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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkPDFMetadata.h"
#include "SkMD5.h"
#include "SkMilestone.h"
#include "SkPDFTypes.h"
#include "SkTo.h"
#include "SkUtils.h"
#include <utility>
#define SKPDF_STRING(X) SKPDF_STRING_IMPL(X)
#define SKPDF_STRING_IMPL(X) #X
#define SKPDF_PRODUCER "Skia/PDF m" SKPDF_STRING(SK_MILESTONE)
#define SKPDF_CUSTOM_PRODUCER_KEY "ProductionLibrary"
static SkString pdf_date(const SkTime::DateTime& dt) {
int timeZoneMinutes = SkToInt(dt.fTimeZoneMinutes);
char timezoneSign = timeZoneMinutes >= 0 ? '+' : '-';
int timeZoneHours = SkTAbs(timeZoneMinutes) / 60;
timeZoneMinutes = SkTAbs(timeZoneMinutes) % 60;
return SkStringPrintf(
"D:%04u%02u%02u%02u%02u%02u%c%02d'%02d'",
static_cast<unsigned>(dt.fYear), static_cast<unsigned>(dt.fMonth),
static_cast<unsigned>(dt.fDay), static_cast<unsigned>(dt.fHour),
static_cast<unsigned>(dt.fMinute),
static_cast<unsigned>(dt.fSecond), timezoneSign, timeZoneHours,
timeZoneMinutes);
}
static bool utf8_is_pdfdocencoding(const char* src, size_t len) {
const uint8_t* end = (const uint8_t*)src + len;
for (const uint8_t* ptr = (const uint8_t*)src; ptr < end; ++ptr) {
uint8_t v = *ptr;
// See Table D.2 (PDFDocEncoding Character Set) in the PDF3200_2008 spec.
if ((v > 23 && v < 32) || v > 126) {
return false;
}
}
return true;
}
void write_utf16be(char** ptr, uint16_t value) {
*(*ptr)++ = (value >> 8);
*(*ptr)++ = (value & 0xFF);
}
// Please Note: This "abuses" the SkString, which "should" only hold UTF8.
// But the SkString is written as if it is really just a ref-counted array of
// chars, so this works, as long as we handle endiness and conversions ourselves.
//
// Input: UTF-8
// Output UTF-16-BE
static SkString to_utf16be(const char* src, size_t len) {
SkString ret;
const char* const end = src + len;
size_t n = 1; // BOM
for (const char* ptr = src; ptr < end;) {
SkUnichar u = SkUTF8_NextUnicharWithError(&ptr, end);
if (u < 0) {
break;
}
n += SkUTF16_FromUnichar(u);
}
ret.resize(2 * n);
char* out = ret.writable_str();
write_utf16be(&out, 0xFEFF); // BOM
for (const char* ptr = src; ptr < end;) {
SkUnichar u = SkUTF8_NextUnicharWithError(&ptr, end);
if (u < 0) {
break;
}
uint16_t utf16[2];
size_t l = SkUTF16_FromUnichar(u, utf16);
write_utf16be(&out, utf16[0]);
if (l == 2) {
write_utf16be(&out, utf16[1]);
}
}
SkASSERT(out == ret.writable_str() + 2 * n);
return ret;
}
// Input: UTF-8
// Output UTF-16-BE OR PDFDocEncoding (if that encoding is identical to ASCII encoding).
//
// See sections 14.3.3 (Document Information Dictionary) and 7.9.2.2 (Text String Type)
// of the PDF32000_2008 spec.
static SkString convert(const SkString& s) {
return utf8_is_pdfdocencoding(s.c_str(), s.size()) ? s : to_utf16be(s.c_str(), s.size());
}
static SkString convert(const char* src) {
size_t len = strlen(src);
return utf8_is_pdfdocencoding(src, len) ? SkString(src, len) : to_utf16be(src, len);
}
namespace {
static const struct {
const char* const key;
SkString SkDocument::PDFMetadata::*const valuePtr;
} gMetadataKeys[] = {
{"Title", &SkDocument::PDFMetadata::fTitle},
{"Author", &SkDocument::PDFMetadata::fAuthor},
{"Subject", &SkDocument::PDFMetadata::fSubject},
{"Keywords", &SkDocument::PDFMetadata::fKeywords},
{"Creator", &SkDocument::PDFMetadata::fCreator},
};
} // namespace
sk_sp<SkPDFObject> SkPDFMetadata::MakeDocumentInformationDict(
const SkDocument::PDFMetadata& metadata) {
auto dict = sk_make_sp<SkPDFDict>();
for (const auto keyValuePtr : gMetadataKeys) {
const SkString& value = metadata.*(keyValuePtr.valuePtr);
if (value.size() > 0) {
dict->insertString(keyValuePtr.key, convert(value));
}
}
if (metadata.fProducer.isEmpty()) {
dict->insertString("Producer", convert(SKPDF_PRODUCER));
} else {
dict->insertString("Producer", convert(metadata.fProducer));
dict->insertString(SKPDF_CUSTOM_PRODUCER_KEY, convert(SKPDF_PRODUCER));
}
if (metadata.fCreation.fEnabled) {
dict->insertString("CreationDate", pdf_date(metadata.fCreation.fDateTime));
}
if (metadata.fModified.fEnabled) {
dict->insertString("ModDate", pdf_date(metadata.fModified.fDateTime));
}
return std::move(dict);
}
SkPDFMetadata::UUID SkPDFMetadata::CreateUUID(
const SkDocument::PDFMetadata& metadata) {
// The main requirement is for the UUID to be unique; the exact
// format of the data that will be hashed is not important.
SkMD5 md5;
const char uuidNamespace[] = "org.skia.pdf\n";
md5.writeText(uuidNamespace);
double msec = SkTime::GetMSecs();
md5.write(&msec, sizeof(msec));
SkTime::DateTime dateTime;
SkTime::GetDateTime(&dateTime);
md5.write(&dateTime, sizeof(dateTime));
if (metadata.fCreation.fEnabled) {
md5.write(&metadata.fCreation.fDateTime,
sizeof(metadata.fCreation.fDateTime));
}
if (metadata.fModified.fEnabled) {
md5.write(&metadata.fModified.fDateTime,
sizeof(metadata.fModified.fDateTime));
}
for (const auto keyValuePtr : gMetadataKeys) {
md5.writeText(keyValuePtr.key);
md5.write("\037", 1);
const SkString& value = metadata.*(keyValuePtr.valuePtr);
md5.write(value.c_str(), value.size());
md5.write("\036", 1);
}
SkMD5::Digest digest;
md5.finish(digest);
// See RFC 4122, page 6-7.
digest.data[6] = (digest.data[6] & 0x0F) | 0x30;
digest.data[8] = (digest.data[6] & 0x3F) | 0x80;
static_assert(sizeof(digest) == sizeof(UUID), "uuid_size");
SkPDFMetadata::UUID uuid;
memcpy(&uuid, &digest, sizeof(digest));
return uuid;
}
sk_sp<SkPDFObject> SkPDFMetadata::MakePdfId(const UUID& doc,
const UUID& instance) {
// /ID [ <81b14aafa313db63dbd6f981e49f94f4>
// <81b14aafa313db63dbd6f981e49f94f4> ]
auto array = sk_make_sp<SkPDFArray>();
static_assert(sizeof(SkPDFMetadata::UUID) == 16, "uuid_size");
array->appendString(
SkString(reinterpret_cast<const char*>(&doc), sizeof(UUID)));
array->appendString(
SkString(reinterpret_cast<const char*>(&instance), sizeof(UUID)));
return std::move(array);
}
// Convert a block of memory to hexadecimal. Input and output pointers will be
// moved to end of the range.
static void hexify(const uint8_t** inputPtr, char** outputPtr, int count) {
SkASSERT(inputPtr && *inputPtr);
SkASSERT(outputPtr && *outputPtr);
while (count-- > 0) {
uint8_t value = *(*inputPtr)++;
*(*outputPtr)++ = SkHexadecimalDigits::gLower[value >> 4];
*(*outputPtr)++ = SkHexadecimalDigits::gLower[value & 0xF];
}
}
static SkString uuid_to_string(const SkPDFMetadata::UUID& uuid) {
// 8-4-4-4-12
char buffer[36]; // [32 + 4]
char* ptr = buffer;
const uint8_t* data = uuid.fData;
hexify(&data, &ptr, 4);
*ptr++ = '-';
hexify(&data, &ptr, 2);
*ptr++ = '-';
hexify(&data, &ptr, 2);
*ptr++ = '-';
hexify(&data, &ptr, 2);
*ptr++ = '-';
hexify(&data, &ptr, 6);
SkASSERT(ptr == buffer + 36);
SkASSERT(data == uuid.fData + 16);
return SkString(buffer, 36);
}
namespace {
class PDFXMLObject final : public SkPDFObject {
public:
PDFXMLObject(SkString xml) : fXML(std::move(xml)) {}
void emitObject(SkWStream* stream,
const SkPDFObjNumMap& omap) const override {
SkPDFDict dict("Metadata");
dict.insertName("Subtype", "XML");
dict.insertInt("Length", fXML.size());
dict.emitObject(stream, omap);
static const char streamBegin[] = " stream\n";
stream->writeText(streamBegin);
// Do not compress this. The standard requires that a
// program that does not understand PDF can grep for
// "<?xpacket" and extract the entire XML.
stream->write(fXML.c_str(), fXML.size());
static const char streamEnd[] = "\nendstream";
stream->writeText(streamEnd);
}
private:
const SkString fXML;
};
} // namespace
static int count_xml_escape_size(const SkString& input) {
int extra = 0;
for (size_t i = 0; i < input.size(); ++i) {
if (input[i] == '&') {
extra += 4; // strlen("&") - strlen("&")
} else if (input[i] == '<') {
extra += 3; // strlen("<") - strlen("<")
}
}
return extra;
}
const SkString escape_xml(const SkString& input,
const char* before = nullptr,
const char* after = nullptr) {
if (input.size() == 0) {
return input;
}
// "&" --> "&" and "<" --> "<"
// text is assumed to be in UTF-8
// all strings are xml content, not attribute values.
size_t beforeLen = before ? strlen(before) : 0;
size_t afterLen = after ? strlen(after) : 0;
int extra = count_xml_escape_size(input);
SkString output(input.size() + extra + beforeLen + afterLen);
char* out = output.writable_str();
if (before) {
strncpy(out, before, beforeLen);
out += beforeLen;
}
static const char kAmp[] = "&";
static const char kLt[] = "<";
for (size_t i = 0; i < input.size(); ++i) {
if (input[i] == '&') {
strncpy(out, kAmp, strlen(kAmp));
out += strlen(kAmp);
} else if (input[i] == '<') {
strncpy(out, kLt, strlen(kLt));
out += strlen(kLt);
} else {
*out++ = input[i];
}
}
if (after) {
strncpy(out, after, afterLen);
out += afterLen;
}
// Validate that we haven't written outside of our string.
SkASSERT(out == &output.writable_str()[output.size()]);
*out = '\0';
return output;
}
sk_sp<SkPDFObject> SkPDFMetadata::MakeXMPObject(
const SkDocument::PDFMetadata& metadata,
const UUID& doc,
const UUID& instance) {
static const char templateString[] =
"<?xpacket begin=\"\" id=\"W5M0MpCehiHzreSzNTczkc9d\"?>\n"
"<x:xmpmeta xmlns:x=\"adobe:ns:meta/\"\n"
" x:xmptk=\"Adobe XMP Core 5.4-c005 78.147326, "
"2012/08/23-13:03:03\">\n"
"<rdf:RDF "
"xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\">\n"
"<rdf:Description rdf:about=\"\"\n"
" xmlns:xmp=\"http://ns.adobe.com/xap/1.0/\"\n"
" xmlns:dc=\"http://purl.org/dc/elements/1.1/\"\n"
" xmlns:xmpMM=\"http://ns.adobe.com/xap/1.0/mm/\"\n"
" xmlns:pdf=\"http://ns.adobe.com/pdf/1.3/\"\n"
" xmlns:pdfaid=\"http://www.aiim.org/pdfa/ns/id/\">\n"
"<pdfaid:part>2</pdfaid:part>\n"
"<pdfaid:conformance>B</pdfaid:conformance>\n"
"%s" // ModifyDate
"%s" // CreateDate
"%s" // xmp:CreatorTool
"<dc:format>application/pdf</dc:format>\n"
"%s" // dc:title
"%s" // dc:description
"%s" // author
"%s" // keywords
"<xmpMM:DocumentID>uuid:%s</xmpMM:DocumentID>\n"
"<xmpMM:InstanceID>uuid:%s</xmpMM:InstanceID>\n"
"%s" // pdf:Producer
"%s" // pdf:Keywords
"</rdf:Description>\n"
"</rdf:RDF>\n"
"</x:xmpmeta>\n" // Note: the standard suggests 4k of padding.
"<?xpacket end=\"w\"?>\n";
SkString creationDate;
SkString modificationDate;
if (metadata.fCreation.fEnabled) {
SkString tmp;
metadata.fCreation.fDateTime.toISO8601(&tmp);
SkASSERT(0 == count_xml_escape_size(tmp));
// YYYY-mm-ddTHH:MM:SS[+|-]ZZ:ZZ; no need to escape
creationDate = SkStringPrintf("<xmp:CreateDate>%s</xmp:CreateDate>\n",
tmp.c_str());
}
if (metadata.fModified.fEnabled) {
SkString tmp;
metadata.fModified.fDateTime.toISO8601(&tmp);
SkASSERT(0 == count_xml_escape_size(tmp));
modificationDate = SkStringPrintf(
"<xmp:ModifyDate>%s</xmp:ModifyDate>\n", tmp.c_str());
}
SkString title =
escape_xml(metadata.fTitle,
"<dc:title><rdf:Alt><rdf:li xml:lang=\"x-default\">",
"</rdf:li></rdf:Alt></dc:title>\n");
SkString author =
escape_xml(metadata.fAuthor, "<dc:creator><rdf:Bag><rdf:li>",
"</rdf:li></rdf:Bag></dc:creator>\n");
// TODO: in theory, XMP can support multiple authors. Split on a delimiter?
SkString subject = escape_xml(
metadata.fSubject,
"<dc:description><rdf:Alt><rdf:li xml:lang=\"x-default\">",
"</rdf:li></rdf:Alt></dc:description>\n");
SkString keywords1 =
escape_xml(metadata.fKeywords, "<dc:subject><rdf:Bag><rdf:li>",
"</rdf:li></rdf:Bag></dc:subject>\n");
SkString keywords2 = escape_xml(metadata.fKeywords, "<pdf:Keywords>",
"</pdf:Keywords>\n");
// TODO: in theory, keywords can be a list too.
SkString producer("<pdf:Producer>" SKPDF_PRODUCER "</pdf:Producer>\n");
if (!metadata.fProducer.isEmpty()) {
// TODO: register a developer prefix to make
// <skia:SKPDF_CUSTOM_PRODUCER_KEY> a real XML tag.
producer = escape_xml(
metadata.fProducer, "<pdf:Producer>",
"</pdf:Producer>\n<!-- <skia:" SKPDF_CUSTOM_PRODUCER_KEY ">"
SKPDF_PRODUCER "</skia:" SKPDF_CUSTOM_PRODUCER_KEY "> -->\n");
}
SkString creator = escape_xml(metadata.fCreator, "<xmp:CreatorTool>",
"</xmp:CreatorTool>\n");
SkString documentID = uuid_to_string(doc); // no need to escape
SkASSERT(0 == count_xml_escape_size(documentID));
SkString instanceID = uuid_to_string(instance);
SkASSERT(0 == count_xml_escape_size(instanceID));
return sk_make_sp<PDFXMLObject>(SkStringPrintf(
templateString, modificationDate.c_str(), creationDate.c_str(),
creator.c_str(), title.c_str(), subject.c_str(), author.c_str(),
keywords1.c_str(), documentID.c_str(), instanceID.c_str(),
producer.c_str(), keywords2.c_str()));
}
#undef SKPDF_CUSTOM_PRODUCER_KEY
#undef SKPDF_PRODUCER
#undef SKPDF_STRING
#undef SKPDF_STRING_IMPL
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