[Pkg-javascript-commits] [pdf.js] 316/414: Parse Type1 font files to determine the various `Length{n}` properties, instead of trusting the PDF file (issue 5686, issue 3928)
David Prévot
taffit at moszumanska.debian.org
Tue Jun 28 17:12:35 UTC 2016
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taffit pushed a commit to branch master
in repository pdf.js.
commit 05cf709f8ef30fbb939f1c1cced3093688988c87
Author: Jonas Jenwald <jonas.jenwald at gmail.com>
Date: Sat Mar 5 22:32:54 2016 +0100
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.
---
src/core/evaluator.js | 2 +
src/core/fonts.js | 125 ++++++++++++++++++++++++++++++++++++++++++++++--
test/pdfs/.gitignore | 2 +
test/pdfs/issue3928.pdf | Bin 0 -> 31272 bytes
test/pdfs/issue5686.pdf | Bin 0 -> 23718 bytes
test/test_manifest.json | 16 +++++++
6 files changed, 141 insertions(+), 4 deletions(-)
diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index d080ac6..aa15c5f 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -2197,6 +2197,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
}
var length1 = fontFile.dict.get('Length1');
var length2 = fontFile.dict.get('Length2');
+ var length3 = fontFile.dict.get('Length3');
}
}
@@ -2207,6 +2208,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
file: fontFile,
length1: length1,
length2: length2,
+ length3: length3,
loadedName: baseDict.loadedName,
composite: composite,
wideChars: composite,
diff --git a/src/core/fonts.js b/src/core/fonts.js
index 7fb4060..4fb0269 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -54,6 +54,7 @@ var shadow = sharedUtil.shadow;
var stringToBytes = sharedUtil.stringToBytes;
var string32 = sharedUtil.string32;
var warn = sharedUtil.warn;
+var MissingDataException = sharedUtil.MissingDataException;
var Stream = coreStream.Stream;
var Lexer = coreParser.Lexer;
var getGlyphsUnicode = coreGlyphList.getGlyphsUnicode;
@@ -3638,6 +3639,120 @@ var CFFStandardStrings = [
// Type1Font is also a CIDFontType0.
var Type1Font = (function Type1FontClosure() {
+ function findBlock(streamBytes, signature, startIndex) {
+ var streamBytesLength = streamBytes.length;
+ var signatureLength = signature.length;
+ var scanLength = streamBytesLength - signatureLength;
+
+ var i = startIndex, j, found = false;
+ while (i < scanLength) {
+ j = 0;
+ while (j < signatureLength && streamBytes[i + j] === signature[j]) {
+ j++;
+ }
+ if (j >= signatureLength) { // `signature` found, skip over whitespace.
+ i += j;
+ while (i < streamBytesLength && Lexer.isSpace(streamBytes[i])) {
+ i++;
+ }
+ found = true;
+ break;
+ }
+ i++;
+ }
+ return {
+ found: found,
+ length: i,
+ };
+ }
+
+ function getHeaderBlock(stream, suggestedLength) {
+ var EEXEC_SIGNATURE = [0x65, 0x65, 0x78, 0x65, 0x63];
+
+ var streamStartPos = stream.pos; // Save the initial stream position.
+ var headerBytes, headerBytesLength, block;
+ try {
+ headerBytes = stream.getBytes(suggestedLength);
+ headerBytesLength = headerBytes.length;
+ } catch (ex) {
+ if (ex instanceof MissingDataException) {
+ throw ex;
+ }
+ // Ignore errors if the `suggestedLength` is huge enough that a Uint8Array
+ // cannot hold the result of `getBytes`, and fallback to simply checking
+ // the entire stream (fixes issue3928.pdf).
+ }
+
+ if (headerBytesLength === suggestedLength) {
+ // Most of the time `suggestedLength` is correct, so to speed things up we
+ // initially only check the last few bytes to see if the header was found.
+ // Otherwise we (potentially) check the entire stream to prevent errors in
+ // `Type1Parser` (fixes issue5686.pdf).
+ block = findBlock(headerBytes, EEXEC_SIGNATURE,
+ suggestedLength - 2 * EEXEC_SIGNATURE.length);
+
+ if (block.found && block.length === suggestedLength) {
+ return {
+ stream: new Stream(headerBytes),
+ length: suggestedLength,
+ };
+ }
+ }
+ warn('Invalid "Length1" property in Type1 font -- trying to recover.');
+ stream.pos = streamStartPos; // Reset the stream position.
+
+ var SCAN_BLOCK_LENGTH = 2048;
+ var actualLength;
+ while (true) {
+ var scanBytes = stream.peekBytes(SCAN_BLOCK_LENGTH);
+ block = findBlock(scanBytes, EEXEC_SIGNATURE, 0);
+
+ if (block.length === 0) {
+ break;
+ }
+ stream.pos += block.length; // Update the stream position.
+
+ if (block.found) {
+ actualLength = stream.pos - streamStartPos;
+ break;
+ }
+ }
+ stream.pos = streamStartPos; // Reset the stream position.
+
+ if (actualLength) {
+ return {
+ stream: new Stream(stream.getBytes(actualLength)),
+ length: actualLength,
+ };
+ }
+ warn('Unable to recover "Length1" property in Type1 font -- using as is.');
+ return {
+ stream: new Stream(stream.getBytes(suggestedLength)),
+ length: suggestedLength,
+ };
+ }
+
+ function getEexecBlock(stream, suggestedLength) {
+ // We should ideally parse the eexec block to ensure that `suggestedLength`
+ // is correct, so we don't truncate the block data if it's too small.
+ // However, this would also require checking if the fixed-content portion
+ // exists (using the 'Length3' property), and ensuring that it's valid.
+ //
+ // Given that `suggestedLength` almost always is correct, all the validation
+ // would require a great deal of unnecessary parsing for most fonts.
+ // To save time, we always fetch the entire stream instead, which also avoid
+ // issues if `suggestedLength` is huge (see comment in `getHeaderBlock`).
+ //
+ // NOTE: This means that the function can include the fixed-content portion
+ // in the returned eexec block. In practice this does *not* seem to matter,
+ // since `Type1Parser_extractFontProgram` will skip over any non-commands.
+ var eexecBytes = stream.getBytes();
+ return {
+ stream: new Stream(eexecBytes),
+ length: eexecBytes.length,
+ };
+ }
+
function Type1Font(name, file, properties) {
// Some bad generators embed pfb file as is, we have to strip 6-byte header.
// Also, length1 and length2 might be off by 6 bytes as well.
@@ -3654,8 +3769,9 @@ var Type1Font = (function Type1FontClosure() {
}
// Get the data block containing glyphs and subrs informations
- var headerBlock = new Stream(file.getBytes(headerBlockLength));
- var headerBlockParser = new Type1Parser(headerBlock);
+ var headerBlock = getHeaderBlock(file, headerBlockLength);
+ headerBlockLength = headerBlock.length;
+ var headerBlockParser = new Type1Parser(headerBlock.stream);
headerBlockParser.extractFontHeader(properties);
if (pfbHeaderPresent) {
@@ -3665,8 +3781,9 @@ var Type1Font = (function Type1FontClosure() {
}
// Decrypt the data blocks and retrieve it's content
- var eexecBlock = new Stream(file.getBytes(eexecBlockLength));
- var eexecBlockParser = new Type1Parser(eexecBlock, true);
+ var eexecBlock = getEexecBlock(file, eexecBlockLength);
+ eexecBlockLength = eexecBlock.length;
+ var eexecBlockParser = new Type1Parser(eexecBlock.stream, true);
var data = eexecBlockParser.extractFontProgram();
for (var info in data.properties) {
properties[info] = data.properties[info];
diff --git a/test/pdfs/.gitignore b/test/pdfs/.gitignore
index b675adf..9cdc808 100644
--- a/test/pdfs/.gitignore
+++ b/test/pdfs/.gitignore
@@ -49,6 +49,8 @@
!issue3207r.pdf
!issue3263r.pdf
!issue3879r.pdf
+!issue5686.pdf
+!issue3928.pdf
!close-path-bug.pdf
!issue6019.pdf
!issue6621.pdf
diff --git a/test/pdfs/issue3928.pdf b/test/pdfs/issue3928.pdf
new file mode 100644
index 0000000..f47c146
Binary files /dev/null and b/test/pdfs/issue3928.pdf differ
diff --git a/test/pdfs/issue5686.pdf b/test/pdfs/issue5686.pdf
new file mode 100644
index 0000000..6525d11
Binary files /dev/null and b/test/pdfs/issue5686.pdf differ
diff --git a/test/test_manifest.json b/test/test_manifest.json
index 6113fcd..c0efbe3 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -1443,6 +1443,22 @@
"link": false,
"type": "eq"
},
+ { "id": "issue5686",
+ "file": "pdfs/issue5686.pdf",
+ "md5": "78d16b9df07a355ad00d70504a9194f8",
+ "rounds": 1,
+ "link": false,
+ "type": "eq",
+ "about": "Type1 font where Length1/Length2 are slightly incorrect."
+ },
+ { "id": "issue3928",
+ "file": "pdfs/issue3928.pdf",
+ "md5": "1963493f843e981cbe768b707ef7f08a",
+ "rounds": 1,
+ "link": false,
+ "type": "eq",
+ "about": "Type1 font where Length1/Length2 are several orders of magnitude too large."
+ },
{ "id": "html5checker",
"file": "pdfs/html5checker.pdf",
"md5": "74bbd80d1e7eb5f2951582233ef9ebab",
--
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