softpipe: check if so_target is NULL before accessing it

No idea if this is working right but copied straight from llvmpipe.
(Not only does this check the so_target but also use buffer->data instead
of buffer for the mapping.)
Just trying to get rid of a segfault testing something else...

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>

diff --git a/src/gallium/drivers/softpipe/sp_draw_arrays.c b/src/gallium/drivers/softpipe/sp_draw_arrays.c
index 6b06f70..4d56b1c 100644 (file)
--- a/src/gallium/drivers/softpipe/sp_draw_arrays.c
+++ b/src/gallium/drivers/softpipe/sp_draw_arrays.c
@@ -107,8 +107,11 @@ softpipe_draw_vbo(struct pipe_context *pipe,
 
 
    for (i = 0; i < sp->num_so_targets; i++) {
-      void *buf = softpipe_resource_data(sp->so_targets[i]->target.buffer);
-      sp->so_targets[i]->mapping = buf;
+      void *buf = 0;
+      if (sp->so_targets[i]) {
+         buf = softpipe_resource(sp->so_targets[i]->target.buffer)->data;
+         sp->so_targets[i]->mapping = buf;
+      }
    }
 
    draw_set_mapped_so_targets(draw, sp->num_so_targets,