[MPlayer-dev-eng] [CRASH] mpi->planes[0] needs to be aligned at least to 16 byte or put_pixels16_sse2 will crash

[Gianluigi Tiesi]

On Wed, Mar 17, 2010 at 09:02:23AM +0200, Uoti Urpala wrote:
> On Wed, 2010-03-17 at 13:46 +0800, Zuxy Meng wrote:
> > I mentioned this in another thread several days ago. To fix it once
> > and for all we'd substitute all call to malloc/memalign and free to
> > av_malloc and av_free across mplayer, but I can't think of a graceful
> > way to do this in win32. I tried defining my own malloc/memalign and
> > free and linking it before libmsvcrt but it didn't work.
> 
> That won't work. Some allocated strings will come from other libraries
> and must be freed with the standard free(), and possibly vice versa (you
> need to give a pointer freeable with standard free() to something). So
> it's generally not possible to switch the whole program to use an
> incompatible allocator like that.

this is indeed a bad programming pratic, the most common example
is interoperability between c and c++
a library should provide a way to disallocate or mandate the caller
to do so

Btw this works if all libraries are linked statically, this
is ok for my binaries but no good for general usage

> 
> If the system lacks any way to allocate aligned memory freeable with
> standard free() then there is no clean solution.

yes true, but there are already places using selectively av_malloc/av_free
and even libavcodec uses this.

the best way would be not to use memalign, instead wrap calls, and
substitue related free with a wrapped version.

This would require some work, but if interested I can propose a patch

Regards

-- 
Gianluigi Tiesi <sherpya at netfarm.it>
EDP Project Leader
Netfarm S.r.l. - http://www.netfarm.it/
Free Software: http://oss.netfarm.it/