func AppendDMVerity(p *params)
AppendDMVerity instructs the converter to add a dmverity merkle tree for the ext4 filesystem after the filesystem and before the optional VHD footer
func AppendVhdFooter(p *params)
AppendVhdFooter instructs the converter to add a fixed VHD footer to the file.
func Convert(r io.Reader, w io.ReadWriteSeeker, options ...Option) error
Convert wraps ConvertTarToExt4 and conditionally computes (and appends) the file image's cryptographic hashes (merkle tree) or/and appends a VHD footer.
func ConvertAndComputeRootDigest(r io.Reader) (string, error)
ConvertAndComputeRootDigest writes a compact ext4 file system image that contains the files in the input tar stream, computes the resulting file image's cryptographic hashes (merkle tree) and returns merkle tree root digest. Convert is called with minimal options: ConvertWhiteout and MaximumDiskSize set to dmverity.RecommendedVHDSizeGB.
func ConvertTarToExt4(r io.Reader, w io.ReadWriteSeeker, options ...Option) error
ConvertTarToExt4 writes a compact ext4 file system image that contains the files in the input tar stream.
func ConvertToVhd(w io.WriteSeeker) error
ConvertToVhd converts given io.WriteSeeker to VHD, by appending the VHD footer with a fixed size.
func ConvertWhiteout(p *params)
ConvertWhiteout instructs the converter to convert OCI-style whiteouts (beginning with .wh.) to overlay-style whiteouts.
func InlineData(p *params)
InlineData instructs the converter to write small files into the inode structures directly. This creates smaller images but currently is not compatible with DAX.
func ReadExt4SuperBlock(vhdPath string) (*format.SuperBlock, error)
ReadExt4SuperBlock reads and returns ext4 super block from VHD
The layout on disk is as follows: | Group 0 padding | - 1024 bytes | ext4 SuperBlock | - 1 block | Group Descriptors | - many blocks | Reserved GDT Blocks | - many blocks | Data Block Bitmap | - 1 block | inode Bitmap | - 1 block | inode Table | - many blocks | Data Blocks | - many blocks
More details can be found here https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout
Our goal is to skip the Group 0 padding, read and return the ext4 SuperBlock
Option is the type for optional parameters to Convert.
type Option func(*params)
func MaximumDiskSize(size int64) Option
MaximumDiskSize instructs the writer to limit the disk size to the specified value. This also reserves enough metadata space for the specified disk size. If not provided, then 16GB is the default.