tor-browser

feat.cc (6287B)

---

// Copyright (c) 2009-2017 The OTS 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 "feat.h"

#include "name.h"

namespace ots {

bool OpenTypeFEAT::Parse(const uint8_t* data, size_t length) {
 Buffer table(data, length);

 if (!table.ReadU32(&this->version)) {
   return DropGraphite("Failed to read version");
 }
 if (this->version >> 16 != 1 && this->version >> 16 != 2) {
   return DropGraphite("Unsupported table version: %u", this->version >> 16);
 }
 if (!table.ReadU16(&this->numFeat)) {
   return DropGraphite("Failed to read numFeat");
 }
 if (!table.ReadU16(&this->reserved)) {
   return DropGraphite("Failed to read reserved");
 }
 if (this->reserved != 0) {
   Warning("Nonzero reserved");
 }
 if (!table.ReadU32(&this->reserved2)) {
   return DropGraphite("Failed to read valid reserved2");
 }
 if (this->reserved2 != 0) {
   Warning("Nonzero reserved2");
 }

 std::unordered_set<size_t> unverified;
 //this->features.resize(this->numFeat, this);
 for (unsigned i = 0; i < this->numFeat; ++i) {
   this->features.emplace_back(this);
   FeatureDefn& feature = this->features[i];
   if (!feature.ParsePart(table)) {
     return DropGraphite("Failed to read features[%u]", i);
   }
   this->feature_ids.insert(feature.id);
   for (unsigned j = 0; j < feature.numSettings; ++j) {
     size_t offset = feature.offset + j * 4;
     if (offset < feature.offset || offset > length) {
       return DropGraphite("Invalid FeatSettingDefn offset %zu/%zu",
                           offset, length);
     }
     unverified.insert(offset);
       // need to verify that this FeatureDefn points to valid
       // FeatureSettingDefn
   }
 }

 while (table.remaining()) {
   bool used = unverified.erase(table.offset());
   FeatureSettingDefn featSetting(this);
   if (!featSetting.ParsePart(table, used)) {
     return DropGraphite("Failed to read a FeatureSettingDefn");
   }
   featSettings.push_back(featSetting);
 }

 if (!unverified.empty()) {
   return DropGraphite("%zu incorrect offsets into featSettings",
                       unverified.size());
 }
 if (table.remaining()) {
   return Warning("%zu bytes unparsed", table.remaining());
 }
 return true;
}

bool OpenTypeFEAT::Serialize(OTSStream* out) {
 if (!out->WriteU32(this->version) ||
     !out->WriteU16(this->numFeat) ||
     !out->WriteU16(this->reserved) ||
     !out->WriteU32(this->reserved2) ||
     !SerializeParts(this->features, out) ||
     !SerializeParts(this->featSettings, out)) {
   return Error("Failed to write table");
 }
 return true;
}

bool OpenTypeFEAT::IsValidFeatureId(uint32_t id) const {
 return feature_ids.count(id);
}

bool OpenTypeFEAT::FeatureDefn::ParsePart(Buffer& table) {
 OpenTypeNAME* name = static_cast<OpenTypeNAME*>(
     parent->GetFont()->GetTypedTable(OTS_TAG_NAME));
 if (!name) {
   return parent->Error("FeatureDefn: Required name table is missing");
 }

 if (parent->version >> 16 >= 2 && !table.ReadU32(&this->id)) {
   return parent->Error("FeatureDefn: Failed to read id");
 }
 if (parent->version >> 16 == 1)  {
   uint16_t id;
   if (!table.ReadU16(&id)) {
     return parent->Error("FeatureDefn: Failed to read id");
   }
   this->id = id;
 }
 if (!table.ReadU16(&this->numSettings)) {
   return parent->Error("FeatureDefn: Failed to read numSettings");
 }
 if (parent->version >> 16 >= 2) {
   if (!table.ReadU16(&this->reserved)) {
     return parent->Error("FeatureDefn: Failed to read reserved");
   }
   if (this->reserved != 0) {
     parent->Warning("FeatureDefn: Nonzero reserved");
   }
 }
 if (!table.ReadU32(&this->offset)) {
   return parent->Error("FeatureDefn: Failed to read offset");
 }  // validity of offset verified in OpenTypeFEAT::Parse
 if (!table.ReadU16(&this->flags)) {
   return parent->Error("FeatureDefn: Failed to read flags");
 }
 if ((this->flags & RESERVED) != 0) {
   this->flags &= ~RESERVED;
   parent->Warning("FeatureDefn: Nonzero (flags & 0x%x) repaired", RESERVED);
 }
 if (this->flags & HAS_DEFAULT_SETTING &&
     (this->flags & DEFAULT_SETTING) >= this->numSettings) {
   return parent->Error("FeatureDefn: (flags & 0x%x) is set but (flags & 0x%x "
                        "is not a valid setting index", HAS_DEFAULT_SETTING,
                        DEFAULT_SETTING);
 }
 if (!table.ReadU16(&this->label)) {
   return parent->Error("FeatureDefn: Failed to read label");
 }
 if (!name->IsValidNameId(this->label)) {
   if (this->id == 1 && name->IsValidNameId(this->label, true)) {
     parent->Warning("FeatureDefn: Missing NameRecord repaired for feature"
                     " with id=%u, label=%u", this->id, this->label);
   }
   else {
     return parent->Error("FeatureDefn: Invalid label");
   }
 }
 return true;
}

bool OpenTypeFEAT::FeatureDefn::SerializePart(OTSStream* out) const {
 if ((parent->version >> 16 >= 2 && !out->WriteU32(this->id)) ||
     (parent->version >> 16 == 1 &&
      !out->WriteU16(static_cast<uint16_t>(this->id))) ||
     !out->WriteU16(this->numSettings) ||
     (parent->version >> 16 >= 2 && !out->WriteU16(this->reserved)) ||
     !out->WriteU32(this->offset) ||
     !out->WriteU16(this->flags) ||
     !out->WriteU16(this->label)) {
   return parent->Error("FeatureDefn: Failed to write");
 }
 return true;
}

bool OpenTypeFEAT::FeatureSettingDefn::ParsePart(Buffer& table, bool used) {
 OpenTypeNAME* name = static_cast<OpenTypeNAME*>(
     parent->GetFont()->GetTypedTable(OTS_TAG_NAME));
 if (!name) {
   return parent->Error("FeatureSettingDefn: Required name table is missing");
 }

 if (!table.ReadS16(&this->value)) {
   return parent->Error("FeatureSettingDefn: Failed to read value");
 }
 if (!table.ReadU16(&this->label) ||
     (used && !name->IsValidNameId(this->label))) {
   return parent->Error("FeatureSettingDefn: Failed to read valid label");
 }
 return true;
}

bool OpenTypeFEAT::FeatureSettingDefn::SerializePart(OTSStream* out) const {
 if (!out->WriteS16(this->value) ||
     !out->WriteU16(this->label)) {
   return parent->Error("FeatureSettingDefn: Failed to write");
 }
 return true;
}

}  // namespace ots