On Wed, Aug 14, 2013 at 10:05 PM, Hans de Goede <hdego...@redhat.com> wrote:
> From: Daniel Berrange <berra...@redhat.com>
>
> Since libusb-0.1 did not have any init / exit function, code using the
> libusb-0.1 API will not call libusb_exit.

Hmm, it that true with the latest libusb-compat-0.1.5? As per
the ticket #130 for libusb-compat-0.1, the fix is there.
http://libusb.org/ticket/130

Do we still need the fix below?

> Now, libgphoto uses libusb and will dlopen() and dlclose() it. Unfortunately
> since there is no way to ensure libusb_close() is called, when libgphoto
> dlcloses the libusb.so library, the thread from libusbx.so will not be
> stopped. So a thread will remain running, executing code from a memory
> region that has now been freed. Crash-tastic results ensue.
>
> I don't see a good way to fix this from libusb or libusbx, given the need to
> preserve the existing API of libusb.
>
> If, however, we link libusb.so using  -znodelete, we will prevent it from
> ever being unloaded, despite the dlclose() calls. This is not ideal, but
> better than allowing it to be unloaded which is a guaranteed crash.
>
> Signed-off-by: Hans de Goede <hdego...@redhat.com>
> ---
>  libusb/Makefile.am | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libusb/Makefile.am b/libusb/Makefile.am
> index 33a609a..a20fdb5 100644
> --- a/libusb/Makefile.am
> +++ b/libusb/Makefile.am
> @@ -5,5 +5,5 @@ libusb_la_SOURCES = core.c usbi.h
>  libusb_la_CFLAGS = -fvisibility=hidden $(AM_CFLAGS) $(LIBUSB_1_0_CFLAGS)
>  libusb_la_LIBADD = $(LIBUSB_1_0_LIBS)
>  libusb_la_LDFLAGS = -version-info $(LT_MAJOR):$(LT_REVISION):$(LT_AGE) \
> -       -release 0.1
> +       -release 0.1 -Wl,-z -Wl,nodelete
>

Just wondering if this is applicable for other OS as well
(eg: Mac OS X).

And I am wondering if this is MinGW friendly or not. I know
that currently libusb-compat-0.1 does not support Windows
but there are people who like the idea that libusb-compat-0.1
to support Windows.




-- 
Xiaofan

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