au_hdr
struct au_hdr hdr;
if (!afile_readhdr(f, &hdr, sizeof(struct au_hdr)))
struct au_hdr hdr;
memset(&hdr, 0, sizeof(struct au_hdr));
return afile_writehdr(f, &hdr, sizeof(struct au_hdr));
struct au_hdr au;
f->endpos = f->startpos = sizeof(struct au_hdr);
if (!afile_writehdr(f, &dummy, sizeof(struct au_hdr)))