/// <summary>
/// Detects if the stream contains a SquashFs file system.
/// </summary>
/// <param name="stream">The stream to inspect</param>
/// <returns><c>true</c> if stream appears to be a SquashFs file system.</returns>
public static bool Detect(Stream stream)
{
stream.Position = 0;
SuperBlock superBlock = new SuperBlock();
if (stream.Length < superBlock.Size)
{
return(false);
}
byte[] buffer = Utilities.ReadFully(stream, superBlock.Size);
superBlock.ReadFrom(buffer, 0);
return(superBlock.Magic == SuperBlock.SquashFsMagic);
}
/// <summary>
/// Writes the file system to an existing stream.
/// </summary>
/// <param name="output">The stream to write to.</param>
/// <remarks>The <c>output</c> stream must support seeking and writing.</remarks>
public void Build(Stream output)
{
if (output == null)
{
throw new ArgumentNullException("output");
}
if (!output.CanWrite)
{
throw new ArgumentException("Output stream must be writable", "output");
}
if (!output.CanSeek)
{
throw new ArgumentException("Output stream must support seeking", "output");
}
_context = new BuilderContext()
{
RawStream = output,
DataBlockSize = DefaultBlockSize,
IoBuffer = new byte[DefaultBlockSize],
};
MetablockWriter inodeWriter = new MetablockWriter();
MetablockWriter dirWriter = new MetablockWriter();
FragmentWriter fragWriter = new FragmentWriter(_context);
IdTableWriter idWriter = new IdTableWriter(_context);
_context.AllocateInode = AllocateInode;
_context.AllocateId = idWriter.AllocateId;
_context.WriteDataBlock = WriteDataBlock;
_context.WriteFragment = fragWriter.WriteFragment;
_context.InodeWriter = inodeWriter;
_context.DirectoryWriter = dirWriter;
_nextInode = 1;
SuperBlock superBlock = new SuperBlock();
superBlock.Magic = SuperBlock.SquashFsMagic;
superBlock.CreationTime = DateTime.Now;
superBlock.BlockSize = (uint)_context.DataBlockSize;
superBlock.Compression = 1; // DEFLATE
superBlock.BlockSizeLog2 = (ushort)Utilities.Log2(superBlock.BlockSize);
superBlock.MajorVersion = 4;
superBlock.MinorVersion = 0;
output.Position = superBlock.Size;
GetRoot().Reset();
GetRoot().Write(_context);
fragWriter.Flush();
superBlock.RootInode = GetRoot().InodeRef;
superBlock.InodesCount = _nextInode - 1;
superBlock.FragmentsCount = (uint)fragWriter.FragmentCount;
superBlock.UidGidCount = (ushort)idWriter.IdCount;
superBlock.InodeTableStart = output.Position;
inodeWriter.Persist(output);
superBlock.DirectoryTableStart = output.Position;
dirWriter.Persist(output);
if (fragWriter.FragmentCount > 0)
{
superBlock.FragmentTableStart = output.Position;
fragWriter.Persist();
}
else
{
superBlock.FragmentTableStart = -1;
}
superBlock.LookupTableStart = -1;
if (idWriter.IdCount > 0)
{
superBlock.UidGidTableStart = output.Position;
idWriter.Persist();
}
else
{
superBlock.UidGidTableStart = -1;
}
superBlock.ExtendedAttrsTableStart = -1;
superBlock.BytesUsed = output.Position;
// Pad to 4KB
long end = Utilities.RoundUp(output.Position, 4 * Sizes.OneKiB);
if (end != output.Position)
{
byte[] padding = new byte[(int)(end - output.Position)];
output.Write(padding, 0, padding.Length);
}
// Go back and write the superblock
output.Position = 0;
byte[] buffer = new byte[superBlock.Size];
superBlock.WriteTo(buffer, 0);
output.Write(buffer, 0, buffer.Length);
output.Position = end;
}