/// <summary>
/// Adds the specified addition for this bag.
/// </summary>
/// <param name="addition">The addition to add to this bag.</param>
/// <returns>true if an addition was added from the specified stream; false otherwise.</returns>
public bool Add(TarEntryStream addition)
{
var tmp = 0;
switch (addition.Header.Flag)
{
case TarHeaderFlag.LongName:
Name = addition.ReadString((int)(addition.Header.Size ?? 0), ref tmp);
break;
case TarHeaderFlag.LongLink:
LinkName = addition.ReadString((int)(addition.Header.Size ?? 0), ref tmp);
break;
default:
return(false);
}
_flags.Add(addition.Header.Flag);
return(true);
}
/// <summary>
/// Untars the specified input stream and returns a stream for each file entry.
/// </summary>
/// <param name="inputStream">The input stream.</param>
/// <returns>An enumeration of file entries. The inputstream can be read on each entry with a length of <see cref="TarEntryStream.Length"/></returns>
/// <exception cref="InvalidDataException">If an invalid entry was found</exception>
public static IEnumerable <TarEntryStream> Untar(this Stream inputStream)
{
var header = new byte[512];
long position = 0;
while (true)
{
int zeroBlockCount = 0;
while (true)
{
// Read the 512 byte block header
int length = inputStream.Read(header, 0, header.Length);
if (length < 512)
{
throw new InvalidDataException($"Invalid header block size < 512");
}
position += length;
// Check if the block is full of zero
bool isZero = true;
for (int i = 0; i < header.Length; i++)
{
if (header[i] != 0)
{
isZero = false;
break;
}
}
if (isZero)
{
// If it is full of zero two consecutive times, we have to exit
zeroBlockCount++;
if (zeroBlockCount == 1)
{
yield break;
}
}
else
{
break;
}
}
// Read file name
var fileName = GetString(header, 0, 100);
// read checksum
var checksum = ReadOctal(header, 148, 8);
if (!checksum.HasValue)
{
throw new InvalidDataException($"Invalid checksum for file entry [{fileName}] ");
}
// verify checksum
uint checksumVerif = 0;
for (int i = 0; i < header.Length; i++)
{
var c = header[i];
if (i >= 148 && i < (148 + 8))
{
c = 32;
}
checksumVerif += c;
}
// Checksum is invalid, exit
if (checksum.Value != checksumVerif)
{
throw new InvalidDataException($"Invalid checksum verification for file entry [{fileName}] ");
}
// Read file size
var fileSizeRead = ReadOctal(header, 124, 12);
if (!fileSizeRead.HasValue)
{
throw new InvalidDataException($"Invalid filesize for file entry [{fileName}] ");
}
var fileLength = fileSizeRead.Value;
// Read the type of the file entry
var type = header[156];
// We support only the File type
TarEntryStream tarEntryStream = null;
if (type == '0')
{
// Read timestamp
var unixTimeStamp = ReadOctal(header, 136, 12);
if (!unixTimeStamp.HasValue)
{
throw new InvalidDataException($"Invalid timestamp for file entry [{fileName}] ");
}
var lastModifiedTime = Epoch.AddSeconds(unixTimeStamp.Value).ToLocalTime();
// Double check magic ustar to load prefix filename
var ustar = GetString(header, 257, 8);
// Check for ustar only
if (ustar != null && ustar.Trim() == "ustar")
{
var prefixFileName = GetString(header, 345, 155);
fileName = prefixFileName + fileName;
}
tarEntryStream = new TarEntryStream(inputStream, position, fileLength)
{
FileName = fileName,
LastModifiedTime = lastModifiedTime
};
// Wrap the region into a slice of the original stream
yield return(tarEntryStream);
}
// The end of the file entry is aligned on 512 bytes
var untilPosition = (position + fileLength + 511) & ~511;
if (tarEntryStream != null)
{
position += tarEntryStream.Position;
}
// We seek to untilPosition by reading the remaining bytes
// as we don't want to rely on stream.Seek/Position as it is
// not working with GzipStream for example
int delta;
while ((delta = (int)(untilPosition - position)) > 0)
{
delta = Math.Min(512, delta);
var readCount = inputStream.Read(header, 0, delta);
position += readCount;
if (readCount == 0)
{
break;
}
}
// If we are not at target position, there is an error, so exit
if ((untilPosition - position) != 0)
{
throw new InvalidDataException($"Invalid end of entry after file entry [{fileName}] ");
}
}
}
