[VDPAU] [PATCH] Add VDPAU_DRIVER_PATH support

[Aaron Plattner]

On 02/06/2014 05:57 PM, Emil Velikov wrote:
> Allow the user to specify the location of the backend driver,
> via the VDPAU_DRIVER_PATH environment variable. This allows
> easier testing of VDPAU backends without the need to rebuild
> libvdpau.
> 
> Inspired by LIBGL_DRIVERS_PATH from mesa.
> 
> v2:
>   - Fix compilation issues.
> 
> Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
> ---
> 
> Hi Aaron,
> 
> I've spent a bit of time pondering on your suggestion to control
> the trace library using the same env variable.
> 
> IMHO this will cause unnecessary complexity considering the
> permutations between driver/tracer locations.
> 
> My initial goal was to ease the use and testing of vdpau backends,
> in order to avoid rebuilding libvdpau. As the trace library is part
> of libvdpau (thus defeating the purpose of the whole exercise) I'm
> planning to stick with my original goal.

Thanks, that sounds good.

> Cheers,
> -Emil
> 
>   include/vdpau/vdpau_x11.h |  2 ++
>   src/vdpau_wrapper.c       | 14 ++++++++++++--
>   2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/include/vdpau/vdpau_x11.h b/include/vdpau/vdpau_x11.h
> index ae5a377..1aa66fe 100644
> --- a/include/vdpau/vdpau_x11.h
> +++ b/include/vdpau/vdpau_x11.h
> @@ -81,6 +81,8 @@ extern "C" {
>    *   - \c /usr/lib/vdpau/libvdpau_nvidia.so.1
>    *   - \c /usr/lib/vdpau/libvdpau_intel.so.1
>    *   - \c /usr/lib/vdpau/libvdpau_ati.so.1
> + *   The library path can be overridden by the VDPAU_DRIVER_PATH
> + *   environment variable.
>    *
>    * The VDPAU wrapper library implements just one function; \ref
>    * vdp_device_create_x11. The wrapper will implement this function
> diff --git a/src/vdpau_wrapper.c b/src/vdpau_wrapper.c
> index 9932937..e5f5082 100644
> --- a/src/vdpau_wrapper.c
> +++ b/src/vdpau_wrapper.c
> @@ -30,6 +30,7 @@
>   #include <stdio.h>
>   #include <stdlib.h>
>   #include <string.h>
> +#include <unistd.h>
>   #include <vdpau/vdpau_x11.h>
>   #if DRI2
>   #include "mesa_dri2.h"
> @@ -66,7 +67,7 @@ static void _vdp_wrapper_error_breakpoint(char const * file, int line, char cons
>   
>   #endif
>   
> -#define DRIVER_LIB_FORMAT "%slibvdpau_%s.so%s"
> +#define DRIVER_LIB_FORMAT "%s/libvdpau_%s.so%s"

Unfortunately, this breaks the fallback driver loading because it now searches for /libvdpau_nvidia.so instead of just /libvdpau_nvidia.so.

$ LD_LIBRARY_PATH=.libs vdpauinfo
display: :0   screen: 0
Failed to open VDPAU backend /libvdpau_nvidia.so: cannot open shared object file: No such file or directory
Error creating VDPAU device: 1

(on my system, it hit the fallback path because I built with moduledir set to /usr/local/lib/vdpau but the actual libraries are in /usr/lib/vdpau)

>   static char * _vdp_get_driver_name_from_dri2(
>       Display *             display,
> @@ -107,6 +108,7 @@ static VdpStatus _vdp_open_driver(
>   {
>       char const * vdpau_driver;
>       char * vdpau_driver_dri2 = NULL;
> +    const char * vdpau_driver_path = NULL;
>       char         vdpau_driver_lib[PATH_MAX];
>       char const * vdpau_trace;
>       char const * func_name;
> @@ -120,8 +122,16 @@ static VdpStatus _vdp_open_driver(
>           vdpau_driver = "nvidia";
>       }
>   
> +    if (geteuid() == getuid()) {
> +        /* don't allow setuid apps to use VDPAU_DRIVER_PATH */
> +        vdpau_driver_path = getenv("VDPAU_DRIVER_PATH");
> +    }
> +
> +    if (!vdpau_driver_path)
> +        vdpau_driver_path = VDPAU_MODULEDIR;
> +
>       if (snprintf(vdpau_driver_lib, sizeof(vdpau_driver_lib), DRIVER_LIB_FORMAT,
> -                 VDPAU_MODULEDIR "/", vdpau_driver, ".1") >=
> +                 vdpau_driver_path, vdpau_driver, ".1") >=
>               sizeof(vdpau_driver_lib)) {
>           fprintf(stderr, "Failed to construct driver path: path too long\n");
>           if (vdpau_driver_dri2) {
> 

-- 
Aaron