Some tweaks to reallocation

1 files changed, 27 insertions, 24 deletions

diff --git a/region-iter.c b/region-iter.c
index 9acbe97..96cd675 100644
--- a/region-iter.c
+++ b/region-iter.c
@@ -77,32 +77,37 @@ next_power (size_t n)
     return r;
 }
 
+static void *
+realloc_ab_plus_c (void *m, unsigned int a, unsigned int b, unsigned int c)
+{
+    if (b && a >= INT32_MAX / b)
+	return NULL;
+
+    if (c >= INT32_MAX - a * b)
+	return NULL;
+
+    return realloc (m, a * b + c);
+}
+
 static pixman_region32_data_t *
 region_data_append (pixman_region32_data_t *data, int n)
 {
-    size_t new_size = next_power ((data? data->numRects : 0) + n);
-
-    new_size =
-	sizeof (pixman_region32_data_t) + sizeof (pixman_box32_t) * new_size;
+    size_t new_size, n_rects;
 
-    if (!data)
-    {
-	data = malloc (new_size);
+    n_rects = data? data->numRects : 0;
+    new_size = next_power (n_rects + n);
 
-	if (!data)
-	    return NULL;
+    if (data && data->size == new_size)
+	return data;
 
-	data->numRects = 0;
-    }
-    else
+    if ((data = realloc_ab_plus_c (
+	     data, new_size, sizeof (pixman_box32_t),
+	     sizeof (pixman_region32_data_t))))
     {
-	data = realloc (data, new_size);
-
-	if (!data)
-	    return NULL;
+	data->numRects = n_rects;
+	data->size = new_size;
     }
 
-    data->size = new_size;
     return data;
 }
 
@@ -173,14 +178,14 @@ region_builder_add_box (region_builder_t *builder,
     if (builder->data == BROKEN_DATA)
 	return FALSE;
 
-    if (!(builder->data = region_data_append (builder->data, 1)))
+    if (!(data = region_data_append (builder->data, 1)))
     {
 	free (builder->data);
 	builder->data = BROKEN_DATA;
 	return FALSE;
     }
 
-    data = builder->data;
+    builder->data = data;
 
     if (data->numRects == 0)
 	last_box = NULL;
@@ -194,7 +199,6 @@ region_builder_add_box (region_builder_t *builder,
 	else if (x1 == last_box->x2)
 	{
 	    last_box->x2 = x2;
-	    printf ("coal\n");
 	    return;
 	}
     }
@@ -204,8 +208,6 @@ region_builder_add_box (region_builder_t *builder,
     last_box->y1 = y1;
     last_box->x2 = x2;
     last_box->y2 = y2;
-
-    printf ("added box now %d\n", data->numRects);
 }
 
 static pixman_bool_t
@@ -352,7 +354,8 @@ region_iter_get_row (region_iter_t *iter, row_t *row)
     return TRUE;
 }
 
-/* Overlapped iter */
+/* Overlapped iter
+ */
 typedef struct overlapped_iter_t overlapped_iter_t;
 struct overlapped_iter_t
 {
@@ -577,7 +580,7 @@ segment_iter_get_segment (segment_iter_t *iter, segment_t *segment)
 typedef enum
 {
     INTERSECT	= (1 << BOTH),
-    SUBTRACT	=		(1 << ROW1)
+    SUBTRACT	=		(1 << ROW1),
     XOR		=		(1 << ROW1) | (1 << ROW2),
     UNION	= (1 << BOTH) | (1 << ROW1) | (1 << ROW2),
 } ops_t;