Assorted fixes for dealing with zero-size frame/renderbuffers.

In xmesa_check_and_update_buffer_size() handle xmctx==NULL correctly: still
call _mesa_resize_framebufer().  If we don't we can wind up in a situation
where the framebuffer size is non-zero but an attached renderbuffer size
is still initialized to zero.  This inconsistancy can later cause problems.
Check for zero-size renderbuffers in update_color_draw_buffers() and
update_color_read_buffer().
See bug 7205.

2 files changed, 20 insertions, 13 deletions

diff --git a/src/mesa/main/framebuffer.c b/src/mesa/main/framebuffer.c
index 3136a950e0..cd4f594aa2 100644
--- a/src/mesa/main/framebuffer.c
+++ b/src/mesa/main/framebuffer.c
@@ -647,7 +647,7 @@ update_color_draw_buffers(GLcontext *ctx, struct gl_framebuffer *fb)
             const GLuint bufferBit = 1 << i;
             if (bufferBit & bufferMask) {
                struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
-               if (rb) {
+               if (rb && rb->Width > 0 && rb->Height > 0) {
                   fb->_ColorDrawBuffers[output][count] = rb;
                   count++;
                }
@@ -673,7 +673,10 @@ static void
 update_color_read_buffer(GLcontext *ctx, struct gl_framebuffer *fb)
 {
    (void) ctx;
-   if (fb->_ColorReadBufferIndex == -1 || fb->DeletePending) {
+   if (fb->_ColorReadBufferIndex == -1 ||
+       fb->DeletePending ||
+       fb->Width == 0 ||
+       fb->Height == 0) {
       fb->_ColorReadBuffer = NULL; /* legal! */
    }
    else {
diff --git a/src/mesa/main/renderbuffer.c b/src/mesa/main/renderbuffer.c
index 1cc95a7d3b..e387c42c34 100644
--- a/src/mesa/main/renderbuffer.c
+++ b/src/mesa/main/renderbuffer.c
@@ -1192,18 +1192,22 @@ _mesa_soft_renderbuffer_storage(GLcontext *ctx, struct gl_renderbuffer *rb,
    ASSERT(rb->PutMonoValues);
 
    /* free old buffer storage */
-   if (rb->Data)
+   if (rb->Data) {
       _mesa_free(rb->Data);
-
-   /* allocate new buffer storage */
-   rb->Data = _mesa_malloc(width * height * pixelSize);
-   if (rb->Data == NULL) {
-      rb->Width = 0;
-      rb->Height = 0;
-      _mesa_error(ctx, GL_OUT_OF_MEMORY,
-                  "software renderbuffer allocation (%d x %d x %d)",
-                  width, height, pixelSize);
-      return GL_FALSE;
+      rb->Data = NULL;
+   }
+
+   if (width > 0 && height > 0) {
+      /* allocate new buffer storage */
+      rb->Data = _mesa_malloc(width * height * pixelSize);
+      if (rb->Data == NULL) {
+         rb->Width = 0;
+         rb->Height = 0;
+         _mesa_error(ctx, GL_OUT_OF_MEMORY,
+                     "software renderbuffer allocation (%d x %d x %d)",
+                     width, height, pixelSize);
+         return GL_FALSE;
+      }
    }
 
    rb->Width = width;