xreadatoff
if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr)
if (xreadatoff(fd, shdrp, ehdr.e_shoff, shdrsize, fn) != shdrsize)
if ((size_t)xreadatoff(fd, symtabp, shdrp[symtabsnum].sh_offset,
if ((size_t)xreadatoff(fd, strtabp, shdrp[strtabsnum].sh_offset,