[balsa/64-save-empty-attachment] balsa-mime-widget-callbacks: Handle empty part

[Peter Bloomfield <peterb src gnome org>]

commit 646ec8431f931811ccc50856a90a05a93065b56b
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Fri Jan 14 13:01:58 2022 -0500

    balsa-mime-widget-callbacks: Handle empty part
    
    When saving an attachment to a file, use libbalsa_vfs_ensure_file_exists()
    to make sure that the file is created before saving the attachment's content
    to it.
    
    As noted in https://gitlab.gnome.org/GNOME/balsa/-/issues/64, when
    g_mime_stream_write_to_stream() writes to a destination file that does
    not previously exist, it creates it only if content is written to it. So
    saving an empty attachment did not create the corresponding empty file.
    
    Fixes #64

 src/balsa-mime-widget-callbacks.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/src/balsa-mime-widget-callbacks.c b/src/balsa-mime-widget-callbacks.c
index 895e5a844..30ea58332 100644
--- a/src/balsa-mime-widget-callbacks.c
+++ b/src/balsa-mime-widget-callbacks.c
@@ -153,6 +153,18 @@ balsa_mime_widget_ctx_menu_save(GtkWidget * parent_widget,
     } else
        do_save = TRUE;
 
+    if (do_save) {
+        /* Make sure the file is created.
+         * https://gitlab.gnome.org/GNOME/balsa/-/issues/64 */
+        if (!libbalsa_vfs_ensure_file_exists(save_file, &err)) {
+            balsa_information(LIBBALSA_INFORMATION_ERROR,
+                             _("Could not save %s: %s"),
+                              file_uri, err ? err->message : "Unknown error");
+            g_clear_error(&err);
+            do_save = FALSE;
+        }
+    }
+
     /* save the file */
     if (do_save) {
        if (!libbalsa_message_body_save_vfs(mime_body, save_file,