mcs/class/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib/GZip/GzipInputStream.cs

   1 // GzipInputStream.cs\r
   2 //\r
   3 // Copyright (C) 2001 Mike Krueger\r
   4 //\r
   5 // This file was translated from java, it was part of the GNU Classpath\r
   6 // Copyright (C) 2001 Free Software Foundation, Inc.\r
   7 //\r
   8 // This program is free software; you can redistribute it and/or\r
   9 // modify it under the terms of the GNU General Public License\r
  10 // as published by the Free Software Foundation; either version 2\r
  11 // of the License, or (at your option) any later version.\r
  12 //\r
  13 // This program is distributed in the hope that it will be useful,\r
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  16 // GNU General Public License for more details.\r
  17 //\r
  18 // You should have received a copy of the GNU General Public License\r
  19 // along with this program; if not, write to the Free Software\r
  20 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.\r
  21 //\r
  22 // Linking this library statically or dynamically with other modules is\r
  23 // making a combined work based on this library.  Thus, the terms and\r
  24 // conditions of the GNU General Public License cover the whole\r
  25 // combination.\r
  26 // \r
  27 // As a special exception, the copyright holders of this library give you\r
  28 // permission to link this library with independent modules to produce an\r
  29 // executable, regardless of the license terms of these independent\r
  30 // modules, and to copy and distribute the resulting executable under\r
  31 // terms of your choice, provided that you also meet, for each linked\r
  32 // independent module, the terms and conditions of the license of that\r
  33 // module.  An independent module is a module which is not derived from\r
  34 // or based on this library.  If you modify this library, you may extend\r
  35 // this exception to your version of the library, but you are not\r
  36 // obligated to do so.  If you do not wish to do so, delete this\r
  37 // exception statement from your version.\r
  38 \r
  39 using System;\r
  40 using System.IO;\r
  41 \r
  42 using ICSharpCode.SharpZipLib.Checksums;\r
  43 using ICSharpCode.SharpZipLib.Zip.Compression;\r
  44 using ICSharpCode.SharpZipLib.Zip.Compression.Streams;\r
  45 \r
  46 namespace ICSharpCode.SharpZipLib.GZip \r
  47 {\r
  48         \r
  49         /// <summary>\r
  50         /// This filter stream is used to decompress a "GZIP" format stream.\r
  51         /// The "GZIP" format is described baseInputStream RFC 1952.\r
  52         /// \r
  53         /// author of the original java version : John Leuner\r
  54         /// </summary>\r
  55         /// <example> This sample shows how to unzip a gzipped file\r
  56         /// <code>\r
  57         /// using System;\r
  58         /// using System.IO;\r
  59         /// \r
  60         /// using ICSharpCode.SharpZipLib.GZip;\r
  61         /// \r
  62         /// class MainClass\r
  63         /// {\r
  64         ///     public static void Main(string[] args)\r
  65         ///     {\r
  66         ///             Stream s = new GZipInputStream(File.OpenRead(args[0]));\r
  67         ///             FileStream fs = File.Create(Path.GetFileNameWithoutExtension(args[0]));\r
  68         ///             int size = 2048;\r
  69         ///             byte[] writeData = new byte[2048];\r
  70         ///             while (true) {\r
  71         ///                     size = s.Read(writeData, 0, size);\r
  72         ///                     if (size > 0) {\r
  73         ///                             fs.Write(writeData, 0, size);\r
  74         ///                     } else {\r
  75         ///                             break;\r
  76         ///                     }\r
  77         ///             }\r
  78         ///             s.Close();\r
  79         ///     }\r
  80         /// }   \r
  81         /// </code>\r
  82         /// </example>\r
  83         public class GZipInputStream : InflaterInputStream \r
  84         {\r
  85                 /// <summary>\r
  86                 /// CRC-32 value for uncompressed data\r
  87                 /// </summary>\r
  88                 protected Crc32 crc = new Crc32();\r
  89                 \r
  90                 /// <summary>\r
  91                 /// Indicates end of stream\r
  92                 /// </summary>\r
  93                 protected bool eos;\r
  94                 \r
  95                 // Have we read the GZIP header yet?\r
  96                 bool readGZIPHeader;\r
  97                 \r
  98                 /// <summary>\r
  99                 /// Creates a GzipInputStream with the default buffer size\r
 100                 /// </summary>\r
 101                 /// <param name="baseInputStream">\r
 102                 /// The stream to read compressed data from (baseInputStream GZIP format)\r
 103                 /// </param>\r
 104                 public GZipInputStream(Stream baseInputStream) : this(baseInputStream, 4096)\r
 105                 {\r
 106                 }\r
 107                 \r
 108                 /// <summary>\r
 109                 /// Creates a GZIPInputStream with the specified buffer size\r
 110                 /// </summary>\r
 111                 /// <param name="baseInputStream">\r
 112                 /// The stream to read compressed data from (baseInputStream GZIP format)\r
 113                 /// </param>\r
 114                 /// <param name="size">\r
 115                 /// Size of the buffer to use\r
 116                 /// </param>\r
 117                 public GZipInputStream(Stream baseInputStream, int size) : base(baseInputStream, new Inflater(true), size)\r
 118                 {\r
 119                 }\r
 120                 \r
 121                 /// <summary>\r
 122                 /// Reads uncompressed data into an array of bytes\r
 123                 /// </summary>\r
 124                 /// <param name="buf">\r
 125                 /// The buffer to read uncompressed data into\r
 126                 /// </param>\r
 127                 /// <param name="offset">\r
 128                 /// The offset indicating where the data should be placed\r
 129                 /// </param>\r
 130                 /// <param name="len">\r
 131                 /// The number of uncompressed bytes to be read\r
 132                 /// </param>\r
 133                 public override int Read(byte[] buf, int offset, int len) \r
 134                 {\r
 135                         // We first have to read the GZIP header, then we feed all the\r
 136                         // rest of the data to the base class.\r
 137                         //\r
 138                         // As we do that we continually update the CRC32. Once the data is\r
 139                         // finished, we check the CRC32\r
 140                         //\r
 141                         // This means we don't need our own buffer, as everything is done\r
 142                         // baseInputStream the superclass.\r
 143                         if (!readGZIPHeader) {\r
 144                                 ReadHeader();\r
 145                         }\r
 146                         \r
 147                         if (eos) {\r
 148                                 return 0;\r
 149                         }\r
 150                         \r
 151                         // We don't have to read the header, so we just grab data from the superclass\r
 152                         int numRead = base.Read(buf, offset, len);\r
 153                         if (numRead > 0) {\r
 154                                 crc.Update(buf, offset, numRead);\r
 155                         }\r
 156                         \r
 157                         if (inf.IsFinished) {\r
 158                                 ReadFooter();\r
 159                         }\r
 160                         return numRead;\r
 161                 }\r
 162                 \r
 163                 void ReadHeader() \r
 164                 {\r
 165                         /* 1. Check the two magic bytes */\r
 166                         Crc32 headCRC = new Crc32();\r
 167                         int magic = baseInputStream.ReadByte();\r
 168                         if (magic < 0) {\r
 169                                 eos = true;\r
 170                                 return;\r
 171                         }\r
 172                         headCRC.Update(magic);\r
 173                         if (magic != (GZipConstants.GZIP_MAGIC >> 8)) {\r
 174                                 throw new GZipException("Error baseInputStream GZIP header, first byte doesn't match");\r
 175                         }\r
 176                                 \r
 177                         magic = baseInputStream.ReadByte();\r
 178                         if (magic != (GZipConstants.GZIP_MAGIC & 0xFF)) {\r
 179                                 throw new GZipException("Error baseInputStream GZIP header,  second byte doesn't match");\r
 180                         }\r
 181                         headCRC.Update(magic);\r
 182                         \r
 183                         /* 2. Check the compression type (must be 8) */\r
 184                         int CM = baseInputStream.ReadByte();\r
 185                         if (CM != 8) {\r
 186                                 throw new GZipException("Error baseInputStream GZIP header, data not baseInputStream deflate format");\r
 187                         }\r
 188                         headCRC.Update(CM);\r
 189                         \r
 190                         /* 3. Check the flags */\r
 191                         int flags = baseInputStream.ReadByte();\r
 192                         if (flags < 0) {\r
 193                                 throw new GZipException("Early EOF baseInputStream GZIP header");\r
 194                         }\r
 195                         headCRC.Update(flags);\r
 196                         \r
 197                         /*    This flag byte is divided into individual bits as follows:\r
 198                                 \r
 199                                 bit 0   FTEXT\r
 200                                 bit 1   FHCRC\r
 201                                 bit 2   FEXTRA\r
 202                                 bit 3   FNAME\r
 203                                 bit 4   FCOMMENT\r
 204                                 bit 5   reserved\r
 205                                 bit 6   reserved\r
 206                                 bit 7   reserved\r
 207                                 */\r
 208                                 \r
 209                         /* 3.1 Check the reserved bits are zero */\r
 210                         \r
 211                         if ((flags & 0xd0) != 0) {\r
 212                                 throw new GZipException("Reserved flag bits baseInputStream GZIP header != 0");\r
 213                         }\r
 214                         \r
 215                         /* 4.-6. Skip the modification time, extra flags, and OS type */\r
 216                         for (int i=0; i< 6; i++) {\r
 217                                 int readByte = baseInputStream.ReadByte();\r
 218                                 if (readByte < 0) {\r
 219                                         throw new GZipException("Early EOF baseInputStream GZIP header");\r
 220                                 }\r
 221                                 headCRC.Update(readByte);\r
 222                         }\r
 223                         \r
 224                         /* 7. Read extra field */\r
 225                         if ((flags & GZipConstants.FEXTRA) != 0) {\r
 226                                 /* Skip subfield id */\r
 227                                 for (int i=0; i< 2; i++) {\r
 228                                         int readByte = baseInputStream.ReadByte();\r
 229                                         if (readByte < 0) {\r
 230                                                 throw new GZipException("Early EOF baseInputStream GZIP header");\r
 231                                         }\r
 232                                         headCRC.Update(readByte);\r
 233                                 }\r
 234                                 if (baseInputStream.ReadByte() < 0 || baseInputStream.ReadByte() < 0) {\r
 235                                         throw new GZipException("Early EOF baseInputStream GZIP header");\r
 236                                 }\r
 237                                 \r
 238                                 int len1, len2, extraLen;\r
 239                                 len1 = baseInputStream.ReadByte();\r
 240                                 len2 = baseInputStream.ReadByte();\r
 241                                 if ((len1 < 0) || (len2 < 0)) {\r
 242                                         throw new GZipException("Early EOF baseInputStream GZIP header");\r
 243                                 }\r
 244                                 headCRC.Update(len1);\r
 245                                 headCRC.Update(len2);\r
 246                                 \r
 247                                 extraLen = (len1 << 8) | len2;\r
 248                                 for (int i = 0; i < extraLen;i++) {\r
 249                                         int readByte = baseInputStream.ReadByte();\r
 250                                         if (readByte < 0) \r
 251                                         {\r
 252                                                 throw new GZipException("Early EOF baseInputStream GZIP header");\r
 253                                         }\r
 254                                         headCRC.Update(readByte);\r
 255                                 }\r
 256                         }\r
 257                         \r
 258                         /* 8. Read file name */\r
 259                         if ((flags & GZipConstants.FNAME) != 0) {\r
 260                                 int readByte;\r
 261                                 while ( (readByte = baseInputStream.ReadByte()) > 0) {\r
 262                                         headCRC.Update(readByte);\r
 263                                 }\r
 264                                 if (readByte < 0) {\r
 265                                         throw new GZipException("Early EOF baseInputStream GZIP file name");\r
 266                                 }\r
 267                                 headCRC.Update(readByte);\r
 268                         }\r
 269                         \r
 270                         /* 9. Read comment */\r
 271                         if ((flags & GZipConstants.FCOMMENT) != 0) {\r
 272                                 int readByte;\r
 273                                 while ( (readByte = baseInputStream.ReadByte()) > 0) {\r
 274                                         headCRC.Update(readByte);\r
 275                                 }\r
 276                                 \r
 277                                 if (readByte < 0) {\r
 278                                         throw new GZipException("Early EOF baseInputStream GZIP comment");\r
 279                                 }\r
 280                                 headCRC.Update(readByte);\r
 281                         }\r
 282                         \r
 283                         /* 10. Read header CRC */\r
 284                         if ((flags & GZipConstants.FHCRC) != 0) {\r
 285                                 int tempByte;\r
 286                                 int crcval = baseInputStream.ReadByte();\r
 287                                 if (crcval < 0) {\r
 288                                         throw new GZipException("Early EOF baseInputStream GZIP header");\r
 289                                 }\r
 290                                 \r
 291                                 tempByte = baseInputStream.ReadByte();\r
 292                                 if (tempByte < 0) {\r
 293                                         throw new GZipException("Early EOF baseInputStream GZIP header");\r
 294                                 }\r
 295                                 \r
 296                                 crcval = (crcval << 8) | tempByte;\r
 297                                 if (crcval != ((int) headCRC.Value & 0xffff)) {\r
 298                                         throw new GZipException("Header CRC value mismatch");\r
 299                                 }\r
 300                         }\r
 301                         \r
 302                         readGZIPHeader = true;\r
 303                 }\r
 304                 \r
 305                 void ReadFooter() \r
 306                 {\r
 307                         byte[] footer = new byte[8];\r
 308                         int avail = inf.RemainingInput;\r
 309                         \r
 310                         if (avail > 8) {\r
 311                                 avail = 8;\r
 312                         }\r
 313                         \r
 314          System.Array.Copy(inputBuffer.RawData, inputBuffer.RawLength - inf.RemainingInput, footer, 0, avail);\r
 315          int needed = 8 - avail;\r
 316                         \r
 317                         while (needed > 0) {\r
 318                                 int count = baseInputStream.Read(footer, 8 - needed, needed);\r
 319                                 if (count <= 0) {\r
 320                                         throw new GZipException("Early EOF baseInputStream GZIP footer");\r
 321                                 }\r
 322                                 needed -= count; // Jewel Jan 16\r
 323                         }\r
 324                         int crcval = (footer[0] & 0xff) | ((footer[1] & 0xff) << 8) | ((footer[2] & 0xff) << 16) | (footer[3] << 24);\r
 325                         if (crcval != (int) crc.Value) {\r
 326                                 throw new GZipException("GZIP crc sum mismatch, theirs \"" + crcval + "\" and ours \"" + (int) crc.Value);\r
 327                         }\r
 328                         \r
 329                         int total = (footer[4] & 0xff) | ((footer[5] & 0xff) << 8) | ((footer[6] & 0xff) << 16) | (footer[7] << 24);\r
 330                         if (total != inf.TotalOut) {\r
 331                                 throw new GZipException("Number of bytes mismatch in footer");\r
 332                         }\r
 333                         \r
 334                         /* XXX Should we support multiple members.\r
 335                         * Difficult, since there may be some bytes still baseInputStream dataBuffer\r
 336                         */\r
 337                         eos = true;\r
 338                 }\r
 339         }\r
 340 }\r