core: Factor out params string parsing

Move the routine from the DRM plugin used to parse a comma-separated
key=value set of parameters into cog_key_file_parse_params_string()
which sets values into a GKeyFile. This allows building up the final
set of options into the configuration object held by CogShell, then
using that as canonical source for reading options.

core/cog-utils.c

@@ -384,6 +384,39 @@ cog_option_entries_from_class (GObjectClass *klass)
     return g_steal_pointer (&entries);
 }
 
+/**
+ * cog_key_file_parse_params_string:
+ * @key_file: A key file
+ * @group_name: Name of a key file group
+ * @params_string: Input string
+ * @error: Where to store an error, if any
+ *
+ * Parse parameters string storing values in a key file.
+ *
+ * Since: 0.18
+ */
+void
+cog_key_file_parse_params_string(GKeyFile *key_file, const char *group_name, const char *params_string)
+{
+    g_return_if_fail(key_file);
+    g_return_if_fail(group_name);
+    g_return_if_fail(params_string);
+
+    g_auto(GStrv) params = g_strsplit(params_string, ",", 0);
+    for (unsigned i = 0; params[i]; i++) {
+        g_auto(GStrv) kv = g_strsplit(params[i], "=", 2);
+        if (g_strv_length(kv) != 2) {
+            g_warning("%s: Invalid parameter syntax '%s'.", __func__, params[i]);
+            continue;
+        }
+
+        const char *k = g_strstrip(kv[0]);
+        const char *v = g_strstrip(kv[1]);
+
+        g_key_file_set_value(key_file, group_name, k, v);
+    }
+}
+
 /**
  * cog_apply_properties_from_key_file:
  * @object: An object to set properties on

core/cog-utils.h

@@ -31,8 +31,13 @@ char* cog_uri_guess_from_user_input (const char *uri_like,
 
 COG_API
 GOptionEntry* cog_option_entries_from_class (GObjectClass *klass);
-gboolean
-cog_apply_properties_from_key_file(GObject *object, GKeyFile *key_file, const char *group_name, GError **error);
+
+COG_API void cog_key_file_parse_params_string(GKeyFile *key_file, const char *group_name, const char *params_string);
+
+COG_API gboolean cog_apply_properties_from_key_file(GObject    *object,
+                                                    GKeyFile   *key_file,
+                                                    const char *group_name,
+                                                    GError    **error);
 
 static inline const char*
 cog_g_enum_get_nick (GType enum_type, int value)

platform/drm/cog-platform-drm.c

@@ -241,45 +241,16 @@ static void
 init_config(CogDrmPlatform *self, CogShell *shell, const char *params_string)
 {
     GKeyFile *key_file = cog_shell_get_config_file(shell);
+
+    if (params_string)
+        cog_key_file_parse_params_string(key_file, "drm", params_string);
+
     if (key_file) {
         g_autoptr(GError) error = NULL;
         if (!cog_apply_properties_from_key_file(G_OBJECT(self), key_file, "drm", &error))
             g_warning("Reading config file: %s", error->message);
     }
 
-    if (params_string) {
-        g_auto(GStrv) params = g_strsplit(params_string, ",", 0);
-        for (unsigned i = 0; params[i]; i++) {
-            g_auto(GStrv) kv = g_strsplit(params[i], "=", 2);
-            if (g_strv_length(kv) != 2) {
-                g_warning("Invalid parameter syntax '%s'.", params[i]);
-                continue;
-            }
-
-            const char *k = g_strstrip(kv[0]);
-            const char *v = g_strstrip(kv[1]);
-
-            if (g_strcmp0(k, "renderer") == 0) {
-                if (g_strcmp0(v, "modeset") == 0)
-                    self->use_gles = false;
-                else if (g_strcmp0(v, "gles") == 0)
-                    self->use_gles = true;
-                else
-                    g_warning("Invalid value '%s' for parameter '%s'.", v, k);
-            } else if (g_strcmp0(k, "rotation") == 0) {
-                char       *endp = NULL;
-                const char *str = v ? v : "";
-                uint64_t    val = g_ascii_strtoull(str, &endp, 10);
-                if (val > 3 || *endp != '\0')
-                    g_warning("Invalid value '%s' for parameter '%s'.", v, k);
-                else
-                    self->rotation = val;
-            } else {
-                g_warning("Invalid parameter '%s'.", k);
-            }
-        }
-    }
-
     float device_scale_factor = cog_shell_get_device_scale_factor(shell);
     if (device_scale_factor >= 0.2f) {
         g_debug("%s: Overriding CogDrmPlatform<%p>.device-scale-factor = <%.2f> from shell", __func__, self,