improve zh2tw.go

zh2tw.go

@@ -25,8 +25,11 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"unicode/utf8"
 )
 
+const MaxFileSize = 8 << 20 // 8MB
+
 const usage = `
 Usage: zh2tw dir [nameFilter]
        zh2tw -h
@@ -79,9 +82,9 @@ func main() {
 		if mathed {
 			if changed := convertFile(path, method); changed {
 				fmt.Printf("%s\n", relpath)
-			}
 				total++
 			}
+		}
 		return nil
 	})
 	fmt.Printf("%s total %d\n", method, total)
@@ -93,10 +96,21 @@ func convertFile(path, method string) (changed bool) {
 		log.Fatal("convertFile: filepath.Abs:", err)
 	}
 
+	fi, err := os.Lstat(abspath)
+	if err != nil {
+		log.Fatal("convertFile: os.Lstat:", err)
+	}
+	if fi.Size() > MaxFileSize {
+		return false
+	}
+
 	oldData, err := ioutil.ReadFile(abspath)
 	if err != nil {
 		log.Fatal("convertFile: ioutil.ReadFile:", err)
 	}
+	if !utf8.Valid(oldData) {
+		return false
+	}
 
 	newData := oldData
 	switch {