draw: check for an integer overflow when computing stride

[mesa.git] / src / gallium / auxiliary / draw / draw_pipe_twoside.c

diff --git a/src/gallium/auxiliary/draw/draw_pipe_twoside.c b/src/gallium/auxiliary/draw/draw_pipe_twoside.c
index eef0238b157f89392a72868ea893e633324d4cb0..b1a70a02e479d417e9116fce6c531a1b5eec6eee 100644 (file)
--- a/src/gallium/auxiliary/draw/draw_pipe_twoside.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_twoside.c
@@ -38,8 +38,8 @@
 struct twoside_stage {
    struct draw_stage stage;
    float sign;         /**< +1 or -1 */
-   uint attrib_front0, attrib_back0;
-   uint attrib_front1, attrib_back1;
+   int attrib_front0, attrib_back0;
+   int attrib_front1, attrib_back1;
 };
 
 
@@ -48,9 +48,6 @@ static INLINE struct twoside_stage *twoside_stage( struct draw_stage *stage )
    return (struct twoside_stage *)stage;
 }
 
-
-
-
 /**
  * Copy back color(s) to front color(s).
  */
@@ -60,12 +57,12 @@ copy_bfc( struct twoside_stage *twoside,
           unsigned idx )
 {   
    struct vertex_header *tmp = dup_vert( &twoside->stage, v, idx );
-   
-   if (twoside->attrib_back0) {
+
+   if (twoside->attrib_back0 >= 0 && twoside->attrib_front0 >= 0) {
       COPY_4FV(tmp->data[twoside->attrib_front0],
                tmp->data[twoside->attrib_back0]);
    }
-   if (twoside->attrib_back1) {
+   if (twoside->attrib_back1 >= 0 && twoside->attrib_front1 >= 0) {
       COPY_4FV(tmp->data[twoside->attrib_front1],
                tmp->data[twoside->attrib_back1]);
    }
@@ -109,10 +106,10 @@ static void twoside_first_tri( struct draw_stage *stage,
    const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
    uint i;
 
-   twoside->attrib_front0 = 0;
-   twoside->attrib_front1 = 0;
-   twoside->attrib_back0 = 0;
-   twoside->attrib_back1 = 0;
+   twoside->attrib_front0 = -1;
+   twoside->attrib_front1 = -1;
+   twoside->attrib_back0 = -1;
+   twoside->attrib_back1 = -1;
 
    /* Find which vertex shader outputs are front/back colors */
    for (i = 0; i < vs->info.num_outputs; i++) {
@@ -130,18 +127,12 @@ static void twoside_first_tri( struct draw_stage *stage,
       }
    }
 
-   if (!twoside->attrib_back0)
-      twoside->attrib_front0 = 0;
-
-   if (!twoside->attrib_back1)
-      twoside->attrib_front1 = 0;
-
    /*
     * We'll multiply the primitive's determinant by this sign to determine
     * if the triangle is back-facing (negative).
     * sign = -1 for CCW, +1 for CW
     */
-   twoside->sign = (stage->draw->rasterizer->front_winding == PIPE_WINDING_CCW) ? -1.0f : 1.0f;
+   twoside->sign = stage->draw->rasterizer->front_ccw ? -1.0f : 1.0f;
 
    stage->tri = twoside_tri;
    stage->tri( stage, header );
@@ -177,9 +168,6 @@ struct draw_stage *draw_twoside_stage( struct draw_context *draw )
    if (twoside == NULL)
       goto fail;
 
-   if (!draw_alloc_temp_verts( &twoside->stage, 3 ))
-      goto fail;
-
    twoside->stage.draw = draw;
    twoside->stage.name = "twoside";
    twoside->stage.next = NULL;
@@ -190,6 +178,9 @@ struct draw_stage *draw_twoside_stage( struct draw_context *draw )
    twoside->stage.reset_stipple_counter = twoside_reset_stipple_counter;
    twoside->stage.destroy = twoside_destroy;
 
+   if (!draw_alloc_temp_verts( &twoside->stage, 3 ))
+      goto fail;
+
    return &twoside->stage;
 
  fail: