| public Update ( byte buffer ) : void | ||
| buffer | byte | Contains the data to update the CRC with. |
| return | void | |
public void CRC_32()
{
var underTestCrc32 = new Crc32();
Assert.AreEqual(0x0, underTestCrc32.Value);
underTestCrc32.Update(check);
Assert.AreEqual(0xCBF43926, underTestCrc32.Value);
underTestCrc32.Reset();
Assert.AreEqual(0x0, underTestCrc32.Value);
exceptionTesting(underTestCrc32);
}
bool ReadHeader()
{
// Initialize CRC for this block
crc = new Crc32();
// Make sure there is data in file. We can't rely on ReadLeByte() to fill the buffer, as this could be EOF,
// which is fine, but ReadLeByte() throws an exception if it doesn't find data, so we do this part ourselves.
if (inputBuffer.Available <= 0) {
inputBuffer.Fill();
if (inputBuffer.Available <= 0) {
// No header, EOF.
return false;
}
}
// 1. Check the two magic bytes
var headCRC = new Crc32();
int magic = inputBuffer.ReadLeByte();
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();
magic = inputBuffer.ReadLeByte();
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)
int compressionType = inputBuffer.ReadLeByte();
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
int flags = inputBuffer.ReadLeByte();
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 & 0xE0) != 0) {
throw new GZipException("Reserved flag bits in GZIP header != 0");
}
// 4.-6. Skip the modification time, extra flags, and OS type
for (int i = 0; i < 6; i++) {
int readByte = inputBuffer.ReadLeByte();
if (readByte < 0) {
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(readByte);
}
// 7. Read extra field
if ((flags & GZipConstants.FEXTRA) != 0) {
// XLEN is total length of extra subfields, we will skip them all
int len1, len2;
len1 = inputBuffer.ReadLeByte();
len2 = inputBuffer.ReadLeByte();
if ((len1 < 0) || (len2 < 0)) {
throw new EndOfStreamException("EOS reading GZIP header");
}
headCRC.Update(len1);
headCRC.Update(len2);
int extraLen = (len2 << 8) | len1; // gzip is LSB first
for (int i = 0; i < extraLen; i++) {
int readByte = inputBuffer.ReadLeByte();
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 = inputBuffer.ReadLeByte()) > 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 = inputBuffer.ReadLeByte()) > 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) {
int tempByte;
int crcval = inputBuffer.ReadLeByte();
if (crcval < 0) {
throw new EndOfStreamException("EOS reading GZIP header");
}
tempByte = inputBuffer.ReadLeByte();
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;
return true;
}
public RuntimeInfo(CompressionMethod method, int compressionLevel,
int size, string password, bool getCrc)
{
this.method = method;
this.compressionLevel = compressionLevel;
this.password = password;
this.size = size;
this.random = false;
original = new byte[Size];
if (random) {
var rnd = new Random();
rnd.NextBytes(original);
} else {
for (int i = 0; i < size; ++i) {
original[i] = (byte)'A';
}
}
if (getCrc) {
var crc32 = new Crc32();
crc32.Update(original, 0, size);
crc = crc32.Value;
}
}