Sakurai/pdf.js
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Merge pull request #5124 from jordan-thoms/improve-fingerprinting

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Improve fingerprinting of documents
This commit is contained in:
Yury Delendik 2014-12-15 13:30:14 -06:00
commit ee1b1252ff
1 changed files with 14 additions and 3 deletions
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src/core/core.js
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@ -280,6 +280,10 @@ var Page = (function PageClosure() {
* `PDFDocument` objects on the main thread created. * `PDFDocument` objects on the main thread created.
*/ */
var PDFDocument = (function PDFDocumentClosure() { var PDFDocument = (function PDFDocumentClosure() {
var FINGERPRINT_FIRST_BYTES = 1024;
var EMPTY_FINGERPRINT = '\x00\x00\x00\x00\x00\x00\x00' +
'\x00\x00\x00\x00\x00\x00\x00\x00\x00';
function PDFDocument(pdfManager, arg, password) { function PDFDocument(pdfManager, arg, password) {
if (isStream(arg)) { if (isStream(arg)) {
init.call(this, pdfManager, arg, password); init.call(this, pdfManager, arg, password);
@ -493,14 +497,21 @@ var PDFDocument = (function PDFDocumentClosure() {
get fingerprint() { get fingerprint() {
var xref = this.xref, hash, fileID = ''; var xref = this.xref, hash, fileID = '';
if (xref.trailer.has('ID')) { if (xref.trailer.has('ID') &&
xref.trailer.get('ID')[0] !== EMPTY_FINGERPRINT) {
hash = stringToBytes(xref.trailer.get('ID')[0]); hash = stringToBytes(xref.trailer.get('ID')[0]);
} else { } else {
hash = calculateMD5(this.stream.bytes.subarray(0, 100), 0, 100); if (this.stream.ensureRange) {
this.stream.ensureRange(0,
Math.min(FINGERPRINT_FIRST_BYTES, this.stream.end));
}
hash = calculateMD5(this.stream.bytes.subarray(0,
FINGERPRINT_FIRST_BYTES), 0, FINGERPRINT_FIRST_BYTES);
} }
for (var i = 0, n = hash.length; i < n; i++) { for (var i = 0, n = hash.length; i < n; i++) {
fileID += hash[i].toString(16); var hex = hash[i].toString(16);
fileID += hex.length === 1 ? '0' + hex : hex;
} }
return shadow(this, 'fingerprint', fileID); return shadow(this, 'fingerprint', fileID);