gio: Create a sandbox checking function

gio/gsandbox.c

@@ -0,0 +1,75 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2022 Canonical Ltd
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include "gsandbox.h"
+
+static gboolean
+is_flatpak (void)
+{
+  return g_file_test ("/.flatpak-info", G_FILE_TEST_EXISTS);
+}
+
+static gboolean
+is_snap (void)
+{
+  const gchar *snap_path;
+  gchar *yaml_path;
+  gboolean result;
+
+  snap_path = g_getenv ("SNAP");
+  if (snap_path == NULL)
+    return FALSE;
+
+  yaml_path = g_build_filename (snap_path, "meta", "snap.yaml", NULL);
+  result = g_file_test (yaml_path, G_FILE_TEST_EXISTS);
+  g_free (yaml_path);
+
+  return result;
+}
+
+/*
+ * glib_get_sandbox_type:
+ *
+ * Gets the type of sandbox this process is running inside.
+ *
+ * Checking for sandboxes may involve doing blocking I/O calls, but should not take
+ * any significant time.
+ *
+ * The sandbox will not change over the lifetime of the process, so calling this
+ * function once and reusing the result is valid.
+ *
+ * If this process is not sandboxed then @G_SANDBOX_TYPE_UNKNOWN will be returned.
+ * This is because this function only detects known sandbox types in #GSandboxType.
+ * It may be updated in the future if new sandboxes come into use.
+ *
+ * Returns: a #GSandboxType.
+ */
+GSandboxType
+glib_get_sandbox_type (void)
+{
+  if (is_flatpak ())
+    return G_SANDBOX_TYPE_FLATPAK;
+  else if (is_snap ())
+    return G_SANDBOX_TYPE_SNAP;
+  else
+    return G_SANDBOX_TYPE_UNKNOWN;
+}