url-mode: add support for XDG activation when opening URLs

First, add a ‘token’ argument to spawn(). When non-NULL, spawn() will
set the ‘XDG_ACTIVATION_TOKEN’ environment variable in the forked
process. If DISPLAY is non-NULL, we also set DESKTOP_STARTUP_ID, for
compatibility with X11 applications. Note that failing to set either
of these environment variables are considered non-fatal - i.e. we
ignore failures.

Next, add a helper function, wayl_get_activation_token(), to generate
an XDG activation token, and call a user-provided callback when it’s
‘done (since token generation is asynchronous). This function takes an
optional ‘seat’ and ‘serial’ arguments - when both are non-NULL/zero,
we set the serial on the token. ‘win’ is a required argument, used to
set the surface on the token.

Re-write wayl_win_set_urgent() to use the new helper function.

Finally, rewrite activate_url() to first try to get an activation
token (and spawn the URL launcher in the token callback). If that
fails, or if we don’t have XDG activation support, spawn the URL
launcher immediately (like before this patch).

Closes #1058

url-mode.c

@@ -50,8 +50,86 @@ execute_binding(struct seat *seat, struct terminal *term,
     return true;
 }
 
+static bool
+spawn_url_launcher_with_token(struct terminal *term,
+                              const char *url,
+                              const char *xdg_activation_token)
+{
+    size_t argc;
+    char **argv;
+
+    int dev_null = open("/dev/null", O_RDWR);
+
+    if (dev_null < 0) {
+        LOG_ERRNO("failed to open /dev/null");
+        return false;
+    }
+
+    bool ret = false;
+
+    if (spawn_expand_template(
+            &term->conf->url.launch, 1,
+            (const char *[]){"url"},
+            (const char *[]){url},
+            &argc, &argv))
+    {
+        ret = spawn(term->reaper, term->cwd, argv,
+              dev_null, dev_null, dev_null, xdg_activation_token);
+
+        for (size_t i = 0; i < argc; i++)
+            free(argv[i]);
+        free(argv);
+    }
+
+    close(dev_null);
+    return ret;
+}
+
+#if defined(HAVE_XDG_ACTIVATION)
+struct spawn_activation_context {
+    struct terminal *term;
+    char *url;
+};
+
 static void
-activate_url(struct seat *seat, struct terminal *term, const struct url *url)
+activation_token_done(const char *token, void *data)
+{
+    struct spawn_activation_context *ctx = data;
+
+    spawn_url_launcher_with_token(ctx->term, ctx->url, token);
+    free(ctx->url);
+    free(ctx);
+}
+#endif
+
+static bool
+spawn_url_launcher(struct seat *seat, struct terminal *term, const char *url,
+                   uint32_t serial)
+{
+#if defined(HAVE_XDG_ACTIVATION)
+    struct spawn_activation_context *ctx = xmalloc(sizeof(*ctx));
+    *ctx = (struct spawn_activation_context){
+        .term = term,
+        .url = xstrdup(url),
+    };
+
+    if (wayl_get_activation_token(
+            seat->wayl, seat, serial, term->window, &activation_token_done, ctx))
+    {
+        /* Context free:d by callback */
+        return true;
+    }
+
+    free(ctx->url);
+    free(ctx);
+#endif
+
+    return spawn_url_launcher_with_token(term, url, NULL);
+}
+
+static void
+activate_url(struct seat *seat, struct terminal *term, const struct url *url,
+             uint32_t serial)
 {
     char *url_string = NULL;
 
@@ -87,30 +165,7 @@ activate_url(struct seat *seat, struct terminal *term, const struct url *url)
 
     case URL_ACTION_LAUNCH:
     case URL_ACTION_PERSISTENT: {
-        size_t argc;
-        char **argv;
-
-        int dev_null = open("/dev/null", O_RDWR);
-
-        if (dev_null < 0) {
-            LOG_ERRNO("failed to open /dev/null");
-            break;
-        }
-
-        if (spawn_expand_template(
-                &term->conf->url.launch, 1,
-                (const char *[]){"url"},
-                (const char *[]){url_string},
-                &argc, &argv))
-        {
-            spawn(term->reaper, term->cwd, argv, dev_null, dev_null, dev_null);
-
-            for (size_t i = 0; i < argc; i++)
-                free(argv[i]);
-            free(argv);
-        }
-
-        close(dev_null);
+        spawn_url_launcher(seat, term, url_string, serial);
         break;
     }
     }
@@ -207,7 +262,7 @@ urls_input(struct seat *seat, struct terminal *term,
     }
 
     if (match) {
-        activate_url(seat, term, match);
+        activate_url(seat, term, match, serial);
 
         switch (match->action) {
         case URL_ACTION_COPY: