1 /* 2 * Copyright 2015 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkMD5.h" 9 #include "SkMilestone.h" 10 #include "SkPDFMetadata.h" 11 #include "SkPDFTypes.h" 12 #include <utility> 13 14 #define SKPDF_PRODUCER "Skia/PDF [" SK_MILESTONE "]" 15 #define SKPDF_CUSTOM_PRODUCER_KEY "ProductionLibrary" 16 17 static SkString pdf_date(const SkTime::DateTime& dt) { 18 int timeZoneMinutes = SkToInt(dt.fTimeZoneMinutes); 19 char timezoneSign = timeZoneMinutes >= 0 ? '+' : '-'; 20 int timeZoneHours = SkTAbs(timeZoneMinutes) / 60; 21 timeZoneMinutes = SkTAbs(timeZoneMinutes) % 60; 22 return SkStringPrintf( 23 "D:%04u%02u%02u%02u%02u%02u%c%02d'%02d'", 24 static_cast<unsigned>(dt.fYear), static_cast<unsigned>(dt.fMonth), 25 static_cast<unsigned>(dt.fDay), static_cast<unsigned>(dt.fHour), 26 static_cast<unsigned>(dt.fMinute), 27 static_cast<unsigned>(dt.fSecond), timezoneSign, timeZoneHours, 28 timeZoneMinutes); 29 } 30 31 namespace { 32 static const struct { 33 const char* const key; 34 SkString SkDocument::PDFMetadata::*const valuePtr; 35 } gMetadataKeys[] = { 36 {"Title", &SkDocument::PDFMetadata::fTitle}, 37 {"Author", &SkDocument::PDFMetadata::fAuthor}, 38 {"Subject", &SkDocument::PDFMetadata::fSubject}, 39 {"Keywords", &SkDocument::PDFMetadata::fKeywords}, 40 {"Creator", &SkDocument::PDFMetadata::fCreator}, 41 }; 42 } // namespace 43 44 sk_sp<SkPDFObject> SkPDFMetadata::MakeDocumentInformationDict( 45 const SkDocument::PDFMetadata& metadata) { 46 auto dict = sk_make_sp<SkPDFDict>(); 47 for (const auto keyValuePtr : gMetadataKeys) { 48 const SkString& value = metadata.*(keyValuePtr.valuePtr); 49 if (value.size() > 0) { 50 dict->insertString(keyValuePtr.key, value); 51 } 52 } 53 if (metadata.fProducer.isEmpty()) { 54 dict->insertString("Producer", SKPDF_PRODUCER); 55 } else { 56 dict->insertString("Producer", metadata.fProducer); 57 dict->insertString(SKPDF_CUSTOM_PRODUCER_KEY, SKPDF_PRODUCER); 58 } 59 if (metadata.fCreation.fEnabled) { 60 dict->insertString("CreationDate", 61 pdf_date(metadata.fCreation.fDateTime)); 62 } 63 if (metadata.fModified.fEnabled) { 64 dict->insertString("ModDate", pdf_date(metadata.fModified.fDateTime)); 65 } 66 return dict; 67 } 68 69 SkPDFMetadata::UUID SkPDFMetadata::CreateUUID( 70 const SkDocument::PDFMetadata& metadata) { 71 // The main requirement is for the UUID to be unique; the exact 72 // format of the data that will be hashed is not important. 73 SkMD5 md5; 74 const char uuidNamespace[] = "org.skia.pdf\n"; 75 md5.write(uuidNamespace, strlen(uuidNamespace)); 76 double msec = SkTime::GetMSecs(); 77 md5.write(&msec, sizeof(msec)); 78 SkTime::DateTime dateTime; 79 SkTime::GetDateTime(&dateTime); 80 md5.write(&dateTime, sizeof(dateTime)); 81 if (metadata.fCreation.fEnabled) { 82 md5.write(&metadata.fCreation.fDateTime, 83 sizeof(metadata.fCreation.fDateTime)); 84 } 85 if (metadata.fModified.fEnabled) { 86 md5.write(&metadata.fModified.fDateTime, 87 sizeof(metadata.fModified.fDateTime)); 88 } 89 90 for (const auto keyValuePtr : gMetadataKeys) { 91 md5.write(keyValuePtr.key, strlen(keyValuePtr.key)); 92 md5.write("\037", 1); 93 const SkString& value = metadata.*(keyValuePtr.valuePtr); 94 md5.write(value.c_str(), value.size()); 95 md5.write("\036", 1); 96 } 97 SkMD5::Digest digest; 98 md5.finish(digest); 99 // See RFC 4122, page 6-7. 100 digest.data[6] = (digest.data[6] & 0x0F) | 0x30; 101 digest.data[8] = (digest.data[6] & 0x3F) | 0x80; 102 static_assert(sizeof(digest) == sizeof(UUID), "uuid_size"); 103 SkPDFMetadata::UUID uuid; 104 memcpy(&uuid, &digest, sizeof(digest)); 105 return uuid; 106 } 107 108 sk_sp<SkPDFObject> SkPDFMetadata::MakePdfId(const UUID& doc, 109 const UUID& instance) { 110 // /ID [ <81b14aafa313db63dbd6f981e49f94f4> 111 // <81b14aafa313db63dbd6f981e49f94f4> ] 112 auto array = sk_make_sp<SkPDFArray>(); 113 static_assert(sizeof(SkPDFMetadata::UUID) == 16, "uuid_size"); 114 array->appendString( 115 SkString(reinterpret_cast<const char*>(&doc), sizeof(UUID))); 116 array->appendString( 117 SkString(reinterpret_cast<const char*>(&instance), sizeof(UUID))); 118 return array; 119 } 120 121 #define HEXIFY(INPUT_PTR, OUTPUT_PTR, HEX_STRING, BYTE_COUNT) \ 122 do { \ 123 for (int i = 0; i < (BYTE_COUNT); ++i) { \ 124 uint8_t value = *(INPUT_PTR)++; \ 125 *(OUTPUT_PTR)++ = (HEX_STRING)[value >> 4]; \ 126 *(OUTPUT_PTR)++ = (HEX_STRING)[value & 0xF]; \ 127 } \ 128 } while (false) 129 static SkString uuid_to_string(const SkPDFMetadata::UUID& uuid) { 130 // 8-4-4-4-12 131 char buffer[36]; // [32 + 4] 132 static const char gHex[] = "0123456789abcdef"; 133 SkASSERT(strlen(gHex) == 16); 134 char* ptr = buffer; 135 const uint8_t* data = uuid.fData; 136 HEXIFY(data, ptr, gHex, 4); 137 *ptr++ = '-'; 138 HEXIFY(data, ptr, gHex, 2); 139 *ptr++ = '-'; 140 HEXIFY(data, ptr, gHex, 2); 141 *ptr++ = '-'; 142 HEXIFY(data, ptr, gHex, 2); 143 *ptr++ = '-'; 144 HEXIFY(data, ptr, gHex, 6); 145 SkASSERT(ptr == buffer + 36); 146 SkASSERT(data == uuid.fData + 16); 147 return SkString(buffer, 36); 148 } 149 #undef HEXIFY 150 151 namespace { 152 class PDFXMLObject final : public SkPDFObject { 153 public: 154 PDFXMLObject(SkString xml) : fXML(std::move(xml)) {} 155 void emitObject(SkWStream* stream, 156 const SkPDFObjNumMap& omap) const override { 157 SkPDFDict dict("Metadata"); 158 dict.insertName("Subtype", "XML"); 159 dict.insertInt("Length", fXML.size()); 160 dict.emitObject(stream, omap); 161 static const char streamBegin[] = " stream\n"; 162 stream->write(streamBegin, strlen(streamBegin)); 163 // Do not compress this. The standard requires that a 164 // program that does not understand PDF can grep for 165 // "<?xpacket" and extract the entire XML. 166 stream->write(fXML.c_str(), fXML.size()); 167 static const char streamEnd[] = "\nendstream"; 168 stream->write(streamEnd, strlen(streamEnd)); 169 } 170 171 private: 172 const SkString fXML; 173 }; 174 } // namespace 175 176 static int count_xml_escape_size(const SkString& input) { 177 int extra = 0; 178 for (size_t i = 0; i < input.size(); ++i) { 179 if (input[i] == '&') { 180 extra += 4; // strlen("&") - strlen("&") 181 } else if (input[i] == '<') { 182 extra += 3; // strlen("<") - strlen("<") 183 } 184 } 185 return extra; 186 } 187 188 const SkString escape_xml(const SkString& input, 189 const char* before = nullptr, 190 const char* after = nullptr) { 191 if (input.size() == 0) { 192 return input; 193 } 194 // "&" --> "&" and "<" --> "<" 195 // text is assumed to be in UTF-8 196 // all strings are xml content, not attribute values. 197 size_t beforeLen = before ? strlen(before) : 0; 198 size_t afterLen = after ? strlen(after) : 0; 199 int extra = count_xml_escape_size(input); 200 SkString output(input.size() + extra + beforeLen + afterLen); 201 char* out = output.writable_str(); 202 if (before) { 203 strncpy(out, before, beforeLen); 204 out += beforeLen; 205 } 206 static const char kAmp[] = "&"; 207 static const char kLt[] = "<"; 208 for (size_t i = 0; i < input.size(); ++i) { 209 if (input[i] == '&') { 210 strncpy(out, kAmp, strlen(kAmp)); 211 out += strlen(kAmp); 212 } else if (input[i] == '<') { 213 strncpy(out, kLt, strlen(kLt)); 214 out += strlen(kLt); 215 } else { 216 *out++ = input[i]; 217 } 218 } 219 if (after) { 220 strncpy(out, after, afterLen); 221 out += afterLen; 222 } 223 // Validate that we haven't written outside of our string. 224 SkASSERT(out == &output.writable_str()[output.size()]); 225 *out = '\0'; 226 return output; 227 } 228 229 sk_sp<SkPDFObject> SkPDFMetadata::MakeXMPObject( 230 const SkDocument::PDFMetadata& metadata, 231 const UUID& doc, 232 const UUID& instance) { 233 static const char templateString[] = 234 "<?xpacket begin=\"\" id=\"W5M0MpCehiHzreSzNTczkc9d\"?>\n" 235 "<x:xmpmeta xmlns:x=\"adobe:ns:meta/\"\n" 236 " x:xmptk=\"Adobe XMP Core 5.4-c005 78.147326, " 237 "2012/08/23-13:03:03\">\n" 238 "<rdf:RDF " 239 "xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\">\n" 240 "<rdf:Description rdf:about=\"\"\n" 241 " xmlns:xmp=\"http://ns.adobe.com/xap/1.0/\"\n" 242 " xmlns:dc=\"http://purl.org/dc/elements/1.1/\"\n" 243 " xmlns:xmpMM=\"http://ns.adobe.com/xap/1.0/mm/\"\n" 244 " xmlns:pdf=\"http://ns.adobe.com/pdf/1.3/\"\n" 245 " xmlns:pdfaid=\"http://www.aiim.org/pdfa/ns/id/\">\n" 246 "<pdfaid:part>2</pdfaid:part>\n" 247 "<pdfaid:conformance>B</pdfaid:conformance>\n" 248 "%s" // ModifyDate 249 "%s" // CreateDate 250 "%s" // xmp:CreatorTool 251 "<dc:format>application/pdf</dc:format>\n" 252 "%s" // dc:title 253 "%s" // dc:description 254 "%s" // author 255 "%s" // keywords 256 "<xmpMM:DocumentID>uuid:%s</xmpMM:DocumentID>\n" 257 "<xmpMM:InstanceID>uuid:%s</xmpMM:InstanceID>\n" 258 "%s" // pdf:Producer 259 "%s" // pdf:Keywords 260 "</rdf:Description>\n" 261 "</rdf:RDF>\n" 262 "</x:xmpmeta>\n" // Note: the standard suggests 4k of padding. 263 "<?xpacket end=\"w\"?>\n"; 264 265 SkString creationDate; 266 SkString modificationDate; 267 if (metadata.fCreation.fEnabled) { 268 SkString tmp; 269 metadata.fCreation.fDateTime.toISO8601(&tmp); 270 SkASSERT(0 == count_xml_escape_size(tmp)); 271 // YYYY-mm-ddTHH:MM:SS[+|-]ZZ:ZZ; no need to escape 272 creationDate = SkStringPrintf("<xmp:CreateDate>%s</xmp:CreateDate>\n", 273 tmp.c_str()); 274 } 275 if (metadata.fModified.fEnabled) { 276 SkString tmp; 277 metadata.fModified.fDateTime.toISO8601(&tmp); 278 SkASSERT(0 == count_xml_escape_size(tmp)); 279 modificationDate = SkStringPrintf( 280 "<xmp:ModifyDate>%s</xmp:ModifyDate>\n", tmp.c_str()); 281 } 282 SkString title = 283 escape_xml(metadata.fTitle, 284 "<dc:title><rdf:Alt><rdf:li xml:lang=\"x-default\">", 285 "</rdf:li></rdf:Alt></dc:title>\n"); 286 SkString author = 287 escape_xml(metadata.fAuthor, "<dc:creator><rdf:Bag><rdf:li>", 288 "</rdf:li></rdf:Bag></dc:creator>\n"); 289 // TODO: in theory, XMP can support multiple authors. Split on a delimiter? 290 SkString subject = escape_xml( 291 metadata.fSubject, 292 "<dc:description><rdf:Alt><rdf:li xml:lang=\"x-default\">", 293 "</rdf:li></rdf:Alt></dc:description>\n"); 294 SkString keywords1 = 295 escape_xml(metadata.fKeywords, "<dc:subject><rdf:Bag><rdf:li>", 296 "</rdf:li></rdf:Bag></dc:subject>\n"); 297 SkString keywords2 = escape_xml(metadata.fKeywords, "<pdf:Keywords>", 298 "</pdf:Keywords>\n"); 299 // TODO: in theory, keywords can be a list too. 300 301 SkString producer("<pdf:Producer>" SKPDF_PRODUCER "</pdf:Producer>\n"); 302 if (!metadata.fProducer.isEmpty()) { 303 // TODO: register a developer prefix to make 304 // <skia:SKPDF_CUSTOM_PRODUCER_KEY> a real XML tag. 305 producer = escape_xml( 306 metadata.fProducer, "<pdf:Producer>", 307 "</pdf:Producer>\n<!-- <skia:" SKPDF_CUSTOM_PRODUCER_KEY ">" 308 SKPDF_PRODUCER "</skia:" SKPDF_CUSTOM_PRODUCER_KEY "> -->\n"); 309 } 310 311 SkString creator = escape_xml(metadata.fCreator, "<xmp:CreatorTool>", 312 "</xmp:CreatorTool>\n"); 313 SkString documentID = uuid_to_string(doc); // no need to escape 314 SkASSERT(0 == count_xml_escape_size(documentID)); 315 SkString instanceID = uuid_to_string(instance); 316 SkASSERT(0 == count_xml_escape_size(instanceID)); 317 return sk_make_sp<PDFXMLObject>(SkStringPrintf( 318 templateString, modificationDate.c_str(), creationDate.c_str(), 319 creator.c_str(), title.c_str(), subject.c_str(), author.c_str(), 320 keywords1.c_str(), documentID.c_str(), instanceID.c_str(), 321 producer.c_str(), keywords2.c_str())); 322 } 323 324 #undef SKPDF_CUSTOM_PRODUCER_KEY 325 #undef SKPDF_PRODUCER 326 #undef SKPDF_STRING 327 #undef SKPDF_STRING_IMPL 328
