update image api *os.File to io.Reader (#994)

* update image api *os.File to io.Reader

* update code style

* add reader test

* supplementary reader test

* update the reader in the form builder test

* add commnet

* update comment

* update code style

internal/form_builder.go

@@ -4,8 +4,10 @@ import (
 	"fmt"
 	"io"
 	"mime/multipart"
+	"net/textproto"
 	"os"
-	"path"
+	"path/filepath"
+	"strings"
 )
 
 type FormBuilder interface {
@@ -30,8 +32,37 @@ func (fb *DefaultFormBuilder) CreateFormFile(fieldname string, file *os.File) er
 	return fb.createFormFile(fieldname, file, file.Name())
 }
 
+var quoteEscaper = strings.NewReplacer("\\", "\\\\", `"`, "\\\"")
+
+func escapeQuotes(s string) string {
+	return quoteEscaper.Replace(s)
+}
+
+// CreateFormFileReader creates a form field with a file reader.
+// The filename in parameters can be an empty string.
+// The filename in Content-Disposition is required, But it can be an empty string.
 func (fb *DefaultFormBuilder) CreateFormFileReader(fieldname string, r io.Reader, filename string) error {
-	return fb.createFormFile(fieldname, r, path.Base(filename))
+	h := make(textproto.MIMEHeader)
+	h.Set(
+		"Content-Disposition",
+		fmt.Sprintf(
+			`form-data; name="%s"; filename="%s"`,
+			escapeQuotes(fieldname),
+			escapeQuotes(filepath.Base(filename)),
+		),
+	)
+
+	fieldWriter, err := fb.writer.CreatePart(h)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(fieldWriter, r)
+	if err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func (fb *DefaultFormBuilder) createFormFile(fieldname string, r io.Reader, filename string) error {