Ruby dumps core as follows.

% ./ruby -ryaml -e '
port = Object.new
class << port; self end.send(:define_method, :read) {|len|
  0
}
def port.binmode() end
p YAML::Syck::Parser.new.load(port)
'
-e:7: [BUG] Segmentation fault
ruby 1.9.0 (2004-12-15) [i686-linux]

zsh: abort (core dumped)  ./ruby -ryaml -e 
% gdb ruby core 
GNU gdb 6.1-debian
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-linux"...Using host libthread_db library "/lib/libthread_db.so.1".

Core was generated by `./ruby -ryaml -e 
port = Object.new
class << port; self end.send(:define_method'.
Program terminated with signal 6, Aborted.
Reading symbols from /lib/libdl.so.2...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/libcrypt.so.1...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libm.so.6...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /home/akr/ruby/head-ruby/lib/ruby/1.9/i686-linux/syck.so...done.
Loaded symbols for /home/akr/ruby/head-ruby/lib/ruby/1.9/i686-linux/syck.so
#0  0x4009e6b1 in kill () from /lib/libc.so.6
(gdb) bt
#0  0x4009e6b1 in kill () from /lib/libc.so.6
#1  0x4009e435 in raise () from /lib/libc.so.6
#2  0x4009f978 in abort () from /lib/libc.so.6
#3  0x080d5786 in rb_bug (fmt=0x0) at error.c:214
#4  0x080b2742 in sigsegv (sig=11) at signal.c:446
#5  <signal handler called>
#6  rb_syck_io_str_read (buf=0x81d0bb0 "", str=0x1, max_size=136121264, skip=0) at rubyext.c:141
#7  0x401e5da9 in syck_parser_read (p=0x81d0990) at syck.c:453
#8  0x401e8b6e in sycklex_yaml_utf8 (sycklval=0xbfffe33c, parser=0x81d0990) at token.re:251
#9  0x401e5f3f in sycklex (sycklval=0x0, parser=0x81d0bb0) at token.re:226
#10 0x401dfaa3 in syckparse (parser=0x81d0990) at y.tab.c:1033
#11 0x401e5e82 in syck_parse (p=0x81d0990) at syck.c:494
#12 0x401e366a in syck_parser_load (argc=1, argv=0x1, self=1075795252) at rubyext.c:872
#13 0x0806ac5a in call_cfunc (func=0x401e3570 <syck_parser_load>, recv=1075795252, len=136121264, argc=0, argv=0xbfffeac8)
    at eval.c:5418
#14 0x0805ea12 in rb_call0 (klass=1075584976, recv=1075795252, id=9721, oid=1, argc=1, argv=0xbfffeac8, body=0x401c1ef4, 
    nosuper=0) at eval.c:5559
#15 0x0805ecd8 in rb_call (klass=1075584976, recv=1075795252, mid=9721, argc=1, argv=0xbfffeac8, scope=0) at eval.c:5781
#16 0x080597fa in rb_eval (self=1075673536, n=0x1) at ruby.h:635
#17 0x08059b2b in rb_eval (self=1075673536, n=0x1) at ruby.h:664
#18 0x08055dcd in ruby_exec_internal () at eval.c:1470
#19 0x08055de6 in ruby_exec () at eval.c:1488
#20 0x08055e30 in ruby_run () at eval.c:1505
#21 0x08053e35 in main (argc=1, argv=0x1, envp=0xbffff908) at main.c:38
(gdb) 
-- 
Tanaka Akira