private const string UstarPrefixFormat = "{0}/{1}"; // "prefix/name"
// Attempts to read all the fields of the next header.
// Throws if end of stream is reached or if any data type conversion fails.
// Returns true if all the attributes were read successfully, false otherwise.
internal bool TryGetNextHeader(Stream archiveStream, bool copyData)
{
// The four supported formats have a header that fits in the default record size
byte[] rented = ArrayPool <byte> .Shared.Rent(minimumLength : TarHelpers.RecordSize);
Span <byte> buffer = rented.AsSpan(0, TarHelpers.RecordSize); // minimumLength means the array could've been larger
buffer.Clear(); // Rented arrays aren't clean
TarHelpers.ReadOrThrow(archiveStream, buffer);
try
{
// Confirms if v7 or pax, or tentatively selects ustar
if (!TryReadCommonAttributes(buffer))
{
return(false);
}
// Confirms if gnu, or tentatively selects ustar
ReadMagicAttribute(buffer);
if (_format != TarFormat.V7)
{
// Confirms if gnu
ReadVersionAttribute(buffer);
// Fields that ustar, pax and gnu share identically
ReadPosixAndGnuSharedAttributes(buffer);
Debug.Assert(_format is TarFormat.Ustar or TarFormat.Pax or TarFormat.Gnu);
if (_format == TarFormat.Ustar)
{
ReadUstarAttributes(buffer);
}
else if (_format == TarFormat.Gnu)
{
ReadGnuAttributes(buffer);
}
// In PAX, there is nothing to read in this section (empty space)
}
ProcessDataBlock(archiveStream, copyData);
return(true);
}
finally
{
ArrayPool <byte> .Shared.Return(rented);
}
}
