From d50ba0bfdabd90a8d472ed57a5afcffd7a893340 Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Wed, 4 Oct 2023 19:46:40 +0300
Subject: [PATCH] Hash explicit type

---
 dep.go    | 36 ++++++++++++++++++++++--------------
 depfix.go |  7 +++----
 run.go    |  4 ++--
 3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/dep.go b/dep.go
index 94daa2a..a1e45ae 100644
--- a/dep.go
+++ b/dep.go
@@ -33,15 +33,23 @@ import (
 	"lukechampine.com/blake3"
 )
 
+const HashLen = 32
+
 var (
 	DirPrefix string
 	DepCwd    string
 
 	ErrBadRecFormat = errors.New("invalid format of .rec")
 	InodeCache      = make(map[string][]*Inode)
-	HashCache       = make(map[string][]string)
+	HashCache       = make(map[string][]Hash)
 )
 
+type Hash string
+
+func (h Hash) String() string {
+	return hex.EncodeToString([]byte(h))
+}
+
 func recfileWrite(fdDep io.StringWriter, fields ...recfile.Field) error {
 	w := recfile.NewWriter(fdDep)
 	if _, err := w.RecordStart(); err != nil {
@@ -72,23 +80,23 @@ func stamp(fdDep, src *os.File) error {
 	if err != nil {
 		return err
 	}
-	tracef(CDebug, "stamp: %s <- %s", fdDep.Name(), hex.EncodeToString([]byte(hsh)))
+	tracef(CDebug, "stamp: %s <- %s", fdDep.Name(), hsh)
 	return recfileWrite(
 		fdDep,
 		recfile.Field{Name: "Type", Value: DepTypeStamp},
-		recfile.Field{Name: "Hash", Value: hex.EncodeToString([]byte(hsh))},
+		recfile.Field{Name: "Hash", Value: hsh.String()},
 	)
 }
 
-func fileHash(fd *os.File) (string, error) {
-	h := blake3.New(32, nil)
+func fileHash(fd *os.File) (Hash, error) {
+	h := blake3.New(HashLen, nil)
 	if _, err := io.Copy(h, bufio.NewReader(fd)); err != nil {
 		return "", err
 	}
-	return string(h.Sum(nil)), nil
+	return Hash(h.Sum(nil)), nil
 }
 
-func depWrite(fdDep *os.File, cwd string, tgt *Tgt, hsh string) error {
+func depWrite(fdDep *os.File, cwd string, tgt *Tgt, hsh Hash) error {
 	tracef(CDebug, "ifchange: %s <- %s", fdDep.Name(), tgt)
 	fd, err := os.Open(tgt.a)
 	if err != nil {
@@ -111,7 +119,7 @@ func depWrite(fdDep *os.File, cwd string, tgt *Tgt, hsh string) error {
 	fields := []recfile.Field{
 		{Name: "Type", Value: DepTypeIfchange},
 		{Name: "Target", Value: tgt.RelTo(cwd)},
-		{Name: "Hash", Value: hex.EncodeToString([]byte(hsh))},
+		{Name: "Hash", Value: hsh.String()},
 	}
 	fields = append(fields, inode.RecfileFields()...)
 	return recfileWrite(fdDep, fields...)
@@ -153,23 +161,23 @@ func depsWrite(fdDep *os.File, tgts []*Tgt) error {
 type DepInfoIfchange struct {
 	tgt   *Tgt
 	inode *Inode
-	hash  string
+	hash  Hash
 }
 
 type DepInfo struct {
 	build     string
 	always    bool
-	stamp     string
+	stamp     Hash
 	ifcreates []*Tgt
 	ifchanges []DepInfoIfchange
 }
 
-func mustHexDecode(s string) []byte {
+func mustHashDecode(s string) Hash {
 	b, err := hex.DecodeString(s)
 	if err != nil {
 		log.Fatal(err)
 	}
-	return b
+	return Hash(b)
 }
 
 var missingBuild = errors.New(".rec missing Build:")
@@ -232,7 +240,7 @@ func depRead(tgt *Tgt) (*DepInfo, error) {
 				InodeCache[dep.a] = append(InodeCache[dep.a], inode)
 			}
 
-			hsh := string(mustHexDecode(m["Hash"]))
+			hsh := mustHashDecode(m["Hash"])
 			cachedFound = false
 			for _, cachedHash := range HashCache[dep.a] {
 				if hsh == cachedHash {
@@ -253,7 +261,7 @@ func depRead(tgt *Tgt) (*DepInfo, error) {
 			if hsh == "" {
 				return nil, ErrBadRecFormat
 			}
-			depInfo.stamp = string(mustHexDecode(hsh))
+			depInfo.stamp = mustHashDecode(hsh)
 		default:
 			return nil, ErrBadRecFormat
 		}
diff --git a/depfix.go b/depfix.go
index 87ecd88..bc4452c 100644
--- a/depfix.go
+++ b/depfix.go
@@ -18,7 +18,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 package main
 
 import (
-	"encoding/hex"
 	"errors"
 	"io"
 	"io/fs"
@@ -111,7 +110,7 @@ func depFix(root string) error {
 				if err != nil {
 					return ErrLine(err)
 				}
-				theirHsh := mustHexDecode(m["Hash"])
+				theirHsh := mustHashDecode(m["Hash"])
 				fd, err := os.Open(path.Join(root, dep))
 				if err != nil {
 					if errors.Is(err, fs.ErrNotExist) {
@@ -149,7 +148,7 @@ func depFix(root string) error {
 				if err != nil {
 					return ErrLine(err)
 				}
-				if hsh != string(theirHsh) {
+				if hsh != theirHsh {
 					tracef(
 						CDebug, "depfix: %s/%s -> %s: hash differs",
 						root, entry.Name(), dep,
@@ -159,7 +158,7 @@ func depFix(root string) error {
 				fields = []recfile.Field{
 					{Name: "Type", Value: DepTypeIfchange},
 					{Name: "Target", Value: dep},
-					{Name: "Hash", Value: hex.EncodeToString([]byte(hsh))},
+					{Name: "Hash", Value: hsh.String()},
 				}
 				fields = append(fields, inode.RecfileFields()...)
 				fieldses[len(fieldses)-1] = fields
diff --git a/run.go b/run.go
index 7a6ac37..48c2f10 100644
--- a/run.go
+++ b/run.go
@@ -133,7 +133,7 @@ func mkdirs(pth string) error {
 }
 
 func isModified(depInfo *DepInfo, tgt *Tgt) (
-	modified bool, ourInode *Inode, hshPrev string, err error,
+	modified bool, ourInode *Inode, hshPrev Hash, err error,
 ) {
 	if depInfo == nil {
 		return
@@ -721,7 +721,7 @@ func runScript(tgt *Tgt, errs chan error, forced, traced bool) error {
 				goto Finish
 			}
 		} else {
-			var hsh string
+			var hsh Hash
 			if hshPrev != "" {
 				_, err = fd.Seek(0, io.SeekStart)
 				if err != nil {
-- 
2.44.0