tor-browser

fvar.cc (5523B)

---

// Copyright (c) 2018 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 "fvar.h"

namespace ots {

// -----------------------------------------------------------------------------
// OpenTypeFVAR
// -----------------------------------------------------------------------------

bool OpenTypeFVAR::Parse(const uint8_t* data, size_t length) {
 Buffer table(data, length);
 if (!table.ReadU16(&this->majorVersion) ||
     !table.ReadU16(&this->minorVersion) ||
     !table.ReadU16(&this->axesArrayOffset) ||
     !table.ReadU16(&this->reserved) ||
     !table.ReadU16(&this->axisCount) ||
     !table.ReadU16(&this->axisSize) ||
     !table.ReadU16(&this->instanceCount) ||
     !table.ReadU16(&this->instanceSize)) {
   return DropVariations("Failed to read table header");
 }
 if (this->majorVersion != 1) {
   return DropVariations("Unknown table version");
 }
 if (this->minorVersion > 0) {
   Warning("Downgrading minor version to 0");
   this->minorVersion = 0;
 }
 if (this->axesArrayOffset > length || this->axesArrayOffset < table.offset()) {
   return DropVariations("Bad axesArrayOffset");
 }
 if (this->reserved != 2) {
   Warning("Expected reserved=2");
   this->reserved = 2;
 }
 if (this->axisCount == 0) {
   return DropVariations("No variation axes");
 }
 if (this->axisSize != 20) {
   return DropVariations("Invalid axisSize");
 }
 // instanceCount is not validated
 if (this->instanceSize == this->axisCount * sizeof(Fixed) + 6) {
   this->instancesHavePostScriptNameID = true;
 } else if (this->instanceSize == this->axisCount * sizeof(Fixed) + 4) {
   this->instancesHavePostScriptNameID = false;
 } else {
   return DropVariations("Invalid instanceSize");
 }

 // When we serialize, the axes array will go here, even if it was
 // originally at a different offset. So we update the axesArrayOffset
 // field for the header.
 uint32_t origAxesArrayOffset = this->axesArrayOffset;
 this->axesArrayOffset = table.offset();

 table.set_offset(origAxesArrayOffset);
 for (unsigned i = 0; i < this->axisCount; i++) {
   this->axes.emplace_back();
   auto& axis = this->axes[i];
   if (!table.ReadU32(&axis.axisTag) ||
       !table.ReadS32(&axis.minValue) ||
       !table.ReadS32(&axis.defaultValue) ||
       !table.ReadS32(&axis.maxValue) ||
       !table.ReadU16(&axis.flags) ||
       !table.ReadU16(&axis.axisNameID)) {
     return DropVariations("Failed to read axis record");
   }
   if (!CheckTag(axis.axisTag)) {
     return DropVariations("Bad axis tag");
   }
   if (!(axis.minValue <= axis.defaultValue && axis.defaultValue <= axis.maxValue)) {
     return DropVariations("Bad axis value range");
   }
   if ((axis.flags & 0xFFFEu) != 0) {
     Warning("Discarding unknown axis flags");
     axis.flags &= ~0xFFFEu;
   }
   if (axis.axisNameID <= 255 || axis.axisNameID >= 32768) {
     Warning("Axis nameID out of range");
     // We don't check that the name actually exists -- assume the client can handle
     // a missing name when it tries to read the table.
   }
 }

 for (unsigned i = 0; i < this->instanceCount; i++) {
   this->instances.emplace_back();
   auto& inst = this->instances[i];
   if (!table.ReadU16(&inst.subfamilyNameID) ||
       !table.ReadU16(&inst.flags)) {
     return DropVariations("Failed to read instance record");
   }
   inst.coordinates.reserve(this->axisCount);
   for (unsigned j = 0; j < this->axisCount; j++) {
     inst.coordinates.emplace_back();
     auto& coord = inst.coordinates[j];
     if (!table.ReadS32(&coord)) {
       return DropVariations("Failed to read instance coordinates");
     }
   }
   if (this->instancesHavePostScriptNameID) {
     if (!table.ReadU16(&inst.postScriptNameID)) {
       return DropVariations("Failed to read instance psname ID");
     }
   }
 }

 if (table.remaining()) {
   return Warning("%zu bytes unparsed", table.remaining());
 }

 return true;
}

bool OpenTypeFVAR::Serialize(OTSStream* out) {
 if (!out->WriteU16(this->majorVersion) ||
     !out->WriteU16(this->minorVersion) ||
     !out->WriteU16(this->axesArrayOffset) ||
     !out->WriteU16(this->reserved) ||
     !out->WriteU16(this->axisCount) ||
     !out->WriteU16(this->axisSize) ||
     !out->WriteU16(this->instanceCount) ||
     !out->WriteU16(this->instanceSize)) {
   return Error("Failed to write table");
 }

 for (unsigned i = 0; i < this->axisCount; i++) {
   const auto& axis = this->axes[i];
   if (!out->WriteU32(axis.axisTag) ||
       !out->WriteS32(axis.minValue) ||
       !out->WriteS32(axis.defaultValue) ||
       !out->WriteS32(axis.maxValue) ||
       !out->WriteU16(axis.flags) ||
       !out->WriteU16(axis.axisNameID)) {
     return Error("Failed to write table");
   }
 }

 for (unsigned i = 0; i < this->instanceCount; i++) {
   const auto& inst = this->instances[i];
   if (!out->WriteU16(inst.subfamilyNameID) ||
       !out->WriteU16(inst.flags)) {
     return Error("Failed to write table");
   }
   for (unsigned j = 0; j < this->axisCount; j++) {
     const auto& coord = inst.coordinates[j];
     if (!out->WriteS32(coord)) {
       return Error("Failed to write table");
     }
   }
   if (this->instancesHavePostScriptNameID) {
     if (!out->WriteU16(inst.postScriptNameID)) {
       return Error("Failed to write table");
     }
   }
 }

 return true;
}

}  // namespace ots