Fix file errors in utilities.

Author: icedream

cmd/go-bsdiff/main.go

@@ -13,7 +13,7 @@ var (
 
 	argOld   = cli.Arg("old", "The old file.").Required().ExistingFile()
 	argNew   = cli.Arg("new", "The new file.").Required().ExistingFile()
-	argPatch = cli.Arg("patch", "Where to output the patch file.").Required().File()
+	argPatch = cli.Arg("patch", "Where to output the patch file.").Required().String()
 )
 
 func must(err error) {
@@ -27,7 +27,8 @@ func must(err error) {
 func main() {
 	kingpin.MustParse(cli.Parse(os.Args[1:]))
 
-	patchFile := *argPatch
+	patchFile, err := os.Create(*argPatch)
+	must(err)
 	defer patchFile.Close()
 
 	oldFile, err := os.Open(*argOld)

cmd/go-bspatch/main.go

@@ -12,7 +12,7 @@ var (
 	cli = kingpin.New("go-bspatch", "Applies binary patches generated using the bsdiff algorithm.")
 
 	argOld   = cli.Arg("old", "The old file.").Required().ExistingFile()
-	argNew   = cli.Arg("new", "Where the new file will be written to.").Required().File()
+	argNew   = cli.Arg("new", "Where the new file will be written to.").Required().String()
 	argPatch = cli.Arg("patch", "The patch file.").Required().ExistingFile()
 )
 
@@ -27,13 +27,14 @@ func must(err error) {
 func main() {
 	kingpin.MustParse(cli.Parse(os.Args[1:]))
 
-	newFile := *argNew
-	defer newFile.Close()
-
 	oldFile, err := os.Open(*argOld)
 	must(err)
 	defer oldFile.Close()
 
+	newFile, err := os.Create(*argNew)
+	must(err)
+	defer newFile.Close()
+
 	patchFile, err := os.Open(*argPatch)
 	must(err)
 	defer patchFile.Close()