var util = require('util'), Match = require ('../match'); /** * This class matches UTF-16 and UTF-32, both big- and little-endian. The * BOM will be used if it is present. */ module.exports.UTF_16BE = function() { this.name = function() { return "UTF-16BE"; }; this.match = function(det) { var input = det.fRawInput; if (input.length>=2 && ((input[0] & 0xFF) == 0xFE && (input[1] & 0xFF) == 0xFF)) { var confidence = 100; return new Match(det, this, confidence); } // TODO: Do some statistics to check for unsigned UTF-16BE return null; } }; module.exports.UTF_16LE = function() { this.name = function() { return "UTF-16LE"; }; this.match = function(det) { var input = det.fRawInput; if (input.length >= 2 && ((input[0] & 0xFF) == 0xFF && (input[1] & 0xFF) == 0xFE)) { // An LE BOM is present. if (input.length>=4 && input[2] == 0x00 && input[3] == 0x00) { // It is probably UTF-32 LE, not UTF-16 return null; } var confidence = 100; return new Match(det, this, confidence); } // TODO: Do some statistics to check for unsigned UTF-16LE return null; } }; function UTF_32() {}; UTF_32.prototype.match = function(det) { var input = det.fRawInput, limit = (det.fRawLength / 4) * 4, numValid = 0, numInvalid = 0, hasBOM = false, confidence = 0; if (limit==0) { return null; } if (this.getChar(input, 0) == 0x0000FEFF) { hasBOM = true; } for(var i = 0; i < limit; i += 4) { var ch = this.getChar(input, i); if (ch < 0 || ch >= 0x10FFFF || (ch >= 0xD800 && ch <= 0xDFFF)) { numInvalid += 1; } else { numValid += 1; } } // Cook up some sort of confidence score, based on presence of a BOM // and the existence of valid and/or invalid multi-byte sequences. if (hasBOM && numInvalid==0) { confidence = 100; } else if (hasBOM && numValid > numInvalid*10) { confidence = 80; } else if (numValid > 3 && numInvalid == 0) { confidence = 100; } else if (numValid > 0 && numInvalid == 0) { confidence = 80; } else if (numValid > numInvalid*10) { // Probably corrupt UTF-32BE data. Valid sequences aren't likely by chance. confidence = 25; } // return confidence == 0 ? null : new CharsetMatch(det, this, confidence); return confidence == 0 ? null : new Match(det, this, confidence); }; module.exports.UTF_32BE = function() { this.name = function() { return "UTF-32BE"; }; this.getChar = function(input, index) { return (input[index + 0] & 0xFF) << 24 | (input[index + 1] & 0xFF) << 16 | (input[index + 2] & 0xFF) << 8 | (input[index + 3] & 0xFF); }; }; util.inherits(module.exports.UTF_32BE, UTF_32); module.exports.UTF_32LE = function() { this.name = function() { return "UTF-32LE"; }; this.getChar = function(input, index) { return (input[index + 3] & 0xFF) << 24 | (input[index + 2] & 0xFF) << 16 | (input[index + 1] & 0xFF) << 8 | (input[index + 0] & 0xFF); }; }; util.inherits(module.exports.UTF_32LE, UTF_32);