/// <summary>
/// Get the next entry in this tar archive. This will skip
/// over any remaining data in the current entry, if there
/// is one, and place the input stream at the header of the
/// next entry, and read the header and instantiate a new
/// TarEntry from the header bytes and return that entry.
/// If there are no more entries in the archive, null will
/// be returned to indicate that the end of the archive has
/// been reached.
/// </summary>
/// <returns>
/// The next TarEntry in the archive, or null.
/// </returns>
public TarEntry GetNextEntry()
{
if (hasHitEOF)
{
return(null);
}
if (currentEntry != null)
{
SkipToNextEntry();
}
byte[] headerBuf = tarBuffer.ReadBlock();
if (headerBuf == null)
{
hasHitEOF = true;
}
else if (TarBuffer.IsEndOfArchiveBlock(headerBuf))
{
hasHitEOF = true;
// Read the second zero-filled block
tarBuffer.ReadBlock();
}
else
{
hasHitEOF = false;
}
if (hasHitEOF)
{
currentEntry = null;
}
else
{
try
{
var header = new TarHeader();
header.ParseBuffer(headerBuf);
if (!header.IsChecksumValid)
{
throw new TarException("Header checksum is invalid");
}
this.entryOffset = 0;
this.entrySize = header.Size;
StringBuilder longName = null;
if (header.TypeFlag == TarHeader.LF_GNU_LONGNAME)
{
byte[] nameBuffer = new byte[TarBuffer.BlockSize];
long numToRead = this.entrySize;
longName = new StringBuilder();
while (numToRead > 0)
{
int numRead = this.Read(nameBuffer, 0, (numToRead > nameBuffer.Length ? nameBuffer.Length : (int)numToRead));
if (numRead == -1)
{
throw new InvalidHeaderException("Failed to read long name entry");
}
longName.Append(TarHeader.ParseName(nameBuffer, 0, numRead).ToString());
numToRead -= numRead;
}
SkipToNextEntry();
headerBuf = this.tarBuffer.ReadBlock();
}
else if (header.TypeFlag == TarHeader.LF_GHDR)
{ // POSIX global extended header
// Ignore things we dont understand completely for now
SkipToNextEntry();
headerBuf = this.tarBuffer.ReadBlock();
}
else if (header.TypeFlag == TarHeader.LF_XHDR)
{ // POSIX extended header
byte[] nameBuffer = new byte[TarBuffer.BlockSize];
long numToRead = this.entrySize;
var xhr = new TarExtendedHeaderReader();
while (numToRead > 0)
{
int numRead = this.Read(nameBuffer, 0, (numToRead > nameBuffer.Length ? nameBuffer.Length : (int)numToRead));
if (numRead == -1)
{
throw new InvalidHeaderException("Failed to read long name entry");
}
xhr.Read(nameBuffer, numRead);
numToRead -= numRead;
}
string name;
if (xhr.Headers.TryGetValue("path", out name))
{
longName = new StringBuilder(name);
}
SkipToNextEntry();
headerBuf = this.tarBuffer.ReadBlock();
}
else if (header.TypeFlag == TarHeader.LF_GNU_VOLHDR)
{
// TODO: could show volume name when verbose
SkipToNextEntry();
headerBuf = this.tarBuffer.ReadBlock();
}
else if (header.TypeFlag != TarHeader.LF_NORMAL &&
header.TypeFlag != TarHeader.LF_OLDNORM &&
header.TypeFlag != TarHeader.LF_LINK &&
header.TypeFlag != TarHeader.LF_SYMLINK &&
header.TypeFlag != TarHeader.LF_DIR)
{
// Ignore things we dont understand completely for now
SkipToNextEntry();
headerBuf = tarBuffer.ReadBlock();
}
if (entryFactory == null)
{
currentEntry = new TarEntry(headerBuf);
if (longName != null)
{
currentEntry.Name = longName.ToString();
}
}
else
{
currentEntry = entryFactory.CreateEntry(headerBuf);
}
// Magic was checked here for 'ustar' but there are multiple valid possibilities
// so this is not done anymore.
entryOffset = 0;
// TODO: Review How do we resolve this discrepancy?!
entrySize = this.currentEntry.Size;
}
catch (InvalidHeaderException ex)
{
entrySize = 0;
entryOffset = 0;
currentEntry = null;
string errorText = string.Format("Bad header in record {0} block {1} {2}",
tarBuffer.CurrentRecord, tarBuffer.CurrentBlock, ex.Message);
throw new InvalidHeaderException(errorText);
}
}
return(currentEntry);
}
/// <summary>
/// Parse TarHeader information from a header buffer.
/// </summary>
/// <param name = "header">
/// The tar entry header buffer to get information from.
/// </param>
public void ParseBuffer(byte[] header)
{
if (header == null)
{
throw new ArgumentNullException(nameof(header));
}
int offset = 0;
name = ParseName(header, offset, NAMELEN).ToString();
offset += NAMELEN;
mode = (int)ParseOctal(header, offset, MODELEN);
offset += MODELEN;
UserId = (int)ParseOctal(header, offset, UIDLEN);
offset += UIDLEN;
GroupId = (int)ParseOctal(header, offset, GIDLEN);
offset += GIDLEN;
Size = ParseBinaryOrOctal(header, offset, SIZELEN);
offset += SIZELEN;
ModTime = GetDateTimeFromCTime(ParseOctal(header, offset, MODTIMELEN));
offset += MODTIMELEN;
checksum = (int)ParseOctal(header, offset, CHKSUMLEN);
offset += CHKSUMLEN;
TypeFlag = header[offset++];
LinkName = ParseName(header, offset, NAMELEN).ToString();
offset += NAMELEN;
Magic = ParseName(header, offset, MAGICLEN).ToString();
offset += MAGICLEN;
if (Magic == "ustar")
{
Version = ParseName(header, offset, VERSIONLEN).ToString();
offset += VERSIONLEN;
UserName = ParseName(header, offset, UNAMELEN).ToString();
offset += UNAMELEN;
GroupName = ParseName(header, offset, GNAMELEN).ToString();
offset += GNAMELEN;
DevMajor = (int)ParseOctal(header, offset, DEVLEN);
offset += DEVLEN;
DevMinor = (int)ParseOctal(header, offset, DEVLEN);
offset += DEVLEN;
string prefix = ParseName(header, offset, PREFIXLEN).ToString();
if (!string.IsNullOrEmpty(prefix))
{
Name = prefix + '/' + Name;
}
}
isChecksumValid = Checksum == TarHeader.MakeCheckSum(header);
}
