Parse Type1 font files to determine the various Length{n}
properties, instead of trusting the PDF file (issue 5686, issue 3928)
Fixes 5686. Fixes 3928.
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c40df8a393
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@ -2197,6 +2197,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
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}
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var length1 = fontFile.dict.get('Length1');
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var length2 = fontFile.dict.get('Length2');
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var length3 = fontFile.dict.get('Length3');
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}
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}
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@ -2207,6 +2208,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
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file: fontFile,
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length1: length1,
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length2: length2,
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length3: length3,
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loadedName: baseDict.loadedName,
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composite: composite,
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wideChars: composite,
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@ -54,6 +54,7 @@ var shadow = sharedUtil.shadow;
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var stringToBytes = sharedUtil.stringToBytes;
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var string32 = sharedUtil.string32;
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var warn = sharedUtil.warn;
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var MissingDataException = sharedUtil.MissingDataException;
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var Stream = coreStream.Stream;
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var Lexer = coreParser.Lexer;
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var getGlyphsUnicode = coreGlyphList.getGlyphsUnicode;
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@ -3638,6 +3639,120 @@ var CFFStandardStrings = [
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// Type1Font is also a CIDFontType0.
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var Type1Font = (function Type1FontClosure() {
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function findBlock(streamBytes, signature, startIndex) {
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var streamBytesLength = streamBytes.length;
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var signatureLength = signature.length;
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var scanLength = streamBytesLength - signatureLength;
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var i = startIndex, j, found = false;
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while (i < scanLength) {
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j = 0;
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while (j < signatureLength && streamBytes[i + j] === signature[j]) {
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j++;
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}
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if (j >= signatureLength) { // `signature` found, skip over whitespace.
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i += j;
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while (i < streamBytesLength && Lexer.isSpace(streamBytes[i])) {
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i++;
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}
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found = true;
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break;
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}
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i++;
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}
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return {
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found: found,
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length: i,
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};
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}
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function getHeaderBlock(stream, suggestedLength) {
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var EEXEC_SIGNATURE = [0x65, 0x65, 0x78, 0x65, 0x63];
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var streamStartPos = stream.pos; // Save the initial stream position.
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var headerBytes, headerBytesLength, block;
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try {
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headerBytes = stream.getBytes(suggestedLength);
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headerBytesLength = headerBytes.length;
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} catch (ex) {
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if (ex instanceof MissingDataException) {
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throw ex;
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}
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// Ignore errors if the `suggestedLength` is huge enough that a Uint8Array
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// cannot hold the result of `getBytes`, and fallback to simply checking
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// the entire stream (fixes issue3928.pdf).
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}
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if (headerBytesLength === suggestedLength) {
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// Most of the time `suggestedLength` is correct, so to speed things up we
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// initially only check the last few bytes to see if the header was found.
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// Otherwise we (potentially) check the entire stream to prevent errors in
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// `Type1Parser` (fixes issue5686.pdf).
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block = findBlock(headerBytes, EEXEC_SIGNATURE,
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suggestedLength - 2 * EEXEC_SIGNATURE.length);
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if (block.found && block.length === suggestedLength) {
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return {
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stream: new Stream(headerBytes),
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length: suggestedLength,
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};
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}
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}
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warn('Invalid "Length1" property in Type1 font -- trying to recover.');
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stream.pos = streamStartPos; // Reset the stream position.
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var SCAN_BLOCK_LENGTH = 2048;
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var actualLength;
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while (true) {
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var scanBytes = stream.peekBytes(SCAN_BLOCK_LENGTH);
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block = findBlock(scanBytes, EEXEC_SIGNATURE, 0);
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if (block.length === 0) {
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break;
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}
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stream.pos += block.length; // Update the stream position.
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if (block.found) {
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actualLength = stream.pos - streamStartPos;
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break;
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}
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}
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stream.pos = streamStartPos; // Reset the stream position.
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if (actualLength) {
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return {
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stream: new Stream(stream.getBytes(actualLength)),
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length: actualLength,
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};
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}
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warn('Unable to recover "Length1" property in Type1 font -- using as is.');
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return {
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stream: new Stream(stream.getBytes(suggestedLength)),
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length: suggestedLength,
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};
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}
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function getEexecBlock(stream, suggestedLength) {
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// We should ideally parse the eexec block to ensure that `suggestedLength`
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// is correct, so we don't truncate the block data if it's too small.
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// However, this would also require checking if the fixed-content portion
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// exists (using the 'Length3' property), and ensuring that it's valid.
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//
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// Given that `suggestedLength` almost always is correct, all the validation
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// would require a great deal of unnecessary parsing for most fonts.
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// To save time, we always fetch the entire stream instead, which also avoid
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// issues if `suggestedLength` is huge (see comment in `getHeaderBlock`).
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//
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// NOTE: This means that the function can include the fixed-content portion
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// in the returned eexec block. In practice this does *not* seem to matter,
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// since `Type1Parser_extractFontProgram` will skip over any non-commands.
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var eexecBytes = stream.getBytes();
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return {
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stream: new Stream(eexecBytes),
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length: eexecBytes.length,
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};
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}
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function Type1Font(name, file, properties) {
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// Some bad generators embed pfb file as is, we have to strip 6-byte header.
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// Also, length1 and length2 might be off by 6 bytes as well.
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@ -3654,8 +3769,9 @@ var Type1Font = (function Type1FontClosure() {
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}
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// Get the data block containing glyphs and subrs informations
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var headerBlock = new Stream(file.getBytes(headerBlockLength));
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var headerBlockParser = new Type1Parser(headerBlock);
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var headerBlock = getHeaderBlock(file, headerBlockLength);
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headerBlockLength = headerBlock.length;
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var headerBlockParser = new Type1Parser(headerBlock.stream);
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headerBlockParser.extractFontHeader(properties);
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if (pfbHeaderPresent) {
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@ -3665,8 +3781,9 @@ var Type1Font = (function Type1FontClosure() {
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}
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// Decrypt the data blocks and retrieve it's content
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var eexecBlock = new Stream(file.getBytes(eexecBlockLength));
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var eexecBlockParser = new Type1Parser(eexecBlock, true);
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var eexecBlock = getEexecBlock(file, eexecBlockLength);
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eexecBlockLength = eexecBlock.length;
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var eexecBlockParser = new Type1Parser(eexecBlock.stream, true);
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var data = eexecBlockParser.extractFontProgram();
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for (var info in data.properties) {
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properties[info] = data.properties[info];
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2
test/pdfs/.gitignore
vendored
2
test/pdfs/.gitignore
vendored
@ -49,6 +49,8 @@
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!issue3207r.pdf
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!issue3263r.pdf
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!issue3879r.pdf
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!issue5686.pdf
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!issue3928.pdf
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!close-path-bug.pdf
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!issue6019.pdf
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!issue6621.pdf
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BIN
test/pdfs/issue3928.pdf
Normal file
BIN
test/pdfs/issue3928.pdf
Normal file
Binary file not shown.
BIN
test/pdfs/issue5686.pdf
Normal file
BIN
test/pdfs/issue5686.pdf
Normal file
Binary file not shown.
@ -1443,6 +1443,22 @@
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"link": false,
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"type": "eq"
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},
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{ "id": "issue5686",
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"file": "pdfs/issue5686.pdf",
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"md5": "78d16b9df07a355ad00d70504a9194f8",
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"rounds": 1,
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"link": false,
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"type": "eq",
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"about": "Type1 font where Length1/Length2 are slightly incorrect."
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},
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{ "id": "issue3928",
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"file": "pdfs/issue3928.pdf",
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"md5": "1963493f843e981cbe768b707ef7f08a",
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"rounds": 1,
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"link": false,
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"type": "eq",
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"about": "Type1 font where Length1/Length2 are several orders of magnitude too large."
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},
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{ "id": "html5checker",
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"file": "pdfs/html5checker.pdf",
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"md5": "74bbd80d1e7eb5f2951582233ef9ebab",
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