Bug 277204 – REGRESSION [GTK][WPE] navigating to empty file:// URL ends up in download

• Component: Platform
• Status: RESOLVED FIXED

[Max Schmitt]

Created attachment 471981 [details]
What Playwright uses for now

When compiling WebKit with glib 2.76+ which includes https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3053 zero-size file:// resources will end up in a download instead of getting loaded.

Before glib 2.76 they were loaded which matches Safari / Chromium behaviour.

This affects:

- JHBuild on Ubuntu 24.04
- Flatpak builds

We as Playwright would love to upstream a change similar to the attachment, probably by adding it to `MIMETypeRegistry::supportedNonImageMIMETypes()` which seems like a better place.

Could someone help me where to put a test for that? I didn't find a reasonable LayoutTest, they seem all http:// based.

[Max Schmitt]

We added a workaround on our side in our embedder:

static gboolean response_policy_decision_can_show(WebKitResponsePolicyDecision *responseDecision)
{
    if (webkit_response_policy_decision_is_mime_type_supported(responseDecision))
        return TRUE;
    const gchar* mimeType = webkit_uri_response_get_mime_type(webkit_response_policy_decision_get_response(responseDecision));
    if (!mimeType || mimeType[0] == '\0')
        return FALSE;
    // https://bugs.webkit.org/show_bug.cgi?id=277204 / Ubuntu 24.04 / glib 2.76+ or higher
    if (g_ascii_strcasecmp(mimeType, "application/x-zerosize") == 0)
        return TRUE;
    return FALSE;
}