mesa: Ignore blits to/from missing buffers

The EXT_framebuffer_object spec (and later specs) say:

     "If a buffer is specified in <mask> and does not exist in both
     the read and draw framebuffers, the corresponding bit is silently
     ignored."

Check for color, depth, and stencil that the source and destination
FBOs have the specified buffers.  If the buffer is missing, remove the
bit from the blit request mask and continue.

Fixes the crash in piglit test 'fbo-missing-attachment-blit from', and
fixes 'fbo-missing-attachment-blit es2 from'.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=37739
Reviewed-by: Brian Paul <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

NOTE: This is a candidate for the stable branches.

1 files changed, 37 insertions, 8 deletions

diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
index d4400709aef..2230b262336 100644
--- a/src/mesa/main/fbobject.c
+++ b/src/mesa/main/fbobject.c
@@ -2429,6 +2429,17 @@ _mesa_BlitFramebufferEXT(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
    if (mask & GL_COLOR_BUFFER_BIT) {
       colorReadRb = readFb->_ColorReadBuffer;
       colorDrawRb = drawFb->_ColorDrawBuffers[0];
+
+      /* From the EXT_framebuffer_object spec:
+       *
+       *     "If a buffer is specified in <mask> and does not exist in both
+       *     the read and draw framebuffers, the corresponding bit is silently
+       *     ignored."
+       */
+      if ((colorReadRb == NULL) || (colorDrawRb == NULL)) {
+	 colorReadRb = colorDrawRb = NULL;
+	 mask &= ~GL_COLOR_BUFFER_BIT;
+      }
    }
    else {
       colorReadRb = colorDrawRb = NULL;
@@ -2437,10 +2448,19 @@ _mesa_BlitFramebufferEXT(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
    if (mask & GL_STENCIL_BUFFER_BIT) {
       struct gl_renderbuffer *readRb = readFb->_StencilBuffer;
       struct gl_renderbuffer *drawRb = drawFb->_StencilBuffer;
-      if (!readRb ||
-          !drawRb ||
-          _mesa_get_format_bits(readRb->Format, GL_STENCIL_BITS) != 
-          _mesa_get_format_bits(drawRb->Format, GL_STENCIL_BITS)) {
+
+      /* From the EXT_framebuffer_object spec:
+       *
+       *     "If a buffer is specified in <mask> and does not exist in both
+       *     the read and draw framebuffers, the corresponding bit is silently
+       *     ignored."
+       */
+      if ((readRb == NULL) || (drawRb == NULL)) {
+	 readRb = drawRb = NULL;
+	 mask &= ~GL_STENCIL_BUFFER_BIT;
+      }
+      else if (_mesa_get_format_bits(readRb->Format, GL_STENCIL_BITS) !=
+	       _mesa_get_format_bits(drawRb->Format, GL_STENCIL_BITS)) {
          _mesa_error(ctx, GL_INVALID_OPERATION,
                      "glBlitFramebufferEXT(stencil buffer size mismatch)");
          return;
@@ -2450,10 +2470,19 @@ _mesa_BlitFramebufferEXT(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
    if (mask & GL_DEPTH_BUFFER_BIT) {
       struct gl_renderbuffer *readRb = readFb->_DepthBuffer;
       struct gl_renderbuffer *drawRb = drawFb->_DepthBuffer;
-      if (!readRb ||
-          !drawRb ||
-          _mesa_get_format_bits(readRb->Format, GL_DEPTH_BITS) != 
-          _mesa_get_format_bits(drawRb->Format, GL_DEPTH_BITS)) {
+
+      /* From the EXT_framebuffer_object spec:
+       *
+       *     "If a buffer is specified in <mask> and does not exist in both
+       *     the read and draw framebuffers, the corresponding bit is silently
+       *     ignored."
+       */
+      if ((readRb == NULL) || (drawRb == NULL)) {
+	 readRb = drawRb = NULL;
+	 mask &= ~GL_DEPTH_BUFFER_BIT;
+      }
+      else if (_mesa_get_format_bits(readRb->Format, GL_DEPTH_BITS) !=
+	       _mesa_get_format_bits(drawRb->Format, GL_DEPTH_BITS)) {
          _mesa_error(ctx, GL_INVALID_OPERATION,
                      "glBlitFramebufferEXT(depth buffer size mismatch)");
          return;