Mesa (master): glcpp: Fix attempts to expand recursive macros infinitely ( bug #32835).

Kenneth Graunke kwg at
Sun Apr 17 08:03:08 UTC 2011

Module: Mesa
Branch: master
Commit: 9dacbe222641443af000a82161922a5ade206340

Author: Carl Worth <cworth at>
Date:   Fri Apr 15 12:03:25 2011 -0700

glcpp: Fix attempts to expand recursive macros infinitely (bug #32835).

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)

Here's what was 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.

Signed-off-by: Carl Worth <cworth at>
Reviewed-by: Ian Romanick <ian.d.romanick at>
Reviewed-and-tested-by: Kenneth Graunke <kenneth at>


 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)
@@ -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;

More information about the mesa-commit mailing list