[Mesa-dev] [PATCH] glcpp: Fix attempts to expand recursive macros infinitely (bug #32835).

[Carl Worth]

The 095-recursive-define test case was triggering infinite recursion
with the following test case:

	#define A(a, b) B(a, b)
	#define C A(0, C)
	C

Here's what as happening:

  1. "C" was pushed onto the active list to expand the C node

  2. While expanding the "0" argument, the active list would be
     emptied by the code at the end of _glcpp_parser_expand_token_list

  3. When expanding the "C" argument, the active list was now empty,
     so lather, rinse, repeat.

We fix this by adjusting the final popping at the end of
_glcpp_parser_expand_token_list to never pop more nodes then this
particular invocation had pushed itself. This is as simple as saving
the original state of the active list, and then interrupting the
popping when we reach this same state.

With this fix, all of the glcpp-test tests now pass.
---

As mentioned above, I've tested with the glcpp-test tests. But I
haven't run piglit with this change. If someone could do that while
reviewing the patch, it would be most appreciated.

 src/glsl/glcpp/glcpp-parse.y |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/src/glsl/glcpp/glcpp-parse.y b/src/glsl/glcpp/glcpp-parse.y
index fdc9467..6f15e85 100644
--- a/src/glsl/glcpp/glcpp-parse.y
+++ b/src/glsl/glcpp/glcpp-parse.y
@@ -1563,6 +1563,7 @@ _glcpp_parser_expand_token_list (glcpp_parser_t *parser,
 	token_node_t *node_prev;
 	token_node_t *node, *last = NULL;
 	token_list_t *expansion;
+	active_list_t *active_initial = parser->active;
 
 	if (list == NULL)
 		return;
@@ -1617,7 +1618,10 @@ _glcpp_parser_expand_token_list (glcpp_parser_t *parser,
 		node = node_prev ? node_prev->next : list->head;
 	}
 
-	while (parser->active)
+	/* Remove any lingering effects of this invocation on the
+	 * active list. That is, pop until the list looks like it did
+	 * at the beginning of this function. */
+	while (parser->active && parser->active != active_initial)
 		_parser_active_list_pop (parser);
 
 	list->non_space_tail = list->tail;
-- 
1.7.4.1