The Tor Browser: gfx/ots/src/math.cc@6474c204b198 (annotated)

gfx/ots/src/math.cc@6474c204b198 (annotated)

gfx/ots/src/math.cc

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2014 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.
 // We use an underscore to avoid confusion with the standard math.h library.
 #include "math_.h"
 #include <limits>
 #include <vector>
 #include "layout.h"
 #include "maxp.h"
 // MATH - The MATH Table
 // The specification is not yet public but has been submitted to the MPEG group
 // in response to the 'Call for Proposals for ISO/IEC 14496-22 "Open Font
 // Format" Color Font Technology and MATH layout support'. Meanwhile, you can
 // contact Microsoft's engineer Murray Sargent to obtain a copy.
 #define TABLE_NAME "MATH"
 namespace {
 // The size of MATH header.
 // Version
 // MathConstants
 // MathGlyphInfo
 // MathVariants
 const unsigned kMathHeaderSize = 4 + 3 * 2;
 // The size of the MathGlyphInfo header.
 // MathItalicsCorrectionInfo
 // MathTopAccentAttachment
 // ExtendedShapeCoverage
 // MathKernInfo
 const unsigned kMathGlyphInfoHeaderSize = 4 * 2;
 // The size of the MathValueRecord.
 // Value
 // DeviceTable
 const unsigned kMathValueRecordSize = 2 * 2;
 // The size of the GlyphPartRecord.
 // glyph
 // StartConnectorLength
 // EndConnectorLength
 // FullAdvance
 // PartFlags
 const unsigned kGlyphPartRecordSize = 5 * 2;
 // Shared Table: MathValueRecord
 bool ParseMathValueRecord(const ots::OpenTypeFile *file,
                           ots::Buffer* subtable, const uint8_t *data,
                           const size_t length) {
   // Check the Value field.
   if (!subtable->Skip(2)) {
     return OTS_FAILURE();
   }
   // Check the offset to device table.
   uint16_t offset = 0;
   if (!subtable->ReadU16(&offset)) {
     return OTS_FAILURE();
   }
   if (offset) {
     if (offset >= length) {
       return OTS_FAILURE();
     }
     if (!ots::ParseDeviceTable(file, data + offset, length - offset)) {
       return OTS_FAILURE();
     }
   }
   return true;
 }
 bool ParseMathConstantsTable(const ots::OpenTypeFile *file,
                              const uint8_t *data, size_t length) {
   ots::Buffer subtable(data, length);
   // Part 1: int16 or uint16 constants.
   //  ScriptPercentScaleDown
   //  ScriptScriptPercentScaleDown
   //  DelimitedSubFormulaMinHeight
   //  DisplayOperatorMinHeight
   if (!subtable.Skip(4 * 2)) {
     return OTS_FAILURE();
   }
   // Part 2: MathValueRecord constants.
   // MathLeading
   // AxisHeight
   // AccentBaseHeight
   // FlattenedAccentBaseHeight
   // SubscriptShiftDown
   // SubscriptTopMax
   // SubscriptBaselineDropMin
   // SuperscriptShiftUp
   // SuperscriptShiftUpCramped
   // SuperscriptBottomMin
   //
   // SuperscriptBaselineDropMax
   // SubSuperscriptGapMin
   // SuperscriptBottomMaxWithSubscript
   // SpaceAfterScript
   // UpperLimitGapMin
   // UpperLimitBaselineRiseMin
   // LowerLimitGapMin
   // LowerLimitBaselineDropMin
   // StackTopShiftUp
   // StackTopDisplayStyleShiftUp
   //
   // StackBottomShiftDown
   // StackBottomDisplayStyleShiftDown
   // StackGapMin
   // StackDisplayStyleGapMin
   // StretchStackTopShiftUp
   // StretchStackBottomShiftDown
   // StretchStackGapAboveMin
   // StretchStackGapBelowMin
   // FractionNumeratorShiftUp
   // FractionNumeratorDisplayStyleShiftUp
   //
   // FractionDenominatorShiftDown
   // FractionDenominatorDisplayStyleShiftDown
   // FractionNumeratorGapMin
   // FractionNumDisplayStyleGapMin
   // FractionRuleThickness
   // FractionDenominatorGapMin
   // FractionDenomDisplayStyleGapMin
   // SkewedFractionHorizontalGap
   // SkewedFractionVerticalGap
   // OverbarVerticalGap
   //
   // OverbarRuleThickness
   // OverbarExtraAscender
   // UnderbarVerticalGap
   // UnderbarRuleThickness
   // UnderbarExtraDescender
   // RadicalVerticalGap
   // RadicalDisplayStyleVerticalGap
   // RadicalRuleThickness
   // RadicalExtraAscender
   // RadicalKernBeforeDegree
   //
   // RadicalKernAfterDegree
   for (unsigned i = 0; i < static_cast<unsigned>(51); ++i) {
     if (!ParseMathValueRecord(file, &subtable, data, length)) {
       return OTS_FAILURE();
     }
   }
   // Part 3: uint16 constant
   // RadicalDegreeBottomRaisePercent
   if (!subtable.Skip(2)) {
     return OTS_FAILURE();
   }
   return true;
 }
 bool ParseMathValueRecordSequenceForGlyphs(const ots::OpenTypeFile *file,
                                            ots::Buffer* subtable,
                                            const uint8_t *data,
                                            const size_t length,
                                            const uint16_t num_glyphs) {
   // Check the header.
   uint16_t offset_coverage = 0;
   uint16_t sequence_count = 0;
   if (!subtable->ReadU16(&offset_coverage) ||
       !subtable->ReadU16(&sequence_count)) {
     return OTS_FAILURE();
   }
   const unsigned sequence_end = static_cast<unsigned>(2 * 2) +
       sequence_count * kMathValueRecordSize;
   if (sequence_end > std::numeric_limits<uint16_t>::max()) {
     return OTS_FAILURE();
   }
   // Check coverage table.
   if (offset_coverage < sequence_end || offset_coverage >= length) {
     return OTS_FAILURE();
   }
   if (!ots::ParseCoverageTable(file, data + offset_coverage,
                                length - offset_coverage,
                                num_glyphs, sequence_count)) {
     return OTS_FAILURE();
   }
   // Check sequence.
   for (unsigned i = 0; i < sequence_count; ++i) {
     if (!ParseMathValueRecord(file, subtable, data, length)) {
       return OTS_FAILURE();
     }
   }
   return true;
 }
 bool ParseMathItalicsCorrectionInfoTable(const ots::OpenTypeFile *file,
                                          const uint8_t *data,
                                          size_t length,
                                          const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   return ParseMathValueRecordSequenceForGlyphs(file, &subtable, data, length,
                                                num_glyphs);
 }
 bool ParseMathTopAccentAttachmentTable(const ots::OpenTypeFile *file,
                                        const uint8_t *data,
                                        size_t length,
                                        const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   return ParseMathValueRecordSequenceForGlyphs(file, &subtable, data, length,
                                                num_glyphs);
 }
 bool ParseMathKernTable(const ots::OpenTypeFile *file,
                         const uint8_t *data, size_t length) {
   ots::Buffer subtable(data, length);
   // Check the Height count.
   uint16_t height_count = 0;
   if (!subtable.ReadU16(&height_count)) {
     return OTS_FAILURE();
   }
   // Check the Correction Heights.
   for (unsigned i = 0; i < height_count; ++i) {
     if (!ParseMathValueRecord(file, &subtable, data, length)) {
       return OTS_FAILURE();
     }
   }
   // Check the Kern Values.
   for (unsigned i = 0; i <= height_count; ++i) {
     if (!ParseMathValueRecord(file, &subtable, data, length)) {
       return OTS_FAILURE();
     }
   }
   return true;
 }
 bool ParseMathKernInfoTable(const ots::OpenTypeFile *file,
                             const uint8_t *data, size_t length,
                             const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   // Check the header.
   uint16_t offset_coverage = 0;
   uint16_t sequence_count = 0;
   if (!subtable.ReadU16(&offset_coverage) ||
       !subtable.ReadU16(&sequence_count)) {
     return OTS_FAILURE();
   }
   const unsigned sequence_end = static_cast<unsigned>(2 * 2) +
     sequence_count * 4 * 2;
   if (sequence_end > std::numeric_limits<uint16_t>::max()) {
     return OTS_FAILURE();
   }
   // Check coverage table.
   if (offset_coverage < sequence_end || offset_coverage >= length) {
     return OTS_FAILURE();
   }
   if (!ots::ParseCoverageTable(file, data + offset_coverage, length - offset_coverage,
                                num_glyphs, sequence_count)) {
     return OTS_FAILURE();
   }
   // Check sequence of MathKernInfoRecord
   for (unsigned i = 0; i < sequence_count; ++i) {
     // Check TopRight, TopLeft, BottomRight and BottomLeft Math Kern.
     for (unsigned j = 0; j < 4; ++j) {
       uint16_t offset_math_kern = 0;
       if (!subtable.ReadU16(&offset_math_kern)) {
         return OTS_FAILURE();
       }
       if (offset_math_kern) {
         if (offset_math_kern < sequence_end || offset_math_kern >= length ||
             !ParseMathKernTable(file, data + offset_math_kern,
                                 length - offset_math_kern)) {
           return OTS_FAILURE();
         }
       }
     }
   }
   return true;
 }
 bool ParseMathGlyphInfoTable(const ots::OpenTypeFile *file,
                              const uint8_t *data, size_t length,
                              const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   // Check Header.
   uint16_t offset_math_italics_correction_info = 0;
   uint16_t offset_math_top_accent_attachment = 0;
   uint16_t offset_extended_shaped_coverage = 0;
   uint16_t offset_math_kern_info = 0;
   if (!subtable.ReadU16(&offset_math_italics_correction_info) ||
       !subtable.ReadU16(&offset_math_top_accent_attachment) ||
       !subtable.ReadU16(&offset_extended_shaped_coverage) ||
       !subtable.ReadU16(&offset_math_kern_info)) {
     return OTS_FAILURE();
   }
   // Check subtables.
   // The specification does not say whether the offsets for
   // MathItalicsCorrectionInfo, MathTopAccentAttachment and MathKernInfo may
   // be NULL, but that's the case in some fonts (e.g STIX) so we accept that.
   if (offset_math_italics_correction_info) {
     if (offset_math_italics_correction_info >= length ||
         offset_math_italics_correction_info < kMathGlyphInfoHeaderSize ||
         !ParseMathItalicsCorrectionInfoTable(
             file, data + offset_math_italics_correction_info,
             length - offset_math_italics_correction_info,
             num_glyphs)) {
       return OTS_FAILURE();
     }
   }
   if (offset_math_top_accent_attachment) {
     if (offset_math_top_accent_attachment >= length ||
         offset_math_top_accent_attachment < kMathGlyphInfoHeaderSize ||
         !ParseMathTopAccentAttachmentTable(file, data +
                                            offset_math_top_accent_attachment,
                                            length -
                                            offset_math_top_accent_attachment,
                                            num_glyphs)) {
       return OTS_FAILURE();
     }
   }
   if (offset_extended_shaped_coverage) {
     if (offset_extended_shaped_coverage >= length ||
         offset_extended_shaped_coverage < kMathGlyphInfoHeaderSize ||
         !ots::ParseCoverageTable(file, data + offset_extended_shaped_coverage,
                                  length - offset_extended_shaped_coverage,
                                  num_glyphs)) {
       return OTS_FAILURE();
     }
   }
   if (offset_math_kern_info) {
     if (offset_math_kern_info >= length ||
         offset_math_kern_info < kMathGlyphInfoHeaderSize ||
         !ParseMathKernInfoTable(file, data + offset_math_kern_info,
                                 length - offset_math_kern_info, num_glyphs)) {
       return OTS_FAILURE();
     }
   }
   return true;
 }
 bool ParseGlyphAssemblyTable(const ots::OpenTypeFile *file,
                              const uint8_t *data,
                              size_t length, const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   // Check the header.
   uint16_t part_count = 0;
   if (!ParseMathValueRecord(file, &subtable, data, length) ||
       !subtable.ReadU16(&part_count)) {
     return OTS_FAILURE();
   }
   const unsigned sequence_end = kMathValueRecordSize +
     static_cast<unsigned>(2) + part_count * kGlyphPartRecordSize;
   if (sequence_end > std::numeric_limits<uint16_t>::max()) {
     return OTS_FAILURE();
   }
   // Check the sequence of GlyphPartRecord.
   for (unsigned i = 0; i < part_count; ++i) {
     uint16_t glyph = 0;
     uint16_t part_flags = 0;
     if (!subtable.ReadU16(&glyph) ||
         !subtable.Skip(2 * 3) ||
         !subtable.ReadU16(&part_flags)) {
       return OTS_FAILURE();
     }
     if (glyph >= num_glyphs) {
       OTS_WARNING("bad glyph ID: %u", glyph);
       return OTS_FAILURE();
     }
     if (part_flags & ~0x00000001) {
       OTS_WARNING("unknown part flag: %u", part_flags);
       return OTS_FAILURE();
     }
   }
   return true;
 }
 bool ParseMathGlyphConstructionTable(const ots::OpenTypeFile *file,
                                      const uint8_t *data,
                                      size_t length, const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   // Check the header.
   uint16_t offset_glyph_assembly = 0;
   uint16_t variant_count = 0;
   if (!subtable.ReadU16(&offset_glyph_assembly) ||
       !subtable.ReadU16(&variant_count)) {
     return OTS_FAILURE();
   }
   const unsigned sequence_end = static_cast<unsigned>(2 * 2) +
     variant_count * 2 * 2;
   if (sequence_end > std::numeric_limits<uint16_t>::max()) {
     return OTS_FAILURE();
   }
   // Check the GlyphAssembly offset.
   if (offset_glyph_assembly) {
     if (offset_glyph_assembly >= length ||
         offset_glyph_assembly < sequence_end) {
       return OTS_FAILURE();
     }
     if (!ParseGlyphAssemblyTable(file, data + offset_glyph_assembly,
                                  length - offset_glyph_assembly, num_glyphs)) {
       return OTS_FAILURE();
     }
   }
   // Check the sequence of MathGlyphVariantRecord.
   for (unsigned i = 0; i < variant_count; ++i) {
     uint16_t glyph = 0;
     if (!subtable.ReadU16(&glyph) ||
         !subtable.Skip(2)) {
       return OTS_FAILURE();
     }
     if (glyph >= num_glyphs) {
       OTS_WARNING("bad glyph ID: %u", glyph);
       return OTS_FAILURE();
     }
   }
   return true;
 }
 bool ParseMathGlyphConstructionSequence(const ots::OpenTypeFile *file,
                                         ots::Buffer* subtable,
                                         const uint8_t *data,
                                         size_t length,
                                         const uint16_t num_glyphs,
                                         uint16_t offset_coverage,
                                         uint16_t glyph_count,
                                         const unsigned sequence_end) {
   // Check coverage table.
   if (offset_coverage < sequence_end || offset_coverage >= length) {
     return OTS_FAILURE();
   }
   if (!ots::ParseCoverageTable(file, data + offset_coverage,
                                length - offset_coverage,
                                num_glyphs, glyph_count)) {
     return OTS_FAILURE();
   }
   // Check sequence of MathGlyphConstruction.
   for (unsigned i = 0; i < glyph_count; ++i) {
       uint16_t offset_glyph_construction = 0;
       if (!subtable->ReadU16(&offset_glyph_construction)) {
         return OTS_FAILURE();
       }
       if (offset_glyph_construction < sequence_end ||
           offset_glyph_construction >= length ||
           !ParseMathGlyphConstructionTable(file, data + offset_glyph_construction,
                                            length - offset_glyph_construction,
                                            num_glyphs)) {
         return OTS_FAILURE();
       }
   }
   return true;
 }
 bool ParseMathVariantsTable(const ots::OpenTypeFile *file,
                             const uint8_t *data,
                             size_t length, const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
   // Check the header.
   uint16_t offset_vert_glyph_coverage = 0;
   uint16_t offset_horiz_glyph_coverage = 0;
   uint16_t vert_glyph_count = 0;
   uint16_t horiz_glyph_count = 0;
   if (!subtable.Skip(2) ||  // MinConnectorOverlap
       !subtable.ReadU16(&offset_vert_glyph_coverage) ||
       !subtable.ReadU16(&offset_horiz_glyph_coverage) ||
       !subtable.ReadU16(&vert_glyph_count) ||
       !subtable.ReadU16(&horiz_glyph_count)) {
     return OTS_FAILURE();
   }
   const unsigned sequence_end = 5 * 2 + vert_glyph_count * 2 +
     horiz_glyph_count * 2;
   if (sequence_end > std::numeric_limits<uint16_t>::max()) {
     return OTS_FAILURE();
   }
   if (!ParseMathGlyphConstructionSequence(file, &subtable, data, length, num_glyphs,
                                           offset_vert_glyph_coverage,
                                           vert_glyph_count,
                                           sequence_end) ||
       !ParseMathGlyphConstructionSequence(file, &subtable, data, length, num_glyphs,
                                           offset_horiz_glyph_coverage,
                                           horiz_glyph_count,
                                           sequence_end)) {
     return OTS_FAILURE();
   }
   return true;
 }
 }  // namespace
 #define DROP_THIS_TABLE \
   do { file->math->data = 0; file->math->length = 0; } while (0)
 namespace ots {
 bool ots_math_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
   // Grab the number of glyphs in the file from the maxp table to check
   // GlyphIDs in MATH table.
   if (!file->maxp) {
     return OTS_FAILURE();
   }
   const uint16_t num_glyphs = file->maxp->num_glyphs;
   Buffer table(data, length);
   OpenTypeMATH* math = new OpenTypeMATH;
   file->math = math;
   uint32_t version = 0;
   if (!table.ReadU32(&version)) {
     return OTS_FAILURE();
   }
   if (version != 0x00010000) {
     OTS_WARNING("bad MATH version");
     DROP_THIS_TABLE;
     return true;
   }
   uint16_t offset_math_constants = 0;
   uint16_t offset_math_glyph_info = 0;
   uint16_t offset_math_variants = 0;
   if (!table.ReadU16(&offset_math_constants) ||
       !table.ReadU16(&offset_math_glyph_info) ||
       !table.ReadU16(&offset_math_variants)) {
     return OTS_FAILURE();
   }
   if (offset_math_constants >= length ||
       offset_math_constants < kMathHeaderSize ||
       offset_math_glyph_info >= length ||
       offset_math_glyph_info < kMathHeaderSize ||
       offset_math_variants >= length ||
       offset_math_variants < kMathHeaderSize) {
     OTS_WARNING("bad offset in MATH header");
     DROP_THIS_TABLE;
     return true;
   }
   if (!ParseMathConstantsTable(file, data + offset_math_constants,
                                length - offset_math_constants)) {
     DROP_THIS_TABLE;
     return true;
   }
   if (!ParseMathGlyphInfoTable(file, data + offset_math_glyph_info,
                                length - offset_math_glyph_info, num_glyphs)) {
     DROP_THIS_TABLE;
     return true;
   }
   if (!ParseMathVariantsTable(file, data + offset_math_variants,
                               length - offset_math_variants, num_glyphs)) {
     DROP_THIS_TABLE;
     return true;
   }
   math->data = data;
   math->length = length;
   return true;
 }
 bool ots_math_should_serialise(OpenTypeFile *file) {
   return file->math != NULL && file->math->data != NULL;
 }
 bool ots_math_serialise(OTSStream *out, OpenTypeFile *file) {
   if (!out->Write(file->math->data, file->math->length)) {
     return OTS_FAILURE();
   }
   return true;
 }
 void ots_math_free(OpenTypeFile *file) {
   delete file->math;
 }
 }  // namespace ots

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gfx/ots/src/math.cc@6474c204b198 (annotated)

gfx/ots/src/math.cc