impr: comply with rfc 2397 for binary files in request

Author: nalgeon

internal/fileio/fileio.go

@@ -72,10 +72,12 @@ func ReadJson[T any](path string) (T, error) {
 
 // WriteFile writes the file to disk.
 // The content can be text or binary (encoded as a data URL),
-// e.g. data:application/octet-stream;base64,MTIz
+// e.g. data:;base64,MTIz
 func WriteFile(path, content string, perm fs.FileMode) (err error) {
 	var data []byte
-	if strings.HasPrefix(content, "data:") {
+	// TODO: only check for "data:;base64," to comply with RFC 2397.
+	// Remove the "data:" check after the snippet reaches 0.16.
+	if strings.HasPrefix(content, "data:") || strings.HasPrefix(content, "data:;base64,") {
 		// data-url encoded file
 		_, encoded, found := strings.Cut(content, ",")
 		if !found {

internal/fileio/fileio_test.go

@@ -175,7 +175,7 @@ func TestWriteFile(t *testing.T) {
 
 	t.Run("binary", func(t *testing.T) {
 		path := filepath.Join(dir, "data.bin")
-		err = WriteFile(path, "data:application/octet-stream;base64,MTIz", 0444)
+		err = WriteFile(path, "data:;base64,MTIz", 0444)
 		if err != nil {
 			t.Fatalf("expected nil err, got %v", err)
 		}
@@ -215,7 +215,7 @@ func TestWriteFile(t *testing.T) {
 
 	t.Run("invalid binary value", func(t *testing.T) {
 		path := filepath.Join(dir, "data.bin")
-		err = WriteFile(path, "data:application/octet-stream;base64,12345", 0444)
+		err = WriteFile(path, "data:;base64,12345", 0444)
 		if err == nil {
 			t.Fatal("expected error, got nil")
 		}