Re: libstc++ (?) problem on CURRENT?

On Sat, Nov 6, 2010 at 10:57 AM, Barbara <barbara.xxx1975_at_libero.it> wrote:
>
> I had a problem running the IcedTea java plugin on CURRENT i386, while it
> works on 8_STABLE.
> But maybe it's not a problem related to the port.
> Just to be clear, I'm not looking for a solution about the port here, I'm just
> wondering why the same c++ code is working on 8_STABLE and it's segfaulting on
> CURRENT, considering also that AFAIK the gcc version in both the base systems
> is the same.
>
> In the part of the code causing the crash, a std::map is read with an iterator
> in a for loop, and if a condition is met, an entry is erased.
> The following is the bt I'm getting:
> #0  0x29e36247 in kill () from /lib/libc.so.7
> #1  0x29e361a6 in raise () from /lib/libc.so.7
> #2  0x282424f6 in XRE_LockProfileDirectory () from
>        /usr/local/lib/firefox3/libxul.so
> #3  <signal handler called>
> #4  0x29c8f1b2 in std::_Rb_tree_increment () from
>        /usr/lib/libstdc++.so.6 #5  0x2ef92402 in
>        IcedTeaPluginUtilities::invalidateInstance () from
>        /usr/local/openjdk6/jre/lib/IcedTeaPlugin.so
> ...
>
> I wrote a "patch" for the IcedTea plugin, replacing the for loop with a while
> and increasing the iterator before erasing from the map, and it seems working.
> Then I wrote a simple program that do something similar to IcedTea, so there
> is no need to build the whole java/openjdk6 port to do some testing.
> Running it on 8_STABLE it works, on CURRENT it crashes.
> You can find more details in this discussion on the freebsd-java ml:
> http://lists.freebsd.org/pipermail/freebsd-java/2010-November/008978.html
>
> You can find the patch and the sample code in the discussion above, anyway I'm
> reporting them here too:
> icedtea patch:
> http://pastebin.com/b2KKFNSG
> test case:
> http://pastebin.com/Amk4UJ0g

You appear to invalidate the iterator inside the loop and then
increment it. Do the following:

-- cut here --
for (iter = cars.begin(); iter != cars.end(); ) {
 if ((*iter).second == modelName)
  cars.erase(iter++);
 else
  ++iter;
}
-- and here --

In this example, you first increment the iterator and then erase its
previous value.


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