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Removes vtmx and vhea tables; sanitizes fpgm and prep

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This commit is contained in:
Yury Delendik 2012-11-07 11:32:55 -06:00
parent 57ed958318
commit 05148e8e7d
3 changed files with 173 additions and 25 deletions
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176
src/fonts.js
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@ -3014,17 +3014,10 @@ var Font = (function FontClosure() {
};
function sanitizeMetrics(font, header, metrics, numGlyphs) {
if (!header && !metrics)
return;
// The vhea/vmtx tables are not required, so it happens that
// some fonts embed a vmtx table without a vhea table. In this
// situation the sanitizer assume numOfLongVerMetrics = 1. As
// a result it tries to read numGlyphs - 1 SHORT from the vmtx
// table, and if it is not possible, the font is rejected.
// So remove the vmtx table if there is no vhea table.
if (!header && metrics) {
metrics.data = null;
if (!header) {
if (metrics) {
metrics.data = null;
}
return;
}
@ -3256,17 +3249,148 @@ var Font = (function FontClosure() {
return true;
}
var TTOpsStackDeltas = [
0, 0, 0, 0, 0, 0, 0, 0, -2, -2, -2, -2, 0, 0, -2, -5,
-1, -1, -1, -1, -1, -1, -1, -1, 0, 0, -1, 0, -1, -1, -1, -1,
1, -1, -999, 0, 1, 0, 0, -2, 0, -1, -2, -1, -999, -999, -1, -1,
0, 0, -999, -999, -1, -1, -1, -1, -2, -999, -2, -2, -2, 0, -2, -2,
0, 0, -2, 0, -2, 0, 0, 0, -2, -1, -1, 1, 1, 0, 0, -1,
-1, -1, -1, -1, -1, -1, 0, 0, -1, 0, -1, -1, 0, -999, -1, -1,
-1, -1, -1, -1, 0, 0, 0, 0, -1, -1, 0, 0, 0, 0, 0, 0,
-2, -999, -999, -999, -999, -999, -1, -1, -2, -2, 0, 0, 0, 0, -1, -1,
-999, -2, -2, 0, 0, -1, -2, -2, 0, -999, 0, 0, 0, -1, -2];
// 0xC0-DF == -1 and 0xE0-FF == -2
function sanitizeTTProgram(table, ttContext) {
var data = table.data;
var i = 0, n, lastEndf = 0, lastDeff = 0;
var stack = [];
var tooComplexToFollowFunctions =
ttContext.tooComplexToFollowFunctions;
for (var ii = data.length; i < ii;) {
var op = data[i++];
// The TrueType instruction set docs can be found at
// https://developer.apple.com/fonts/TTRefMan/RM05/Chap5.html
if (op === 0x40) { // NPUSHB - pushes n bytes
n = data[i++];
for (var j = 0; j < n; j++) {
stack.push(data[i++]);
}
} else if (op === 0x41) { // NPUSHW - pushes n words
n = data[i++];
for (var j = 0; j < n; j++) {
var b = data[i++];
stack.push((b << 8) | data[i++]);
}
} else if ((op & 0xF8) === 0xB0) { // PUSHB - pushes bytes
n = op - 0xB0 + 1;
for (var j = 0; j < n; j++) {
stack.push(data[i++]);
}
} else if ((op & 0xF8) === 0xB8) { // PUSHW - pushes words
n = op - 0xB8 + 1;
for (var j = 0; j < n; j++) {
var b = data[i++];
stack.push((b << 8) | data[i++]);
}
} else if (op === 0x2B && !tooComplexToFollowFunctions) { // CALL
// collecting inforamtion about which functions are used
var funcId = stack[stack.length - 1];
ttContext.functionsUsed[funcId] = true;
if (i >= 2 && data[i - 2] === 0x2B) {
// all data in stack, calls are performed in sequence
tooComplexToFollowFunctions = true;
}
} else if (op === 0x2C && !tooComplexToFollowFunctions) { // FDEF
// collecting inforamtion about which functions are defined
lastDeff = i;
var funcId = stack[stack.length - 1];
ttContext.functionsDefined[funcId] = true;
if (i >= 2 && data[i - 2] === 0x2D) {
// all function ids in stack, FDEF/ENDF perfomed in sequence
tooComplexToFollowFunctions = true;
}
} else if (op === 0x2D) { // ENDF - end of function
lastEndf = i;
} else if (op === 0x89) { // IDEF - instruction definition
// recording it as a function to track ENDF
lastDeff = i;
}
// Adjusting stack not extactly, but just enough to get function id
var stackDelta = op <= 0x8E ? TTOpsStackDeltas[op] :
op >= 0xC0 && op <= 0xDF ? -1 : op >= 0xE0 ? -2 : 0;
while (stackDelta < 0 && stack.length > 0) {
stack.pop();
stackDelta++;
}
while (stackDelta > 0) {
stack.push(NaN); // pushing any number into stack
stackDelta--;
}
}
ttContext.tooComplexToFollowFunctions = tooComplexToFollowFunctions;
var content = [data];
if (i > data.length) {
content.push(new Uint8Array(i - data.length));
}
if (lastDeff > lastEndf) {
// new function definition started, but not finished
// complete function by [CLEAR, ENDF]
content.push(new Uint8Array([0x22, 0x2D]));
}
if (ttContext.defineMissingFunctions && !tooComplexToFollowFunctions) {
for (var j = 0, jj = ttContext.functionsUsed.length; j < jj; j++) {
if (!ttContext.functionsUsed[j] || ttContext.functionsDefined[j]) {
continue;
}
// function is used, but not defined
// creating empty one [PUSHB, function-id, FDEF, ENDF]
content.push(new Uint8Array([0xB0, j, 0x2C, 0x2D]));
}
}
if (content.length > 1) {
// concatenating the content items
var newLength = 0;
for (var j = 0, jj = content.length; j < jj; j++) {
newLength += content[j].length;
}
newLength = (newLength + 3) & ~3;
var result = new Uint8Array(newLength);
var pos = 0;
for (var j = 0, jj = content.length; j < jj; j++) {
result.set(content[j], pos);
pos += content[j].length;
}
table.data = result;
table.length = newLength;
}
}
function sanitizeTTPrograms(fpgm, prep) {
var ttContext = {
functionsDefined: [],
functionsUsed: [],
tooComplexToFollowFunctions: false
};
if (prep) {
// collecting prep functions info first
sanitizeTTProgram(prep, ttContext);
}
if (fpgm) {
ttContext.defineMissingFunctions = true;
sanitizeTTProgram(fpgm, ttContext);
}
}
// Check that required tables are present
var requiredTables = ['OS/2', 'cmap', 'head', 'hhea',
'hmtx', 'maxp', 'name', 'post'];
var optionalTables = ['cvt ', 'fpgm', 'glyf', 'loca', 'prep',
'CFF ', 'VORG', 'vhea', 'vmtx'];
var header = readOpenTypeHeader(font);
var numTables = header.numTables;
var cmap, post, maxp, hhea, hmtx, vhea, vmtx, head, loca, glyf, os2;
var cmap, post, maxp, hhea, hmtx, head, os2;
var glyf, fpgm, loca, prep, cvt;
var tables = [];
for (var i = 0; i < numTables; i++) {
var table = readTableEntry(font);
@ -3288,18 +3412,19 @@ var Font = (function FontClosure() {
os2 = table;
requiredTables.splice(index, 1);
} else if (optionalTables.indexOf(table.tag) < 0) {
// skipping table if it's not a required or optional table
continue;
} else {
if (table.tag == 'vmtx')
vmtx = table;
else if (table.tag == 'vhea')
vhea = table;
else if (table.tag == 'loca')
if (table.tag == 'loca')
loca = table;
else if (table.tag == 'glyf')
glyf = table;
else if (table.tag == 'fpgm')
fpgm = table;
else if (table.tag == 'prep')
prep = table;
else if (table.tag == 'cvt ')
cvt = table;
else // skipping table if it's not a required or optional table
continue;
}
tables.push(table);
}
@ -3324,14 +3449,15 @@ var Font = (function FontClosure() {
os2 = null;
}
// Ensure the [h/v]mtx tables contains the advance width and
// Ensure the hmtx table contains the advance width and
// sidebearings information for numGlyphs in the maxp table
font.pos = (font.start || 0) + maxp.offset;
var version = int16(font.getBytes(4));
var numGlyphs = int16(font.getBytes(2));
sanitizeMetrics(font, hhea, hmtx, numGlyphs);
sanitizeMetrics(font, vhea, vmtx, numGlyphs);
sanitizeTTPrograms(fpgm, prep);
var isGlyphLocationsLong = int16([head.data[50], head.data[51]]);
if (head && loca && glyf) {

21
test/font/font_fpgm_spec.js Normal file
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1
test/font/font_test.html
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@ -39,6 +39,7 @@
<script type="text/javascript" src="font_core_spec.js"></script>
<script type="text/javascript" src="font_os2_spec.js"></script>
<script type="text/javascript" src="font_post_spec.js"></script>
<script type="text/javascript" src="font_fpgm_spec.js"></script>
<script type="text/javascript">
'use strict';