[cairo-commit] src/cairo-path-fixed.c

[Chris Wilson]

 src/cairo-path-fixed.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

New commits:
commit d8169b8cef041b4dbcea44e050df28659f4846aa
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Thu Dec 27 10:45:25 2007 +0000

    [cairo-path-fixed] Ensure the array of points is correctly aligned.
    
    In http://bugs.gentoo.org/show_bug.cgi?id=203282, it was identified that
    the cairo_path_buf was causing unaligned accesses (thus generating SIGBUS
    on architectures like the SPARC) to its array of points. As we manually
    allocate a single block of memory for the cairo_path_buf_t and its
    arrays, we must also manually ensure correct alignment - as opposed to
    cairo_path_buf_fixed_t for which the compiler automatically aligns the
    embedded arrays.

diff --git a/src/cairo-path-fixed.c b/src/cairo-path-fixed.c
index ad73845..d485364 100644
--- a/src/cairo-path-fixed.c
+++ b/src/cairo-path-fixed.c
@@ -404,10 +404,12 @@ _cairo_path_buf_create (int buf_size)
 {
     cairo_path_buf_t *buf;
 
+#define align(ptr__, alignment__) \
+    ((void *) (((long) (ptr__) + (alignment__) - 1) & -(alignment__)))
     buf = _cairo_malloc_ab_plus_c (buf_size,
 	                           sizeof (cairo_path_op_t) +
 				   2 * sizeof (cairo_point_t),
-				   sizeof (cairo_path_buf_t));
+				   sizeof (cairo_path_buf_t) + sizeof (double));
     if (buf) {
 	buf->next = NULL;
 	buf->prev = NULL;
@@ -415,9 +417,10 @@ _cairo_path_buf_create (int buf_size)
 	buf->num_points = 0;
 	buf->buf_size = buf_size;
 
-	buf->op = (cairo_path_op_t *) (buf + 1);
-	buf->points = (cairo_point_t *) (buf->op + buf_size);
+	buf->points = (cairo_point_t *) align (buf + 1, sizeof (double));
+	buf->op = (cairo_path_op_t *) (buf->points + 2 * buf_size);
     }
+#undef align
 
     return buf;
 }