Prepare the way to decode Type1 charStrings
This commit is contained in:
Vivien Nicolas
parent
fe11af4b57
commit
3064305d91
232
PDFFont.js
232
PDFFont.js
@ -1,10 +1,39 @@
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var Type1Parser = function(aAsciiStream, aBinaryStream) {
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var lexer = new Lexer(aAsciiStream);
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var Type1Parser = function(aLexer) {
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var lexer = aLexer;
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// Turn on this flag for additional debugging logs
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var debug = false;
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/*
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var dump = function(aData) {
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if (debug)
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log(aData);
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};
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/*
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* Decrypt a Sequence of Ciphertext Bytes to Produce the Original Sequence
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* of Plaintext Bytes. The function took a key as a parameter which can be
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* for decrypting the eexec block of for decoding charStrings.
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*/
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var kEexecEncryptionKey = 55665;
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var kCharStringsEncryptionKey = 4330;
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function decrypt(aStream, aKey, aDiscardNumber) {
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var r = aKey, c1 = 52845, c2 = 22719;
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var decryptedString = [];
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var value = null;
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var count = aStream.length;
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for (var i = 0; i < count; i++) {
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value = aStream.getByte();
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decryptedString[i] = String.fromCharCode(value ^ (r >> 8));
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r = ((value + r) * c1 + c2) & ((1 << 16) - 1);
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}
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return decryptedString.slice(aDiscardNumber);
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}
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/*
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* The operand stack holds arbitrary PostScript objects that are the operands
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* and results of PostScript operators being executed. The interpreter pushes
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* objects on the operand stack when it encounters them as literal data in a
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@ -13,8 +42,28 @@ var Type1Parser = function(aLexer) {
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* operator returns one or more results, it does so by pushing them on the
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* operand stack.
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*/
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var operandStack = [];
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var operandStack = {
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__innerStack__: [],
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push: function(aOperand) {
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this.__innerStack__.push(aOperand);
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},
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pop: function() {
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return this.__innerStack__.pop();
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},
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peek: function() {
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return this.__innerStack__[this.__innerStack__.length - 1];
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},
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get length() {
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return this.__innerStack__.length;
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}
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};
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// Flag indicating if the topmost operand of the operandStack is an array
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var operandIsArray = false;
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/*
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* The dictionary stack holds only dictionary objects. The current set of
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@ -28,7 +77,6 @@ var Type1Parser = function(aLexer) {
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var systemDict = new Dict(),
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globalDict = new Dict(),
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userDict = new Dict();
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var dictionaryStack = {
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__innerStack__: [systemDict, globalDict],
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@ -46,10 +94,12 @@ var Type1Parser = function(aLexer) {
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peek: function() {
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return this.__innerStack__[this.__innerStack__.length - 1];
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},
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get length() {
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return this.__innerStack__.length;
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}
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}
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var currentDict = dictionaryStack.peek();
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/*
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* The execution stack holds executable objects (mainly procedures and files)
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@ -61,150 +111,134 @@ var Type1Parser = function(aLexer) {
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* object off the execution stack and resumes executing the suspended object
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* beneath it.
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*/
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var isExecutionStack = false;
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var executionStack = [];
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/* Stub to inhibit the logs */
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this.getObj = function() {
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var obj = lexer.getObj();
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if (isExecutionStack && !IsCmd(obj, "}") && !IsCmd(obj, "]")) {
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executionStack.push(obj);
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if (operandIsArray && !IsCmd(obj, "}") && !IsCmd(obj, "]")) {
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operandStack.peek().push(obj);
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this.getObj();
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} else if (IsCmd(obj, "{") || IsCmd(obj, "[")) {
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dump("Start Array: " + obj);
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operandStack.push([]);
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operandIsArray = true;
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this.getObj();
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} else if (IsCmd(obj, "}") || IsCmd(obj, "]")) {
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dump("End Array: " + obj);
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operandIsArray = false;
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this.getObj();
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} else if (IsBool(obj) || IsInt(obj) || IsNum(obj) || IsString(obj)) {
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log("Value: " + obj);
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dump("Value: " + obj);
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operandStack.push(obj);
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this.getObj();
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} else if (IsCmd(obj, "dup") || IsCmd(obj, "readonly") ||
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IsCmd(obj, "currentdict") || IsCmd(obj, "currentfile")) {
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} else if (IsCmd(obj, "dup")) {
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dump("Duplicate");
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operandStack.push(operandStack.peek());
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this.getObj();
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} else if (IsCmd(obj, "currentdict")) {
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dump("currentdict");
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operandStack.push(dictionaryStack.peek());
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this.getObj();
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} else if (IsCmd(obj, "systemdict")) {
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dump("systemdict");
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operandStack.push(systemDict);
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this.getObj();
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} else if (IsCmd(obj, "readonly") || IsCmd(obj, "executeonly") ||
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IsCmd(obj, "currentfile")) {
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// Do nothing for the moment
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this.getObj();
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} else if (IsName(obj)) {
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log("Name: " + obj.name);
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dump("Name: " + obj.name);
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operandStack.push(obj.name);
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this.getObj();
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} else if (IsCmd(obj, "dict")) {
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log("Dict: " + obj);
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// XXX handling of dictionary is wrong here
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dump("Dict: " + obj);
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var size = operandStack.pop();
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var name = operandStack.pop();
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if (!name) {
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log ("Creating the global dict");
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currentDict = dictionaryStack.peek();
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} else {
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var dict = new Dict();
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log("Assign name: " + name + " for the dictionary");
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currentDict.set(name, dict);
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dictionaryStack.push(dict);
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}
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var dict = new Dict(size);
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operandStack.push(dict);
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this.getObj();
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} else if (IsCmd(obj, "begin")) {
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log("begin a dictionary");
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currentDict = dictionaryStack.peek();
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dump("begin a dictionary");
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dictionaryStack.push(operandStack.pop());
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this.getObj();
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} else if (IsCmd(obj, "end")) {
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log("Ending a dictionary");
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dump("Ending a dictionary");
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dictionaryStack.pop();
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currentDict = dictionaryStack.peek();
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this.getObj();
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} else if (IsCmd(obj, "def")) {
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if (executionStack.length) {
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var value = [];
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while (executionStack.length)
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value.push(executionStack.shift());
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} else {
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var value = operandStack.pop();
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}
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var value = operandStack.pop();
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var key = operandStack.pop();
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// XXX this happen because of a bad way to handle dictionary
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if (key) {
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log("def: " + key + " = " + value);
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currentDict.set(key, value);
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}
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this.getObj();
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} else if (IsCmd(obj, "{")) {
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log("Start Proc: " + obj);
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executionStack = [];
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isExecutionStack = true;
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this.getObj();
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} else if (IsCmd(obj, "}")) {
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log("End Proc: " + obj);
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isExecutionStack = false;
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this.getObj();
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} else if (IsCmd(obj, "[")) {
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isExecutionStack = true;
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executionStack = [];
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this.getObj();
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log("Start array: " + obj);
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} else if (IsCmd(obj, "]")) {
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log("End array: " + obj);
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isExecutionStack = false;
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dump("def: " + key + " = " + value);
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dictionaryStack.peek().set(key, value);
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this.getObj();
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} else if (IsCmd(obj, "eexec")) {
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return; // end of the ASCII header
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// All the first segment data has been read, decrypt the second segment
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// and start interpreting it in order to decode it
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var eexecString = decrypt(aBinaryStream, kEexecEncryptionKey, 4).join("");
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lexer = new Lexer(new StringStream(eexecString));
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this.getObj();
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} else if (IsCmd(obj, "known")) {
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dump("known");
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var name = operandStack.pop();
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var dict = operandStack.pop();
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// returns dict.hasKey(name);
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this.getObj();
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} else if (IsCmd(obj, "RD")) {
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dump("RD");
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var size = operandStack.pop();
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var key = operandStack.pop();
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var stream = lexer.stream.makeSubStream(lexer.stream.pos, size);
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var charString = decrypt(stream, kCharStringsEncryptionKey, 4).join("");
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// XXX do we want to store that on the top dictionary or somewhere else
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dictionaryStack.peek().set(key, new StringStream(charString));
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log (new StringStream(charString));
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this.getObj();
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} else if (IsCmd(obj, "LenIV")) {
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error("LenIV: argh! we need to modify the length of discard characters for charStrings");
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} else {
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log("Getting an unknow token, adding it to the stack just in case");
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log(obj);
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dump("Getting an unknow token, adding it to the stack just in case");
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dump(obj);
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operandStack.push(obj);
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this.getObj();
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}
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return currentDict;
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return operandStack.peek();
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}
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};
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var hack = false;
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var Type1Font = function(aFontName, aFontFile) {
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// All type1 font program should begin with the comment %!
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// All Type1 font program should begin with the comment %!
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var validHeader = aFontFile.getByte() == 0x25 && aFontFile.getByte() == 0x21;
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if (!validHeader)
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error("Invalid file header");
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var programType = "PS-AdobeFont";
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for (var i = 0; i< programType.length; i++)
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for (var i = 0; i < programType.length; i++)
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aFontFile.getChar();
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// Ignore the '-' separator
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aFontFile.getChar();
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var version = parseFloat(aFontFile.getChar() + aFontFile.getChar() + aFontFile.getChar());
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if (!hack) {
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log(aFontName);
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log("Version is: " + version);
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var ASCIIStream = aFontFile.makeSubStream(0, aFontFile.dict.get("Length1"), aFontFile.dict);
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this.parser = new Type1Parser(new Lexer(ASCIIStream));
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var binaryStream = aFontFile.makeSubStream(aFontFile.dict.get("Length1"), aFontFile.dict.get("Length2"), aFontFile.dict);
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this.parser = new Type1Parser(ASCIIStream, binaryStream);
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var fontDictionary = this.parser.getObj();
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log(fontDictionary + "\t" +
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"fontInfo: " + fontDictionary.get("FontInfo") + "\t" +
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"charStrings: " + fontDictionary.get("charStrings"));
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var binaryStream = aFontFile.makeSubStream(aFontFile.dict.get("Length1"), aFontFile.dict.get("Length2"), aFontFile.dict);
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function decrypt(aBinaryStream, aKey) {
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var c1 = 52845, c2 = 22719;
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var R = aKey;
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var streamSize = aBinaryStream.length;
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var decryptedString = [];
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var value = null;
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for (var i = 0; i < streamSize; i++) {
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value = aBinaryStream.getByte();
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decryptedString[i] = String.fromCharCode(value ^ (R >> 8));
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R = ((value + R) * c1 + c2) & ((1 << 16) - 1);
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}
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return decryptedString.slice(4);
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}
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var eexecString = decrypt(binaryStream, 55665).join("");
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log(eexecString);
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TODO("decrypt charStrings data with the key 4330");
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log(fontDictionary + "\t" + "fontInfo: " + fontDictionary.get("FontInfo"));
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hack = true;
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}
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