mirror of https://github.com/minio/minio.git
110 lines
2.1 KiB
Go
110 lines
2.1 KiB
Go
package binarydist
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import (
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"bytes"
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"compress/bzip2"
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"encoding/binary"
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"errors"
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"io"
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"io/ioutil"
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)
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var ErrCorrupt = errors.New("corrupt patch")
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// Patch applies patch to old, according to the bspatch algorithm,
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// and writes the result to new.
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func Patch(old io.Reader, new io.Writer, patch io.Reader) error {
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var hdr header
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err := binary.Read(patch, signMagLittleEndian{}, &hdr)
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if err != nil {
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return err
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}
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if hdr.Magic != magic {
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return ErrCorrupt
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}
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if hdr.CtrlLen < 0 || hdr.DiffLen < 0 || hdr.NewSize < 0 {
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return ErrCorrupt
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}
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ctrlbuf := make([]byte, hdr.CtrlLen)
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_, err = io.ReadFull(patch, ctrlbuf)
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if err != nil {
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return err
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}
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cpfbz2 := bzip2.NewReader(bytes.NewReader(ctrlbuf))
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diffbuf := make([]byte, hdr.DiffLen)
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_, err = io.ReadFull(patch, diffbuf)
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if err != nil {
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return err
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}
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dpfbz2 := bzip2.NewReader(bytes.NewReader(diffbuf))
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// The entire rest of the file is the extra block.
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epfbz2 := bzip2.NewReader(patch)
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obuf, err := ioutil.ReadAll(old)
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if err != nil {
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return err
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}
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nbuf := make([]byte, hdr.NewSize)
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var oldpos, newpos int64
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for newpos < hdr.NewSize {
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var ctrl struct{ Add, Copy, Seek int64 }
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err = binary.Read(cpfbz2, signMagLittleEndian{}, &ctrl)
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if err != nil {
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return err
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}
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// Sanity-check
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if newpos+ctrl.Add > hdr.NewSize {
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return ErrCorrupt
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}
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// Read diff string
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_, err = io.ReadFull(dpfbz2, nbuf[newpos:newpos+ctrl.Add])
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if err != nil {
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return ErrCorrupt
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}
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// Add old data to diff string
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for i := int64(0); i < ctrl.Add; i++ {
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if oldpos+i >= 0 && oldpos+i < int64(len(obuf)) {
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nbuf[newpos+i] += obuf[oldpos+i]
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}
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}
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// Adjust pointers
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newpos += ctrl.Add
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oldpos += ctrl.Add
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// Sanity-check
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if newpos+ctrl.Copy > hdr.NewSize {
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return ErrCorrupt
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}
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// Read extra string
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_, err = io.ReadFull(epfbz2, nbuf[newpos:newpos+ctrl.Copy])
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if err != nil {
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return ErrCorrupt
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}
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// Adjust pointers
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newpos += ctrl.Copy
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oldpos += ctrl.Seek
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}
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// Write the new file
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for len(nbuf) > 0 {
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n, err := new.Write(nbuf)
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if err != nil {
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return err
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}
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nbuf = nbuf[n:]
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}
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return nil
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}
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