storage: add save/load functionality

Prints can now be saved to disk (but you currently must classify which
finger they are) and you can load them later.

Added 2 simple example programs to demonstrate this.

libfprint/data.c

@@ -18,12 +18,55 @@
  */
 
 #include <config.h>
+#include <errno.h>
 #include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 #include <glib.h>
 
 #include "fp_internal.h"
 
+#define DIR_PERMS 0700
+
+/* FIXME: should free this during library shutdown */
+static char *base_store = NULL;
+
+static void storage_setup(void)
+{
+	const char *homedir;
+
+	homedir = g_getenv("HOME");
+	if (!homedir)
+		homedir = g_get_home_dir();
+	if (!homedir)
+		return;
+
+	base_store = g_build_filename(homedir, ".fprint/prints", NULL);
+	g_mkdir_with_parents(base_store, DIR_PERMS);
+	/* FIXME handle failure */
+}
+
+static const char *finger_code_to_str(enum fp_finger finger)
+{
+	const char *names[] = {
+		[LEFT_THUMB] = "lthu",
+		[LEFT_INDEX] = "lind",
+		[LEFT_MIDDLE] = "lmid",
+		[LEFT_RING] = "lrin",
+		[LEFT_LITTLE] = "llit",
+		[RIGHT_THUMB] = "rthu",
+		[RIGHT_INDEX] = "rind",
+		[RIGHT_MIDDLE] = "rmid",
+		[RIGHT_RING] = "rrin",
+		[RIGHT_LITTLE] = "rlit",
+	};
+	if (finger < LEFT_THUMB || finger > RIGHT_LITTLE)
+		return NULL;
+	return names[finger];
+}
+
 struct fp_print_data *fpi_print_data_new(struct fp_dev *dev, size_t length)
 {
 	struct fp_print_data *data = g_malloc(sizeof(*data) + length);
@@ -33,6 +76,82 @@ struct fp_print_data *fpi_print_data_new(struct fp_dev *dev, size_t length)
 	return data;
 }
 
+API_EXPORTED int fp_print_data_save(struct fp_print_data *data,
+	enum fp_finger finger)
+{
+	GError *err = NULL;
+	char *path;
+	char *dirpath;
+	const char *fingerstr = finger_code_to_str(finger);
+	int r;
+
+	if (!fingerstr)
+		return -EINVAL;
+
+	if (!base_store)
+		storage_setup();
+
+	fp_dbg("save %s print from %s", fingerstr, data->driver_name);
+	dirpath = g_build_filename(base_store, data->driver_name, NULL);
+	r = g_mkdir_with_parents(dirpath, DIR_PERMS);
+	if (r < 0) {
+		fp_err("couldn't create storage directory");
+		g_free(dirpath);
+		return r;
+	}
+
+	path = g_build_filename(dirpath, fingerstr, NULL);
+	fp_dbg("saving to %s", path);
+	g_file_set_contents(path, data->buffer, data->length, &err);
+	g_free(dirpath);
+	g_free(path);
+	if (err) {
+		r = err->code;
+		fp_err("%s save failed: %s", fingerstr, err->message);
+		g_error_free(err);
+		return r;
+	}
+
+	return 0;
+}
+
+API_EXPORTED int fp_print_data_load(struct fp_dev *dev,
+	enum fp_finger finger, struct fp_print_data **data)
+{
+	const char *fingerstr = finger_code_to_str(finger);
+	gchar *path;
+	gsize length;
+	gchar *contents;
+	GError *err = NULL;
+	struct fp_print_data *fdata;
+
+	if (!fingerstr)
+		return -EINVAL;
+
+	if (!base_store)
+		storage_setup();
+
+	path = g_build_filename(base_store, dev->drv->name, fingerstr, NULL);
+	fp_dbg("from %s", path);
+	g_file_get_contents(path, &contents, &length, &err);
+	g_free(path);
+	if (err) {
+		int r = err->code;
+		fp_err("%s load failed: %s", fingerstr, err->message);
+		g_error_free(err);
+		if (r == G_FILE_ERROR_NOENT)
+			return -ENOENT;
+		else
+			return r;
+	}
+
+	fdata = fpi_print_data_new(dev, length);
+	memcpy(fdata->buffer, contents, length);
+	g_free(contents);
+	*data = fdata;
+	return 0;
+}
+
 API_EXPORTED void fp_print_data_free(struct fp_print_data *data)
 {
 	g_free(data);