public RuntimeInfo(CompressionMethod method, int compressionLevel, int size, string password, bool getCrc)
{
this.method = method;
this.compressionLevel = compressionLevel;
this.password = password;
this.size = size;
random = false;
original = new byte[Size];
if (random)
{
var rnd = new Random();
rnd.NextBytes(original);
}
else
{
for (var i = 0; i < size; ++i)
{
original[i] = (byte) 'A';
}
}
if (getCrc)
{
var crc32 = new Crc32();
crc32.Update(original, 0, size);
crc = crc32.Value;
}
}
private void ReadHeader()
{
// 1. Check the two magic bytes
var headCRC = new Crc32();
var magic = baseInputStream.ReadByte();
if (magic < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(magic);
if (magic != (GZipConstants.GZIP_MAGIC >> 8))
{
throw new GZipException("Error GZIP header, first magic byte doesn't match");
}
magic = baseInputStream.ReadByte();
if (magic < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
if (magic != (GZipConstants.GZIP_MAGIC & 0xFF))
{
throw new GZipException("Error GZIP header, second magic byte doesn't match");
}
headCRC.Update(magic);
// 2. Check the compression type (must be 8)
var compressionType = baseInputStream.ReadByte();
if (compressionType < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
if (compressionType != 8)
{
throw new GZipException("Error GZIP header, data not in deflate format");
}
headCRC.Update(compressionType);
// 3. Check the flags
var flags = baseInputStream.ReadByte();
if (flags < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(flags);
/* This flag byte is divided into individual bits as follows:
bit 0 FTEXT
bit 1 FHCRC
bit 2 FEXTRA
bit 3 FNAME
bit 4 FCOMMENT
bit 5 reserved
bit 6 reserved
bit 7 reserved
*/
// 3.1 Check the reserved bits are zero
if ((flags & 0xd0) != 0)
{
throw new GZipException("Reserved flag bits in GZIP header != 0");
}
// 4.-6. Skip the modification time, extra flags, and OS type
for (var i = 0; i < 6; i++)
{
var readByte = baseInputStream.ReadByte();
if (readByte < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(readByte);
}
// 7. Read extra field
if ((flags & GZipConstants.FEXTRA) != 0)
{
// Skip subfield id
for (var i = 0; i < 2; i++)
{
var readByte = baseInputStream.ReadByte();
if (readByte < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(readByte);
}
if (baseInputStream.ReadByte() < 0 || baseInputStream.ReadByte() < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
var len1 = baseInputStream.ReadByte();
var len2 = baseInputStream.ReadByte();
if ((len1 < 0) || (len2 < 0))
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(len1);
headCRC.Update(len2);
var extraLen = (len1 << 8) | len2;
for (var i = 0; i < extraLen; i++)
{
var readByte = baseInputStream.ReadByte();
if (readByte < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(readByte);
}
}
// 8. Read file name
if ((flags & GZipConstants.FNAME) != 0)
{
int readByte;
while ((readByte = baseInputStream.ReadByte()) > 0)
{
headCRC.Update(readByte);
}
if (readByte < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(readByte);
}
// 9. Read comment
if ((flags & GZipConstants.FCOMMENT) != 0)
{
int readByte;
while ((readByte = baseInputStream.ReadByte()) > 0)
{
headCRC.Update(readByte);
}
if (readByte < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(readByte);
}
// 10. Read header CRC
if ((flags & GZipConstants.FHCRC) != 0)
{
var crcval = baseInputStream.ReadByte();
if (crcval < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
int tempByte = baseInputStream.ReadByte();
if (tempByte < 0)
{
throw new EndOfStreamException("EOS reading GZIP header");
}
crcval = (crcval << 8) | tempByte;
if (crcval != ((int) headCRC.Value & 0xffff))
{
throw new GZipException("Header CRC value mismatch");
}
}
readGZIPHeader = true;
}