private async Task <PartialZipInfo> Open()
{
bool supportsPartialZip = await _httpService.SupportsPartialZip();
if (!supportsPartialZip)
{
throw new PartialZipNotSupportedException("The web server does not support PartialZip as byte ranges are not accepted.");
}
PartialZipInfo info = new PartialZipInfo();
info.Length = await _httpService.GetContentLength();
byte[] eocdBuffer = await _httpService.GetRange(info.Length - EndOfCentralDirectory.Size, info.Length - 1);
info.EndOfCentralDirectory = new EndOfCentralDirectory(eocdBuffer);
ulong startCD, endCD;
if (info.EndOfCentralDirectory.IsZip64)
{
byte[] eocdLocator64Buffer = await _httpService.GetRange(info.Length - EndOfCentralDirectory.Size - EndOfCentralDirectoryLocator64.Size, info.Length - EndOfCentralDirectory.Size);
info.EndOfCentralDirectoryLocator64 = new EndOfCentralDirectoryLocator64(eocdLocator64Buffer);
byte[] eocd64Buffer = await _httpService.GetRange(info.EndOfCentralDirectoryLocator64.EndOfCentralDirectory64StartOffset, info.EndOfCentralDirectoryLocator64.EndOfCentralDirectory64StartOffset + EndOfCentralDirectory64.Size - 1);
info.EndOfCentralDirectory64 = new EndOfCentralDirectory64(eocd64Buffer);
startCD = info.EndOfCentralDirectory64.CentralDirectoryStartOffset;
endCD = info.EndOfCentralDirectory64.CentralDirectoryStartOffset + info.EndOfCentralDirectory64.CentralDirectorySize + EndOfCentralDirectory64.Size - 1;
info.CentralDirectoryEntries = info.EndOfCentralDirectory64.CentralDirectoryRecordCount;
}
else
{
startCD = info.EndOfCentralDirectory.CentralDirectoryStartOffset;
endCD = info.EndOfCentralDirectory.CentralDirectoryStartOffset + info.EndOfCentralDirectory.CentralDirectorySize + EndOfCentralDirectory.Size - 1;
info.CentralDirectoryEntries = info.EndOfCentralDirectory.CentralDirectoryRecordCount;
}
byte[] cdBuffer = await _httpService.GetRange(startCD, endCD);
info.CentralDirectory = CentralDirectoryHeader.GetFromBuffer(cdBuffer, info.CentralDirectoryEntries);
return(info);
}
