[gnome-software/wip/mcrha/odrs-download-etag: 11/11] gs-plugin: Use ETag in gs_plugin_download_file()

[Milan Crha <mcrha src gnome org>]

commit 5aae0e45ca444daf4998ebb1e6a184ecf61e3857
Author: Milan Crha <mcrha redhat com>
Date:   Mon Oct 18 17:41:04 2021 +0200

    gs-plugin: Use ETag in gs_plugin_download_file()
    
    Let it use the ETag-s to avoid downloading of a file, which
    did not change on the server.

 lib/gs-plugin.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/lib/gs-plugin.c b/lib/gs-plugin.c
index 767bb2332..c964e4931 100644
--- a/lib/gs-plugin.c
+++ b/lib/gs-plugin.c
@@ -1083,6 +1083,7 @@ gs_plugin_download_file (GsPlugin *plugin,
 {
        GsPluginPrivate *priv = gs_plugin_get_instance_private (plugin);
        GsPluginDownloadHelper helper;
+       const gchar *new_etag;
        guint status_code;
        g_autoptr(GError) error_local = NULL;
        g_autoptr(SoupMessage) msg = NULL;
@@ -1134,7 +1135,14 @@ gs_plugin_download_file (GsPlugin *plugin,
                                  G_CALLBACK (gs_plugin_download_chunk_cb),
                                  &helper);
        }
+       if (g_file_test (filename, G_FILE_TEST_EXISTS)) {
+               g_autofree gchar *last_etag = gs_utils_get_file_etag (filename, cancellable);
+               if (last_etag != NULL && *last_etag != '\0')
+                       soup_message_headers_append (msg->request_headers, "If-None-Match", last_etag);
+       }
        status_code = soup_session_send_message (priv->soup_session, msg);
+       if (status_code == SOUP_STATUS_NOT_MODIFIED)
+               return TRUE;
        if (status_code != SOUP_STATUS_OK) {
                g_autoptr(GString) str = g_string_new (NULL);
                g_string_append (str, soup_status_get_phrase (status_code));
@@ -1162,6 +1170,10 @@ gs_plugin_download_file (GsPlugin *plugin,
                             error_local->message);
                return FALSE;
        }
+       new_etag = soup_message_headers_get_one (msg->response_headers, "ETag");
+       if (new_etag != NULL && *new_etag == '\0')
+               new_etag = NULL;
+       gs_utils_set_file_etag (filename, new_etag, cancellable);
        return TRUE;
 }