gecko/gfx/ots/src/gsub.cc

684 lines
19 KiB
C++

// 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 "gsub.h"
#include <limits>
#include <vector>
#include "gdef.h"
#include "gpos.h"
#include "layout.h"
#include "maxp.h"
// GSUB - The Glyph Substitution Table
// http://www.microsoft.com/typography/otspec/gsub.htm
#define TABLE_NAME "GSUB"
namespace {
// The GSUB header size
const size_t kGsubHeaderSize = 8;
enum GSUB_TYPE {
GSUB_TYPE_SINGLE = 1,
GSUB_TYPE_MULTIPLE = 2,
GSUB_TYPE_ALTERNATE = 3,
GSUB_TYPE_LIGATURE = 4,
GSUB_TYPE_CONTEXT = 5,
GSUB_TYPE_CHANGING_CONTEXT = 6,
GSUB_TYPE_EXTENSION_SUBSTITUTION = 7,
GSUB_TYPE_REVERSE_CHAINING_CONTEXT_SINGLE = 8,
GSUB_TYPE_RESERVED = 9
};
// Lookup type parsers.
bool ParseSingleSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length);
bool ParseMutipleSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length);
bool ParseAlternateSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length);
bool ParseLigatureSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length);
bool ParseContextSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length);
bool ParseChainingContextSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data,
const size_t length);
bool ParseExtensionSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length);
bool ParseReverseChainingContextSingleSubstitution(
const ots::OpenTypeFile *file, const uint8_t *data, const size_t length);
const ots::LookupSubtableParser::TypeParser kGsubTypeParsers[] = {
{GSUB_TYPE_SINGLE, ParseSingleSubstitution},
{GSUB_TYPE_MULTIPLE, ParseMutipleSubstitution},
{GSUB_TYPE_ALTERNATE, ParseAlternateSubstitution},
{GSUB_TYPE_LIGATURE, ParseLigatureSubstitution},
{GSUB_TYPE_CONTEXT, ParseContextSubstitution},
{GSUB_TYPE_CHANGING_CONTEXT, ParseChainingContextSubstitution},
{GSUB_TYPE_EXTENSION_SUBSTITUTION, ParseExtensionSubstitution},
{GSUB_TYPE_REVERSE_CHAINING_CONTEXT_SINGLE,
ParseReverseChainingContextSingleSubstitution}
};
// TODO(bashi): Port Chromium's arraysize macro and use it instead of sizeof().
const ots::LookupSubtableParser kGsubLookupSubtableParser = {
sizeof(kGsubTypeParsers) / sizeof(kGsubTypeParsers[0]),
GSUB_TYPE_EXTENSION_SUBSTITUTION, kGsubTypeParsers
};
// Lookup Type 1:
// Single Substitution Subtable
bool ParseSingleSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length) {
ots::Buffer subtable(data, length);
uint16_t format = 0;
uint16_t offset_coverage = 0;
if (!subtable.ReadU16(&format) ||
!subtable.ReadU16(&offset_coverage)) {
return OTS_FAILURE();
}
const uint16_t num_glyphs = file->maxp->num_glyphs;
if (format == 1) {
// Parse SingleSubstFormat1
int16_t delta_glyph_id = 0;
if (!subtable.ReadS16(&delta_glyph_id)) {
return OTS_FAILURE();
}
if (std::abs(delta_glyph_id) >= num_glyphs) {
return OTS_FAILURE();
}
} else if (format == 2) {
// Parse SingleSubstFormat2
uint16_t glyph_count = 0;
if (!subtable.ReadU16(&glyph_count)) {
return OTS_FAILURE();
}
if (glyph_count > num_glyphs) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < glyph_count; ++i) {
uint16_t substitute = 0;
if (!subtable.ReadU16(&substitute)) {
return OTS_FAILURE();
}
if (substitute >= num_glyphs) {
OTS_WARNING("too large substitute: %u", substitute);
return OTS_FAILURE();
}
}
} else {
return OTS_FAILURE();
}
if (offset_coverage < subtable.offset() || offset_coverage >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offset_coverage,
length - offset_coverage, num_glyphs)) {
return OTS_FAILURE();
}
return true;
}
bool ParseSequenceTable(const uint8_t *data, const size_t length,
const uint16_t num_glyphs) {
ots::Buffer subtable(data, length);
uint16_t glyph_count = 0;
if (!subtable.ReadU16(&glyph_count)) {
return OTS_FAILURE();
}
if (glyph_count > num_glyphs) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < glyph_count; ++i) {
uint16_t substitute = 0;
if (!subtable.ReadU16(&substitute)) {
return OTS_FAILURE();
}
if (substitute >= num_glyphs) {
return OTS_FAILURE();
}
}
return true;
}
// Lookup Type 2:
// Multiple Substitution Subtable
bool ParseMutipleSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length) {
ots::Buffer subtable(data, length);
uint16_t format = 0;
uint16_t offset_coverage = 0;
uint16_t sequence_count = 0;
if (!subtable.ReadU16(&format) ||
!subtable.ReadU16(&offset_coverage) ||
!subtable.ReadU16(&sequence_count)) {
return OTS_FAILURE();
}
if (format != 1) {
return OTS_FAILURE();
}
const uint16_t num_glyphs = file->maxp->num_glyphs;
const unsigned sequence_end = static_cast<unsigned>(6) +
sequence_count * 2;
if (sequence_end > std::numeric_limits<uint16_t>::max()) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < sequence_count; ++i) {
uint16_t offset_sequence = 0;
if (!subtable.ReadU16(&offset_sequence)) {
return OTS_FAILURE();
}
if (offset_sequence < sequence_end || offset_sequence >= length) {
return OTS_FAILURE();
}
if (!ParseSequenceTable(data + offset_sequence, length - offset_sequence,
num_glyphs)) {
return OTS_FAILURE();
}
}
if (offset_coverage < sequence_end || offset_coverage >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offset_coverage,
length - offset_coverage, num_glyphs)) {
return OTS_FAILURE();
}
return true;
}
bool ParseAlternateSetTable(const uint8_t *data, const size_t length,
const uint16_t num_glyphs) {
ots::Buffer subtable(data, length);
uint16_t glyph_count = 0;
if (!subtable.ReadU16(&glyph_count)) {
return OTS_FAILURE();
}
if (glyph_count > num_glyphs) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < glyph_count; ++i) {
uint16_t alternate = 0;
if (!subtable.ReadU16(&alternate)) {
return OTS_FAILURE();
}
if (alternate >= num_glyphs) {
OTS_WARNING("too large alternate: %u", alternate);
return OTS_FAILURE();
}
}
return true;
}
// Lookup Type 3:
// Alternate Substitution Subtable
bool ParseAlternateSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length) {
ots::Buffer subtable(data, length);
uint16_t format = 0;
uint16_t offset_coverage = 0;
uint16_t alternate_set_count = 0;
if (!subtable.ReadU16(&format) ||
!subtable.ReadU16(&offset_coverage) ||
!subtable.ReadU16(&alternate_set_count)) {
return OTS_FAILURE();
}
if (format != 1) {
return OTS_FAILURE();
}
const uint16_t num_glyphs = file->maxp->num_glyphs;
const unsigned alternate_set_end = static_cast<unsigned>(6) +
alternate_set_count * 2;
if (alternate_set_end > std::numeric_limits<uint16_t>::max()) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < alternate_set_count; ++i) {
uint16_t offset_alternate_set = 0;
if (!subtable.ReadU16(&offset_alternate_set)) {
return OTS_FAILURE();
}
if (offset_alternate_set < alternate_set_end ||
offset_alternate_set >= length) {
return OTS_FAILURE();
}
if (!ParseAlternateSetTable(data + offset_alternate_set,
length - offset_alternate_set,
num_glyphs)) {
return OTS_FAILURE();
}
}
if (offset_coverage < alternate_set_end || offset_coverage >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offset_coverage,
length - offset_coverage, num_glyphs)) {
return OTS_FAILURE();
}
return true;
}
bool ParseLigatureTable(const uint8_t *data, const size_t length,
const uint16_t num_glyphs) {
ots::Buffer subtable(data, length);
uint16_t lig_glyph = 0;
uint16_t comp_count = 0;
if (!subtable.ReadU16(&lig_glyph) ||
!subtable.ReadU16(&comp_count)) {
return OTS_FAILURE();
}
if (lig_glyph >= num_glyphs) {
OTS_WARNING("too large lig_glyph: %u", lig_glyph);
return OTS_FAILURE();
}
if (comp_count == 0 || comp_count > num_glyphs) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < comp_count - static_cast<unsigned>(1); ++i) {
uint16_t component = 0;
if (!subtable.ReadU16(&component)) {
return OTS_FAILURE();
}
if (component >= num_glyphs) {
return OTS_FAILURE();
}
}
return true;
}
bool ParseLigatureSetTable(const uint8_t *data, const size_t length,
const uint16_t num_glyphs) {
ots::Buffer subtable(data, length);
uint16_t ligature_count = 0;
if (!subtable.ReadU16(&ligature_count)) {
return OTS_FAILURE();
}
const unsigned ligature_end = static_cast<unsigned>(2) + ligature_count * 2;
if (ligature_end > std::numeric_limits<uint16_t>::max()) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < ligature_count; ++i) {
uint16_t offset_ligature = 0;
if (!subtable.ReadU16(&offset_ligature)) {
return OTS_FAILURE();
}
if (offset_ligature < ligature_end || offset_ligature >= length) {
return OTS_FAILURE();
}
if (!ParseLigatureTable(data + offset_ligature, length - offset_ligature,
num_glyphs)) {
return OTS_FAILURE();
}
}
return true;
}
// Lookup Type 4:
// Ligature Substitution Subtable
bool ParseLigatureSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length) {
ots::Buffer subtable(data, length);
uint16_t format = 0;
uint16_t offset_coverage = 0;
uint16_t lig_set_count = 0;
if (!subtable.ReadU16(&format) ||
!subtable.ReadU16(&offset_coverage) ||
!subtable.ReadU16(&lig_set_count)) {
return OTS_FAILURE();
}
if (format != 1) {
return OTS_FAILURE();
}
const uint16_t num_glyphs = file->maxp->num_glyphs;
const unsigned ligature_set_end = static_cast<unsigned>(6) +
lig_set_count * 2;
if (ligature_set_end > std::numeric_limits<uint16_t>::max()) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < lig_set_count; ++i) {
uint16_t offset_ligature_set = 0;
if (!subtable.ReadU16(&offset_ligature_set)) {
return OTS_FAILURE();
}
if (offset_ligature_set < ligature_set_end ||
offset_ligature_set >= length) {
return OTS_FAILURE();
}
if (!ParseLigatureSetTable(data + offset_ligature_set,
length - offset_ligature_set, num_glyphs)) {
return OTS_FAILURE();
}
}
if (offset_coverage < ligature_set_end || offset_coverage >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offset_coverage,
length - offset_coverage, num_glyphs)) {
return OTS_FAILURE();
}
return true;
}
// Lookup Type 5:
// Contextual Substitution Subtable
bool ParseContextSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length) {
return ots::ParseContextSubtable(data, length, file->maxp->num_glyphs,
file->gsub->num_lookups);
}
// Lookup Type 6:
// Chaining Contextual Substitution Subtable
bool ParseChainingContextSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data,
const size_t length) {
return ots::ParseChainingContextSubtable(data, length,
file->maxp->num_glyphs,
file->gsub->num_lookups);
}
// Lookup Type 7:
// Extension Substition
bool ParseExtensionSubstitution(const ots::OpenTypeFile *file,
const uint8_t *data, const size_t length) {
return ots::ParseExtensionSubtable(file, data, length,
&kGsubLookupSubtableParser);
}
// Lookup Type 8:
// Reverse Chaining Contexual Single Substitution Subtable
bool ParseReverseChainingContextSingleSubstitution(
const ots::OpenTypeFile *file, const uint8_t *data, const size_t length) {
ots::Buffer subtable(data, length);
uint16_t format = 0;
uint16_t offset_coverage = 0;
if (!subtable.ReadU16(&format) ||
!subtable.ReadU16(&offset_coverage)) {
return OTS_FAILURE();
}
const uint16_t num_glyphs = file->maxp->num_glyphs;
uint16_t backtrack_glyph_count = 0;
if (!subtable.ReadU16(&backtrack_glyph_count)) {
return OTS_FAILURE();
}
if (backtrack_glyph_count > num_glyphs) {
return OTS_FAILURE();
}
std::vector<uint16_t> offsets_backtrack;
offsets_backtrack.reserve(backtrack_glyph_count);
for (unsigned i = 0; i < backtrack_glyph_count; ++i) {
uint16_t offset = 0;
if (!subtable.ReadU16(&offset)) {
return OTS_FAILURE();
}
offsets_backtrack.push_back(offset);
}
uint16_t lookahead_glyph_count = 0;
if (!subtable.ReadU16(&lookahead_glyph_count)) {
return OTS_FAILURE();
}
if (lookahead_glyph_count > num_glyphs) {
return OTS_FAILURE();
}
std::vector<uint16_t> offsets_lookahead;
offsets_lookahead.reserve(lookahead_glyph_count);
for (unsigned i = 0; i < lookahead_glyph_count; ++i) {
uint16_t offset = 0;
if (!subtable.ReadU16(&offset)) {
return OTS_FAILURE();
}
offsets_lookahead.push_back(offset);
}
uint16_t glyph_count = 0;
if (!subtable.ReadU16(&glyph_count)) {
return OTS_FAILURE();
}
if (glyph_count > num_glyphs) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < glyph_count; ++i) {
uint16_t substitute = 0;
if (!subtable.ReadU16(&substitute)) {
return OTS_FAILURE();
}
if (substitute >= num_glyphs) {
return OTS_FAILURE();
}
}
const unsigned substitute_end = static_cast<unsigned>(10) +
(backtrack_glyph_count + lookahead_glyph_count + glyph_count) * 2;
if (substitute_end > std::numeric_limits<uint16_t>::max()) {
return OTS_FAILURE();
}
if (offset_coverage < substitute_end || offset_coverage >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offset_coverage,
length - offset_coverage, num_glyphs)) {
return OTS_FAILURE();
}
for (unsigned i = 0; i < backtrack_glyph_count; ++i) {
if (offsets_backtrack[i] < substitute_end ||
offsets_backtrack[i] >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offsets_backtrack[i],
length - offsets_backtrack[i], num_glyphs)) {
return OTS_FAILURE();
}
}
for (unsigned i = 0; i < lookahead_glyph_count; ++i) {
if (offsets_lookahead[i] < substitute_end ||
offsets_lookahead[i] >= length) {
return OTS_FAILURE();
}
if (!ots::ParseCoverageTable(data + offsets_lookahead[i],
length - offsets_lookahead[i], num_glyphs)) {
return OTS_FAILURE();
}
}
return true;
}
} // namespace
#define DROP_THIS_TABLE \
do { \
file->gsub->data = 0; \
file->gsub->length = 0; \
OTS_FAILURE_MSG("OpenType layout data discarded"); \
} while (0)
namespace ots {
// As far as I checked, following fonts contain invalid values in GSUB table.
// OTS will drop their GSUB table.
//
// # too large substitute (value is 0xFFFF)
// kaiu.ttf
// mingliub2.ttf
// mingliub1.ttf
// mingliub0.ttf
// GraublauWeb.otf
// GraublauWebBold.otf
//
// # too large alternate (value is 0xFFFF)
// ManchuFont.ttf
//
// # bad offset to lang sys table (NULL offset)
// DejaVuMonoSansBold.ttf
// DejaVuMonoSansBoldOblique.ttf
// DejaVuMonoSansOblique.ttf
// DejaVuSansMono-BoldOblique.ttf
// DejaVuSansMono-Oblique.ttf
// DejaVuSansMono-Bold.ttf
//
// # bad start coverage index
// GenBasBI.ttf
// GenBasI.ttf
// AndBasR.ttf
// GenBkBasI.ttf
// CharisSILR.ttf
// CharisSILBI.ttf
// CharisSILI.ttf
// CharisSILB.ttf
// DoulosSILR.ttf
// CharisSILBI.ttf
// GenBkBasB.ttf
// GenBkBasR.ttf
// GenBkBasBI.ttf
// GenBasB.ttf
// GenBasR.ttf
//
// # glyph range is overlapping
// KacstTitleL.ttf
// KacstDecorative.ttf
// KacstTitle.ttf
// KacstArt.ttf
// KacstPoster.ttf
// KacstQurn.ttf
// KacstDigital.ttf
// KacstBook.ttf
// KacstFarsi.ttf
bool ots_gsub_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
// Parsing gsub table requires |file->maxp->num_glyphs|
if (!file->maxp) {
return OTS_FAILURE();
}
Buffer table(data, length);
OpenTypeGSUB *gsub = new OpenTypeGSUB;
file->gsub = gsub;
uint32_t version = 0;
uint16_t offset_script_list = 0;
uint16_t offset_feature_list = 0;
uint16_t offset_lookup_list = 0;
if (!table.ReadU32(&version) ||
!table.ReadU16(&offset_script_list) ||
!table.ReadU16(&offset_feature_list) ||
!table.ReadU16(&offset_lookup_list)) {
OTS_WARNING("incomplete GSUB table");
DROP_THIS_TABLE;
return true;
}
if (version != 0x00010000) {
OTS_WARNING("bad GSUB version");
DROP_THIS_TABLE;
return true;
}
if ((offset_script_list < kGsubHeaderSize ||
offset_script_list >= length) ||
(offset_feature_list < kGsubHeaderSize ||
offset_feature_list >= length) ||
(offset_lookup_list < kGsubHeaderSize ||
offset_lookup_list >= length)) {
OTS_WARNING("bad offset in GSUB header");
DROP_THIS_TABLE;
return true;
}
if (!ParseLookupListTable(file, data + offset_lookup_list,
length - offset_lookup_list,
&kGsubLookupSubtableParser,
&gsub->num_lookups)) {
OTS_WARNING("failed to parse lookup list table");
DROP_THIS_TABLE;
return true;
}
uint16_t num_features = 0;
if (!ParseFeatureListTable(data + offset_feature_list,
length - offset_feature_list, gsub->num_lookups,
&num_features)) {
OTS_WARNING("failed to parse feature list table");
DROP_THIS_TABLE;
return true;
}
if (!ParseScriptListTable(data + offset_script_list,
length - offset_script_list, num_features)) {
OTS_WARNING("failed to parse script list table");
DROP_THIS_TABLE;
return true;
}
gsub->data = data;
gsub->length = length;
return true;
}
bool ots_gsub_should_serialise(OpenTypeFile *file) {
const bool needed_tables_dropped =
(file->gdef && file->gdef->data == NULL) ||
(file->gpos && file->gpos->data == NULL);
return file->gsub != NULL && file->gsub->data != NULL
&& !needed_tables_dropped;
}
bool ots_gsub_serialise(OTSStream *out, OpenTypeFile *file) {
if (!out->Write(file->gsub->data, file->gsub->length)) {
return OTS_FAILURE();
}
return true;
}
void ots_gsub_free(OpenTypeFile *file) {
delete file->gsub;
}
} // namespace ots