1 // Copyright 2013 Google Inc. All Rights Reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // Font management utilities 16 17 #include "./font.h" 18 19 #include <algorithm> 20 21 #include "./buffer.h" 22 #include "./port.h" 23 #include "./store_bytes.h" 24 #include "./table_tags.h" 25 26 namespace woff2 { 27 28 Font::Table* Font::FindTable(uint32_t tag) { 29 std::map<uint32_t, Font::Table>::iterator it = tables.find(tag); 30 return it == tables.end() ? 0 : &it->second; 31 } 32 33 const Font::Table* Font::FindTable(uint32_t tag) const { 34 std::map<uint32_t, Font::Table>::const_iterator it = tables.find(tag); 35 return it == tables.end() ? 0 : &it->second; 36 } 37 38 bool ReadFont(const uint8_t* data, size_t len, Font* font) { 39 Buffer file(data, len); 40 41 // We don't care about the search_range, entry_selector and range_shift 42 // fields, they will always be computed upon writing the font. 43 if (!file.ReadU32(&font->flavor) || 44 !file.ReadU16(&font->num_tables) || 45 !file.Skip(6)) { 46 return FONT_COMPRESSION_FAILURE(); 47 } 48 49 std::map<uint32_t, uint32_t> intervals; 50 for (uint16_t i = 0; i < font->num_tables; ++i) { 51 Font::Table table; 52 if (!file.ReadU32(&table.tag) || 53 !file.ReadU32(&table.checksum) || 54 !file.ReadU32(&table.offset) || 55 !file.ReadU32(&table.length)) { 56 return FONT_COMPRESSION_FAILURE(); 57 } 58 if ((table.offset & 3) != 0 || 59 table.length > len || 60 len - table.length < table.offset) { 61 return FONT_COMPRESSION_FAILURE(); 62 } 63 intervals[table.offset] = table.length; 64 table.data = data + table.offset; 65 if (font->tables.find(table.tag) != font->tables.end()) { 66 return FONT_COMPRESSION_FAILURE(); 67 } 68 font->tables[table.tag] = table; 69 } 70 71 // Check that tables are non-overlapping. 72 uint32_t last_offset = 12UL + 16UL * font->num_tables; 73 for (const auto& i : intervals) { 74 if (i.first < last_offset || i.first + i.second < i.first) { 75 return FONT_COMPRESSION_FAILURE(); 76 } 77 last_offset = i.first + i.second; 78 } 79 return true; 80 } 81 82 size_t FontFileSize(const Font& font) { 83 size_t max_offset = 12ULL + 16ULL * font.num_tables; 84 for (const auto& i : font.tables) { 85 const Font::Table& table = i.second; 86 size_t padding_size = (4 - (table.length & 3)) & 3; 87 size_t end_offset = (padding_size + table.offset) + table.length; 88 max_offset = std::max(max_offset, end_offset); 89 } 90 return max_offset; 91 } 92 93 bool WriteFont(const Font& font, uint8_t* dst, size_t dst_size) { 94 if (dst_size < 12ULL + 16ULL * font.num_tables) { 95 return FONT_COMPRESSION_FAILURE(); 96 } 97 size_t offset = 0; 98 StoreU32(font.flavor, &offset, dst); 99 Store16(font.num_tables, &offset, dst); 100 uint16_t max_pow2 = font.num_tables ? Log2Floor(font.num_tables) : 0; 101 uint16_t search_range = max_pow2 ? 1 << (max_pow2 + 4) : 0; 102 uint16_t range_shift = (font.num_tables << 4) - search_range; 103 Store16(search_range, &offset, dst); 104 Store16(max_pow2, &offset, dst); 105 Store16(range_shift, &offset, dst); 106 for (const auto& i : font.tables) { 107 const Font::Table& table = i.second; 108 StoreU32(table.tag, &offset, dst); 109 StoreU32(table.checksum, &offset, dst); 110 StoreU32(table.offset, &offset, dst); 111 StoreU32(table.length, &offset, dst); 112 if (table.offset + table.length < table.offset || 113 dst_size < table.offset + table.length) { 114 return FONT_COMPRESSION_FAILURE(); 115 } 116 memcpy(dst + table.offset, table.data, table.length); 117 size_t padding_size = (4 - (table.length & 3)) & 3; 118 if (table.offset + table.length + padding_size < padding_size || 119 dst_size < table.offset + table.length + padding_size) { 120 return FONT_COMPRESSION_FAILURE(); 121 } 122 memset(dst + table.offset + table.length, 0, padding_size); 123 } 124 return true; 125 } 126 127 int NumGlyphs(const Font& font) { 128 const Font::Table* head_table = font.FindTable(kHeadTableTag); 129 const Font::Table* loca_table = font.FindTable(kLocaTableTag); 130 if (head_table == NULL || loca_table == NULL || head_table->length < 52) { 131 return 0; 132 } 133 int index_fmt = head_table->data[51]; 134 return (loca_table->length / (index_fmt == 0 ? 2 : 4)) - 1; 135 } 136 137 bool GetGlyphData(const Font& font, int glyph_index, 138 const uint8_t** glyph_data, size_t* glyph_size) { 139 if (glyph_index < 0) { 140 return FONT_COMPRESSION_FAILURE(); 141 } 142 const Font::Table* head_table = font.FindTable(kHeadTableTag); 143 const Font::Table* loca_table = font.FindTable(kLocaTableTag); 144 const Font::Table* glyf_table = font.FindTable(kGlyfTableTag); 145 if (head_table == NULL || loca_table == NULL || glyf_table == NULL || 146 head_table->length < 52) { 147 return FONT_COMPRESSION_FAILURE(); 148 } 149 int index_fmt = head_table->data[51]; 150 Buffer loca_buf(loca_table->data, loca_table->length); 151 if (index_fmt == 0) { 152 uint16_t offset1, offset2; 153 if (!loca_buf.Skip(2 * glyph_index) || 154 !loca_buf.ReadU16(&offset1) || 155 !loca_buf.ReadU16(&offset2) || 156 offset2 < offset1 || 157 2 * offset2 > glyf_table->length) { 158 return FONT_COMPRESSION_FAILURE(); 159 } 160 *glyph_data = glyf_table->data + 2 * offset1; 161 *glyph_size = 2 * (offset2 - offset1); 162 } else { 163 uint32_t offset1, offset2; 164 if (!loca_buf.Skip(4 * glyph_index) || 165 !loca_buf.ReadU32(&offset1) || 166 !loca_buf.ReadU32(&offset2) || 167 offset2 < offset1 || 168 offset2 > glyf_table->length) { 169 return FONT_COMPRESSION_FAILURE(); 170 } 171 *glyph_data = glyf_table->data + offset1; 172 *glyph_size = offset2 - offset1; 173 } 174 return true; 175 } 176 177 bool RemoveDigitalSignature(Font* font) { 178 std::map<uint32_t, Font::Table>::iterator it = 179 font->tables.find(kDsigTableTag); 180 if (it != font->tables.end()) { 181 font->tables.erase(it); 182 font->num_tables = font->tables.size(); 183 } 184 return true; 185 } 186 187 } // namespace woff2 188
