Add FNV-1a content hash to detect same-size changesHEADmain

1 files changed, 25 insertions, 0 deletions

diff --git a/types.go b/types.go
index bf5dd00..60e1ea9 100644
--- a/types.go
+++ b/types.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"hash/fnv"
 	"os"
 	"time"
 )
@@ -17,6 +18,7 @@ type FileMeta struct {
 	Mode    os.FileMode
 	ModTime time.Time
 	Symlink string
+	Hash    uint64
 }
 
 type FileMetaJSON struct {
@@ -24,6 +26,7 @@ type FileMetaJSON struct {
 	Mode    uint32 `json:"mode"`
 	ModTime string `json:"modtime"`
 	Symlink string `json:"symlink,omitempty"`
+	Hash    uint64 `json:"hash,omitempty"`
 }
 
 type Manifest struct {
@@ -45,6 +48,7 @@ func (m *Manifest) ToJSON() map[string]FileMetaJSON {
 			Mode:    uint32(v.Mode),
 			ModTime: v.ModTime.UTC().Format(time.RFC3339Nano),
 			Symlink: v.Symlink,
+			Hash:    v.Hash,
 		}
 	}
 	return files
@@ -59,6 +63,7 @@ func ManifestFromJSON(files map[string]FileMetaJSON) *Manifest {
 			Mode:    os.FileMode(v.Mode),
 			ModTime: t,
 			Symlink: v.Symlink,
+			Hash:    v.Hash,
 		}
 	}
 	return m
@@ -75,3 +80,23 @@ func DecodeMessage(data []byte) (*ProtocolMessage, error) {
 func EncodeMessage(msg *ProtocolMessage) ([]byte, error) {
 	return json.Marshal(msg)
 }
+
+func hashFile(path string) uint64 {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0
+	}
+	defer f.Close()
+	h := fnv.New64a()
+	buf := make([]byte, 32*1024)
+	for {
+		n, err := f.Read(buf)
+		if n > 0 {
+			h.Write(buf[:n])
+		}
+		if err != nil {
+			break
+		}
+	}
+	return h.Sum64()
+}