1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 // Determine coverage of font given its raw "cmap" OpenType table 18 19 #define LOG_TAG "Minikin" 20 #include <cutils/log.h> 21 22 #include <vector> 23 using std::vector; 24 25 #include <minikin/SparseBitSet.h> 26 #include <minikin/CmapCoverage.h> 27 28 namespace android { 29 30 // These could perhaps be optimized to use __builtin_bswap16 and friends. 31 static uint32_t readU16(const uint8_t* data, size_t offset) { 32 return ((uint32_t)data[offset]) << 8 | ((uint32_t)data[offset + 1]); 33 } 34 35 static uint32_t readU32(const uint8_t* data, size_t offset) { 36 return ((uint32_t)data[offset]) << 24 | ((uint32_t)data[offset + 1]) << 16 | 37 ((uint32_t)data[offset + 2]) << 8 | ((uint32_t)data[offset + 3]); 38 } 39 40 static void addRange(vector<uint32_t> &coverage, uint32_t start, uint32_t end) { 41 #ifdef VERBOSE_DEBUG 42 ALOGD("adding range %d-%d\n", start, end); 43 #endif 44 if (coverage.empty() || coverage.back() < start) { 45 coverage.push_back(start); 46 coverage.push_back(end); 47 } else { 48 coverage.back() = end; 49 } 50 } 51 52 // Get the coverage information out of a Format 4 subtable, storing it in the coverage vector 53 static bool getCoverageFormat4(vector<uint32_t>& coverage, const uint8_t* data, size_t size) { 54 const size_t kSegCountOffset = 6; 55 const size_t kEndCountOffset = 14; 56 const size_t kHeaderSize = 16; 57 const size_t kSegmentSize = 8; // total size of array elements for one segment 58 if (kEndCountOffset > size) { 59 return false; 60 } 61 size_t segCount = readU16(data, kSegCountOffset) >> 1; 62 if (kHeaderSize + segCount * kSegmentSize > size) { 63 return false; 64 } 65 for (size_t i = 0; i < segCount; i++) { 66 uint32_t end = readU16(data, kEndCountOffset + 2 * i); 67 uint32_t start = readU16(data, kHeaderSize + 2 * (segCount + i)); 68 if (end < start) { 69 // invalid segment range: size must be positive 70 android_errorWriteLog(0x534e4554, "26413177"); 71 return false; 72 } 73 uint32_t rangeOffset = readU16(data, kHeaderSize + 2 * (3 * segCount + i)); 74 if (rangeOffset == 0) { 75 uint32_t delta = readU16(data, kHeaderSize + 2 * (2 * segCount + i)); 76 if (((end + delta) & 0xffff) > end - start) { 77 addRange(coverage, start, end + 1); 78 } else { 79 for (uint32_t j = start; j < end + 1; j++) { 80 if (((j + delta) & 0xffff) != 0) { 81 addRange(coverage, j, j + 1); 82 } 83 } 84 } 85 } else { 86 for (uint32_t j = start; j < end + 1; j++) { 87 uint32_t actualRangeOffset = kHeaderSize + 6 * segCount + rangeOffset + 88 (i + j - start) * 2; 89 if (actualRangeOffset + 2 > size) { 90 // invalid rangeOffset is considered a "warning" by OpenType Sanitizer 91 continue; 92 } 93 uint32_t glyphId = readU16(data, actualRangeOffset); 94 if (glyphId != 0) { 95 addRange(coverage, j, j + 1); 96 } 97 } 98 } 99 } 100 return true; 101 } 102 103 // Get the coverage information out of a Format 12 subtable, storing it in the coverage vector 104 static bool getCoverageFormat12(vector<uint32_t>& coverage, const uint8_t* data, size_t size) { 105 const size_t kNGroupsOffset = 12; 106 const size_t kFirstGroupOffset = 16; 107 const size_t kGroupSize = 12; 108 const size_t kStartCharCodeOffset = 0; 109 const size_t kEndCharCodeOffset = 4; 110 const size_t kMaxNGroups = 0xfffffff0 / kGroupSize; // protection against overflow 111 // For all values < kMaxNGroups, kFirstGroupOffset + nGroups * kGroupSize fits in 32 bits. 112 if (kFirstGroupOffset > size) { 113 return false; 114 } 115 uint32_t nGroups = readU32(data, kNGroupsOffset); 116 if (nGroups >= kMaxNGroups || kFirstGroupOffset + nGroups * kGroupSize > size) { 117 android_errorWriteLog(0x534e4554, "25645298"); 118 return false; 119 } 120 for (uint32_t i = 0; i < nGroups; i++) { 121 uint32_t groupOffset = kFirstGroupOffset + i * kGroupSize; 122 uint32_t start = readU32(data, groupOffset + kStartCharCodeOffset); 123 uint32_t end = readU32(data, groupOffset + kEndCharCodeOffset); 124 if (end < start) { 125 // invalid group range: size must be positive 126 android_errorWriteLog(0x534e4554, "26413177"); 127 return false; 128 } 129 addRange(coverage, start, end + 1); // file is inclusive, vector is exclusive 130 } 131 return true; 132 } 133 134 bool CmapCoverage::getCoverage(SparseBitSet& coverage, const uint8_t* cmap_data, size_t cmap_size, 135 bool* has_cmap_format14_subtable) { 136 vector<uint32_t> coverageVec; 137 const size_t kHeaderSize = 4; 138 const size_t kNumTablesOffset = 2; 139 const size_t kTableSize = 8; 140 const size_t kPlatformIdOffset = 0; 141 const size_t kEncodingIdOffset = 2; 142 const size_t kOffsetOffset = 4; 143 const uint16_t kUnicodePlatformId = 0; 144 const uint16_t kMicrosoftPlatformId = 3; 145 const uint16_t kUnicodeBmpEncodingId = 1; 146 const uint16_t kVariationSequencesEncodingId = 5; 147 const uint16_t kUnicodeUcs4EncodingId = 10; 148 const uint32_t kNoTable = UINT32_MAX; 149 if (kHeaderSize > cmap_size) { 150 return false; 151 } 152 uint32_t numTables = readU16(cmap_data, kNumTablesOffset); 153 if (kHeaderSize + numTables * kTableSize > cmap_size) { 154 return false; 155 } 156 uint32_t bestTable = kNoTable; 157 bool hasCmapFormat14Subtable = false; 158 for (uint32_t i = 0; i < numTables; i++) { 159 uint16_t platformId = readU16(cmap_data, kHeaderSize + i * kTableSize + kPlatformIdOffset); 160 uint16_t encodingId = readU16(cmap_data, kHeaderSize + i * kTableSize + kEncodingIdOffset); 161 if (platformId == kMicrosoftPlatformId && encodingId == kUnicodeUcs4EncodingId) { 162 bestTable = i; 163 break; 164 } else if (platformId == kMicrosoftPlatformId && encodingId == kUnicodeBmpEncodingId) { 165 bestTable = i; 166 } else if (platformId == kUnicodePlatformId && 167 encodingId == kVariationSequencesEncodingId) { 168 uint32_t offset = readU32(cmap_data, kHeaderSize + i * kTableSize + kOffsetOffset); 169 if (offset <= cmap_size - 2 && readU16(cmap_data, offset) == 14) { 170 hasCmapFormat14Subtable = true; 171 } 172 } 173 } 174 *has_cmap_format14_subtable = hasCmapFormat14Subtable; 175 #ifdef VERBOSE_DEBUG 176 ALOGD("best table = %d\n", bestTable); 177 #endif 178 if (bestTable == kNoTable) { 179 return false; 180 } 181 uint32_t offset = readU32(cmap_data, kHeaderSize + bestTable * kTableSize + kOffsetOffset); 182 if (offset > cmap_size - 2) { 183 return false; 184 } 185 uint16_t format = readU16(cmap_data, offset); 186 bool success = false; 187 const uint8_t* tableData = cmap_data + offset; 188 const size_t tableSize = cmap_size - offset; 189 if (format == 4) { 190 success = getCoverageFormat4(coverageVec, tableData, tableSize); 191 } else if (format == 12) { 192 success = getCoverageFormat12(coverageVec, tableData, tableSize); 193 } 194 if (success) { 195 coverage.initFromRanges(&coverageVec.front(), coverageVec.size() >> 1); 196 } 197 #ifdef VERBOSE_DEBUG 198 for (size_t i = 0; i < coverageVec.size(); i += 2) { 199 ALOGD("%x:%x\n", coverageVec[i], coverageVec[i + 1]); 200 } 201 ALOGD("success = %d", success); 202 #endif 203 return success; 204 } 205 206 } // namespace android 207
