Fix some issues with glDrawBuffer(GL_NONE), bug 14198

Set _ColorDrawBuffers[0] = NULL if no renderbuffers enabled.
Check that _ColorDrawBuffers[0] is non-null before dereferencing in a few places.

3 files changed, 13 insertions, 7 deletions

diff --git a/src/mesa/swrast/s_blit.c b/src/mesa/swrast/s_blit.c
index a2c40bd9a6..af4350990c 100644
--- a/src/mesa/swrast/s_blit.c
+++ b/src/mesa/swrast/s_blit.c
@@ -745,6 +745,9 @@ _swrast_BlitFramebuffer(GLcontext *ctx,
    };
    GLint i;
 
+   if (!ctx->DrawBuffer->_NumColorDrawBuffers)
+      return;
+
    if (!clip_blit(ctx, &srcX0, &srcY0, &srcX1, &srcY1,
                   &dstX0, &dstY0, &dstX1, &dstY1)) {
       return;
diff --git a/src/mesa/swrast/s_drawpix.c b/src/mesa/swrast/s_drawpix.c
index 7bab14f200..4733d10bb5 100644
--- a/src/mesa/swrast/s_drawpix.c
+++ b/src/mesa/swrast/s_drawpix.c
@@ -54,7 +54,7 @@ fast_draw_rgba_pixels(GLcontext *ctx, GLint x, GLint y,
 {
    const GLint imgX = x, imgY = y;
    struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];
-   const GLenum rbType = rb->DataType;
+   GLenum rbType;
    SWcontext *swrast = SWRAST_CONTEXT(ctx);
    SWspan span;
    GLboolean simpleZoom;
@@ -62,6 +62,11 @@ fast_draw_rgba_pixels(GLcontext *ctx, GLint x, GLint y,
    struct gl_pixelstore_attrib unpack;
    GLint destX, destY, drawWidth, drawHeight; /* post clipping */
 
+   if (!rb)
+      return GL_TRUE; /* no-op */
+
+   rbType = rb->DataType;
+
    if ((swrast->_RasterMask & ~CLIP_BIT) ||
        ctx->Texture._EnabledCoordUnits ||
        userUnpack->SwapBytes ||
diff --git a/src/mesa/swrast/s_triangle.c b/src/mesa/swrast/s_triangle.c
index 5036020b7c..59e15645f3 100644
--- a/src/mesa/swrast/s_triangle.c
+++ b/src/mesa/swrast/s_triangle.c
@@ -130,7 +130,7 @@ _swrast_culltriangle( GLcontext *ctx,
 #define T_SCALE theight
 
 #define SETUP_CODE							\
-   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];\
+   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];	\
    struct gl_texture_object *obj = ctx->Texture.Unit[0].Current2D;	\
    const GLint b = obj->BaseLevel;					\
    const GLfloat twidth = (GLfloat) obj->Image[0][b]->Width;		\
@@ -139,8 +139,7 @@ _swrast_culltriangle( GLcontext *ctx,
    const GLchan *texture = (const GLchan *) obj->Image[0][b]->Data;	\
    const GLint smask = obj->Image[0][b]->Width - 1;			\
    const GLint tmask = obj->Image[0][b]->Height - 1;			\
-   if (!texture) {							\
-      /* this shouldn't happen */					\
+   if (!rb || !texture) {						\
       return;								\
    }
 
@@ -182,7 +181,7 @@ _swrast_culltriangle( GLcontext *ctx,
 #define T_SCALE theight
 
 #define SETUP_CODE							\
-   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];\
+   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];	\
    struct gl_texture_object *obj = ctx->Texture.Unit[0].Current2D;	\
    const GLint b = obj->BaseLevel;					\
    const GLfloat twidth = (GLfloat) obj->Image[0][b]->Width;		\
@@ -191,8 +190,7 @@ _swrast_culltriangle( GLcontext *ctx,
    const GLchan *texture = (const GLchan *) obj->Image[0][b]->Data;	\
    const GLint smask = obj->Image[0][b]->Width - 1;			\
    const GLint tmask = obj->Image[0][b]->Height - 1;			\
-   if (!texture) {							\
-      /* this shouldn't happen */					\
+   if (!rb || !texture) {						\
       return;								\
    }