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iconFont_create/node_modules/ttf2woff2/csrc/woff2/woff2_dec.cc

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// Copyright 2014 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Library for converting WOFF2 format font files to their TTF versions.
#include "./woff2_dec.h"
#include <stdlib.h>
#include <algorithm>
#include <complex>
#include <cstring>
#include <limits>
#include <string>
#include <vector>
#include <map>
#include "./buffer.h"
#include "./decode.h"
#include "./round.h"
#include "./store_bytes.h"
#include "./table_tags.h"
#include "./variable_length.h"
#include "./woff2_common.h"
namespace woff2 {
namespace {
using std::string;
using std::vector;
// simple glyph flags
const int kGlyfOnCurve = 1 << 0;
const int kGlyfXShort = 1 << 1;
const int kGlyfYShort = 1 << 2;
const int kGlyfRepeat = 1 << 3;
const int kGlyfThisXIsSame = 1 << 4;
const int kGlyfThisYIsSame = 1 << 5;
// composite glyph flags
// See CompositeGlyph.java in sfntly for full definitions
const int FLAG_ARG_1_AND_2_ARE_WORDS = 1 << 0;
const int FLAG_WE_HAVE_A_SCALE = 1 << 3;
const int FLAG_MORE_COMPONENTS = 1 << 5;
const int FLAG_WE_HAVE_AN_X_AND_Y_SCALE = 1 << 6;
const int FLAG_WE_HAVE_A_TWO_BY_TWO = 1 << 7;
const int FLAG_WE_HAVE_INSTRUCTIONS = 1 << 8;
const size_t kCheckSumAdjustmentOffset = 8;
const size_t kEndPtsOfContoursOffset = 10;
const size_t kCompositeGlyphBegin = 10;
// metadata for a TTC font entry
struct TtcFont {
uint32_t flavor;
uint32_t dst_offset;
std::vector<uint16_t> table_indices;
};
int WithSign(int flag, int baseval) {
// Precondition: 0 <= baseval < 65536 (to avoid integer overflow)
return (flag & 1) ? baseval : -baseval;
}
bool TripletDecode(const uint8_t* flags_in, const uint8_t* in, size_t in_size,
unsigned int n_points, std::vector<Point>* result,
size_t* in_bytes_consumed) {
int x = 0;
int y = 0;
if (n_points > in_size) {
return FONT_COMPRESSION_FAILURE();
}
unsigned int triplet_index = 0;
for (unsigned int i = 0; i < n_points; ++i) {
uint8_t flag = flags_in[i];
bool on_curve = !(flag >> 7);
flag &= 0x7f;
unsigned int n_data_bytes;
if (flag < 84) {
n_data_bytes = 1;
} else if (flag < 120) {
n_data_bytes = 2;
} else if (flag < 124) {
n_data_bytes = 3;
} else {
n_data_bytes = 4;
}
if (triplet_index + n_data_bytes > in_size ||
triplet_index + n_data_bytes < triplet_index) {
return FONT_COMPRESSION_FAILURE();
}
int dx, dy;
if (flag < 10) {
dx = 0;
dy = WithSign(flag, ((flag & 14) << 7) + in[triplet_index]);
} else if (flag < 20) {
dx = WithSign(flag, (((flag - 10) & 14) << 7) + in[triplet_index]);
dy = 0;
} else if (flag < 84) {
int b0 = flag - 20;
int b1 = in[triplet_index];
dx = WithSign(flag, 1 + (b0 & 0x30) + (b1 >> 4));
dy = WithSign(flag >> 1, 1 + ((b0 & 0x0c) << 2) + (b1 & 0x0f));
} else if (flag < 120) {
int b0 = flag - 84;
dx = WithSign(flag, 1 + ((b0 / 12) << 8) + in[triplet_index]);
dy = WithSign(flag >> 1,
1 + (((b0 % 12) >> 2) << 8) + in[triplet_index + 1]);
} else if (flag < 124) {
int b2 = in[triplet_index + 1];
dx = WithSign(flag, (in[triplet_index] << 4) + (b2 >> 4));
dy = WithSign(flag >> 1, ((b2 & 0x0f) << 8) + in[triplet_index + 2]);
} else {
dx = WithSign(flag, (in[triplet_index] << 8) + in[triplet_index + 1]);
dy = WithSign(flag >> 1,
(in[triplet_index + 2] << 8) + in[triplet_index + 3]);
}
triplet_index += n_data_bytes;
// Possible overflow but coordinate values are not security sensitive
x += dx;
y += dy;
result->push_back(Point());
Point& back = result->back();
back.x = x;
back.y = y;
back.on_curve = on_curve;
}
*in_bytes_consumed = triplet_index;
return true;
}
// This function stores just the point data. On entry, dst points to the
// beginning of a simple glyph. Returns true on success.
bool StorePoints(const std::vector<Point>& points,
unsigned int n_contours, unsigned int instruction_length,
uint8_t* dst, size_t dst_size, size_t* glyph_size) {
// I believe that n_contours < 65536, in which case this is safe. However, a
// comment and/or an assert would be good.
unsigned int flag_offset = kEndPtsOfContoursOffset + 2 * n_contours + 2 +
instruction_length;
int last_flag = -1;
int repeat_count = 0;
int last_x = 0;
int last_y = 0;
unsigned int x_bytes = 0;
unsigned int y_bytes = 0;
for (unsigned int i = 0; i < points.size(); ++i) {
const Point& point = points[i];
int flag = point.on_curve ? kGlyfOnCurve : 0;
int dx = point.x - last_x;
int dy = point.y - last_y;
if (dx == 0) {
flag |= kGlyfThisXIsSame;
} else if (dx > -256 && dx < 256) {
flag |= kGlyfXShort | (dx > 0 ? kGlyfThisXIsSame : 0);
x_bytes += 1;
} else {
x_bytes += 2;
}
if (dy == 0) {
flag |= kGlyfThisYIsSame;
} else if (dy > -256 && dy < 256) {
flag |= kGlyfYShort | (dy > 0 ? kGlyfThisYIsSame : 0);
y_bytes += 1;
} else {
y_bytes += 2;
}
if (flag == last_flag && repeat_count != 255) {
dst[flag_offset - 1] |= kGlyfRepeat;
repeat_count++;
} else {
if (repeat_count != 0) {
if (flag_offset >= dst_size) {
return FONT_COMPRESSION_FAILURE();
}
dst[flag_offset++] = repeat_count;
}
if (flag_offset >= dst_size) {
return FONT_COMPRESSION_FAILURE();
}
dst[flag_offset++] = flag;
repeat_count = 0;
}
last_x = point.x;
last_y = point.y;
last_flag = flag;
}
if (repeat_count != 0) {
if (flag_offset >= dst_size) {
return FONT_COMPRESSION_FAILURE();
}
dst[flag_offset++] = repeat_count;
}
unsigned int xy_bytes = x_bytes + y_bytes;
if (xy_bytes < x_bytes ||
flag_offset + xy_bytes < flag_offset ||
flag_offset + xy_bytes > dst_size) {
return FONT_COMPRESSION_FAILURE();
}
int x_offset = flag_offset;
int y_offset = flag_offset + x_bytes;
last_x = 0;
last_y = 0;
for (unsigned int i = 0; i < points.size(); ++i) {
int dx = points[i].x - last_x;
if (dx == 0) {
// pass
} else if (dx > -256 && dx < 256) {
dst[x_offset++] = std::abs(dx);
} else {
// will always fit for valid input, but overflow is harmless
x_offset = Store16(dst, x_offset, dx);
}
last_x += dx;
int dy = points[i].y - last_y;
if (dy == 0) {
// pass
} else if (dy > -256 && dy < 256) {
dst[y_offset++] = std::abs(dy);
} else {
y_offset = Store16(dst, y_offset, dy);
}
last_y += dy;
}
*glyph_size = y_offset;
return true;
}
// Compute the bounding box of the coordinates, and store into a glyf buffer.
// A precondition is that there are at least 10 bytes available.
void ComputeBbox(const std::vector<Point>& points, uint8_t* dst) {
int x_min = 0;
int y_min = 0;
int x_max = 0;
int y_max = 0;
for (unsigned int i = 0; i < points.size(); ++i) {
int x = points[i].x;
int y = points[i].y;
if (i == 0 || x < x_min) x_min = x;
if (i == 0 || x > x_max) x_max = x;
if (i == 0 || y < y_min) y_min = y;
if (i == 0 || y > y_max) y_max = y;
}
size_t offset = 2;
offset = Store16(dst, offset, x_min);
offset = Store16(dst, offset, y_min);
offset = Store16(dst, offset, x_max);
offset = Store16(dst, offset, y_max);
}
// Process entire bbox stream. This is done as a separate pass to allow for
// composite bbox computations (an optional more aggressive transform).
bool ProcessBboxStream(Buffer* bbox_stream, unsigned int n_glyphs,
const std::vector<uint32_t>& loca_values, uint8_t* glyf_buf,
size_t glyf_buf_length) {
const uint8_t* buf = bbox_stream->buffer();
if (n_glyphs >= 65536 || loca_values.size() != n_glyphs + 1) {
return FONT_COMPRESSION_FAILURE();
}
// Safe because n_glyphs is bounded
unsigned int bitmap_length = ((n_glyphs + 31) >> 5) << 2;
if (!bbox_stream->Skip(bitmap_length)) {
return FONT_COMPRESSION_FAILURE();
}
for (unsigned int i = 0; i < n_glyphs; ++i) {
if (buf[i >> 3] & (0x80 >> (i & 7))) {
uint32_t loca_offset = loca_values[i];
if (loca_values[i + 1] - loca_offset < kEndPtsOfContoursOffset) {
return FONT_COMPRESSION_FAILURE();
}
if (glyf_buf_length < 2 + 10 ||
loca_offset > glyf_buf_length - 2 - 10) {
return FONT_COMPRESSION_FAILURE();
}
if (!bbox_stream->Read(glyf_buf + loca_offset + 2, 8)) {
return FONT_COMPRESSION_FAILURE();
}
}
}
return true;
}
bool ProcessComposite(Buffer* composite_stream, uint8_t* dst,
size_t dst_size, size_t* glyph_size, bool* have_instructions) {
size_t start_offset = composite_stream->offset();
bool we_have_instructions = false;
uint16_t flags = FLAG_MORE_COMPONENTS;
while (flags & FLAG_MORE_COMPONENTS) {
if (!composite_stream->ReadU16(&flags)) {
return FONT_COMPRESSION_FAILURE();
}
we_have_instructions |= (flags & FLAG_WE_HAVE_INSTRUCTIONS) != 0;
size_t arg_size = 2; // glyph index
if (flags & FLAG_ARG_1_AND_2_ARE_WORDS) {
arg_size += 4;
} else {
arg_size += 2;
}
if (flags & FLAG_WE_HAVE_A_SCALE) {
arg_size += 2;
} else if (flags & FLAG_WE_HAVE_AN_X_AND_Y_SCALE) {
arg_size += 4;
} else if (flags & FLAG_WE_HAVE_A_TWO_BY_TWO) {
arg_size += 8;
}
if (!composite_stream->Skip(arg_size)) {
return FONT_COMPRESSION_FAILURE();
}
}
size_t composite_glyph_size = composite_stream->offset() - start_offset;
if (composite_glyph_size + kCompositeGlyphBegin > dst_size) {
return FONT_COMPRESSION_FAILURE();
}
Store16(dst, 0, 0xffff); // nContours = -1 for composite glyph
std::memcpy(dst + kCompositeGlyphBegin,
composite_stream->buffer() + start_offset,
composite_glyph_size);
*glyph_size = kCompositeGlyphBegin + composite_glyph_size;
*have_instructions = we_have_instructions;
return true;
}
// Build TrueType loca table
bool StoreLoca(const std::vector<uint32_t>& loca_values, int index_format,
uint8_t* dst, size_t dst_size) {
const uint64_t loca_size = loca_values.size();
const uint64_t offset_size = index_format ? 4 : 2;
if ((loca_size << 2) >> 2 != loca_size) {
return FONT_COMPRESSION_FAILURE();
}
if (offset_size * loca_size > dst_size) {
return FONT_COMPRESSION_FAILURE();
}
size_t offset = 0;
for (size_t i = 0; i < loca_values.size(); ++i) {
uint32_t value = loca_values[i];
if (index_format) {
offset = StoreU32(dst, offset, value);
} else {
offset = Store16(dst, offset, value >> 1);
}
}
return true;
}
// Reconstruct entire glyf table based on transformed original
bool ReconstructGlyf(const uint8_t* data, size_t data_size,
uint8_t* dst, size_t dst_size,
uint8_t* loca_buf, size_t loca_size) {
static const int kNumSubStreams = 7;
Buffer file(data, data_size);
uint32_t version;
std::vector<std::pair<const uint8_t*, size_t> > substreams(kNumSubStreams);
if (!file.ReadU32(&version)) {
return FONT_COMPRESSION_FAILURE();
}
uint16_t num_glyphs;
uint16_t index_format;
if (!file.ReadU16(&num_glyphs) ||
!file.ReadU16(&index_format)) {
return FONT_COMPRESSION_FAILURE();
}
unsigned int offset = (2 + kNumSubStreams) * 4;
if (offset > data_size) {
return FONT_COMPRESSION_FAILURE();
}
// Invariant from here on: data_size >= offset
for (int i = 0; i < kNumSubStreams; ++i) {
uint32_t substream_size;
if (!file.ReadU32(&substream_size)) {
return FONT_COMPRESSION_FAILURE();
}
if (substream_size > data_size - offset) {
return FONT_COMPRESSION_FAILURE();
}
substreams[i] = std::make_pair(data + offset, substream_size);
offset += substream_size;
}
Buffer n_contour_stream(substreams[0].first, substreams[0].second);
Buffer n_points_stream(substreams[1].first, substreams[1].second);
Buffer flag_stream(substreams[2].first, substreams[2].second);
Buffer glyph_stream(substreams[3].first, substreams[3].second);
Buffer composite_stream(substreams[4].first, substreams[4].second);
Buffer bbox_stream(substreams[5].first, substreams[5].second);
Buffer instruction_stream(substreams[6].first, substreams[6].second);
std::vector<uint32_t> loca_values(num_glyphs + 1);
std::vector<unsigned int> n_points_vec;
std::vector<Point> points;
uint32_t loca_offset = 0;
for (unsigned int i = 0; i < num_glyphs; ++i) {
size_t glyph_size = 0;
uint16_t n_contours = 0;
if (!n_contour_stream.ReadU16(&n_contours)) {
return FONT_COMPRESSION_FAILURE();
}
uint8_t* glyf_dst = dst + loca_offset;
size_t glyf_dst_size = dst_size - loca_offset;
if (n_contours == 0xffff) {
// composite glyph
bool have_instructions = false;
unsigned int instruction_size = 0;
if (!ProcessComposite(&composite_stream, glyf_dst, glyf_dst_size,
&glyph_size, &have_instructions)) {
return FONT_COMPRESSION_FAILURE();
}
if (have_instructions) {
if (!Read255UShort(&glyph_stream, &instruction_size)) {
return FONT_COMPRESSION_FAILURE();
}
if (instruction_size + 2 > glyf_dst_size - glyph_size) {
return FONT_COMPRESSION_FAILURE();
}
Store16(glyf_dst, glyph_size, instruction_size);
if (!instruction_stream.Read(glyf_dst + glyph_size + 2,
instruction_size)) {
return FONT_COMPRESSION_FAILURE();
}
glyph_size += instruction_size + 2;
}
} else if (n_contours > 0) {
// simple glyph
n_points_vec.clear();
points.clear();
unsigned int total_n_points = 0;
unsigned int n_points_contour;
for (unsigned int j = 0; j < n_contours; ++j) {
if (!Read255UShort(&n_points_stream, &n_points_contour)) {
return FONT_COMPRESSION_FAILURE();
}
n_points_vec.push_back(n_points_contour);
if (total_n_points + n_points_contour < total_n_points) {
return FONT_COMPRESSION_FAILURE();
}
total_n_points += n_points_contour;
}
unsigned int flag_size = total_n_points;
if (flag_size > flag_stream.length() - flag_stream.offset()) {
return FONT_COMPRESSION_FAILURE();
}
const uint8_t* flags_buf = flag_stream.buffer() + flag_stream.offset();
const uint8_t* triplet_buf = glyph_stream.buffer() +
glyph_stream.offset();
size_t triplet_size = glyph_stream.length() - glyph_stream.offset();
size_t triplet_bytes_consumed = 0;
if (!TripletDecode(flags_buf, triplet_buf, triplet_size, total_n_points,
&points, &triplet_bytes_consumed)) {
return FONT_COMPRESSION_FAILURE();
}
const uint32_t header_and_endpts_contours_size =
kEndPtsOfContoursOffset + 2 * n_contours;
if (glyf_dst_size < header_and_endpts_contours_size) {
return FONT_COMPRESSION_FAILURE();
}
Store16(glyf_dst, 0, n_contours);
ComputeBbox(points, glyf_dst);
size_t offset = kEndPtsOfContoursOffset;
int end_point = -1;
for (unsigned int contour_ix = 0; contour_ix < n_contours; ++contour_ix) {
end_point += n_points_vec[contour_ix];
if (end_point >= 65536) {
return FONT_COMPRESSION_FAILURE();
}
offset = Store16(glyf_dst, offset, end_point);
}
if (!flag_stream.Skip(flag_size)) {
return FONT_COMPRESSION_FAILURE();
}
if (!glyph_stream.Skip(triplet_bytes_consumed)) {
return FONT_COMPRESSION_FAILURE();
}
unsigned int instruction_size;
if (!Read255UShort(&glyph_stream, &instruction_size)) {
return FONT_COMPRESSION_FAILURE();
}
if (glyf_dst_size - header_and_endpts_contours_size <
instruction_size + 2) {
return FONT_COMPRESSION_FAILURE();
}
uint8_t* instruction_dst = glyf_dst + header_and_endpts_contours_size;
Store16(instruction_dst, 0, instruction_size);
if (!instruction_stream.Read(instruction_dst + 2, instruction_size)) {
return FONT_COMPRESSION_FAILURE();
}
if (!StorePoints(points, n_contours, instruction_size,
glyf_dst, glyf_dst_size, &glyph_size)) {
return FONT_COMPRESSION_FAILURE();
}
} else {
glyph_size = 0;
}
loca_values[i] = loca_offset;
if (glyph_size + 3 < glyph_size) {
return FONT_COMPRESSION_FAILURE();
}
glyph_size = Round4(glyph_size);
if (glyph_size > dst_size - loca_offset) {
// This shouldn't happen, but this test defensively maintains the
// invariant that loca_offset <= dst_size.
return FONT_COMPRESSION_FAILURE();
}
loca_offset += glyph_size;
}
loca_values[num_glyphs] = loca_offset;
if (!ProcessBboxStream(&bbox_stream, num_glyphs, loca_values,
dst, dst_size)) {
return FONT_COMPRESSION_FAILURE();
}
return StoreLoca(loca_values, index_format, loca_buf, loca_size);
}
// This is linear search, but could be changed to binary because we
// do have a guarantee that the tables are sorted by tag. But the total
// cpu time is expected to be very small in any case.
const Table* FindTable(const std::vector<Table>& tables, uint32_t tag) {
size_t n_tables = tables.size();
for (size_t i = 0; i < n_tables; ++i) {
if (tables[i].tag == tag) {
return &tables[i];
}
}
return NULL;
}
bool ReconstructTransformedGlyf(const uint8_t* transformed_buf,
size_t transformed_size, const Table* glyf_table, const Table* loca_table,
uint8_t* dst, size_t dst_length) {
if (glyf_table == NULL || loca_table == NULL) {
return FONT_COMPRESSION_FAILURE();
}
if (static_cast<uint64_t>(glyf_table->dst_offset + glyf_table->dst_length) >
dst_length) {
return FONT_COMPRESSION_FAILURE();
}
if (static_cast<uint64_t>(loca_table->dst_offset + loca_table->dst_length) >
dst_length) {
return FONT_COMPRESSION_FAILURE();
}
return ReconstructGlyf(transformed_buf, transformed_size,
dst + glyf_table->dst_offset, glyf_table->dst_length,
dst + loca_table->dst_offset, loca_table->dst_length);
}
bool ReconstructTransformed(const std::vector<Table>& tables, uint32_t tag,
const uint8_t* transformed_buf, size_t transformed_size,
uint8_t* dst, size_t dst_length) {
if (tag == kGlyfTableTag) {
const Table* glyf_table = FindTable(tables, tag);
const Table* loca_table = FindTable(tables, kLocaTableTag);
return ReconstructTransformedGlyf(transformed_buf, transformed_size,
glyf_table, loca_table, dst, dst_length);
} else if (tag == kLocaTableTag) {
// processing was already done by glyf table, but validate
if (!FindTable(tables, kGlyfTableTag)) {
return FONT_COMPRESSION_FAILURE();
}
} else {
// transform for the tag is not known
return FONT_COMPRESSION_FAILURE();
}
return true;
}
uint32_t ComputeChecksum(const Table* table, const uint8_t* dst) {
return ComputeULongSum(dst + table->dst_offset, table->dst_length);
}
const Table* FindTable(TtcFont ttc_font, const std::vector<Table>& tables,
uint32_t tag) {
for (const auto i : ttc_font.table_indices) {
if (tables[i].tag == tag) return &tables[i];
}
return NULL;
}
bool FixCollectionChecksums(size_t header_version,
const std::vector<Table>& tables, const std::vector<TtcFont>& ttc_fonts,
uint8_t* dst) {
size_t offset = CollectionHeaderSize(header_version, ttc_fonts.size());
for (const auto& ttc_font : ttc_fonts) {
offset += 12; // move to start of Offset Table
const std::vector<uint16_t>& table_indices = ttc_font.table_indices;
const Table* head_table = FindTable(ttc_font, tables, kHeadTableTag);
if (head_table == NULL ||
head_table->dst_length < kCheckSumAdjustmentOffset + 4) {
return FONT_COMPRESSION_FAILURE();
}
size_t first_table_offset = std::numeric_limits<size_t>::max();
for (const auto index : table_indices) {
const auto& table = tables[index];
if (table.dst_offset < first_table_offset) {
first_table_offset = table.dst_offset;
}
}
size_t adjustment_offset = head_table->dst_offset
+ kCheckSumAdjustmentOffset;
StoreU32(dst, adjustment_offset, 0);
uint32_t file_checksum = 0;
// compute each tables checksum
for (auto i = 0; i < table_indices.size(); i++) {
const Table& table = tables[table_indices[i]];
uint32_t table_checksum = ComputeChecksum(&table, dst);
size_t checksum_offset = offset + 4; // skip past tag to checkSum
// write the checksum for the Table Record
StoreU32(dst, checksum_offset, table_checksum);
file_checksum += table_checksum;
// next Table Record
offset += 16;
}
size_t header_size = kSfntHeaderSize +
kSfntEntrySize * table_indices.size();
uint32_t header_checksum = ComputeULongSum(dst + ttc_font.dst_offset,
header_size);
file_checksum += header_checksum;
uint32_t checksum_adjustment = 0xb1b0afba - file_checksum;
StoreU32(dst, adjustment_offset, checksum_adjustment);
}
return true;
}
bool FixChecksums(const std::vector<Table>& tables, uint8_t* dst) {
const Table* head_table = FindTable(tables, kHeadTableTag);
if (head_table == NULL ||
head_table->dst_length < kCheckSumAdjustmentOffset + 4) {
return FONT_COMPRESSION_FAILURE();
}
size_t adjustment_offset = head_table->dst_offset + kCheckSumAdjustmentOffset;
StoreU32(dst, adjustment_offset, 0);
size_t n_tables = tables.size();
uint32_t file_checksum = 0;
for (size_t i = 0; i < n_tables; ++i) {
uint32_t checksum = ComputeChecksum(&tables[i], dst);
StoreU32(dst, kSfntHeaderSize + i * kSfntEntrySize + 4, checksum);
file_checksum += checksum;
}
file_checksum += ComputeULongSum(dst,
kSfntHeaderSize + kSfntEntrySize * n_tables);
uint32_t checksum_adjustment = 0xb1b0afba - file_checksum;
StoreU32(dst, adjustment_offset, checksum_adjustment);
return true;
}
bool Woff2Uncompress(uint8_t* dst_buf, size_t dst_size,
const uint8_t* src_buf, size_t src_size) {
size_t uncompressed_size = dst_size;
int ok = BrotliDecompressBuffer(src_size, src_buf,
&uncompressed_size, dst_buf);
if (!ok || uncompressed_size != dst_size) {
return FONT_COMPRESSION_FAILURE();
}
return true;
}
bool ReadTableDirectory(Buffer* file, std::vector<Table>* tables,
size_t num_tables) {
for (size_t i = 0; i < num_tables; ++i) {
Table* table = &(*tables)[i];
uint8_t flag_byte;
if (!file->ReadU8(&flag_byte)) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t tag;
if ((flag_byte & 0x3f) == 0x3f) {
if (!file->ReadU32(&tag)) {
return FONT_COMPRESSION_FAILURE();
}
} else {
tag = kKnownTags[flag_byte & 0x3f];
}
// Bits 6 and 7 are reserved and must be 0.
if ((flag_byte & 0xC0) != 0) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t flags = 0;
if (i > 0) {
flags |= kWoff2FlagsContinueStream;
}
// Always transform the glyf and loca tables
if (tag == kGlyfTableTag || tag == kLocaTableTag) {
flags |= kWoff2FlagsTransform;
}
uint32_t dst_length;
if (!ReadBase128(file, &dst_length)) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t transform_length = dst_length;
if ((flags & kWoff2FlagsTransform) != 0) {
if (!ReadBase128(file, &transform_length)) {
return FONT_COMPRESSION_FAILURE();
}
if (tag == kLocaTableTag && transform_length) {
return FONT_COMPRESSION_FAILURE();
}
}
table->tag = tag;
table->flags = flags;
table->transform_length = transform_length;
table->dst_length = dst_length;
}
return true;
}
} // namespace
size_t ComputeWOFF2FinalSize(const uint8_t* data, size_t length) {
Buffer file(data, length);
uint32_t total_length;
if (!file.Skip(16) ||
!file.ReadU32(&total_length)) {
return 0;
}
return total_length;
}
// Writes a single Offset Table entry
size_t StoreOffsetTable(uint8_t* result, size_t offset, uint32_t flavor,
uint16_t num_tables) {
offset = StoreU32(result, offset, flavor); // sfnt version
offset = Store16(result, offset, num_tables); // num_tables
unsigned max_pow2 = 0;
while (1u << (max_pow2 + 1) <= num_tables) {
max_pow2++;
}
const uint16_t output_search_range = (1u << max_pow2) << 4;
offset = Store16(result, offset, output_search_range); // searchRange
offset = Store16(result, offset, max_pow2); // entrySelector
// rangeShift
offset = Store16(result, offset, (num_tables << 4) - output_search_range);
return offset;
}
size_t StoreTableEntry(uint8_t* result, const Table& table, size_t offset) {
offset = StoreU32(result, offset, table.tag);
offset = StoreU32(result, offset, 0); // checksum, to fill in later
offset = StoreU32(result, offset, table.dst_offset);
offset = StoreU32(result, offset, table.dst_length);
return offset;
}
// First table goes after all the headers, table directory, etc
uint64_t ComputeOffsetToFirstTable(const uint32_t header_version,
const uint16_t num_tables,
const std::vector<TtcFont>& ttc_fonts) {
uint64_t offset = kSfntHeaderSize +
kSfntEntrySize * static_cast<uint64_t>(num_tables);
if (header_version) {
offset = CollectionHeaderSize(header_version, ttc_fonts.size())
+ kSfntHeaderSize * ttc_fonts.size();
for (const auto& ttc_font : ttc_fonts) {
offset +=
kSfntEntrySize * ttc_font.table_indices.size();
}
}
return offset;
}
bool ConvertWOFF2ToTTF(uint8_t* result, size_t result_length,
const uint8_t* data, size_t length) {
Buffer file(data, length);
uint32_t signature;
uint32_t flavor;
if (!file.ReadU32(&signature) || signature != kWoff2Signature ||
!file.ReadU32(&flavor)) {
return FONT_COMPRESSION_FAILURE();
}
// TODO(user): Should call IsValidVersionTag() here.
uint32_t reported_length;
if (!file.ReadU32(&reported_length) || length != reported_length) {
return FONT_COMPRESSION_FAILURE();
}
uint16_t num_tables;
if (!file.ReadU16(&num_tables) || !num_tables) {
return FONT_COMPRESSION_FAILURE();
}
// We don't care about these fields of the header:
// uint16_t reserved
// uint32_t total_sfnt_size, the caller already passes it as result_length
if (!file.Skip(6)) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t compressed_length;
if (!file.ReadU32(&compressed_length)) {
return FONT_COMPRESSION_FAILURE();
}
// We don't care about these fields of the header:
// uint16_t major_version, minor_version
if (!file.Skip(2 * 2)) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t meta_offset;
uint32_t meta_length;
uint32_t meta_length_orig;
if (!file.ReadU32(&meta_offset) ||
!file.ReadU32(&meta_length) ||
!file.ReadU32(&meta_length_orig)) {
return FONT_COMPRESSION_FAILURE();
}
if (meta_offset) {
if (meta_offset >= length || length - meta_offset < meta_length) {
return FONT_COMPRESSION_FAILURE();
}
}
uint32_t priv_offset;
uint32_t priv_length;
if (!file.ReadU32(&priv_offset) ||
!file.ReadU32(&priv_length)) {
return FONT_COMPRESSION_FAILURE();
}
if (priv_offset) {
if (priv_offset >= length || length - priv_offset < priv_length) {
return FONT_COMPRESSION_FAILURE();
}
}
std::vector<Table> tables(num_tables);
if (!ReadTableDirectory(&file, &tables, num_tables)) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t header_version = 0;
// for each font in a ttc, metadata to use when rebuilding
std::vector<TtcFont> ttc_fonts;
std::map<const Table*, const Table*> loca_by_glyf;
if (flavor == kTtcFontFlavor) {
if (!file.ReadU32(&header_version)) {
return FONT_COMPRESSION_FAILURE();
}
uint32_t num_fonts;
if (!Read255UShort(&file, &num_fonts) || !num_fonts) {
return FONT_COMPRESSION_FAILURE();
}
ttc_fonts.resize(num_fonts);
for (auto i = 0; i < num_fonts; i++) {
TtcFont& ttc_font = ttc_fonts[i];
uint32_t num_tables;
if (!Read255UShort(&file, &num_tables) || !num_tables) {
return FONT_COMPRESSION_FAILURE();
}
if (!file.ReadU32(&ttc_font.flavor)) {
return FONT_COMPRESSION_FAILURE();
}
ttc_font.table_indices.resize(num_tables);
const Table* glyf_table = NULL;
const Table* loca_table = NULL;
uint16_t glyf_idx;
uint16_t loca_idx;
for (auto j = 0; j < num_tables; j++) {
unsigned int table_idx;
if (!Read255UShort(&file, &table_idx)) {
return FONT_COMPRESSION_FAILURE();
}
ttc_font.table_indices[j] = table_idx;
const Table& table = tables[table_idx];
if (table.tag == kLocaTableTag) {
loca_table = &table;
loca_idx = table_idx;
}
if (table.tag == kGlyfTableTag) {
glyf_table = &table;
glyf_idx = table_idx;
}
}
if ((glyf_table == NULL) != (loca_table == NULL)) {
fprintf(stderr, "Cannot have just one of glyf/loca\n");
return FONT_COMPRESSION_FAILURE();
}
if (glyf_table != NULL && loca_table != NULL) {
loca_by_glyf[glyf_table] = loca_table;
}
}
}
const uint64_t first_table_offset =
ComputeOffsetToFirstTable(header_version, num_tables, ttc_fonts);
if (first_table_offset > result_length) {
return FONT_COMPRESSION_FAILURE();
}
uint64_t src_offset = file.offset();
uint64_t dst_offset = first_table_offset;
uint64_t uncompressed_sum = 0;
for (uint16_t i = 0; i < num_tables; ++i) {
Table* table = &tables[i];
table->src_offset = src_offset;
table->src_length = (i == 0 ? compressed_length : 0);
src_offset += table->src_length;
if (src_offset > std::numeric_limits<uint32_t>::max()) {
return FONT_COMPRESSION_FAILURE();
}
src_offset = Round4(src_offset);
table->dst_offset = dst_offset;
dst_offset += table->dst_length;
if (dst_offset > std::numeric_limits<uint32_t>::max()) {
return FONT_COMPRESSION_FAILURE();
}
dst_offset = Round4(dst_offset);
uncompressed_sum += table->src_length;
if (uncompressed_sum > std::numeric_limits<uint32_t>::max()) {
return FONT_COMPRESSION_FAILURE();
}
}
// Enforce same 30M limit on uncompressed tables as OTS
if (uncompressed_sum > 30 * 1024 * 1024) {
return FONT_COMPRESSION_FAILURE();
}
if (src_offset > length || dst_offset != result_length) {
fprintf(stderr, "offset fail; src_offset %lu length %lu "
"dst_offset %lu result_length %lu\n",
src_offset, length, dst_offset, result_length);
return FONT_COMPRESSION_FAILURE();
}
// Re-order tables in output (OTSpec) order
if (header_version) {
// collection; we have to sort the table offset vector in each font
for (auto& ttc_font : ttc_fonts) {
std::map<uint32_t, uint16_t> sorted_index_by_tag;
for (auto table_index : ttc_font.table_indices) {
sorted_index_by_tag[tables[table_index].tag] = table_index;
}
uint16_t index = 0;
for (auto& i : sorted_index_by_tag) {
ttc_font.table_indices[index++] = i.second;
}
}
} else {
// non-collection; we can just sort the tables
std::sort(tables.begin(), tables.end());
}
if (meta_offset) {
if (src_offset != meta_offset) {
return FONT_COMPRESSION_FAILURE();
}
src_offset = Round4(meta_offset + meta_length);
if (src_offset > std::numeric_limits<uint32_t>::max()) {
return FONT_COMPRESSION_FAILURE();
}
}
if (priv_offset) {
if (src_offset != priv_offset) {
return FONT_COMPRESSION_FAILURE();
}
src_offset = Round4(priv_offset + priv_length);
if (src_offset > std::numeric_limits<uint32_t>::max()) {
return FONT_COMPRESSION_FAILURE();
}
}
if (src_offset != Round4(length)) {
return FONT_COMPRESSION_FAILURE();
}
// Start building the font
size_t offset = 0;
size_t offset_table = 0;
if (header_version) {
// TTC header
offset = StoreU32(result, offset, flavor); // TAG TTCTag
offset = StoreU32(result, offset, header_version); // FIXED Version
offset = StoreU32(result, offset, ttc_fonts.size()); // ULONG numFonts
// Space for ULONG OffsetTable[numFonts] (zeroed initially)
offset_table = offset; // keep start of offset table for later
for (int i = 0; i < ttc_fonts.size(); i++) {
offset = StoreU32(result, offset, 0); // will fill real values in later
}
// space for DSIG fields for header v2
if (header_version == 0x00020000) {
offset = StoreU32(result, offset, 0); // ULONG ulDsigTag
offset = StoreU32(result, offset, 0); // ULONG ulDsigLength
offset = StoreU32(result, offset, 0); // ULONG ulDsigOffset
}
// write Offset Tables and store the location of each in TTC Header
for (auto& ttc_font : ttc_fonts) {
// write Offset Table location into TTC Header
offset_table = StoreU32(result, offset_table, offset);
// write the actual offset table so our header doesn't lie
ttc_font.dst_offset = offset;
offset = StoreOffsetTable(result, offset, ttc_font.flavor,
ttc_font.table_indices.size());
// write table entries
for (const auto table_index : ttc_font.table_indices) {
offset = StoreTableEntry(result, tables[table_index], offset);
}
}
} else {
offset = StoreOffsetTable(result, offset, flavor, num_tables);
for (uint16_t i = 0; i < num_tables; ++i) {
offset = StoreTableEntry(result, tables[i], offset);
}
}
std::vector<uint8_t> uncompressed_buf;
bool continue_valid = false;
const uint8_t* transform_buf = NULL;
for (uint16_t i = 0; i < num_tables; ++i) {
const Table* table = &tables[i];
uint32_t flags = table->flags;
const uint8_t* src_buf = data + table->src_offset;
size_t transform_length = table->transform_length;
if ((flags & kWoff2FlagsContinueStream) != 0) {
if (!continue_valid) {
return FONT_COMPRESSION_FAILURE();
}
} else if ((flags & kWoff2FlagsContinueStream) == 0) {
uint64_t total_size = transform_length;
for (uint16_t j = i + 1; j < num_tables; ++j) {
if ((tables[j].flags & kWoff2FlagsContinueStream) == 0) {
break;
}
total_size += tables[j].transform_length;
if (total_size > std::numeric_limits<uint32_t>::max()) {
return FONT_COMPRESSION_FAILURE();
}
}
uncompressed_buf.resize(total_size);
if (!Woff2Uncompress(&uncompressed_buf[0], total_size,
src_buf, compressed_length)) {
return FONT_COMPRESSION_FAILURE();
}
transform_buf = &uncompressed_buf[0];
continue_valid = true;
} else {
return FONT_COMPRESSION_FAILURE();
}
if ((flags & kWoff2FlagsTransform) == 0) {
if (transform_length != table->dst_length) {
return FONT_COMPRESSION_FAILURE();
}
if (static_cast<uint64_t>(table->dst_offset + transform_length) >
result_length) {
return FONT_COMPRESSION_FAILURE();
}
std::memcpy(result + table->dst_offset, transform_buf,
transform_length);
} else {
if (header_version) {
if (table->tag == kGlyfTableTag) {
const Table* loca_table = loca_by_glyf[table];
if (!ReconstructTransformedGlyf(transform_buf, transform_length,
table, loca_table, result, result_length)) {
return FONT_COMPRESSION_FAILURE();
}
} else if (table->tag != kLocaTableTag) {
// transform for this tag not known
return FONT_COMPRESSION_FAILURE();
}
} else {
if (!ReconstructTransformed(tables, table->tag,
transform_buf, transform_length, result, result_length)) {
return FONT_COMPRESSION_FAILURE();
}
}
}
if (continue_valid) {
transform_buf += transform_length;
if (transform_buf > &uncompressed_buf[0] + uncompressed_buf.size()) {
return FONT_COMPRESSION_FAILURE();
}
}
}
if (header_version) {
if (!FixCollectionChecksums(header_version, tables, ttc_fonts, result)) {
return FONT_COMPRESSION_FAILURE();
}
} else {
if (!FixChecksums(tables, result)) {
return FONT_COMPRESSION_FAILURE();
}
}
return true;
}
} // namespace woff2