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83 lines
1.9 KiB
83 lines
1.9 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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)
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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.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) sum(prefix []byte) []byte {
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out := make([]byte, len(prefix), len(prefix)+s.hash.Size())
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copy(out, prefix)
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return s.hash.Sum(out)
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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.hash.Write(s.varintBuf[:n]); err != nil {
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panic(fmt.Sprintf("error writing %x to %T: %v", s.varintBuf[:n], s.hash, 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.hash.Write([]byte(str))
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}
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func (s *hashHelper) writeChangedFiles(changedFiles []ChangedFile) {
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sort.Slice(changedFiles, func(i, j int) bool {
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return changedFiles[i].Path < changedFiles[j].Path
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})
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s.writeUint(uint64(len(changedFiles)))
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for _, fileChanged := range changedFiles {
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s.writeStr(fileChanged.Path)
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s.hash.Write(fileChanged.FromMode.Bytes())
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s.hash.Write(fileChanged.FromHash[:])
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s.hash.Write(fileChanged.ToMode.Bytes())
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s.hash.Write(fileChanged.ToHash[:])
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}
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}
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var (
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changeHashVersion = []byte{0}
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commentHashVersion = []byte{0}
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)
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// if h is nil it then defaultHashHelperAlgo will be used
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func genChangeFingerprint(h hash.Hash, msg string, changedFiles []ChangedFile) []byte {
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s := newHashHelper(h)
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s.writeStr(msg)
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s.writeChangedFiles(changedFiles)
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return s.sum(changeHashVersion)
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}
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// if h is nil it then defaultHashHelperAlgo will be used
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func genCommentFingerprint(h hash.Hash, comment string) []byte {
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s := newHashHelper(h)
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s.writeStr(comment)
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return s.sum(commentHashVersion)
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}
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