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75 lines
1.6 KiB
75 lines
1.6 KiB
package dehub
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import (
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"crypto/sha256"
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"encoding/binary"
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"fmt"
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"hash"
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"sort"
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"gopkg.in/src-d/go-git.v4/plumbing/object"
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)
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var (
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defaultHashHelperAlgo = sha256.New
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)
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type hashHelper struct {
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hash.Hash
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varintBuf []byte
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}
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// if h is nil it then defaultHashHelperAlgo will be used
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func newHashHelper(h hash.Hash) *hashHelper {
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if h == nil {
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h = defaultHashHelperAlgo()
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}
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s := &hashHelper{
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Hash: h,
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varintBuf: make([]byte, binary.MaxVarintLen64),
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}
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return s
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}
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func (s *hashHelper) writeUint(i uint64) {
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n := binary.PutUvarint(s.varintBuf, i)
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if _, err := s.Write(s.varintBuf[:n]); err != nil {
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panic(fmt.Sprintf("error writing %x to sha256 sum: %v", s.varintBuf[:n], err))
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}
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}
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func (s *hashHelper) writeStr(str string) {
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s.writeUint(uint64(len(str)))
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s.Write([]byte(str))
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}
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func (s *hashHelper) writeTreeDiff(from, to *object.Tree) {
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filesChanged, err := calcDiff(from, to)
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if err != nil {
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panic(err.Error())
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}
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sort.Slice(filesChanged, func(i, j int) bool {
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return filesChanged[i].path < filesChanged[j].path
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})
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s.writeUint(uint64(len(filesChanged)))
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for _, fileChanged := range filesChanged {
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s.writeStr(fileChanged.path)
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s.Write(fileChanged.fromMode.Bytes())
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s.Write(fileChanged.fromHash[:])
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s.Write(fileChanged.toMode.Bytes())
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s.Write(fileChanged.toHash[:])
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}
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}
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var changeHashVersion = []byte{0}
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// if h is nil it then defaultHashHelperAlgo will be used
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func genChangeHash(h hash.Hash, msg string, from, to *object.Tree) []byte {
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s := newHashHelper(h)
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s.writeStr(msg)
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s.writeTreeDiff(from, to)
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return s.Sum(changeHashVersion)
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}
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