rtld_fstat
extern int rtld_fstat(int, rtld_stat_t *restrict);
(void) rtld_fstat(fd, &status);
(void) rtld_fstat(dbg_fd, &status);
if ((rtld_fstat(dbg_fd, &status) == -1) ||
(void) rtld_fstat(dbg_fd, &status);
if ((rtld_fstat(fd, &status) == -1) ||
(void) rtld_fstat(fd, &status);