#0  PerlIO_fast_gets (f=0x826cf88) at perlio.c:1790
#1  0x08120b86 in PerlIOBuf_fill (f=0x8264724) at perlio.c:3868
#2  0x0811f42e in PerlIOBase_read (f=0x8264724, vbuf=0xbfadde57, count=1)
    at perlio.c:2143
#3  0x0811f550 in PerlIO_getc (f=0x8264724) at perlio.c:5066
#4  0x080d693a in Perl_sv_gets (sv=0x8269e10, fp=0x8264724, append=0)
    at sv.c:6852
#5  0x0807ff22 in Perl_filter_read (idx=0, buf_sv=0x8269e10, maxlen=0)
    at toke.c:2955
#6  0x08080124 in S_filter_gets (sv=0x8269e10, fp=0x8264724, append=136761200)
    at toke.c:2997
#7  0x08084d7a in Perl_yylex () at toke.c:3757
#8  0x08092368 in Perl_yyparse () at perly.c:409
#9  0x080e9918 in S_doeval (gimme=0, startop=0x0, outside=0x0, seq=0)
    at pp_ctl.c:2981
#10 0x080eafeb in Perl_pp_require () at pp_ctl.c:3573
#11 0x080c053e in Perl_runops_standard () at run.c:40
#12 0x0806fede in Perl_call_sv (sv=0x8269d10, flags=6) at perl.c:2717
#13 0x0807023b in Perl_call_list (oldscope=2, paramList=0x8269db0)
    at perl.c:5264
#14 0x0805f3e8 in S_process_special_blocks (fullname=<value optimized out>,
    gv=0x8269d90, cv=0x8269d10) at op.c:5860
#15 0x08068ec9 in Perl_newATTRSUB (floor=27, o=0x826cda0, proto=0x0,
    attrs=0x0, block=0x826cd60) at op.c:5831
#16 0x08067e00 in Perl_utilize (aver=1, floor=27, version=0x0, idop=0x826cb70,
    arg=0x0) at op.c:3878
#17 0x080944dd in Perl_yyparse () at perly.y:659
#18 0x08071e0a in S_parse_body (env=0x0, xsinit=0x805e580 <xs_init>)
    at perl.c:2274
#19 0x08072ad7 in perl_parse (my_perl=0x8256008, xsinit=0x805e580 <xs_init>,
    argc=3, argv=0xbfae0c64, env=0x0) at perl.c:1687
#20 0x0805e52b in main (argc=3, argv=0xbfae0c64, env=0xbfae0c74)
    at perlmain.c:115

##</code><code>##

int
PerlIO_fast_gets(PerlIO *f)
{
    if (PerlIOValid(f) && (PerlIOBase(f)->flags & PERLIO_F_FASTGETS)) {
         const PerlIO_funcs * const tab = PerlIOBase(f)->tab;

         if (tab)
              return (tab->Set_ptrcnt != NULL);
         SETERRNO(EINVAL, LIB_INVARG);
    }
    else
         SETERRNO(EBADF, SS_IVCHAN);

    return 0;
}