Linux AppImage: bundled libsoup-3.0/libnghttp2 shadow system libs on non-Debian distros, breaking system GStreamer WebRTC plugins #3494

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1. scottsanpedro commented on Jul 29, 2026

   

   scottsanpedro

   on Jul 29, 2026

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   Companion permission-layer issue (the remaining blocker once this is fixed): #3495
2. scottsanpedro commented on Jul 29, 2026

   

   scottsanpedro

   on Jul 29, 2026

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   Still present in 0.5.1 — the two bundled libs are byte-identical to the 0.5.0 ones:

   lib	sha256 (first 16)	0.5.0	0.5.1
   usr/lib/libsoup-3.0.so.0	2cb93d9fb132840a	✔	✔
   usr/lib/libnghttp2.so.14	5696eaac037a57e6	✔	✔

   (checked by --appimage-extract-ing usr/lib/libsoup* / usr/lib/libnghttp2* straight out of a freshly downloaded Buzz_0.5.1_amd64.AppImage, so it is not a stale local copy.)

   The rename workaround from the original report still applies unchanged and still works on 0.5.1 — I have it scripted now so it re-applies on every update, since a fresh extract silently reintroduces the problem and the symptom (huddles with no webrtcbin) gives no hint as to why.

   Environment as before, current system versions: Arch, libsoup3 3.6.6-2, libnghttp2 1.69.0-1, gstreamer/gst-plugins-bad 1.28.5-4, libnice 0.1.23-1, gupnp 1.6.10-1, webkit2gtk-4.1 2.52.5-2.
3. balter-io commented on Jul 30, 2026

   

   balter-io

   on Jul 30, 2026

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   For anyone hitting this on a current release: the fix from #3607 merged the day after v0.5.2 was cut, so every released build (≤ 0.5.2) still fails with the NotAllowedError. Until the next release ships, here's the workaround I've been running with — a tiny GTK3 module that auto-allows WebKit's user-media/device-info permission requests in the Buzz process.

   It works by adding a GObject emission hook on WebKitWebView::permission-request and calling webkit_permission_request_allow() for WebKitUserMediaPermissionRequest / WebKitDeviceInfoPermissionRequest only. WebKit permission requests honour a single decision, so the early allow makes the unhandled-signal default deny a no-op. All webkit symbols are resolved via dlsym, so it builds without webkit2gtk headers and binds to whatever webkit/glib the app actually loaded (works fine against the AppImage's bundled webkit). If the symbols aren't there it logs and deactivates itself.

   buzz-webkit-mic-shim.c

   /*
    * buzz-webkit-mic-shim — auto-allow WebKitGTK media permission requests in Buzz.
    */
   
   #include <glib-object.h>
   #include <gmodule.h>
   #include <dlfcn.h>
   #include <stdio.h>
   #include <string.h>
   
   typedef GType (*get_type_fn)(void);
   typedef void (*allow_fn)(gpointer);
   
   static allow_fn perm_allow;
   
   static gboolean
   permission_hook(GSignalInvocationHint *ihint, guint n_param_values,
                   const GValue *param_values, gpointer data)
   {
     (void)ihint;
     (void)data;
   
     if (n_param_values < 2)
       return TRUE;
   
     gpointer request = g_value_get_object(&param_values[1]);
     if (!request)
       return TRUE;
   
     const char *tname = G_OBJECT_TYPE_NAME(request);
     if (tname && (strcmp(tname, "WebKitUserMediaPermissionRequest") == 0
                   || strcmp(tname, "WebKitDeviceInfoPermissionRequest") == 0)) {
       perm_allow(request);
       fprintf(stderr, "[buzz-mic-shim] allowed %s\n", tname);
     }
   
     return TRUE; /* keep the hook installed */
   }
   
   G_MODULE_EXPORT void
   gtk_module_init(gint *argc, gchar ***argv)
   {
     (void)argc;
     (void)argv;
   
     get_type_fn wv_get_type =
         (get_type_fn)dlsym(RTLD_DEFAULT, "webkit_web_view_get_type");
     perm_allow = (allow_fn)dlsym(RTLD_DEFAULT, "webkit_permission_request_allow");
   
     if (!wv_get_type || !perm_allow) {
       fprintf(stderr, "[buzz-mic-shim] webkit symbols not found; shim inactive\n");
       return;
     }
   
     GType webview_type = wv_get_type();
     /* Signals are registered in class_init; force it before the lookup. */
     gpointer klass = g_type_class_ref(webview_type);
     guint signal_id = g_signal_lookup("permission-request", webview_type);
     if (signal_id == 0) {
       fprintf(stderr, "[buzz-mic-shim] permission-request signal not found\n");
       g_type_class_unref(klass);
       return;
     }
   
     g_signal_add_emission_hook(signal_id, 0, permission_hook, NULL, NULL);
     /* klass ref intentionally kept for process lifetime. */
     fprintf(stderr, "[buzz-mic-shim] installed permission-request hook\n");
   }

   Build (no webkit headers needed — deliberately no -l libs so glib symbols bind at load time to the glib already in the process):

   gcc -shared -fPIC -O2 -Wall -Wextra \
       $(pkg-config --cflags glib-2.0 gobject-2.0 gmodule-2.0) \
       buzz-webkit-mic-shim.c -o ~/.local/lib/buzz-webkit-mic-shim.so

   Load it by setting GTK3_MODULES for the Buzz process, e.g.:

   GTK3_MODULES=$HOME/.local/lib/buzz-webkit-mic-shim.so ./Buzz_0.5.2_amd64.AppImage

   (For an extracted-AppImage install you can add that export to apprun-hooks/linuxdeploy-plugin-gtk.sh instead.)

   On a successful start you'll see [buzz-mic-shim] installed permission-request hook on stderr, and huddle mic capture works normally after that.

   Two caveats:

   • This blanket-allows user-media requests for the whole Buzz process — fine for a workaround, but the real fix in desktop: enable getUserMedia in the Linux WebKitGTK webview #3607 is stricter (trusted app origin + device-type check), so drop the shim once you're on a release containing desktop: enable getUserMedia in the Linux WebKitGTK webview #3607 rather than keeping both. An emission hook runs before regular signal handlers, so leaving it in place would bypass the new origin check.
   • Mic capture also needs the GStreamer WebRTC plugins resolving correctly per Linux AppImage: bundled libsoup-3.0/libnghttp2 shadow system libs on non-Debian distros, breaking system GStreamer WebRTC plugins #3494 — the shim only fixes the permission layer.