dehub/fingerprint.go
mediocregopher b01fe1524a Completely refactor naming of everything, in light of new SPEC
---
type: change
description: |-
  Completely refactor naming of everything, in light of new SPEC

  Writing the SPEC shed some light on just how weakly a lot of concepts, like
  "commit", had been defined, and prompted the delineation of a lot of things
  along specific lines (commit vs payload, repo vs project). This commit makes the
  code reflect the SPEC much better in quite a few ways:

  * Repo is now Project
  * Commit is now Payload
  * GitCommit is now just Commit
  * Hash is now Fingerprint
  * A lot of minor fields got renamed
  * All the XXXInterface types are now just XXX, and their old XXX type is now
    XXXUnion.

  More than likely there's still some comments and variable names that have
  slipped passed, but overall I feel like I got most of the changes.
fingerprint: AKkDC5BKhKbfXzZQ/F4KquHeMgVvcNxgLmkZFz/nP/tY
credentials:
- type: pgp_signature
  pub_key_id: 95C46FA6A41148AC
  body: 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
  account: mediocregopher
2020-04-26 14:23:10 -06:00

84 lines
1.9 KiB
Go

package dehub
import (
"crypto/sha256"
"encoding/binary"
"fmt"
"hash"
"sort"
)
var (
defaultHashHelperAlgo = sha256.New
)
type hashHelper struct {
hash hash.Hash
varintBuf []byte
}
// if h is nil it then defaultHashHelperAlgo will be used
func newHashHelper(h hash.Hash) *hashHelper {
if h == nil {
h = defaultHashHelperAlgo()
}
s := &hashHelper{
hash: h,
varintBuf: make([]byte, binary.MaxVarintLen64),
}
return s
}
func (s *hashHelper) sum(prefix []byte) []byte {
out := make([]byte, len(prefix), len(prefix)+s.hash.Size())
copy(out, prefix)
return s.hash.Sum(out)
}
func (s *hashHelper) writeUint(i uint64) {
n := binary.PutUvarint(s.varintBuf, i)
if _, err := s.hash.Write(s.varintBuf[:n]); err != nil {
panic(fmt.Sprintf("error writing %x to %T: %v", s.varintBuf[:n], s.hash, err))
}
}
func (s *hashHelper) writeStr(str string) {
s.writeUint(uint64(len(str)))
s.hash.Write([]byte(str))
}
func (s *hashHelper) writeChangedFiles(changedFiles []ChangedFile) {
sort.Slice(changedFiles, func(i, j int) bool {
return changedFiles[i].Path < changedFiles[j].Path
})
s.writeUint(uint64(len(changedFiles)))
for _, fileChanged := range changedFiles {
s.writeStr(fileChanged.Path)
s.hash.Write(fileChanged.FromMode.Bytes())
s.hash.Write(fileChanged.FromHash[:])
s.hash.Write(fileChanged.ToMode.Bytes())
s.hash.Write(fileChanged.ToHash[:])
}
}
var (
changeHashVersion = []byte{0}
commentHashVersion = []byte{0}
)
// if h is nil it then defaultHashHelperAlgo will be used
func genChangeFingerprint(h hash.Hash, msg string, changedFiles []ChangedFile) []byte {
s := newHashHelper(h)
s.writeStr(msg)
s.writeChangedFiles(changedFiles)
return s.sum(changeHashVersion)
}
// if h is nil it then defaultHashHelperAlgo will be used
func genCommentFingerprint(h hash.Hash, comment string) []byte {
s := newHashHelper(h)
s.writeStr(comment)
return s.sum(commentHashVersion)
}