fssh_lseek
#define lseek fssh_lseek
extern fssh_off_t fssh_lseek(int fd, fssh_off_t offset, int whence);
fssh_ssize_t bytesRead = _kern_read(fd, fssh_lseek(fd, 0, FSSH_SEEK_CUR),
fssh_lseek(fd, bytesRead, FSSH_SEEK_CUR);
fssh_ssize_t written = write_pos(fd, fssh_lseek(fd, 0, FSSH_SEEK_CUR),
fssh_lseek(fd, written, FSSH_SEEK_CUR);