Do not reference error objects directly

This makes it possible to observe the creation of error objects by
breaking on the appropriate _cairo_*_create_in_error() function and
makes the code cleaner by passing around the status obtained from
_cairo_error() instead of throwing the error.

9 files changed, 31 insertions, 58 deletions

diff --git a/src/cairo-beos-surface.cpp b/src/cairo-beos-surface.cpp
index 2e0f42c6e..a345d485d 100644
--- a/src/cairo-beos-surface.cpp
+++ b/src/cairo-beos-surface.cpp
@@ -917,10 +917,8 @@ _cairo_beos_surface_create_internal (BView*   view,
     // Must use malloc, because cairo code will use free() on the surface
     cairo_beos_surface_t *surface = static_cast<cairo_beos_surface_t*>(
 					malloc(sizeof(cairo_beos_surface_t)));
-    if (surface == NULL) {
-	_cairo_error (CAIRO_STATUS_NO_MEMORY);
-        return const_cast<cairo_surface_t*>(&_cairo_surface_nil);
-    }
+    if (unlikely (surface == NULL))
+	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     cairo_content_t content = CAIRO_CONTENT_COLOR;
     if (bmp && (bmp->ColorSpace() == B_RGBA32 || bmp->ColorSpace() == B_RGBA15))
diff --git a/src/cairo-clip.c b/src/cairo-clip.c
index 6355a977b..f7a7e794a 100644
--- a/src/cairo-clip.c
+++ b/src/cairo-clip.c
@@ -610,10 +610,8 @@ _cairo_rectangle_list_create_in_error (cairo_status_t status)
 	return (cairo_rectangle_list_t*) &_cairo_rectangles_not_representable;
 
     list = malloc (sizeof (*list));
-    if (unlikely (list == NULL)) {
-	status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_rectangle_list_t*) &_cairo_rectangles_nil;
-    }
+    if (unlikely (list == NULL))
+	return _cairo_rectangle_list_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     list->status = status;
     list->rectangles = NULL;
diff --git a/src/cairo-device.c b/src/cairo-device.c
index fd1ec71de..610e57d38 100644
--- a/src/cairo-device.c
+++ b/src/cairo-device.c
@@ -159,8 +159,7 @@ _cairo_device_create_in_error (cairo_status_t status)
     case CAIRO_STATUS_INVALID_MESH_CONSTRUCTION:
     case CAIRO_STATUS_DEVICE_FINISHED:
     default:
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_device_t *) &_nil_device;
+	return _cairo_device_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 }
 
diff --git a/src/cairo-path.c b/src/cairo-path.c
index d3d91311f..b58e58414 100644
--- a/src/cairo-path.c
+++ b/src/cairo-path.c
@@ -294,10 +294,8 @@ _cairo_path_create_in_error (cairo_status_t status)
 	return (cairo_path_t*) &_cairo_path_nil;
 
     path = malloc (sizeof (cairo_path_t));
-    if (unlikely (path == NULL)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_path_t*) &_cairo_path_nil;
-    }
+    if (unlikely (path == NULL))
+	return _cairo_path_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     path->num_data = 0;
     path->data = NULL;
@@ -314,10 +312,8 @@ _cairo_path_create_internal (cairo_path_fixed_t *path_fixed,
     cairo_path_t *path;
 
     path = malloc (sizeof (cairo_path_t));
-    if (unlikely (path == NULL)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_path_t*) &_cairo_path_nil;
-    }
+    if (unlikely (path == NULL))
+	return _cairo_path_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     path->num_data = _cairo_path_count (path, path_fixed,
 					cairo_get_tolerance (cr),
@@ -332,8 +328,7 @@ _cairo_path_create_internal (cairo_path_fixed_t *path_fixed,
 				       sizeof (cairo_path_data_t));
 	if (unlikely (path->data == NULL)) {
 	    free (path);
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_path_t*) &_cairo_path_nil;
+	    return _cairo_path_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	}
 
 	path->status = _cairo_path_populate (path, path_fixed, cr, flatten);
diff --git a/src/cairo-pattern.c b/src/cairo-pattern.c
index cb6bba845..7a98e4f0f 100644
--- a/src/cairo-pattern.c
+++ b/src/cairo-pattern.c
@@ -549,10 +549,8 @@ _cairo_pattern_create_solid (const cairo_color_t *color)
     if (unlikely (pattern == NULL)) {
 	/* None cached, need to create a new pattern. */
 	pattern = malloc (sizeof (cairo_solid_pattern_t));
-	if (unlikely (pattern == NULL)) {
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_pattern_t *) &_cairo_pattern_nil;
-	}
+	if (unlikely (pattern == NULL))
+	    return _cairo_pattern_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     _cairo_pattern_init_solid (pattern, color);
@@ -665,10 +663,8 @@ cairo_pattern_create_for_surface (cairo_surface_t *surface)
 {
     cairo_surface_pattern_t *pattern;
 
-    if (surface == NULL) {
-	_cairo_error_throw (CAIRO_STATUS_NULL_POINTER);
-	return (cairo_pattern_t*) &_cairo_pattern_nil_null_pointer;
-    }
+    if (unlikely (surface == NULL))
+	return _cairo_pattern_create_in_error (_cairo_error (CAIRO_STATUS_NULL_POINTER));
 
     if (surface->status)
 	return _cairo_pattern_create_in_error (surface->status);
@@ -677,10 +673,8 @@ cairo_pattern_create_for_surface (cairo_surface_t *surface)
 	_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_SURFACE]);
     if (unlikely (pattern == NULL)) {
 	pattern = malloc (sizeof (cairo_surface_pattern_t));
-	if (unlikely (pattern == NULL)) {
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_pattern_t *)&_cairo_pattern_nil.base;
-	}
+	if (unlikely (pattern == NULL))
+	    return _cairo_pattern_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     CAIRO_MUTEX_INITIALIZE ();
@@ -727,10 +721,8 @@ cairo_pattern_create_linear (double x0, double y0, double x1, double y1)
 	_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_LINEAR]);
     if (unlikely (pattern == NULL)) {
 	pattern = malloc (sizeof (cairo_linear_pattern_t));
-	if (unlikely (pattern == NULL)) {
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_pattern_t *) &_cairo_pattern_nil.base;
-	}
+	if (unlikely (pattern == NULL))
+	    return _cairo_pattern_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     CAIRO_MUTEX_INITIALIZE ();
@@ -779,10 +771,8 @@ cairo_pattern_create_radial (double cx0, double cy0, double radius0,
 	_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_RADIAL]);
     if (unlikely (pattern == NULL)) {
 	pattern = malloc (sizeof (cairo_radial_pattern_t));
-	if (unlikely (pattern == NULL)) {
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_pattern_t *) &_cairo_pattern_nil.base;
-	}
+	if (unlikely (pattern == NULL))
+	    return _cairo_pattern_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     CAIRO_MUTEX_INITIALIZE ();
@@ -957,10 +947,8 @@ cairo_pattern_create_mesh (void)
 	_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_MESH]);
     if (unlikely (pattern == NULL)) {
 	pattern = malloc (sizeof (cairo_mesh_pattern_t));
-	if (unlikely (pattern == NULL)) {
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_pattern_t *) &_cairo_pattern_nil.base;
-	}
+	if (unlikely (pattern == NULL))
+	    return _cairo_pattern_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     CAIRO_MUTEX_INITIALIZE ();
diff --git a/src/cairo-region.c b/src/cairo-region.c
index f3ccb898a..3dced6cf2 100644
--- a/src/cairo-region.c
+++ b/src/cairo-region.c
@@ -107,8 +107,7 @@ _cairo_region_create_in_error (cairo_status_t status)
     case CAIRO_STATUS_INVALID_MESH_CONSTRUCTION:
     case CAIRO_STATUS_DEVICE_FINISHED:
     default:
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_region_t *) &_cairo_region_nil;
+	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 }
 
@@ -197,7 +196,7 @@ cairo_region_create (void)
 
     region = _cairo_malloc (sizeof (cairo_region_t));
     if (region == NULL)
-	return (cairo_region_t *) &_cairo_region_nil;
+	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     region->status = CAIRO_STATUS_SUCCESS;
     CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
@@ -297,7 +296,7 @@ cairo_region_create_rectangle (const cairo_rectangle_int_t *rectangle)
 
     region = _cairo_malloc (sizeof (cairo_region_t));
     if (unlikely (region == NULL))
-	return (cairo_region_t *) &_cairo_region_nil;
+	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     region->status = CAIRO_STATUS_SUCCESS;
     CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
@@ -330,7 +329,7 @@ cairo_region_copy (const cairo_region_t *original)
     cairo_region_t *copy;
 
     if (original != NULL && original->status)
-	return (cairo_region_t *) &_cairo_region_nil;
+	return _cairo_region_create_in_error (original->status);
 
     copy = cairo_region_create ();
     if (unlikely (copy->status))
@@ -340,7 +339,7 @@ cairo_region_copy (const cairo_region_t *original)
 	! pixman_region32_copy (&copy->rgn, CONST_CAST &original->rgn))
     {
 	cairo_region_destroy (copy);
-	return (cairo_region_t *) &_cairo_region_nil;
+	return _cairo_region_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     return copy;
diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
index b0afb0995..683137496 100644
--- a/src/cairo-scaled-font.c
+++ b/src/cairo-scaled-font.c
@@ -1120,8 +1120,7 @@ _cairo_scaled_font_create_in_error (cairo_status_t status)
 	scaled_font = malloc (sizeof (cairo_scaled_font_t));
 	if (unlikely (scaled_font == NULL)) {
 	    CAIRO_MUTEX_UNLOCK (_cairo_scaled_font_error_mutex);
-	    _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	    return (cairo_scaled_font_t *) &_cairo_scaled_font_nil;
+	    return _cairo_scaled_font_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	}
 
 	*scaled_font = _cairo_scaled_font_nil;
diff --git a/src/cairo-spans.c b/src/cairo-spans.c
index f6586506b..c39f63e26 100644
--- a/src/cairo-spans.c
+++ b/src/cairo-spans.c
@@ -238,8 +238,7 @@ _cairo_scan_converter_create_in_error (cairo_status_t status)
     default:
 	break;
     }
-    status = CAIRO_STATUS_NO_MEMORY;
-    RETURN_NIL;
+    return _cairo_scan_converter_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 #undef RETURN_NIL
 }
 
@@ -350,7 +349,6 @@ _cairo_span_renderer_create_in_error (cairo_status_t status)
     default:
 	break;
     }
-    status = CAIRO_STATUS_NO_MEMORY;
-    RETURN_NIL;
+    return _cairo_span_renderer_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 #undef RETURN_NIL
 }
diff --git a/src/cairo-surface.c b/src/cairo-surface.c
index 2512d8dc9..6a1641afd 100644
--- a/src/cairo-surface.c
+++ b/src/cairo-surface.c
@@ -3246,8 +3246,7 @@ _cairo_surface_create_in_error (cairo_status_t status)
     case CAIRO_STATUS_INVALID_MESH_CONSTRUCTION:
     case CAIRO_STATUS_DEVICE_FINISHED:
     default:
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_surface_t *) &_cairo_surface_nil;
+	return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 }