examples: Add simple storage implementation using GVariant

This is useful so that the enroll and verify examples will not use the
deprecated API anymore.

examples/storage.c

@@ -0,0 +1,136 @@
+/*
+ * Trivial storage driver for example programs
+ *
+ * Copyright (C) 2019 Benjamin Berg <bberg@redhat.com>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <glib.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <libfprint/fprint.h>
+
+#define STORAGE_FILE "test-storage.variant"
+
+static char *
+get_print_data_descriptor (struct fp_print_data *data, struct fp_dev *dev, enum fp_finger finger)
+{
+	gint drv_id;
+	gint devtype;
+
+	if (data) {
+		drv_id = fp_print_data_get_driver_id (data);
+		devtype = fp_print_data_get_devtype (data);
+	} else {
+		drv_id = fp_driver_get_driver_id(fp_dev_get_driver (dev));
+		devtype = fp_dev_get_devtype (dev);
+	}
+
+	return g_strdup_printf("%x/%08x/%x",
+			       drv_id,
+			       devtype,
+			       finger);
+}
+
+static GVariantDict*
+load_data(void)
+{
+	GVariantDict *res;
+	GVariant *var;
+	gchar *contents = NULL;
+	gssize length = 0;
+
+	if (!g_file_get_contents (STORAGE_FILE, &contents, &length, NULL)) {
+		g_warning ("Error loading storage, assuming it is empty");
+		return g_variant_dict_new(NULL);
+	}
+
+	var = g_variant_new_from_data (G_VARIANT_TYPE_VARDICT, contents, length, FALSE, NULL, NULL);
+
+	res = g_variant_dict_new(var);
+	g_variant_unref(var);
+	return res;
+}
+
+static int
+save_data(GVariant *data)
+{
+	const gchar *contents = NULL;
+	gsize length;
+
+	length = g_variant_get_size(data);
+	contents = (gchar*) g_variant_get_data (data);
+
+	if (!g_file_set_contents (STORAGE_FILE, contents, length, NULL)) {
+		g_warning ("Error saving storage,!");
+		return -1;
+	}
+
+	g_variant_ref_sink(data);
+	g_variant_unref(data);
+
+	return 0;
+}
+
+int
+print_data_save(struct fp_print_data *fp_data, enum fp_finger finger)
+{
+	gchar *descr = get_print_data_descriptor (fp_data, NULL, finger);
+	GVariantDict *dict;
+	GVariant *val;
+	guchar *data;
+	gsize size;
+	int res;
+
+	dict = load_data();
+
+	size = fp_print_data_get_data(fp_data, &data);
+	val = g_variant_new_fixed_array (G_VARIANT_TYPE("y"), data, size, 1);
+	g_variant_dict_insert_value (dict, descr, val);
+
+	res = save_data(g_variant_dict_end(dict));
+	g_variant_dict_unref(dict);
+
+	return res;
+}
+
+struct fp_print_data*
+print_data_load(struct fp_dev *dev, enum fp_finger finger)
+{
+	gchar *descr = get_print_data_descriptor (NULL, dev, finger);
+	GVariantDict *dict;
+	guchar *stored_data;
+	gsize stored_len;
+	GVariant *val;
+	struct fp_print_data *res = NULL;
+
+	dict = load_data();
+	val = g_variant_dict_lookup_value (dict, descr, G_VARIANT_TYPE ("ay"));
+
+	if (val) {
+		stored_data = (guchar*) g_variant_get_fixed_array (val, &stored_len, 1);
+		res = fp_print_data_from_data(stored_data, stored_len);
+
+		g_variant_unref(val);
+	}
+
+	g_variant_dict_unref(dict);
+	g_free(descr);
+
+	return res;
+}

examples/storage.h

@@ -0,0 +1,27 @@
+/*
+ * Trivial storage driver for example programs
+ *
+ * Copyright (C) 2019 Benjamin Berg <bberg@redhat.com>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __STORAGE_H
+#define __STORAGE_H
+
+int print_data_save(struct fp_print_data *fp_data, enum fp_finger finger);
+struct fp_print_data* print_data_load(struct fp_dev *dev, enum fp_finger finger);
+
+#endif /* __STORAGE_H */