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Merge pull request #3855 from dgageot/retore-pad4

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Fix initrd image padding
This commit is contained in:
Rolf Neugebauer 2022-10-22 11:40:25 +01:00 committed by GitHub
commit 25c8e68f98
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 1 additions and 54 deletions
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9
src/cmd/linuxkit/initrd/initrd.go
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@ -9,14 +9,12 @@ import (
// drop-in 100% compatible replacement and 17% faster than compress/gzip.
gzip "github.com/klauspost/pgzip"
"github.com/linuxkit/linuxkit/src/cmd/linuxkit/pad4"
"github.com/surma/gocpio"
)
// Writer is an io.WriteCloser that writes to an initrd
// This is a compressed cpio archive, zero padded to 4 bytes
type Writer struct {
pw *pad4.Writer
gw *gzip.Writer
cw *cpio.Writer
}
@ -136,8 +134,7 @@ func CopySplitTar(w *Writer, r *tar.Reader) (kernel []byte, cmdline string, ucod
// NewWriter creates a writer that will output an initrd stream
func NewWriter(w io.Writer) *Writer {
initrd := new(Writer)
initrd.pw = pad4.NewWriter(w)
initrd.gw = gzip.NewWriter(initrd.pw)
initrd.gw = gzip.NewWriter(w)
initrd.cw = cpio.NewWriter(initrd.gw)
return initrd
@ -157,15 +154,11 @@ func (w *Writer) Write(b []byte) (n int, e error) {
func (w *Writer) Close() error {
err1 := w.cw.Close()
err2 := w.gw.Close()
err3 := w.pw.Close()
if err1 != nil {
return err1
}
if err2 != nil {
return err2
}
if err3 != nil {
return err3
}
return nil
}

46
src/cmd/linuxkit/pad4/pad4.go
View File

@ -1,46 +0,0 @@
package pad4
import (
"bytes"
"io"
)
// A Writer is an io.WriteCloser. Writes are padded with zeros to 4 byte boundary
type Writer struct {
w io.Writer
count int
}
// Write writes output
func (pad *Writer) Write(p []byte) (int, error) {
n, err := pad.w.Write(p)
if err != nil {
return 0, err
}
pad.count += n
return n, nil
}
// Close adds the padding
func (pad *Writer) Close() error {
mod4 := pad.count & 3
if mod4 == 0 {
return nil
}
zero := make([]byte, 4-mod4)
buf := bytes.NewBuffer(zero)
n, err := io.Copy(pad.w, buf)
if err != nil {
return err
}
pad.count += int(n)
return nil
}
// NewWriter provides a new io.WriteCloser that zero pads the
// output to a multiple of four bytes
func NewWriter(w io.Writer) *Writer {
pad := new(Writer)
pad.w = w
return pad
}