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Diffstat (limited to 'third_party/woff2/src/woff2_dec.cc')
| -rw-r--r-- | third_party/woff2/src/woff2_dec.cc | 901 |
1 files changed, 901 insertions, 0 deletions
diff --git a/third_party/woff2/src/woff2_dec.cc b/third_party/woff2/src/woff2_dec.cc new file mode 100644 index 0000000..e2bf6fb --- /dev/null +++ b/third_party/woff2/src/woff2_dec.cc @@ -0,0 +1,901 @@ +// 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 <complex> +#include <cstring> +#include <limits> +#include <string> +#include <algorithm> +#include <vector> + +#include "./buffer.h" +#include "./decode.h" +#include "./round.h" +#include "./store_bytes.h" +#include "./table_tags.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 kSfntHeaderSize = 12; +const size_t kSfntEntrySize = 16; +const size_t kCheckSumAdjustmentOffset = 8; + +const size_t kEndPtsOfContoursOffset = 10; +const size_t kCompositeGlyphBegin = 10; + +// Based on section 6.1.1 of MicroType Express draft spec +bool Read255UShort(Buffer* buf, unsigned int* value) { + static const int kWordCode = 253; + static const int kOneMoreByteCode2 = 254; + static const int kOneMoreByteCode1 = 255; + static const int kLowestUCode = 253; + uint8_t code = 0; + if (!buf->ReadU8(&code)) { + return FONT_COMPRESSION_FAILURE(); + } + if (code == kWordCode) { + uint16_t result = 0; + if (!buf->ReadU16(&result)) { + return FONT_COMPRESSION_FAILURE(); + } + *value = result; + return true; + } else if (code == kOneMoreByteCode1) { + uint8_t result = 0; + if (!buf->ReadU8(&result)) { + return FONT_COMPRESSION_FAILURE(); + } + *value = result + kLowestUCode; + return true; + } else if (code == kOneMoreByteCode2) { + uint8_t result = 0; + if (!buf->ReadU8(&result)) { + return FONT_COMPRESSION_FAILURE(); + } + *value = result + kLowestUCode * 2; + return true; + } else { + *value = code; + return true; + } +} + +bool ReadBase128(Buffer* buf, uint32_t* value) { + uint32_t result = 0; + for (size_t i = 0; i < 5; ++i) { + uint8_t code = 0; + if (!buf->ReadU8(&code)) { + return FONT_COMPRESSION_FAILURE(); + } + // If any of the top seven bits are set then we're about to overflow. + if (result & 0xfe000000) { + return FONT_COMPRESSION_FAILURE(); + } + result = (result << 7) | (code & 0x7f); + if ((code & 0x80) == 0) { + *value = result; + return true; + } + } + // Make sure not to exceed the size bound + return FONT_COMPRESSION_FAILURE(); +} + +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 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); + 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); + } 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 uint8_t* buf, size_t size) { + uint32_t checksum = 0; + for (size_t i = 0; i < size; i += 4) { + // We assume the addition is mod 2^32, which is valid because unsigned + checksum += (buf[i] << 24) | (buf[i + 1] << 16) | + (buf[i + 2] << 8) | buf[i + 3]; + } + return checksum; +} + +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) { + const Table* table = &tables[i]; + size_t table_length = table->dst_length; + uint8_t* table_data = dst + table->dst_offset; + uint32_t checksum = ComputeChecksum(table_data, table_length); + StoreU32(dst, kSfntHeaderSize + i * kSfntEntrySize + 4, checksum); + file_checksum += checksum; + } + file_checksum += ComputeChecksum(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 ReadShortDirectory(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(); + } + } + 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; +} + +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 + 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 + // uint32_t meta_offset, meta_length, meta_orig_length + // uint32_t priv_offset, priv_length + if (!file.Skip(24)) { + return FONT_COMPRESSION_FAILURE(); + } + std::vector<Table> tables(num_tables); + // Note: change below to ReadLongDirectory to enable long format. + if (!ReadShortDirectory(&file, &tables, num_tables)) { + return FONT_COMPRESSION_FAILURE(); + } + uint64_t src_offset = file.offset(); + uint64_t dst_offset = kSfntHeaderSize + + kSfntEntrySize * static_cast<uint64_t>(num_tables); + 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); // TODO: reconsider + 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) { + return FONT_COMPRESSION_FAILURE(); + } + + const uint32_t sfnt_header_and_table_directory_size = 12 + 16 * num_tables; + if (sfnt_header_and_table_directory_size > result_length) { + return FONT_COMPRESSION_FAILURE(); + } + + // Start building the font + size_t offset = 0; + offset = StoreU32(result, offset, flavor); + offset = Store16(result, offset, 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); + offset = Store16(result, offset, max_pow2); + offset = Store16(result, offset, (num_tables << 4) - output_search_range); + + // sort tags in the table directory in ascending alphabetical order + std::vector<Table> sorted_tables(tables); + std::sort(sorted_tables.begin(), sorted_tables.end()); + + for (uint16_t i = 0; i < num_tables; ++i) { + const Table* table = &sorted_tables[i]; + 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); + } + 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 (!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(); + } + } + } + + return FixChecksums(sorted_tables, result); +} + +} // namespace woff2 |