From eb8f4e83434b20644aea30bff9755b29199c29b5 Mon Sep 17 00:00:00 2001
From: mduan <duan.mack@gmail.com>
Date: Tue, 8 Jan 2013 15:28:08 -0800
Subject: [PATCH] Handle some illegal characters in hex string
Do not throw exception when hex strings are in the wrong format
Currently pdf.js is throwing an exception for the following hex string:
`<7 0 2 15 5 2 2 2 4 3 2 4>`
The issue is that the 15 is not a valid hex character so pdf.js ends up
throwing an exception.
This diff changes the parser to process the above hex string as follow:
`70 21 55 2 24 32` (Note: the final 4 of the hex string is ignored)
replicating the behaviour of MuPDF, and doesn't throw an exception.
---
src/parser.js | 42 +++++++++++++++++++++++-----------------
test/unit/parser_spec.js | 11 +++++++++++
2 files changed, 35 insertions(+), 18 deletions(-)
diff --git a/src/parser.js b/src/parser.js
index 6987bbf03..6f738b80e 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -460,28 +460,34 @@ var Lexer = (function LexerClosure() {
getHexString: function Lexer_getHexString(ch) {
var str = '';
var stream = this.stream;
- for (;;) {
+ var isFirstHex = true;
+ var firstDigit;
+ var secondDigit;
+ while (true) {
ch = stream.getChar();
- if (ch == '>') {
- break;
- }
if (!ch) {
warn('Unterminated hex string');
break;
- }
- if (specialChars[ch.charCodeAt(0)] != 1) {
- var x, x2;
- if ((x = toHexDigit(ch)) == -1)
- error('Illegal character in hex string: ' + ch);
-
- ch = stream.getChar();
- while (specialChars[ch.charCodeAt(0)] == 1)
- ch = stream.getChar();
-
- if ((x2 = toHexDigit(ch)) == -1)
- error('Illegal character in hex string: ' + ch);
-
- str += String.fromCharCode((x << 4) | x2);
+ } else if (ch === '>') {
+ break;
+ } else if (specialChars[ch.charCodeAt(0)] === 1) {
+ continue;
+ } else {
+ if (isFirstHex) {
+ firstDigit = toHexDigit(ch);
+ if (firstDigit === -1) {
+ warn("Ignoring invalid character '" + ch + "' in hex string");
+ continue;
+ }
+ } else {
+ secondDigit = toHexDigit(ch);
+ if (secondDigit === -1) {
+ warn("Ignoring invalid character '" + ch + "' in hex string");
+ continue;
+ }
+ str += String.fromCharCode((firstDigit << 4) | secondDigit);
+ }
+ isFirstHex = !isFirstHex;
}
}
return str;
diff --git a/test/unit/parser_spec.js b/test/unit/parser_spec.js
index 69a6be954..a9dcc2e74 100644
--- a/test/unit/parser_spec.js
+++ b/test/unit/parser_spec.js
@@ -12,6 +12,17 @@ describe('parser', function() {
expect(result).toEqual(11.234);
});
+
+ it('should not throw exception on bad input', function() {
+ // '8 0 2 15 5 2 2 2 4 3 2 4'
+ // should be parsed as
+ // '80 21 55 22 24 32'
+ var input = new StringStream('7 0 2 15 5 2 2 2 4 3 2 4>');
+ var lexer = new Lexer(input);
+ var result = lexer.getHexString('<');
+
+ expect(result).toEqual('p!U"$2');
+ });
});
});