jar-reader.js

var readJarContent = ((function() {
  function BitReader(reader)
  {
      this.bitsLength = 0;
      this.bits = 0;
      this.reader = reader;
      this.readBit = function() {
          if(this.bitsLength == 0) {
              var nextByte = this.reader.readByte();
              if(nextByte < 0) throw new "Unexpected end of stream";
              this.bits = nextByte;
              this.bitsLength = 8;
          }            

          var bit = (this.bits & 1) != 0;
          this.bits >>= 1;
          --this.bitsLength;
          return bit;
      };
      this.align = function() { this.bitsLength = 0; }
      this.readLSB = function(length) {
          var data = 0;
          for(var i=0;i<length;++i)
          {
               if(this.readBit()) data |= 1 << i;
          }
          return data;
      };
      this.readMSB = function(length) {
          var data = 0;
          for(var i=0;i<length;++i)
          {                 
               if(this.readBit()) data = (data << 1) | 1; else data <<= 1;
          }
          return data;
      };
  }

  /* inflate stuff - RFC 1950 */

  var staticCodes, staticDistances;

  var encodedLengthStart = new Array(3,4,5,6,7,8,9,10,
          11,13,15,17,19,23,27,31,35,43,51,59,67,83,99,
          115,131,163,195,227,258);
          
  var encodedLengthAdditionalBits = new Array(0,0,0,0,0,0,0,0,
          1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0);

  var encodedDistanceStart = new Array(1,2,3,4, 5,7,9,
          13,17,25, 33,49,65, 97,129,193,257,385,513,769,1025,1537,2049,
          3073,4097,6145,8193,12289,16385,24577);

  var encodedDistanceAdditionalBits = new Array(0,0,0,0,1,1,2,2,3,3,4,4,
          5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13);

  var clenMap = new Array(16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15);

  function buildCodes(lengths)
  {
      var codes = new Array(lengths.length);
      var maxBits = lengths[0];
      for (var i=1; i<lengths.length; i++)
      {
          if (maxBits < lengths[i]) maxBits = lengths[i];
      }

      var bitLengthsCount = new Array(maxBits + 1);
      for (var i=0; i<=maxBits; i++) bitLengthsCount[i]=0;
      
      for (var i=0; i<lengths.length; i++)
      {
          ++bitLengthsCount[lengths[i]];
      }

      var nextCode = new Array(maxBits + 1);
      var code = 0;
      bitLengthsCount[0] = 0;
      for (var bits=1; bits<=maxBits; bits++)
      {
          code = (code + bitLengthsCount[bits - 1]) << 1;
          nextCode[bits] = code;
      }

      for (var n=0; n<codes.length; n++)
      {
          var len = lengths[n];
          if (len != 0)
          {
              codes[n] = nextCode[len];
              nextCode[len]++;
          }
      }
      return codes;
  }

  function initializeStaticTrees()
  {
      var codes = new Array(288);
      var codesLengths = new Array(288);
      
      for (var i = 0; i <= 143; i++)
      {
          codes[i] = 0x0030 + i;
          codesLengths[i] = 8;
      }
      for (var i = 144; i <= 255; i++)
      {
          codes[i] = 0x0190 + i - 144;
          codesLengths[i] = 9;
      }
      for (var i = 256; i <= 279; i++)
      {
          codes[i] = 0x0000 + i - 256;
          codesLengths[i] = 7;
      }
      for (var i = 280; i <= 287; i++)
      {
          codes[i] = 0x00C0 + i - 280;
          codesLengths[i] = 8;
      }
      staticCodes = buildTree(codes, codesLengths);

      var distances = new Array(32);
      var distancesLengths = new Array(32);
      for (var i = 0; i <= 31; i++)
      {
          distances[i] = i;
          distancesLengths[i] = 5;
      }
      staticDistances = buildTree(distances, distancesLengths);
  }

  function buildTree(codes, lengths)
  {
      var nonEmptyCodes = new Array(0);
      for(var i=0; i<codes.length; ++i)
      {
          if(lengths[i] > 0)
          {
              var code = new Object();
              code.bits = codes[i];
              code.length = lengths[i];
              code.index = i;
              nonEmptyCodes.push(code);
          }
      }
      return buildTreeBranch(nonEmptyCodes, 0, 0);
  }

  function buildTreeBranch(codes, prefix, prefixLength)
  {
      if(codes.length == 0) return null;
      
      var zeros = new Array(0);
      var ones = new Array(0);
      var branch = new Object();
      branch.isLeaf = false;
      for(var i=0; i<codes.length; ++i)
      {
          if(codes[i].length == prefixLength && codes[i].bits == prefix)
          {
              branch.isLeaf = true;
              branch.index = codes[i].index;
              break;
          }
          else
          {
              var nextBit = ((codes[i].bits >> (codes[i].length - prefixLength - 1)) & 1) > 0;
              if(nextBit)
              {
                  ones.push(codes[i]);
              }
              else
              {
                  zeros.push(codes[i]);
              }
          }
      }
      if(!branch.isLeaf)
      {
          branch.zero = buildTreeBranch(zeros, (prefix << 1), prefixLength + 1);
          branch.one = buildTreeBranch(ones, (prefix << 1) | 1, prefixLength + 1);
      }
      return branch;
  }

  function readDynamicTrees(bitReader)
  {
      var hlit = bitReader.readLSB(5) + 257;
      var hdist = bitReader.readLSB(5) + 1;
      var hclen = bitReader.readLSB(4) + 4;
      
      var clen = new Array(19);
      for(var i=0; i<clen.length; ++i) clen[i] = 0;
      for(var i=0; i<hclen; ++i) clen[clenMap[i]] = bitReader.readLSB(3);
      
      var clenCodes = buildCodes(clen);
      var clenTree = buildTree(clenCodes, clen);
      
      var lengthsSequence = new Array(0);
      while(lengthsSequence.length < hlit + hdist)
      {
          var p = clenTree;
          while(!p.isLeaf)
          {
              p = bitReader.readBit() ? p.one : p.zero;
          }
          
          var code = p.index;
          if(code <= 15)
              lengthsSequence.push(code);
          else if(code == 16)
          {
              var repeat = bitReader.readLSB(2) + 3;
              for(var q=0; q<repeat; ++q)
                  lengthsSequence.push(lengthsSequence[lengthsSequence.length - 1]);
          }
          else if(code == 17)
          {
              var repeat = bitReader.readLSB(3) + 3;
              for(var q=0; q<repeat; ++q)
                  lengthsSequence.push(0);
          }
          else if(code == 18)
          {
              var repeat = bitReader.readLSB(7) + 11;
              for(var q=0; q<repeat; ++q)
                  lengthsSequence.push(0);
          }
      }
      
      var codesLengths = lengthsSequence.slice(0, hlit);
      var codes = buildCodes(codesLengths);
      var distancesLengths = lengthsSequence.slice(hlit, hlit + hdist);
      var distances = buildCodes(distancesLengths);
      
      var result = new Object();
      result.codesTree = buildTree(codes, codesLengths);
      result.distancesTree = buildTree(distances, distancesLengths);
      return result;
  }
          
  function Inflator(reader)
  {
      this.reader = reader;
      this.bitReader = new BitReader(reader);
      this.buffer = new Array(0);
      this.bufferPosition = 0;
      this.state = 0;
      this.blockFinal = false;
      this.readByte = function() {
          while(this.bufferPosition >= this.buffer.length)
          {
              var item = this.decodeItem();
              if(item == null) return -1;
              switch(item.itemType)
              {
                  case 0:
                      this.buffer = this.buffer.concat(item.array);
                      break;
                  case 2:
                      this.buffer.push(item.symbol);
                      break;
                  case 3:
                      var j = this.buffer.length - item.distance;
                      for(var i=0;i<item.length;i++)
                      {
                          this.buffer.push(this.buffer[j++]);
                      }
                      break;
              }
          }
          var symbol = this.buffer[this.bufferPosition++];
          if(this.bufferPosition > 0xC000)
          {
              var shift = this.buffer.length - 0x8000;
              if(shift > this.bufferPosition) shift = this.bufferPosition;
              this.buffer.splice(0, shift);
              this.bufferPosition -= shift;
          }
          return symbol;
      }
      
      this.decodeItem = function() {
          if(this.state == 2) return null;
          
          var item;
          if(this.state == 0)
          {
              this.blockFinal = this.bitReader.readBit();
              var blockType = this.bitReader.readLSB(2);
              switch(blockType)
              {
                  case 0:
                      this.bitReader.align();
                      var len = this.bitReader.readLSB(16);
                      var nlen = this.bitReader.readLSB(16);
                      if((len & ~nlen) != len) throw "Invalid block type 0 length";
                      
                      item = new Object();
                      item.itemType = 0;
                      item.array = new Array(len);
                      for(var i=0;i<len;++i)
                      {
                          var nextByte = this.reader.readByte();
                          if(nextByte < 0) throw "Uncomplete block";
                          item.array[i] = nextByte;
                      }
                      if(this.blockFinal) this.state = 2;                 
                      return item;
                  case 1:
                      this.codesTree = staticCodes;
                      this.distancesTree = staticDistances;
                      this.state = 1;
                      break;
                  case 2:
                      var dynamicTrees = readDynamicTrees(this.bitReader);
                      this.codesTree = dynamicTrees.codesTree;
                      this.distancesTree = dynamicTrees.distancesTree;
                      this.state = 1;
                      break;
                  default:    
                      throw new "Invalid block type (3)";
              }
          }

          item = new Object();
          var p = this.codesTree;
          while(!p.isLeaf)
          {
              p = this.bitReader.readBit() ? p.one : p.zero;
          }
          if(p.index < 256)
          {
              item.itemType = 2;
              item.symbol = p.index;
          }
          else if(p.index > 256)
          {
              var lengthCode = p.index;
              if(lengthCode > 285) throw new "Invalid length code";
              
              var length = encodedLengthStart[lengthCode - 257];
              if(encodedLengthAdditionalBits[lengthCode - 257] > 0) 
              {
                  length += this.bitReader.readLSB(encodedLengthAdditionalBits[lengthCode - 257]);
              }
          
              p = this.distancesTree;
              while(!p.isLeaf)
              {
                  p = this.bitReader.readBit() ? p.one : p.zero;
              }
              
              var distanceCode = p.index;
              var distance = encodedDistanceStart[distanceCode];
              if(encodedDistanceAdditionalBits[distanceCode] > 0)
              {
                  distance += this.bitReader.readLSB(encodedDistanceAdditionalBits[distanceCode]);
              }
          
              item.itemType = 3;
              item.distance = distance;
              item.length = length;
          }
          else
          {
              item.itemType = 1;
              this.state = this.blockFinal ? 2 : 0;
          }
          return item;
      };
  }

  /* initialization */
  initializeStaticTrees();

  function DataReader(data) {
    var dataLength = data.length;
    var position = 0;
    this.readByte = function() {
      if (position >= dataLength) {
        return -1;
      }
      return data[position++];
    };
    this.readU16 = function() {
      var number = data[position] | (data[position + 1] << 8);
      position += 2;
      return number;
    };
    this.readU32 = function() {
      var number = (data[position] | (data[position + 1] << 8) | (data[position + 2] << 16) ) + 
        2 * (data[position + 3] << 23);
      position += 4;
      return number;
    };
    this.readBlock = function(size) {
      var result = [];
      result.length = size;
      for(var i = 0; i < size; ++i) {
        result[i] = data[position++];
      }
      return result;
    };
    this.seek = function(offset) {
      return (position += offset);
    };
    this.setPosition = function(newPosition) {
      position = newPosition;
    };
  }

  function readContent(data) {
    var reader = new DataReader(data);
    var entries = {};
    reader.setPosition(data.length - 22);
    if (reader.readU32() !== 0x06054b50) {
      throw new "Invalid jar file";
    }
    reader.seek(12);
    reader.setPosition(reader.readU32()); // set to directory
    var offsets = [];
    while (reader.readU32() === 0x02014b50) {
      reader.seek(16);
      var compressedSize = reader.readU32();
      var size = reader.readU32();      
      var extraLength = reader.readU16() +reader.readU16() + reader.readU16();
      reader.seek(8);
      var offset = reader.readU32();
      reader.seek(extraLength);
      if (size > 0) {
        // interested only in non-empty files
        offsets.push({offset:offset, size: size, compressedSize: compressedSize});
      }
    }
    // processing the local zip files
    while (offsets.length > 0) {
      reader.setPosition(offsets[0].offset);
      if (reader.readU32() !== 0x04034b50) {
        throw "Invalid jar file entry";
      }
      reader.seek(22);
      var compressedSize = offsets[0].compressedSize;
      var size = offsets[0].size;
      var filenameLength = reader.readU16();
      var extraLength = reader.readU16();
      var filename = "";
      for (var i = 0; i < filenameLength; ++i) {
        filename += String.fromCharCode(reader.readByte());
      }
      reader.seek(extraLength);

      var uncompressedData = [], inflator = new Inflator(reader);
      uncompressedData.length = size;
      for (var i = 0; i < size; ++i) {
        uncompressedData[i] = inflator.readByte();
      }
      entries[filename] = uncompressedData;

      offsets.shift();
    }
    return entries;
  }

  return readContent;
})());