Bug: segfault when using super and method_missing

Ruby
1

Hello,

The following code produces a segfault with ruby-1.8.4 from gentoo,
as well as with ruby-1.8 from cvs and 1.9 from cvs. There appears to
be an issue when super is called in the subclass and the parent class
has method_missing defined. Strangely, if super is called with
explicit arguments, no segfault occurs. Likewise, if the method
definition in the subclass is modified slightly (see below) the
segfault is avoided.

Thanks,
Brad

class BaseClass
def method_missing(*args)
p args
end
end

class Article < BaseClass

if this is defined as title=(arg) the segfault does not occur

def title=(*args)
super(args) # works
super(*args) # works
super # segfault…
end
end

a = Article.new
a.body = ‘body’
a.title = ‘foo’

2

Hi,

This works for me. I’ve tried both:

ruby 1.8.2 (2004-12-25) [i386-mswin32] (Windows)
ruby 1.8.4 (2005-12-24) [i386-linux] (gentoo linux)

Just a guess, but maybe you compiled ruby with to much optimizations in
CFLAGS ? Mine are

CFLAGS="-O2 -fomit-frame-pointer"

Hope this helps…

Guillaume

3

Hi,

In message “Re: bug: segfault when using super and method_missing”
on Thu, 23 Mar 2006 10:09:37 +0900, Brad H. [email protected]
writes:

|The following code produces a segfault with ruby-1.8.4 from gentoo,
|as well as with ruby-1.8 from cvs and 1.9 from cvs. There appears to
|be an issue when super is called in the subclass and the parent class
|has method_missing defined. Strangely, if super is called with
|explicit arguments, no segfault occurs. Likewise, if the method
|definition in the subclass is modified slightly (see below) the
|segfault is avoided.

A bug was in super without any argument. The patch attached should
fix the bug. Thank you for reporting it.

						matz.

— eval.c 3 Mar 2006 17:39:26 -0000 1.616.2.165
+++ eval.c 23 Mar 2006 01:48:22 -0000
@@ -5578,7 +5578,18 @@ method_missing(obj, id, argc, argv, call
}

  • if (argc < 0) {
  • VALUE tmp;
  • nargv = ALLOCA_N(VALUE, argc+1);
  • nargv[0] = ID2SYM(id);
  • MEMCPY(nargv+1, argv, VALUE, argc);

  • argc = -argc-1;

  • tmp = splat_value(argv[argc]);

  • nargv = ALLOCA_N(VALUE, argc + RARRAY(tmp)->len + 1);

  • MEMCPY(nargv+1, argv, VALUE, argc);

  • MEMCPY(nargv+1+argc, RARRAY(tmp)->ptr, VALUE, RARRAY(tmp)->len);

  • argc += RARRAY(tmp)->len;

  • }

  • else {

  • nargv = ALLOCA_N(VALUE, argc+1);

  • MEMCPY(nargv+1, argv, VALUE, argc);

  • }

  • nargv[0] = ID2SYM(id);
    return rb_funcall2(obj, missing, argc+1, nargv);

4

Hi,

In message “Re: bug: segfault when using super and method_missing”
on Thu, 23 Mar 2006 10:50:01 +0900, Joel VanderWerf
[email protected] writes:

|It’s ok on
|
|ruby 1.8.4 (2005-12-24) [i686-linux]
|
|built from source with the default options (on ubuntu).

It happens only on CVS top.

						matz.
5

On Mar 22, 2006, at 5:49 PM, Yukihiro M. wrote:

A bug was in super without any argument. The patch attached should
fix the bug. Thank you for reporting it.

Thanks for your help and the quick patch!

-Brad

6

Brad H. wrote:

Hello,

The following code produces a segfault with ruby-1.8.4 from gentoo, as

It’s ok on

ruby 1.8.4 (2005-12-24) [i686-linux]

built from source with the default options (on ubuntu).