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Attempt to recover valid format 3 FDSelect data from broken CFF fonts (bug 1146106)

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According to the CFF specification, see http://partners.adobe.com/public/developer/en/font/5176.CFF.pdf#G3.46884, for `format 3` FDSelect data: "The first range must have a ‘first’ GID of 0".
Since the PDF file (attached in the bug) violates that part of the specification, this patch tries to recover valid FDSelect data to prevent OTS from rejecting the font.

Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1146106.
This commit is contained in:
Jonas Jenwald 2016-05-26 17:34:00 +02:00
parent bd47440e79
commit 6260fc09a3
5 changed files with 54 additions and 12 deletions
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23
src/core/cff_parser.js
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@ -856,8 +856,8 @@ var CFFParser = (function CFFParserClosure() {
var start = pos;
var bytes = this.bytes;
var format = bytes[pos++];
var fdSelect = [];
var i;
var fdSelect = [], rawBytes;
var i, invalidFirstGID = false;
switch (format) {
case 0:
@ -865,11 +865,18 @@ var CFFParser = (function CFFParserClosure() {
var id = bytes[pos++];
fdSelect.push(id);
}
rawBytes = bytes.subarray(start, pos);
break;
case 3:
var rangesCount = (bytes[pos++] << 8) | bytes[pos++];
for (i = 0; i < rangesCount; ++i) {
var first = (bytes[pos++] << 8) | bytes[pos++];
if (i === 0 && first !== 0) {
warn('parseFDSelect: The first range must have a first GID of 0' +
' -- trying to recover.');
invalidFirstGID = true;
first = 0;
}
var fdIndex = bytes[pos++];
var next = (bytes[pos] << 8) | bytes[pos + 1];
for (var j = first; j < next; ++j) {
@ -878,13 +885,19 @@ var CFFParser = (function CFFParserClosure() {
}
// Advance past the sentinel(next).
pos += 2;
rawBytes = bytes.subarray(start, pos);
if (invalidFirstGID) {
rawBytes[3] = rawBytes[4] = 0; // Adjust the first range, first GID.
}
break;
default:
error('Unknown fdselect format ' + format);
error('parseFDSelect: Unknown format "' + format + '".');
break;
}
var end = pos;
return new CFFFDSelect(fdSelect, bytes.subarray(start, end));
assert(fdSelect.length === length, 'parseFDSelect: Invalid font data.');
return new CFFFDSelect(fdSelect, rawBytes);
}
};
return CFFParser;