branches/zip: mem_heap_block_free(): Fix a bug introduced in r914

while trying to fix r909: invoke mem_erase_buf() before freeing the
buffer, but after interpreting block->buf_block.

mem/mem0mem.c

@@ -492,6 +492,7 @@ mem_heap_block_free(
 	ulint		type;
 	ulint		len;
 	ibool		init_block;
+	buf_block_t*	buf_block;
 
 	if (block->magic_n != MEM_BLOCK_MAGIC_N) {
 		mem_analyze_corruption(block);
@@ -509,32 +510,33 @@ mem_heap_block_free(
 	type = heap->type;
 	len = block->len;
 	init_block = block->init_block;
+	buf_block = block->buf_block;
 	block->magic_n = MEM_FREED_BLOCK_MAGIC_N;
 
+#ifdef UNIV_MEM_DEBUG
+	/* In the debug version we set the memory to a random combination
+	of hex 0xDE and 0xAD. */
+
+	mem_erase_buf((byte*)block, len);
+#endif
+
 	if (init_block) {
 		/* Do not have to free: do nothing */
 
 	} else if (type == MEM_HEAP_DYNAMIC) {
 
-		ut_ad(!block->buf_block);
+		ut_ad(!buf_block);
 		mem_area_free(block, mem_comm_pool);
 	} else {
 		ut_ad(type & MEM_HEAP_BUFFER);
 
 		if (len >= UNIV_PAGE_SIZE / 2) {
-			buf_block_free(block->buf_block);
+			buf_block_free(buf_block);
 		} else {
-			ut_ad(!block->buf_block);
+			ut_ad(!buf_block);
 			mem_area_free(block, mem_comm_pool);
 		}
 	}
-
-#ifdef UNIV_MEM_DEBUG
-	/* In the debug version we set the memory to a random combination
-	of hex 0xDE and 0xAD. */
-
-	mem_erase_buf((byte*)block, len);
-#endif
 }
 
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