read_sysfs_string
ret = read_sysfs_string("name", dev_dir_name, device_name);
ret = read_sysfs_string("name", trig_dev_name, trigger_name);
int read_sysfs_string(const char *filename, const char *basedir, char *str);
ret = read_sysfs_string("name", dev_dir_name, name);
ret = read_sysfs_string("name", dev_dir_name, name);