image: Avoid reusing pixman images for threadsafety.
The pixman_image_ref() and pixman_image_unref() functions
aren't threadsafe in current pixman, so we can't share
pixman images across contexts where they may end up
moving between threads. The main use of these functions
is in keeping a global cache of pixman_image_ts for
solid colours and reusing the same pixman_image_t for
patterns pointing to the same image data where possible.
This patch removes those uses from cairo by wrapping
them in a PIXMAN_HAS_ATOMIC_OPS conditional. There is
no automatic test this, so we will have to manually
turn this code back on when pixman does gain atomic
ops.
The only two remaining calls to pixman_image_ref() are
done on locally created images so they are safe.
Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=34177
diff --git a/src/cairo-image-surface.c b/src/cairo-image-surface.c
index ea6b449..9006492 100644
--- a/src/cairo-image-surface.c
+++ b/src/cairo-image-surface.c
@@ -861,7 +861,7 @@
pixman_image_set_clip_region32 (surface->pixman_image, NULL);
}
-#if HAS_ATOMIC_OPS
+#if PIXMAN_HAS_ATOMIC_OPS
static pixman_image_t *__pixman_transparent_image;
static pixman_image_t *__pixman_black_image;
static pixman_image_t *__pixman_white_image;
@@ -955,23 +955,6 @@
return image;
}
-#else
-static pixman_image_t *
-_pixman_transparent_image (void)
-{
- return _pixman_image_for_solid (&_cairo_pattern_clear);
-}
-static pixman_image_t *
-_pixman_black_image (void)
-{
- return _pixman_image_for_solid (&_cairo_pattern_black);
-}
-static pixman_image_t *
-_pixman_white_image (void)
-{
- return _pixman_image_for_solid (&_cairo_pattern_white);
-}
-#endif
static uint32_t
hars_petruska_f54_1_random (void)
@@ -988,13 +971,33 @@
} cache[16];
static int n_cached;
+#else /* !PIXMAN_HAS_ATOMIC_OPS */
+static pixman_image_t *
+_pixman_transparent_image (void)
+{
+ return _pixman_image_for_solid (&_cairo_pattern_clear);
+}
+
+static pixman_image_t *
+_pixman_black_image (void)
+{
+ return _pixman_image_for_solid (&_cairo_pattern_black);
+}
+
+static pixman_image_t *
+_pixman_white_image (void)
+{
+ return _pixman_image_for_solid (&_cairo_pattern_white);
+}
+#endif /* !PIXMAN_HAS_ATOMIC_OPS */
+
void
_cairo_image_reset_static_data (void)
{
+#if PIXMAN_HAS_ATOMIC_OPS
while (n_cached)
pixman_image_unref (cache[--n_cached].image);
-#if HAS_ATOMIC_OPS
if (__pixman_transparent_image) {
pixman_image_unref (__pixman_transparent_image);
__pixman_transparent_image = NULL;
@@ -1017,9 +1020,10 @@
{
pixman_color_t color;
pixman_image_t *image;
+
+#if PIXMAN_HAS_ATOMIC_OPS
int i;
-#if HAS_ATOMIC_OPS
if (pattern->color.alpha_short <= 0x00ff)
return _pixman_transparent_image ();
@@ -1038,7 +1042,6 @@
return _pixman_white_image ();
}
}
-#endif
CAIRO_MUTEX_LOCK (_cairo_image_solid_cache_mutex);
for (i = 0; i < n_cached; i++) {
@@ -1047,6 +1050,7 @@
goto UNLOCK;
}
}
+#endif
color.red = pattern->color.red_short;
color.green = pattern->color.green_short;
@@ -1054,6 +1058,7 @@
color.alpha = pattern->color.alpha_short;
image = pixman_image_create_solid_fill (&color);
+#if PIXMAN_HAS_ATOMIC_OPS
if (image == NULL)
goto UNLOCK;
@@ -1068,6 +1073,7 @@
UNLOCK:
CAIRO_MUTEX_UNLOCK (_cairo_image_solid_cache_mutex);
+#endif
return image;
}
@@ -1302,6 +1308,7 @@
extend = pattern->base.extend;
filter = sampled_area (pattern, extents, &sample);
+ *ix = *iy = 0;
pixman_image = NULL;
if (pattern->surface->type == CAIRO_SURFACE_TYPE_IMAGE &&
(! is_mask || ! pattern->base.has_component_alpha ||
@@ -1339,6 +1346,7 @@
}
}
+#if PIXMAN_HAS_ATOMIC_OPS
/* avoid allocating a 'pattern' image if we can reuse the original */
*ix = *iy = 0;
if (extend == CAIRO_EXTEND_NONE &&
@@ -1347,6 +1355,7 @@
{
return pixman_image_ref (source->pixman_image);
}
+#endif
pixman_image = pixman_image_create_bits (source->pixman_format,
source->width,
@@ -1381,6 +1390,7 @@
}
}
+#if PIXMAN_HAS_ATOMIC_OPS
*ix = sub->extents.x;
*iy = sub->extents.y;
if (is_contained &&
@@ -1389,13 +1399,17 @@
{
return pixman_image_ref (source->pixman_image);
}
+#endif
/* Avoid sub-byte offsets, force a copy in that case. */
if (PIXMAN_FORMAT_BPP (source->pixman_format) >= 8) {
+ void *data = source->data
+ + sub->extents.x * PIXMAN_FORMAT_BPP(source->pixman_format)/8
+ + sub->extents.y * source->stride;
pixman_image = pixman_image_create_bits (source->pixman_format,
sub->extents.width,
sub->extents.height,
- (uint32_t *) (source->data + sub->extents.x * PIXMAN_FORMAT_BPP(source->pixman_format)/8 + sub->extents.y * source->stride),
+ data,
source->stride);
if (unlikely (pixman_image == NULL))
return NULL;
@@ -1403,8 +1417,6 @@
}
}
- *ix = *iy = 0;
-
if (pixman_image == NULL) {
struct acquire_source_cleanup *cleanup;
cairo_image_surface_t *image;
