public static ArchiveMetaData ReadMetaData(Stream stream)
{
if (!stream.CanRead)
{
throw new IOException("this stream does not support read access");
}
stream.Position = 0;
using (var reader = new BinaryReader(stream, Encoding.UTF8, true))
{
// read magic-number (3 bytes)
const int magicNumberSize = 3;
if (Encoding.ASCII.GetString(reader.ReadBytes(magicNumberSize)) != "PRA")
{
throw new FormatException("invalid PRA header");
}
// read length of the json metadata (4 bytes)
const int metadataLnegthSize = 4;
var metadataLnegth = reader.ReadInt32();
// read the json metadata
var metadataBuffer = reader.ReadBytes(metadataLnegth);
var metadataJson = Encoding.UTF8.GetString(metadataBuffer);
var metadataRaw = ArchiveMetaDataRaw.FromJson(metadataJson);
if (metadataRaw.Version != 1)
{
throw new FormatException("format version is not supported");
}
return(new ArchiveMetaData(metadataRaw, magicNumberSize + metadataLnegthSize + metadataLnegth));
}
}
public static void Write(Stream stream, IReadOnlyCollection <ArchiveItem> items)
{
if (!stream.CanWrite)
{
throw new IOException("this stream does not support write access");
}
var metadataRaw = ArchiveMetaDataRaw.Build(items);
var metadataJson = metadataRaw.ToJson();
stream.Position = 0;
using (var writer = new BinaryWriter(stream, Encoding.UTF8, true))
{
// write magic-number (3 bytes)
writer.Write(Encoding.ASCII.GetBytes("PRA"));
// write length of the json metadata (4 bytes)
writer.Write(metadataJson.Length);
// write the json metadata
writer.Write(Encoding.UTF8.GetBytes(metadataJson));
// file data
foreach (var file in items)
{
writer.Write(file.Buffer.ToArray());
}
}
}
public ArchiveMetaData(ArchiveMetaDataRaw metadataRaw, int payloadBeginOffset)
{
this.Raw = metadataRaw;
this.PayloadBeginOffset = payloadBeginOffset;
}
