dbus-utils: Move from the backends/native/ to backends/

We will move the launcher to backends/ which has a dependency on
dbus-utils so let's also just move dbus-utils there.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4130>

src/backends/meta-dbus-utils.c

@@ -0,0 +1,105 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2014 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Written by:
+ *     Jasper St. Pierre <jstpierre@mecheye.net>
+ */
+
+#include "config.h"
+
+#include "backends/meta-dbus-utils.h"
+
+#include <glib.h>
+
+/* Stolen from tp_escape_as_identifier, from tp-glib,
+ * which follows the same escaping convention as systemd.
+ */
+static inline gboolean
+_esc_ident_bad (gchar c, gboolean is_first)
+{
+  return ((c < 'a' || c > 'z') &&
+          (c < 'A' || c > 'Z') &&
+          (c < '0' || c > '9' || is_first));
+}
+
+static gchar *
+escape_dbus_component (const gchar *name)
+{
+  gboolean bad = FALSE;
+  size_t len = 0;
+  GString *op;
+  const gchar *ptr, *first_ok;
+
+  g_return_val_if_fail (name != NULL, NULL);
+
+  /* fast path for empty name */
+  if (name[0] == '\0')
+    return g_strdup ("_");
+
+  for (ptr = name; *ptr; ptr++)
+    {
+      if (_esc_ident_bad (*ptr, ptr == name))
+        {
+          bad = TRUE;
+          len += 3;
+        }
+      else
+        len++;
+    }
+
+  /* fast path if it's clean */
+  if (!bad)
+    return g_strdup (name);
+
+  /* If strictly less than ptr, first_ok is the first uncopied safe character.
+   */
+  first_ok = name;
+  op = g_string_sized_new (len);
+  for (ptr = name; *ptr; ptr++)
+    {
+      if (_esc_ident_bad (*ptr, ptr == name))
+        {
+          /* copy preceding safe characters if any */
+          if (first_ok < ptr)
+            {
+              g_string_append_len (op, first_ok, ptr - first_ok);
+            }
+          /* escape the unsafe character */
+          g_string_append_printf (op, "_%02x", (unsigned char)(*ptr));
+          /* restart after it */
+          first_ok = ptr + 1;
+        }
+    }
+  /* copy trailing safe characters if any */
+  if (first_ok < ptr)
+    {
+      g_string_append_len (op, first_ok, ptr - first_ok);
+    }
+  return g_string_free (op, FALSE);
+}
+
+char *
+get_escaped_dbus_path (const char *prefix,
+                       const char *component)
+{
+  char *escaped_component = escape_dbus_component (component);
+  char *path = g_strconcat (prefix, "/", escaped_component, NULL);
+
+  g_free (escaped_component);
+  return path;
+}