[MPlayer-users] Re: Failed assertion on Solaris

[Rémi Guyomarch]

On Tue, Apr 23, 2002 at 07:15:27PM +0200, Martin Olschewski wrote:
...
> After building mplayer with debug support from the current cvs
> snapshot, I got the following output when the movie has finished:
> 
> playtree.c:468: failed assertion `iter->stack_size > 0'

Hmmm, I've already seen that ...

> The real problem is here, that realloc on sparc solaris systems does
> not return NULL if it is called with size 0.  Of course it frees the
> memory, but it returns the old pointer.

Nice catch ! On FreeBSD there's a different but similiar behaviour,
from malloc(3) :

[speaking about malloc() tunable options]

     V       Attempting to allocate zero bytes will return a NULL pointer
             instead of a valid pointer.  (The default behavior is to make a
             minimal allocation and return a pointer to it.)  This option is
             provided for System V compatibility.  This option is incompatible
             with the ``X'' option.

The OpenBSD man page goes into more details, but it means the same
thing :
	If size is zero and ptr is not a null pointer, the object it
	points to is freed and a new zero size object is returned.

So it seems that the semantics of realloc(xx,0) isn't portable. Since
Solaris is SysV, I'm wondering which platform does have this
realloc(x,0) returns NULL behavior, beside Linux. In fact I'm
wondering if it's not another Linuxism...

Fortunately, on FreeBSD (but not on OpenBSD) I can change this
behaviour both at runtime and at compile-time, but it's probably not
the case on other platforms ...

> Unfortunatelly I am not real sure if this is the only occasion where
> mplayer relies on this behavier,

No, it's not the only occasion. :-((
For example, the playlist parser does make this bogus assumption and
crash on my BSD box.

> And now to something completely different...
> 
> The reason why I build the version with debug support was, that I
> cannot use gl for the video output any more.  It worked fine with
> the csv snapshot for 26.03.02, but I get
> 
> X11 error: BadDrawable (invalid Pixmap or Window parameter)
> 
> after a few frame with the current snapshot.  No coredump, no crash
> message, nothing that could give any helpful informations, just this
> line and mplayer terminates.  Has anybody the same problem?

Yes, I have the same problem. Others too.

-- 
Rémi