feat(internal): Expose raw cpio header also

Signed-off-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>

initrd/file.go

@@ -43,7 +43,7 @@ func NewFromFile(_ context.Context, path string, opts ...InitrdOption) (Initrd,
 
 	// Iterate through the files in the archive.
 	for {
-		hdr, err := reader.Next()
+		hdr, _, err := reader.Next()
 		if err == io.EOF {
 			// end of cpio archive
 			break

internal/cli/kraft/cloud/volume/import/cpio.go

@@ -9,7 +9,6 @@ import (
 	"bytes"
 	"context"
 	"crypto/tls"
-	"encoding/binary"
 	"errors"
 	"fmt"
 	"io"
@@ -22,99 +21,6 @@ import (
 	"kraftkit.sh/internal/cpio"
 )
 
-// header is the cpio header used inside the volume importer
-type packedHeader struct {
-	magic    [6]byte
-	inode    [8]byte
-	mode     [8]byte
-	uid      [8]byte
-	gid      [8]byte
-	nlink    [8]byte
-	mtime    [8]byte
-	filesize [8]byte
-	major    [8]byte
-	minor    [8]byte
-	refMajor [8]byte
-	refMinor [8]byte
-	nameSize [8]byte
-	checksum [8]byte
-}
-
-func NewFromHeader(hdr cpio.Header) packedHeader {
-	var p packedHeader
-
-	// Magic
-	buf := new(bytes.Buffer)
-	buf.WriteString("070701")
-	copy(p.magic[:], buf.Bytes())
-
-	// Inode
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Inode))
-	copy(p.inode[:], buf.Bytes())
-
-	// Mode
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Mode))
-	copy(p.mode[:], buf.Bytes())
-
-	// Uid
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Uid))
-	copy(p.uid[:], buf.Bytes())
-
-	// Gid
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Guid))
-	copy(p.gid[:], buf.Bytes())
-
-	// Nlink
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Links))
-	copy(p.nlink[:], buf.Bytes())
-
-	// ModTime
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.ModTime.Unix()))
-	copy(p.mtime[:], buf.Bytes())
-
-	// FileSize
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Size))
-	copy(p.filesize[:], buf.Bytes())
-
-	// NameSize
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(len(hdr.Name)))
-	copy(p.nameSize[:], buf.Bytes())
-
-	// Checksum
-	buf = new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, int64(hdr.Checksum))
-	copy(p.checksum[:], buf.Bytes())
-
-	return p
-}
-
-func (p packedHeader) Pack() []byte {
-	buf := new(bytes.Buffer)
-	binary.Write(buf, binary.LittleEndian, p.magic)
-	binary.Write(buf, binary.LittleEndian, p.inode)
-	binary.Write(buf, binary.LittleEndian, p.mode)
-	binary.Write(buf, binary.LittleEndian, p.uid)
-	binary.Write(buf, binary.LittleEndian, p.gid)
-	binary.Write(buf, binary.LittleEndian, p.nlink)
-	binary.Write(buf, binary.LittleEndian, p.mtime)
-	binary.Write(buf, binary.LittleEndian, p.filesize)
-	binary.Write(buf, binary.LittleEndian, p.major)
-	binary.Write(buf, binary.LittleEndian, p.minor)
-	binary.Write(buf, binary.LittleEndian, p.refMajor)
-	binary.Write(buf, binary.LittleEndian, p.refMinor)
-	binary.Write(buf, binary.LittleEndian, p.nameSize)
-	binary.Write(buf, binary.LittleEndian, p.checksum)
-	return buf.Bytes()
-}
-
 // buildCPIO generates a CPIO archive from the data at the given source.
 func buildCPIO(ctx context.Context, source string) (path string, size int64, err error) {
 	if source == "." {
@@ -187,7 +93,7 @@ func copyCPIO(ctx context.Context, conn *tls.Conn, auth, path string, size int64
 
 	// Iterate through the files in the archive.
 	for {
-		hdr, err := reader.Next()
+		hdr, raw, err := reader.Next()
 		if err == io.EOF {
 			// end of cpio archive
 			break
@@ -196,10 +102,8 @@ func copyCPIO(ctx context.Context, conn *tls.Conn, auth, path string, size int64
 			return err
 		}
 
-		packedHdr := NewFromHeader(*hdr)
-
 		// io.Copy the header
-		_, err = io.Copy(conn, bytes.NewBuffer(packedHdr.Pack()))
+		_, err = io.Copy(conn, bytes.NewBuffer(raw.Bytes()))
 		if err != nil {
 			return err
 		}

internal/cpio/header.go

@@ -90,6 +90,14 @@ type Header struct {
 	pad int64 // bytes to pad before next header
 }
 
+// RawHeader exposes the unparsed header data.
+type RawHeader [110]byte
+
+// Bytes returns the header as a byte slice.
+func (rh *RawHeader) Bytes() []byte {
+	return rh[:]
+}
+
 // FileInfo returns an fs.FileInfo for the Header.
 func (h *Header) FileInfo() os.FileInfo {
 	return fileInfo{h}

internal/cpio/reader.go

@@ -2,7 +2,6 @@ package cpio
 
 import (
 	"io"
-	"io/ioutil"
 )
 
 // Reader provides sequential access to the contents of a CPIO archive.
@@ -46,27 +45,27 @@ func (r *Reader) Read(p []byte) (n int, err error) {
 // in the current file is automatically discarded.
 //
 // io.EOF is returned at the end of the input.
-func (r *Reader) Next() (*Header, error) {
+func (r *Reader) Next() (*Header, *RawHeader, error) {
 	if r.hdr == nil {
 		return r.next()
 	}
 	skp := r.eof + r.hdr.pad
 	if skp > 0 {
-		_, err := io.CopyN(ioutil.Discard, r.r, skp)
+		_, err := io.CopyN(io.Discard, r.r, skp)
 		if err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 	}
 	return r.next()
 }
 
-func (r *Reader) next() (*Header, error) {
+func (r *Reader) next() (*Header, *RawHeader, error) {
 	r.eof = 0
-	hdr, err := readSVR4Header(r.r)
+	hdr, raw, err := readSVR4Header(r.r)
 	if err != nil {
-		return nil, err
+		return nil, raw, err
 	}
 	r.hdr = hdr
 	r.eof = hdr.Size
-	return hdr, nil
+	return hdr, raw, nil
 }

internal/cpio/svr4.go

@@ -26,23 +26,23 @@ func writeHex(b []byte, i int64) {
 	copy(b, fmt.Sprintf("%08X", i))
 }
 
-func readSVR4Header(r io.Reader) (*Header, error) {
-	var buf [110]byte
+func readSVR4Header(r io.Reader) (*Header, *RawHeader, error) {
+	var buf RawHeader
 	if _, err := io.ReadFull(r, buf[:]); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	// TODO: check endianness
 
 	// check magic
 	hasCRC := false
 	if !bytes.HasPrefix(buf[:], svr4Magic[:5]) {
-		return nil, ErrHeader
+		return nil, nil, ErrHeader
 	}
 	if buf[5] == '2' {
 		hasCRC = true
 	} else if buf[5] != '1' {
-		return nil, ErrHeader
+		return nil, nil, ErrHeader
 	}
 
 	asc := string(buf[:])
@@ -56,24 +56,24 @@ func readSVR4Header(r io.Reader) (*Header, error) {
 		Size:    readHex(asc[54:62]),
 	}
 	if hdr.Size > svr4MaxFileSize {
-		return nil, ErrHeader
+		return nil, nil, ErrHeader
 	}
 	nameSize := readHex(asc[94:102])
 	if nameSize < 1 || nameSize > svr4MaxNameSize {
-		return nil, ErrHeader
+		return nil, nil, ErrHeader
 	}
 	hdr.Checksum = uint32(readHex(asc[102:110]))
 	if !hasCRC && hdr.Checksum != 0 {
-		return nil, ErrHeader
+		return nil, nil, ErrHeader
 	}
 
 	name := make([]byte, nameSize)
 	if _, err := io.ReadFull(r, name); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	hdr.Name = string(name[:nameSize-1])
 	if hdr.Name == headerEOF {
-		return nil, io.EOF
+		return nil, nil, io.EOF
 	}
 
 	// store padding between end of file and next header
@@ -83,24 +83,24 @@ func readSVR4Header(r io.Reader) (*Header, error) {
 	pad := (4 - (len(buf)+len(name))%4) % 4
 	if pad > 0 {
 		if _, err := io.ReadFull(r, buf[:pad]); err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 	}
 
 	// read link name
 	if hdr.Mode&^ModePerm == TypeSymlink {
 		if hdr.Size < 1 || hdr.Size > svr4MaxNameSize {
-			return nil, ErrHeader
+			return nil, nil, ErrHeader
 		}
 		b := make([]byte, hdr.Size)
 		if _, err := io.ReadFull(r, b); err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 		hdr.Linkname = string(b)
 		hdr.Size = 0
 	}
 
-	return hdr, nil
+	return hdr, &buf, nil
 }
 
 func writeSVR4Header(w io.Writer, hdr *Header) (pad int64, err error) {