From: "Ara.T.Howard" <ahoward@...>
Date: 2003-12-04T15:52:08+09:00
Subject: debugging [BUG] messages/c ext woes


c extenders-

i'm getting a fatal error using a little c extention i've written, one of
these (rb_fatal?) kinds:

  ./nfsstore.rb:123: [BUG] Segmentation fault

i'm unsure if this is truly a 'BUG' or bad code on my part - here's the call
in c:

VALUE
rb_lockfile_s_create(klass, lockfile, retrycnt, flags)
    VALUE klass;
    VALUE lockfile;
    VALUE retrycnt;
    VALUE flags;
{
  return 
    INT2NUM(lockfile_create(StringValuePtr(lockfile),NUM2INT(retrycnt),NUM2INT(flags)));
}

lockfile_create has this signature:

  int lockfile_create( const char *lockfile, int retrycnt, int flags );

i'm calling this from ruby as in

  lockfile_create ("foobar.lock", 16, 0)
    
thing is, this _does_ work.  sometimes.  ;-)

othertimes it core dumps.

my understanding of StringValuePtr is that it would modifiy lockfile (lvalue)
in place and return a char * but this is the first extenstion i've written
since it was introduced.  am i doing something silly there?  should i be
taking a copy (dup) of lockfile before doing this? everything thing else looks
o.k. to me.


thanks for for any insight.

if there's nothing wrong with the above i'll start looking into
lockfile_create, which is from liblockfile and could be buggy.

-a
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