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-rw-r--r--gfx/ots/src/glyf.cc521
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diff --git a/gfx/ots/src/glyf.cc b/gfx/ots/src/glyf.cc
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+// 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 "glyf.h"
+
+#include <algorithm>
+#include <limits>
+
+#include "head.h"
+#include "loca.h"
+#include "maxp.h"
+
+// glyf - Glyph Data
+// http://www.microsoft.com/typography/otspec/glyf.htm
+
+namespace ots {
+
+bool OpenTypeGLYF::ParseFlagsForSimpleGlyph(Buffer &glyph,
+ uint32_t num_flags,
+ uint32_t *flag_index,
+ uint32_t *coordinates_length) {
+ uint8_t flag = 0;
+ if (!glyph.ReadU8(&flag)) {
+ return Error("Can't read flag");
+ }
+
+ uint32_t delta = 0;
+ if (flag & (1u << 1)) { // x-Short
+ ++delta;
+ } else if (!(flag & (1u << 4))) {
+ delta += 2;
+ }
+
+ if (flag & (1u << 2)) { // y-Short
+ ++delta;
+ } else if (!(flag & (1u << 5))) {
+ delta += 2;
+ }
+
+ /* MS and Apple specs say this bit is reserved and must be set to zero, but
+ * Apple spec then contradicts itself and says it should be set on the first
+ * contour flag for simple glyphs with overlapping contours:
+ * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6AATIntro.html
+ * (“Overlapping contours” section) */
+ if (flag & (1u << 6) && *flag_index != 0) {
+ return Error("Bad glyph flag (%d), "
+ "bit 6 must be set to zero for flag %d", flag, *flag_index);
+ }
+
+ if (flag & (1u << 3)) { // repeat
+ if (*flag_index + 1 >= num_flags) {
+ return Error("Count too high (%d + 1 >= %d)", *flag_index, num_flags);
+ }
+ uint8_t repeat = 0;
+ if (!glyph.ReadU8(&repeat)) {
+ return Error("Can't read repeat value");
+ }
+ if (repeat == 0) {
+ return Error("Zero repeat");
+ }
+ delta += (delta * repeat);
+
+ *flag_index += repeat;
+ if (*flag_index >= num_flags) {
+ return Error("Count too high (%d >= %d)", *flag_index, num_flags);
+ }
+ }
+
+ if (flag & (1u << 7)) { // reserved flag
+ return Error("Bad glyph flag (%d), reserved bit 7 must be set to zero", flag);
+ }
+
+ *coordinates_length += delta;
+ if (glyph.length() < *coordinates_length) {
+ return Error("Glyph coordinates length bigger than glyph length (%d > %d)",
+ *coordinates_length, glyph.length());
+ }
+
+ return true;
+}
+
+bool OpenTypeGLYF::ParseSimpleGlyph(Buffer &glyph,
+ int16_t num_contours) {
+ // read the end-points array
+ uint16_t num_flags = 0;
+ for (int i = 0; i < num_contours; ++i) {
+ uint16_t tmp_index = 0;
+ if (!glyph.ReadU16(&tmp_index)) {
+ return Error("Can't read contour index %d", i);
+ }
+ if (tmp_index == 0xffffu) {
+ return Error("Bad contour index %d", i);
+ }
+ // check if the indices are monotonically increasing
+ if (i && (tmp_index + 1 <= num_flags)) {
+ return Error("Decreasing contour index %d + 1 <= %d", tmp_index, num_flags);
+ }
+ num_flags = tmp_index + 1;
+ }
+
+ if (this->maxp->version_1 &&
+ num_flags > this->maxp->max_points) {
+ Warning("Number of contour points exceeds maxp maxPoints, adjusting limit.");
+ this->maxp->max_points = num_flags;
+ }
+
+ uint16_t bytecode_length = 0;
+ if (!glyph.ReadU16(&bytecode_length)) {
+ return Error("Can't read bytecode length");
+ }
+
+ if (this->maxp->version_1 &&
+ this->maxp->max_size_glyf_instructions < bytecode_length) {
+ Warning("Bytecode length is bigger than maxp.maxSizeOfInstructions %d: %d",
+ this->maxp->max_size_glyf_instructions, bytecode_length);
+ this->maxp->max_size_glyf_instructions = bytecode_length;
+ }
+
+ if (!glyph.Skip(bytecode_length)) {
+ return Error("Can't read bytecode of length %d", bytecode_length);
+ }
+
+ uint32_t coordinates_length = 0;
+ for (uint32_t i = 0; i < num_flags; ++i) {
+ if (!ParseFlagsForSimpleGlyph(glyph, num_flags, &i, &coordinates_length)) {
+ return Error("Failed to parse glyph flags %d", i);
+ }
+ }
+
+ if (!glyph.Skip(coordinates_length)) {
+ return Error("Glyph too short %d", glyph.length());
+ }
+
+ if (glyph.remaining() > 3) {
+ // We allow 0-3 bytes difference since gly_length is 4-bytes aligned,
+ // zero-padded length.
+ Warning("Extra bytes at end of the glyph: %d", glyph.remaining());
+ }
+
+ this->iov.push_back(std::make_pair(glyph.buffer(), glyph.offset()));
+
+ return true;
+}
+
+#define ARG_1_AND_2_ARE_WORDS (1u << 0)
+#define WE_HAVE_A_SCALE (1u << 3)
+#define MORE_COMPONENTS (1u << 5)
+#define WE_HAVE_AN_X_AND_Y_SCALE (1u << 6)
+#define WE_HAVE_A_TWO_BY_TWO (1u << 7)
+#define WE_HAVE_INSTRUCTIONS (1u << 8)
+
+bool OpenTypeGLYF::ParseCompositeGlyph(
+ Buffer &glyph,
+ ComponentPointCount* component_point_count) {
+ uint16_t flags = 0;
+ uint16_t gid = 0;
+ do {
+ if (!glyph.ReadU16(&flags) || !glyph.ReadU16(&gid)) {
+ return Error("Can't read composite glyph flags or glyphIndex");
+ }
+
+ if (gid >= this->maxp->num_glyphs) {
+ return Error("Invalid glyph id used in composite glyph: %d", gid);
+ }
+
+ if (flags & ARG_1_AND_2_ARE_WORDS) {
+ int16_t argument1;
+ int16_t argument2;
+ if (!glyph.ReadS16(&argument1) || !glyph.ReadS16(&argument2)) {
+ return Error("Can't read argument1 or argument2");
+ }
+ } else {
+ uint8_t argument1;
+ uint8_t argument2;
+ if (!glyph.ReadU8(&argument1) || !glyph.ReadU8(&argument2)) {
+ return Error("Can't read argument1 or argument2");
+ }
+ }
+
+ if (flags & WE_HAVE_A_SCALE) {
+ int16_t scale;
+ if (!glyph.ReadS16(&scale)) {
+ return Error("Can't read scale");
+ }
+ } else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) {
+ int16_t xscale;
+ int16_t yscale;
+ if (!glyph.ReadS16(&xscale) || !glyph.ReadS16(&yscale)) {
+ return Error("Can't read xscale or yscale");
+ }
+ } else if (flags & WE_HAVE_A_TWO_BY_TWO) {
+ int16_t xscale;
+ int16_t scale01;
+ int16_t scale10;
+ int16_t yscale;
+ if (!glyph.ReadS16(&xscale) ||
+ !glyph.ReadS16(&scale01) ||
+ !glyph.ReadS16(&scale10) ||
+ !glyph.ReadS16(&yscale)) {
+ return Error("Can't read transform");
+ }
+ }
+
+ // Push inital components on stack at level 1
+ // to traverse them in parent function.
+ component_point_count->gid_stack.push_back({gid, 1});
+ } while (flags & MORE_COMPONENTS);
+
+ if (flags & WE_HAVE_INSTRUCTIONS) {
+ uint16_t bytecode_length;
+ if (!glyph.ReadU16(&bytecode_length)) {
+ return Error("Can't read instructions size");
+ }
+
+ if (this->maxp->version_1 &&
+ this->maxp->max_size_glyf_instructions < bytecode_length) {
+ Warning("Bytecode length is bigger than maxp.maxSizeOfInstructions "
+ "%d: %d",
+ this->maxp->max_size_glyf_instructions, bytecode_length);
+ this->maxp->max_size_glyf_instructions = bytecode_length;
+ }
+
+ if (!glyph.Skip(bytecode_length)) {
+ return Error("Can't read bytecode of length %d", bytecode_length);
+ }
+ }
+
+ this->iov.push_back(std::make_pair(glyph.buffer(), glyph.offset()));
+
+ return true;
+}
+
+bool OpenTypeGLYF::Parse(const uint8_t *data, size_t length) {
+ OpenTypeMAXP *maxp = static_cast<OpenTypeMAXP*>(
+ GetFont()->GetTypedTable(OTS_TAG_MAXP));
+ OpenTypeLOCA *loca = static_cast<OpenTypeLOCA*>(
+ GetFont()->GetTypedTable(OTS_TAG_LOCA));
+ OpenTypeHEAD *head = static_cast<OpenTypeHEAD*>(
+ GetFont()->GetTypedTable(OTS_TAG_HEAD));
+ if (!maxp || !loca || !head) {
+ return Error("Missing maxp or loca or head table needed by glyf table");
+ }
+
+ this->maxp = maxp;
+
+ const unsigned num_glyphs = maxp->num_glyphs;
+ std::vector<uint32_t> &offsets = loca->offsets;
+
+ if (offsets.size() != num_glyphs + 1) {
+ return Error("Invalid glyph offsets size %ld != %d", offsets.size(), num_glyphs + 1);
+ }
+
+ std::vector<uint32_t> resulting_offsets(num_glyphs + 1);
+ uint32_t current_offset = 0;
+
+ for (unsigned i = 0; i < num_glyphs; ++i) {
+
+ Buffer glyph(GetGlyphBufferSection(data, length, offsets, i));
+ if (!glyph.buffer())
+ return false;
+
+ if (!glyph.length()) {
+ resulting_offsets[i] = current_offset;
+ continue;
+ }
+
+ int16_t num_contours, xmin, ymin, xmax, ymax;
+ if (!glyph.ReadS16(&num_contours) ||
+ !glyph.ReadS16(&xmin) ||
+ !glyph.ReadS16(&ymin) ||
+ !glyph.ReadS16(&xmax) ||
+ !glyph.ReadS16(&ymax)) {
+ return Error("Can't read glyph %d header", i);
+ }
+
+ if (num_contours <= -2) {
+ // -2, -3, -4, ... are reserved for future use.
+ return Error("Bad number of contours %d in glyph %d", num_contours, i);
+ }
+
+ // workaround for fonts in http://www.princexml.com/fonts/
+ if ((xmin == 32767) &&
+ (xmax == -32767) &&
+ (ymin == 32767) &&
+ (ymax == -32767)) {
+ Warning("bad xmin/xmax/ymin/ymax values");
+ xmin = xmax = ymin = ymax = 0;
+ }
+
+ if (xmin > xmax || ymin > ymax) {
+ return Error("Bad bounding box values bl=(%d, %d), tr=(%d, %d) in glyph %d", xmin, ymin, xmax, ymax, i);
+ }
+
+ if (num_contours == 0) {
+ // This is an empty glyph and shouldn’t have any glyph data, but if it
+ // does we will simply ignore it.
+ glyph.set_offset(0);
+ } else if (num_contours > 0) {
+ if (!ParseSimpleGlyph(glyph, num_contours)) {
+ return Error("Failed to parse glyph %d", i);
+ }
+ } else {
+
+ ComponentPointCount component_point_count;
+ if (!ParseCompositeGlyph(glyph, &component_point_count)) {
+ return Error("Failed to parse glyph %d", i);
+ }
+
+ // Check maxComponentDepth and validate maxComponentPoints.
+ // ParseCompositeGlyph placed the first set of component glyphs on the
+ // component_point_count.gid_stack, which we start to process below. If a
+ // nested glyph is in turn a component glyph, additional glyphs are placed
+ // on the stack.
+ while (component_point_count.gid_stack.size()) {
+ GidAtLevel stack_top_gid = component_point_count.gid_stack.back();
+ component_point_count.gid_stack.pop_back();
+
+ Buffer points_count_glyph(GetGlyphBufferSection(
+ data,
+ length,
+ offsets,
+ stack_top_gid.gid));
+
+ if (!points_count_glyph.buffer())
+ return false;
+
+ if (!points_count_glyph.length())
+ continue;
+
+ if (!TraverseComponentsCountingPoints(points_count_glyph,
+ i,
+ stack_top_gid.level,
+ &component_point_count)) {
+ return Error("Error validating component points and depth.");
+ }
+
+ if (component_point_count.accumulated_component_points >
+ std::numeric_limits<uint16_t>::max()) {
+ return Error("Illegal composite points value "
+ "exceeding 0xFFFF for base glyph %d.", i);
+ } else if (this->maxp->version_1 &&
+ component_point_count.accumulated_component_points >
+ this->maxp->max_c_points) {
+ Warning("Number of composite points in glyph %d exceeds "
+ "maxp maxCompositePoints: %d vs %d, adjusting limit.",
+ i,
+ component_point_count.accumulated_component_points,
+ this->maxp->max_c_points
+ );
+ this->maxp->max_c_points =
+ component_point_count.accumulated_component_points;
+ }
+ }
+ }
+
+ size_t new_size = glyph.offset();
+ resulting_offsets[i] = current_offset;
+ // glyphs must be four byte aligned
+ // TODO(yusukes): investigate whether this padding is really necessary.
+ // Which part of the spec requires this?
+ const unsigned padding = (4 - (new_size & 3)) % 4;
+ if (padding) {
+ this->iov.push_back(std::make_pair(
+ reinterpret_cast<const uint8_t*>("\x00\x00\x00\x00"),
+ static_cast<size_t>(padding)));
+ new_size += padding;
+ }
+ current_offset += new_size;
+ }
+ resulting_offsets[num_glyphs] = current_offset;
+
+ const uint16_t max16 = std::numeric_limits<uint16_t>::max();
+ if ((*std::max_element(resulting_offsets.begin(),
+ resulting_offsets.end()) >= (max16 * 2u)) &&
+ (head->index_to_loc_format != 1)) {
+ head->index_to_loc_format = 1;
+ }
+
+ loca->offsets = resulting_offsets;
+
+ if (this->iov.empty()) {
+ // As a special case when all glyph in the font are empty, add a zero byte
+ // to the table, so that we don’t reject it down the way, and to make the
+ // table work on Windows as well.
+ // See https://github.com/khaledhosny/ots/issues/52
+ static const uint8_t kZero = 0;
+ this->iov.push_back(std::make_pair(&kZero, 1));
+ }
+
+ return true;
+}
+
+bool OpenTypeGLYF::TraverseComponentsCountingPoints(
+ Buffer &glyph,
+ uint16_t base_glyph_id,
+ uint32_t level,
+ ComponentPointCount* component_point_count) {
+
+ int16_t num_contours;
+ if (!glyph.ReadS16(&num_contours) ||
+ !glyph.Skip(8)) {
+ return Error("Can't read glyph header.");
+ }
+
+ if (num_contours <= -2) {
+ return Error("Bad number of contours %d in glyph.", num_contours);
+ }
+
+ if (num_contours == 0)
+ return true;
+
+ // FontTools counts a component level for each traversed recursion. We start
+ // counting at level 0. If we reach a level that's deeper than
+ // maxComponentDepth, we expand maxComponentDepth unless it's larger than
+ // the maximum possible depth.
+ if (level > std::numeric_limits<uint16_t>::max()) {
+ return Error("Illegal component depth exceeding 0xFFFF in base glyph id %d.",
+ base_glyph_id);
+ } else if (this->maxp->version_1 &&
+ level > this->maxp->max_c_depth) {
+ this->maxp->max_c_depth = level;
+ Warning("Component depth exceeds maxp maxComponentDepth "
+ "in glyph %d, adjust limit to %d.",
+ base_glyph_id, level);
+ }
+
+ if (num_contours > 0) {
+ uint16_t num_points = 0;
+ for (int i = 0; i < num_contours; ++i) {
+ // Simple glyph, add contour points.
+ uint16_t tmp_index = 0;
+ if (!glyph.ReadU16(&tmp_index)) {
+ return Error("Can't read contour index %d", i);
+ }
+ num_points = tmp_index + 1;
+ }
+
+ component_point_count->accumulated_component_points += num_points;
+ return true;
+ } else {
+ assert(num_contours == -1);
+
+ // Composite glyph, add gid's to stack.
+ uint16_t flags = 0;
+ uint16_t gid = 0;
+ do {
+ if (!glyph.ReadU16(&flags) || !glyph.ReadU16(&gid)) {
+ return Error("Can't read composite glyph flags or glyphIndex");
+ }
+
+ size_t skip_bytes = 0;
+ skip_bytes += flags & ARG_1_AND_2_ARE_WORDS ? 4 : 2;
+
+ if (flags & WE_HAVE_A_SCALE) {
+ skip_bytes += 2;
+ } else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) {
+ skip_bytes += 4;
+ } else if (flags & WE_HAVE_A_TWO_BY_TWO) {
+ skip_bytes += 8;
+ }
+
+ if (!glyph.Skip(skip_bytes)) {
+ return Error("Failed to parse component glyph.");
+ }
+
+ if (gid >= this->maxp->num_glyphs) {
+ return Error("Invalid glyph id used in composite glyph: %d", gid);
+ }
+
+ component_point_count->gid_stack.push_back({gid, level + 1u});
+ } while (flags & MORE_COMPONENTS);
+ return true;
+ }
+}
+
+Buffer OpenTypeGLYF::GetGlyphBufferSection(
+ const uint8_t *data,
+ size_t length,
+ const std::vector<uint32_t>& loca_offsets,
+ unsigned glyph_id) {
+
+ Buffer null_buffer(nullptr, 0);
+
+ const unsigned gly_offset = loca_offsets[glyph_id];
+ // The LOCA parser checks that these values are monotonic
+ const unsigned gly_length = loca_offsets[glyph_id + 1] - loca_offsets[glyph_id];
+ if (!gly_length) {
+ // this glyph has no outline (e.g. the space character)
+ return Buffer(data + gly_offset, 0);
+ }
+
+ if (gly_offset >= length) {
+ Error("Glyph %d offset %d too high %ld", glyph_id, gly_offset, length);
+ return null_buffer;
+ }
+ // Since these are unsigned types, the compiler is not allowed to assume
+ // that they never overflow.
+ if (gly_offset + gly_length < gly_offset) {
+ Error("Glyph %d length (%d < 0)!", glyph_id, gly_length);
+ return null_buffer;
+ }
+ if (gly_offset + gly_length > length) {
+ Error("Glyph %d length %d too high", glyph_id, gly_length);
+ return null_buffer;
+ }
+
+ return Buffer(data + gly_offset, gly_length);
+}
+
+bool OpenTypeGLYF::Serialize(OTSStream *out) {
+ for (unsigned i = 0; i < this->iov.size(); ++i) {
+ if (!out->Write(this->iov[i].first, this->iov[i].second)) {
+ return Error("Falied to write glyph %d", i);
+ }
+ }
+
+ return true;
+}
+
+} // namespace ots
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