From e0a7e4af12c3e18229f2b42583ae27961eaf3d68 Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Tue, 6 Aug 2024 18:24:27 +0300
Subject: [PATCH] Hash type for convenience

---
 dep.go    | 12 ++++++------
 depfix.go |  4 ++--
 hash.go   |  6 ++++--
 run.go    |  4 ++--
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/dep.go b/dep.go
index 8fe4fff..b43a583 100644
--- a/dep.go
+++ b/dep.go
@@ -78,9 +78,9 @@ func (ifchange *Ifchange) Hash() Hash {
 }
 
 type Dep struct {
-	stamp     Hash
 	ifcreates []*Tgt
 	ifchanges []*Ifchange
+	stamp     Hash
 	build     uuid.UUID
 	always    bool
 }
@@ -104,7 +104,7 @@ func always(w io.Writer, fdDepName string) (err error) {
 func stamp(w io.Writer, fdDepName string, hsh Hash) (err error) {
 	tracef(CDebug, "stamp: %s <- %s", fdDepName, hsh)
 	_, err = io.Copy(w, bytes.NewBuffer(chunkWrite(append(
-		[]byte{DepTypeStamp}, []byte(hsh)...,
+		[]byte{DepTypeStamp}, hsh[:]...,
 	))))
 	return
 }
@@ -112,7 +112,7 @@ func stamp(w io.Writer, fdDepName string, hsh Hash) (err error) {
 func fileHash(fd io.Reader) (Hash, error) {
 	h := blake3.New(HashLen, nil)
 	if _, err := io.Copy(h, bufio.NewReader(fd)); err != nil {
-		return "", err
+		return HashNull, err
 	}
 	return Hash(h.Sum(nil)), nil
 }
@@ -131,7 +131,7 @@ func depWrite(w io.Writer, fdDepName, cwd string, tgt *Tgt, hsh Hash) (err error
 	if isDir {
 		return nil
 	}
-	if hsh == "" {
+	if hsh == HashNull {
 		hsh, err = fileHash(fd)
 		if err != nil {
 			return ErrLine(err)
@@ -140,7 +140,7 @@ func depWrite(w io.Writer, fdDepName, cwd string, tgt *Tgt, hsh Hash) (err error
 	_, err = io.Copy(w, bytes.NewBuffer(chunkWrite(bytes.Join([][]byte{
 		{DepTypeIfchange},
 		inode[:],
-		[]byte(hsh),
+		hsh[:],
 		[]byte(tgt.RelTo(cwd)),
 	}, nil))))
 	return
@@ -170,7 +170,7 @@ func depsWrite(fdDep *os.File, tgts []*Tgt) error {
 		}
 		tgtDir := path.Join(cwd, DirPrefix)
 		if _, errStat := os.Stat(tgt.a); errStat == nil {
-			err = ErrLine(depWrite(fdDepW, fdDep.Name(), tgtDir, tgt, ""))
+			err = ErrLine(depWrite(fdDepW, fdDep.Name(), tgtDir, tgt, HashNull))
 		} else {
 			tgtRel := tgt.RelTo(tgtDir)
 			err = ErrLine(depWriteNonex(fdDepW, fdDep.Name(), tgtRel))
diff --git a/depfix.go b/depfix.go
index bbe2ae8..585e93c 100644
--- a/depfix.go
+++ b/depfix.go
@@ -177,7 +177,7 @@ func depFix(root string) error {
 							chunkWrite(bytes.Join([][]byte{
 								{DepTypeIfchange},
 								inode[:],
-								[]byte(hsh),
+								hsh[:],
 								[]byte(name),
 							}, nil))))
 					case DepTypeIfchangeNonex:
@@ -266,7 +266,7 @@ func depFix(root string) error {
 							chunkWrite(bytes.Join([][]byte{
 								{DepTypeIfchange},
 								inode[:],
-								[]byte(hsh),
+								hsh[:],
 								[]byte(name),
 							}, nil))))
 					}
diff --git a/hash.go b/hash.go
index 420937d..6c0e6d1 100644
--- a/hash.go
+++ b/hash.go
@@ -6,8 +6,10 @@ import (
 
 const HashLen = 32
 
-type Hash string
+type Hash [HashLen]byte
+
+var HashNull Hash
 
 func (h Hash) String() string {
-	return hex.EncodeToString([]byte(h))
+	return hex.EncodeToString(h[:])
 }
diff --git a/run.go b/run.go
index 4921548..035cd59 100644
--- a/run.go
+++ b/run.go
@@ -359,7 +359,7 @@ func runScript(tgt *Tgt, errs chan error, forced, traced bool) error {
 		}
 	}
 
-	if err = depWrite(fdDepW, fdDep.Name(), tgtH, doFile, ""); err != nil {
+	if err = depWrite(fdDepW, fdDep.Name(), tgtH, doFile, HashNull); err != nil {
 		cleanup()
 		return TgtError{tgt, ErrLine(err)}
 	}
@@ -739,7 +739,7 @@ func runScript(tgt *Tgt, errs chan error, forced, traced bool) error {
 			}
 		} else {
 			var hsh Hash
-			if hshPrev != "" {
+			if hshPrev != HashNull {
 				_, err = fd.Seek(0, io.SeekStart)
 				if err != nil {
 					err = ErrLine(err)
-- 
2.48.1