ReadU16(&chain_class_set_count)) { + return OTS_FAILURE_MSG("Failed to read header of chain context format 2"); + } + + const unsigned chain_class_set_end = + 2 * static_cast<unsigned>(chain_class_set_count) + 12; + if (chain_class_set_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad chain class set end %d in chain context format 2", chain_class_set_end); + } + if (offset_coverage < chain_class_set_end || offset_coverage >= length) { + return OTS_FAILURE_MSG("Bad coverage offset %d in chain context format 2", offset_coverage); + } + if (!ots::ParseCoverageTable(font, data + offset_coverage, + length - offset_coverage, num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse coverage table in chain context format 2"); + } + + // Classes for backtrack/lookahead sequences might not be defined. + if (offset_backtrack_class_def) { + if (offset_backtrack_class_def < chain_class_set_end || + offset_backtrack_class_def >= length) { + return OTS_FAILURE_MSG("Bad backtrack class offset %d in chain context format 2", offset_backtrack_class_def); + } + if (!ots::ParseClassDefTable(font, data + offset_backtrack_class_def, + length - offset_backtrack_class_def, + num_glyphs, kMaxClassDefValue)) { + return OTS_FAILURE_MSG("Failed to parse backtrack class defn table in chain context format 2"); + } + } + + if (offset_input_class_def < chain_class_set_end || + offset_input_class_def >= length) { + return OTS_FAILURE_MSG("Bad input class defn offset %d in chain context format 2", offset_input_class_def); + } + if (!ots::ParseClassDefTable(font, data + offset_input_class_def, + length - offset_input_class_def, + num_glyphs, kMaxClassDefValue)) { + return OTS_FAILURE_MSG("Failed to parse input class defn in chain context format 2"); + } + + if (offset_lookahead_class_def) { + if (offset_lookahead_class_def < chain_class_set_end || + offset_lookahead_class_def >= length) { + return OTS_FAILURE_MSG("Bad lookahead class defn offset %d in chain context format 2", offset_lookahead_class_def); + } + if (!ots::ParseClassDefTable(font, data + offset_lookahead_class_def, + length - offset_lookahead_class_def, + num_glyphs, kMaxClassDefValue)) { + return OTS_FAILURE_MSG("Failed to parse lookahead class defn in chain context format 2"); + } + } + + for (unsigned i = 0; i < chain_class_set_count; ++i) { + uint16_t offset_chain_class_set = 0; + if (!subtable.ReadU16(&offset_chain_class_set)) { + return OTS_FAILURE_MSG("Failed to read chain class set offset %d", i); + } + // |offset_chain_class_set| could be NULL. + if (offset_chain_class_set) { + if (offset_chain_class_set < chain_class_set_end || + offset_chain_class_set >= length) { + return OTS_FAILURE_MSG("Bad chain set class offset %d for chain set %d in chain context format 2", offset_chain_class_set, i); + } + if (!ParseChainClassSetTable(font, data + offset_chain_class_set, + length - offset_chain_class_set, + num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chain class set table %d in chain context format 2", i); + } + } + } + + return true; +} + +bool ParseChainContextFormat3(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + ots::Buffer subtable(data, length); + + uint16_t backtrack_count = 0; + // Skip format field. + if (!subtable.Skip(2) || + !subtable.ReadU16(&backtrack_count)) { + return OTS_FAILURE_MSG("Failed to read backtrack count in chain context format 3"); + } + + if (backtrack_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad backtrack count %d in chain context format 3", backtrack_count); + } + std::vector<uint16_t> offsets_backtrack; + offsets_backtrack.reserve(backtrack_count); + for (unsigned i = 0; i < backtrack_count; ++i) { + uint16_t offset = 0; + if (!subtable.ReadU16(&offset)) { + return OTS_FAILURE_MSG("Failed to read backtrack offset %d in chain context format 3", i); + } + offsets_backtrack.push_back(offset); + } + if (offsets_backtrack.size() != backtrack_count) { + return OTS_FAILURE_MSG("Bad backtrack offsets size %ld in chain context format 3", offsets_backtrack.size()); + } + + uint16_t input_count = 0; + if (!subtable.ReadU16(&input_count)) { + return OTS_FAILURE_MSG("Failed to read input count in chain context format 3"); + } + if (input_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad input count %d in chain context format 3", input_count); + } + std::vector<uint16_t> offsets_input; + offsets_input.reserve(input_count); + for (unsigned i = 0; i < input_count; ++i) { + uint16_t offset = 0; + if (!subtable.ReadU16(&offset)) { + return OTS_FAILURE_MSG("Failed to read input offset %d in chain context format 3", i); + } + offsets_input.push_back(offset); + } + if (offsets_input.size() != input_count) { + return OTS_FAILURE_MSG("Bad input offsets size %ld in chain context format 3", offsets_input.size()); + } + + uint16_t lookahead_count = 0; + if (!subtable.ReadU16(&lookahead_count)) { + return OTS_FAILURE_MSG("Failed ot read lookahead count in chain context format 3"); + } + if (lookahead_count >= num_glyphs) { + return OTS_FAILURE_MSG("Bad lookahead count %d in chain context format 3", lookahead_count); + } + std::vector<uint16_t> offsets_lookahead; + offsets_lookahead.reserve(lookahead_count); + for (unsigned i = 0; i < lookahead_count; ++i) { + uint16_t offset = 0; + if (!subtable.ReadU16(&offset)) { + return OTS_FAILURE_MSG("Failed to read lookahead offset %d in chain context format 3", i); + } + offsets_lookahead.push_back(offset); + } + if (offsets_lookahead.size() != lookahead_count) { + return OTS_FAILURE_MSG("Bad lookahead offsets size %ld in chain context format 3", offsets_lookahead.size()); + } + + uint16_t lookup_count = 0; + if (!subtable.ReadU16(&lookup_count)) { + return OTS_FAILURE_MSG("Failed to read lookup count in chain context format 3"); + } + for (unsigned i = 0; i < lookup_count; ++i) { + if (!ParseLookupRecord(font, &subtable, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse lookup %d in chain context format 3", i); + } + } + + const unsigned lookup_record_end = + 2 * (static_cast<unsigned>(backtrack_count) + + static_cast<unsigned>(input_count) + + static_cast<unsigned>(lookahead_count)) + + 4 * static_cast<unsigned>(lookup_count) + 10; + if (lookup_record_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of lookup record %d in chain context format 3", lookup_record_end); + } + for (unsigned i = 0; i < backtrack_count; ++i) { + if (offsets_backtrack[i] < lookup_record_end || + offsets_backtrack[i] >= length) { + return OTS_FAILURE_MSG("Bad backtrack offset of %d for backtrack %d in chain context format 3", offsets_backtrack[i], i); + } + if (!ots::ParseCoverageTable(font, data + offsets_backtrack[i], + length - offsets_backtrack[i], num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse backtrack coverage %d in chain context format 3", i); + } + } + for (unsigned i = 0; i < input_count; ++i) { + if (offsets_input[i] < lookup_record_end || offsets_input[i] >= length) { + return OTS_FAILURE_MSG("Bad input offset %d for input %d in chain context format 3", offsets_input[i], i); + } + if (!ots::ParseCoverageTable(font, data + offsets_input[i], + length - offsets_input[i], num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse input coverage table %d in chain context format 3", i); + } + } + for (unsigned i = 0; i < lookahead_count; ++i) { + if (offsets_lookahead[i] < lookup_record_end || + offsets_lookahead[i] >= length) { + return OTS_FAILURE_MSG("Bad lookadhead offset %d for lookahead %d in chain context format 3", offsets_lookahead[i], i); + } + if (!ots::ParseCoverageTable(font, data + offsets_lookahead[i], + length - offsets_lookahead[i], num_glyphs)) { + return OTS_FAILURE_MSG("Failed to parse lookahead coverage table %d in chain context format 3", i); + } + } + + return true; +} + +} // namespace + +namespace ots { + +bool LookupSubtableParser::Parse(const Font *font, const uint8_t *data, + const size_t length, + const uint16_t lookup_type) const { + for (unsigned i = 0; i < num_types; ++i) { + if (parsers[i].type == lookup_type && parsers[i].parse) { + if (!parsers[i].parse(font, data, length)) { + return OTS_FAILURE_MSG("Failed to parse lookup subtable %d", i); + } + return true; + } + } + return OTS_FAILURE_MSG("No lookup subtables to parse"); +} + +// Parsing ScriptListTable requires number of features so we need to +// parse FeatureListTable before calling this function. +bool ParseScriptListTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_features) { + Buffer subtable(data, length); + + uint16_t script_count = 0; + if (!subtable.ReadU16(&script_count)) { + return OTS_FAILURE_MSG("Failed to read script count in script list table"); + } + + const unsigned script_record_end = + 6 * static_cast<unsigned>(script_count) + 2; + if (script_record_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of script record %d in script list table", script_record_end); + } + std::vector<ScriptRecord> script_list; + script_list.reserve(script_count); + uint32_t last_tag = 0; + for (unsigned i = 0; i < script_count; ++i) { + ScriptRecord record; + if (!subtable.ReadU32(&record.tag) || + !subtable.ReadU16(&record.offset)) { + return OTS_FAILURE_MSG("Failed to read script record %d in script list table", i); + } + // Script tags should be arranged alphabetically by tag + if (last_tag != 0 && last_tag > record.tag) { + // Several fonts don't arrange tags alphabetically. + // It seems that the order of tags might not be a security issue + // so we just warn it. + OTS_WARNING("tags aren't arranged alphabetically."); + } + last_tag = record.tag; + if (record.offset < script_record_end || record.offset >= length) { + return OTS_FAILURE_MSG("Bad record offset %d for script %c%c%c%c entry %d in script list table", record.offset, OTS_UNTAG(record.tag), i); + } + script_list.push_back(record); + } + if (script_list.size() != script_count) { + return OTS_FAILURE_MSG("Bad script list size %ld in script list table", script_list.size()); + } + + // Check script records. + for (unsigned i = 0; i < script_count; ++i) { + if (!ParseScriptTable(font, data + script_list[i].offset, + length - script_list[i].offset, + script_list[i].tag, num_features)) { + return OTS_FAILURE_MSG("Failed to parse script table %d", i); + } + } + + return true; +} + +// Parsing FeatureListTable requires number of lookups so we need to parse +// LookupListTable before calling this function. +bool ParseFeatureListTable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_lookups, + uint16_t* num_features) { + Buffer subtable(data, length); + + uint16_t feature_count = 0; + if (!subtable.ReadU16(&feature_count)) { + return OTS_FAILURE_MSG("Failed to read feature count"); + } + + std::vector<FeatureRecord> feature_records; + feature_records.resize(feature_count); + const unsigned feature_record_end = + 6 * static_cast<unsigned>(feature_count) + 2; + if (feature_record_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of feature record %d", feature_record_end); + } + uint32_t last_tag = 0; + for (unsigned i = 0; i < feature_count; ++i) { + if (!subtable.ReadU32(&feature_records[i].tag) || + !subtable.ReadU16(&feature_records[i].offset)) { + return OTS_FAILURE_MSG("Failed to read feature header %d", i); + } + // Feature record array should be arranged alphabetically by tag + if (last_tag != 0 && last_tag > feature_records[i].tag) { + // Several fonts don't arrange tags alphabetically. + // It seems that the order of tags might not be a security issue + // so we just warn it. + OTS_WARNING("tags aren't arranged alphabetically."); + } + last_tag = feature_records[i].tag; + if (feature_records[i].offset < feature_record_end || + feature_records[i].offset >= length) { + return OTS_FAILURE_MSG("Bad feature offset %d for feature %d %c%c%c%c", feature_records[i].offset, i, OTS_UNTAG(feature_records[i].tag)); + } + } + + for (unsigned i = 0; i < feature_count; ++i) { + if (!ParseFeatureTable(font, data + feature_records[i].offset, + length - feature_records[i].offset, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse feature table %d", i); + } + } + *num_features = feature_count; + return true; +} + +// For parsing GPOS/GSUB tables, this function should be called at first to +// obtain the number of lookups because parsing FeatureTableList requires +// the number. +bool ParseLookupListTable(Font *font, const uint8_t *data, + const size_t length, + const LookupSubtableParser* parser, + uint16_t *num_lookups) { + Buffer subtable(data, length); + + if (!subtable.ReadU16(num_lookups)) { + return OTS_FAILURE_MSG("Failed to read number of lookups"); + } + + std::vector<uint16_t> lookups; + lookups.reserve(*num_lookups); + const unsigned lookup_end = + 2 * static_cast<unsigned>(*num_lookups) + 2; + if (lookup_end > std::numeric_limits<uint16_t>::max()) { + return OTS_FAILURE_MSG("Bad end of lookups %d", lookup_end); + } + for (unsigned i = 0; i < *num_lookups; ++i) { + uint16_t offset = 0; + if (!subtable.ReadU16(&offset)) { + return OTS_FAILURE_MSG("Failed to read lookup offset %d", i); + } + if (offset < lookup_end || offset >= length) { + return OTS_FAILURE_MSG("Bad lookup offset %d for lookup %d", offset, i); + } + lookups.push_back(offset); + } + if (lookups.size() != *num_lookups) { + return OTS_FAILURE_MSG("Bad lookup offsets list size %ld", lookups.size()); + } + + for (unsigned i = 0; i < *num_lookups; ++i) { + if (!ParseLookupTable(font, data + lookups[i], length - lookups[i], + parser)) { + return OTS_FAILURE_MSG("Failed to parse lookup %d", i); + } + } + + return true; +} + +bool ParseClassDefTable(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs, + const uint16_t num_classes) { + Buffer subtable(data, length); + + uint16_t format = 0; + if (!subtable.ReadU16(&format)) { + return OTS_FAILURE_MSG("Failed to read class defn format"); + } + if (format == 1) { + return ParseClassDefFormat1(font, data, length, num_glyphs, num_classes); + } else if (format == 2) { + return ParseClassDefFormat2(font, data, length, num_glyphs, num_classes); + } + + return OTS_FAILURE_MSG("Bad class defn format %d", format); +} + +bool ParseCoverageTable(const ots::Font *font, + const uint8_t *data, size_t length, + const uint16_t num_glyphs, + const uint16_t expected_num_glyphs) { + Buffer subtable(data, length); + + uint16_t format = 0; + if (!subtable.ReadU16(&format)) { + return OTS_FAILURE_MSG("Failed to read coverage table format"); + } + if (format == 1) { + return ParseCoverageFormat1(font, data, length, num_glyphs, expected_num_glyphs); + } else if (format == 2) { + return ParseCoverageFormat2(font, data, length, num_glyphs, expected_num_glyphs); + } + + return OTS_FAILURE_MSG("Bad coverage table format %d", format); +} + +bool ParseDeviceTable(const ots::Font *font, + const uint8_t *data, size_t length) { + Buffer subtable(data, length); + + uint16_t start_size = 0; + uint16_t end_size = 0; + uint16_t delta_format = 0; + if (!subtable.ReadU16(&start_size) || + !subtable.ReadU16(&end_size) || + !subtable.ReadU16(&delta_format)) { + return OTS_FAILURE_MSG("Failed to read device table header"); + } + if (start_size > end_size) { + return OTS_FAILURE_MSG("bad size range: %u > %u", start_size, end_size); + } + if (delta_format == 0 || delta_format > kMaxDeltaFormatType) { + return OTS_FAILURE_MSG("bad delta format: %u", delta_format); + } + // The number of delta values per uint16. The device table should contain + // at least |num_units| * 2 bytes compressed data. + const unsigned num_units = (end_size - start_size) / + (1 << (4 - delta_format)) + 1; + // Just skip |num_units| * 2 bytes since the compressed data could take + // arbitrary values. + if (!subtable.Skip(num_units * 2)) { + return OTS_FAILURE_MSG("Failed to skip data in device table"); + } + return true; +} + +bool ParseContextSubtable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + Buffer subtable(data, length); + + uint16_t format = 0; + if (!subtable.ReadU16(&format)) { + return OTS_FAILURE_MSG("Failed to read context subtable format"); + } + + if (format == 1) { + if (!ParseContextFormat1(font, data, length, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse context format 1 subtable"); + } + } else if (format == 2) { + if (!ParseContextFormat2(font, data, length, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse context format 2 subtable"); + } + } else if (format == 3) { + if (!ParseContextFormat3(font, data, length, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse context format 3 subtable"); + } + } else { + return OTS_FAILURE_MSG("Bad context subtable format %d", format); + } + + return true; +} + +bool ParseChainingContextSubtable(const ots::Font *font, + const uint8_t *data, const size_t length, + const uint16_t num_glyphs, + const uint16_t num_lookups) { + Buffer subtable(data, length); + + uint16_t format = 0; + if (!subtable.ReadU16(&format)) { + return OTS_FAILURE_MSG("Failed to read chaining context subtable format"); + } + + if (format == 1) { + if (!ParseChainContextFormat1(font, data, length, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chaining context format 1 subtable"); + } + } else if (format == 2) { + if (!ParseChainContextFormat2(font, data, length, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chaining context format 2 subtable"); + } + } else if (format == 3) { + if (!ParseChainContextFormat3(font, data, length, num_glyphs, num_lookups)) { + return OTS_FAILURE_MSG("Failed to parse chaining context format 3 subtable"); + } + } else { + return OTS_FAILURE_MSG("Bad chaining context subtable format %d", format); + } + + return true; +} + +bool ParseExtensionSubtable(const Font *font, + const uint8_t *data, const size_t length, + const LookupSubtableParser* parser) { + Buffer subtable(data, length); + + uint16_t format = 0; + uint16_t lookup_type = 0; + uint32_t offset_extension = 0; + if (!subtable.ReadU16(&format) || + !subtable.ReadU16(&lookup_type) || + !subtable.ReadU32(&offset_extension)) { + return OTS_FAILURE_MSG("Failed to read extension table header"); + } + + if (format != 1) { + return OTS_FAILURE_MSG("Bad extension table format %d", format); + } + // |lookup_type| should be other than |parser->extension_type|. + if (lookup_type < 1 || lookup_type > parser->num_types || + lookup_type == parser->extension_type) { + return OTS_FAILURE_MSG("Bad lookup type %d in extension table", lookup_type); + } + + const unsigned format_end = static_cast<unsigned>(8); + if (offset_extension < format_end || + offset_extension >= length) { + return OTS_FAILURE_MSG("Bad extension offset %d", offset_extension); + } + + // Parse the extension subtable of |lookup_type|. + if (!parser->Parse(font, data + offset_extension, length - offset_extension, + lookup_type)) { + return OTS_FAILURE_MSG("Failed to parse lookup from extension lookup"); + } + + return true; +} + +} // namespace ots + +#undef TABLE_NAME |