Align node allocations

1 files changed, 12 insertions, 1 deletions

diff --git a/src/reader.c b/src/reader.c
index 44b17704..ceef5fb4 100644
--- a/src/reader.c
+++ b/src/reader.c
@@ -159,15 +159,26 @@ serd_reader_new(SerdWorld* const      world,
                 const SerdSink* const sink,
                 const size_t          stack_size)
 {
+  if (stack_size < 8 * sizeof(SerdNode)) {
+    return NULL;
+  }
+
   SerdReader* me = (SerdReader*)calloc(1, sizeof(SerdReader));
 
   me->world   = world;
   me->sink    = sink;
-  me->stack   = serd_stack_new(stack_size);
+  me->stack   = serd_stack_new(stack_size, sizeof(SerdNode));
   me->syntax  = syntax;
   me->next_id = 1;
   me->strict  = true;
 
+  /* Reserve a bit of space at the end of the stack to zero pad nodes.  This
+     particular kind of overflow could be detected (in emit_statement), but
+     this is simpler and a bit more resilient to mistakes since the reader
+     generally pushes only a few bytes at a time, making it pretty unlikely
+     to overshoot the buffer by this much. */
+  me->stack.buf_size -= 8 * sizeof(size_t);
+
   me->rdf_first = push_node(me, SERD_URI, NS_RDF "first", 48);
   me->rdf_rest  = push_node(me, SERD_URI, NS_RDF "rest", 47);
   me->rdf_nil   = push_node(me, SERD_URI, NS_RDF "nil", 46);