[Mono-dev] glibc detected *** mono: double free or corruption

Rolf Bjarne Kvinge rolflists at ya.com
Tue Oct 16 17:16:58 EDT 2007

> -----Original Message-----
> From: mono-devel-list-bounces at lists.ximian.com [mailto:mono-devel-list-
> bounces at lists.ximian.com] On Behalf Of Stephen A
> Sent: martes, 16 de octubre de 2007 21:58
> To: mono-devel-list at lists.ximian.com
> Subject: Re: [Mono-dev] glibc detected *** mono: double free or
> corruption
> > C-code typically expects the string array to end with a null element, I
> > can't see that you're doing that in your code.
> >
> > Otherwise you might want to try to create the array manually using the
> > System.Runtime.Interop.Marshal class (use AllocHGlobal to create the
> > array memory, then StringTo* to create unmanaged versions of the string)
> > see if that works.
> >
> > Rolf
> >
> I thought that the default marshaller took care of that issue?
> According to MSDN
(http://msdn2.microsoft.com/en-us/library/75dwhxf7(VS.71).aspx), a
> System.String is converted to a null terminated array of chars by default
> (I assume this also happens to arrays of strings). 

I think I expressed myself in a bad way.

What I wanted to say is that arrays (in general) are normally ended with a
null element in C (again, I haven't seen the C-code in question, so I don't
know for this particular case).

Which would give a string array like this:

string arr [] = {"abc", null}

Note that the marshaller will put a \0 at the end of "abc" automatically.

> In any case, adding a \0 does not take care of the issue and, besides, the
same code runs
> fine under .Net - which leads me to believe that the error lies somewhere
> else entirely.

The fact that the code runs on .Net is not a guarantee that your code is
correct :)
Pinvokes on MS has a history of being somewhat forgiving (but I'm not saying
that it isn't a bug with mono either)

> Now that I took a look again, it seems that my error message is a
> little different: "*** glibc detected *** mono: corrupted double-linked
> 0x0000000001bed250 ***". 

Crash messages like these might change, especially if the memory is trashed.


> - Stephen A
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