Пример #1
0
        /// <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);
        }
Пример #2
0
        /// <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;
        }