examples: Add example for deleting prints

When deleting prints, the API user should also delete the print from the
storage (for devices that support on-device storage). Add an example to
show how to do this.

examples/delete.c

@@ -0,0 +1,115 @@
+/*
+ * Example fingerprint delete finger program, which delete the right index
+ * finger which has been previously enrolled to disk.
+ * Copyright (C) 2019 Synaptics Inc
+ *
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <libfprint/fprint.h>
+
+struct fp_dscv_dev *discover_device(struct fp_dscv_dev **discovered_devs)
+{
+	struct fp_dscv_dev *ddev = discovered_devs[0];
+	struct fp_driver *drv;
+	if (!ddev)
+		return NULL;
+
+	drv = fp_dscv_dev_get_driver(ddev);
+	printf("Found device claimed by %s driver\n", fp_driver_get_full_name(drv));
+	return ddev;
+}
+
+
+int main(void)
+{
+	int r = 1;
+	struct fp_dscv_dev *ddev;
+	struct fp_dscv_dev **discovered_devs;
+	struct fp_dev *dev;
+	struct fp_print_data *data;
+
+	setenv ("G_MESSAGES_DEBUG", "all", 0);
+	setenv ("LIBUSB_DEBUG", "3", 0);
+
+	r = fp_init();
+	if (r < 0) {
+		fprintf(stderr, "Failed to initialize libfprint\n");
+		exit(1);
+	}
+
+	discovered_devs = fp_discover_devs();
+	if (!discovered_devs) {
+		fprintf(stderr, "Could not discover devices\n");
+		goto out;
+	}
+
+	ddev = discover_device(discovered_devs);
+	if (!ddev) {
+		fprintf(stderr, "No devices detected.\n");
+		goto out;
+	}
+
+	dev = fp_dev_open(ddev);
+	fp_dscv_devs_free(discovered_devs);
+	if (!dev) {
+		fprintf(stderr, "Could not open device.\n");
+		goto out;
+	}
+
+	printf("Opened device. Loading previously enrolled right index finger "
+		"data...\n");
+
+	r = fp_print_data_load(dev, RIGHT_INDEX, &data);
+	if (r != 0) {
+		fprintf(stderr, "Failed to load fingerprint, error %d\n", r);
+		fprintf(stderr, "Did you remember to enroll your right index finger "
+			"first?\n");
+		goto out_close;
+	}
+
+	printf("Print loaded. delete data in sensor.\n");
+	if(!fp_dev_supports_data_in_sensor(dev))
+	{
+		printf("This driver doesn't support to store data in sensor.\n");
+		goto out_close;
+	}
+
+	r = fp_delete_finger(dev, data);
+	fp_print_data_free(data);
+	if (r) {
+		printf("delete finger failed with error %d :(\n", r);
+	}
+	else
+	{
+		printf("sensor data deleted. now delete host data");
+		r = fp_print_data_delete(dev, RIGHT_INDEX);
+		if (r < 0) {
+			printf("Delete sensor data successfully but delete host data failed. %d :(\n", r);
+		}
+	}
+
+out_close:
+	fp_dev_close(dev);
+out:
+	fp_exit();
+	return r;
+}
+
+

examples/meson.build

@@ -1,5 +1,5 @@
 
-examples = [ 'verify_live', 'enroll', 'verify', 'img_capture' ]
+examples = [ 'verify_live', 'enroll', 'verify', 'img_capture', 'delete' ]
 foreach example: examples
     executable(example,
                example + '.c',