Align node allocations

7 files changed, 61 insertions, 21 deletions

diff --git a/src/node.c b/src/node.c
index 0322dd64..0da9d0ed 100644
--- a/src/node.c
+++ b/src/node.c
@@ -18,6 +18,7 @@
 
 #include "static_nodes.h"
 #include "string_utils.h"
+#include "system.h"
 
 #include "exess/exess.h"
 #include "serd/serd.h"
@@ -97,7 +98,7 @@ SerdNode*
 serd_node_malloc(size_t n_bytes, SerdNodeFlags flags, SerdNodeType type)
 {
   const size_t size = sizeof(SerdNode) + serd_node_pad_size(n_bytes);
-  SerdNode*    node = (SerdNode*)calloc(1, size);
+  SerdNode*    node = (SerdNode*)serd_calloc_aligned(sizeof(SerdNode), size);
 
   node->n_bytes = 0;
   node->flags   = flags;
@@ -112,7 +113,8 @@ serd_node_set(SerdNode** dst, const SerdNode* src)
 {
   const size_t size = serd_node_total_size(src);
   if (serd_node_total_size(*dst) < size) {
-    (*dst) = (SerdNode*)realloc(*dst, size);
+    serd_free_aligned(*dst);
+    *dst = (SerdNode*)serd_calloc_aligned(sizeof(SerdNode), size);
   }
 
   memcpy(*dst, src, size);
@@ -345,7 +347,7 @@ serd_node_copy(const SerdNode* node)
   }
 
   const size_t size = serd_node_total_size(node);
-  SerdNode*    copy = (SerdNode*)calloc(1, size + 3);
+  SerdNode*    copy = (SerdNode*)serd_calloc_aligned(sizeof(SerdNode), size);
 
   memcpy(copy, node, size);
   return copy;
@@ -749,5 +751,5 @@ serd_node_flags(const SerdNode* node)
 void
 serd_node_free(SerdNode* node)
 {
-  free(node);
+  serd_free_aligned(node);
 }
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);
diff --git a/src/stack.h b/src/stack.h
index f6d33f51..0eae1b75 100644
--- a/src/stack.h
+++ b/src/stack.h
@@ -17,6 +17,8 @@
 #ifndef SERD_STACK_H
 #define SERD_STACK_H
 
+#include "system.h"
+
 #include <assert.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -37,10 +39,12 @@ typedef struct {
 #define SERD_STACK_BOTTOM sizeof(void*)
 
 static inline SerdStack
-serd_stack_new(size_t size)
+serd_stack_new(size_t size, size_t align)
 {
+  const size_t aligned_size = (size + (align - 1)) / align * align;
+
   SerdStack stack;
-  stack.buf      = (char*)calloc(size, 1);
+  stack.buf      = (char*)serd_calloc_aligned(align, aligned_size);
   stack.buf_size = size;
   stack.size     = SERD_STACK_BOTTOM;
   return stack;
diff --git a/src/system.c b/src/system.c
index 4f6c37c6..323ed62e 100644
--- a/src/system.c
+++ b/src/system.c
@@ -27,6 +27,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 void*
 serd_malloc_aligned(const size_t alignment, const size_t size)
@@ -44,6 +45,21 @@ serd_malloc_aligned(const size_t alignment, const size_t size)
 }
 
 void*
+serd_calloc_aligned(const size_t alignment, const size_t size)
+{
+#if defined(_WIN32) || defined(USE_POSIX_MEMALIGN)
+  void* const ptr = serd_malloc_aligned(alignment, size);
+  if (ptr) {
+    memset(ptr, 0, size);
+  }
+  return ptr;
+#else
+  (void)alignment;
+  return calloc(1, size);
+#endif
+}
+
+void*
 serd_allocate_buffer(const size_t size)
 {
   return serd_malloc_aligned(SERD_PAGE_SIZE, size);
diff --git a/src/system.h b/src/system.h
index a5fb7459..f0e6e267 100644
--- a/src/system.h
+++ b/src/system.h
@@ -27,6 +27,11 @@ SERD_I_MALLOC_FUNC
 void*
 serd_malloc_aligned(size_t alignment, size_t size);
 
+/// Allocate a zeroed buffer aligned to `alignment` bytes
+SERD_I_MALLOC_FUNC
+void*
+serd_calloc_aligned(size_t alignment, size_t size);
+
 /// Allocate an aligned buffer for I/O
 SERD_I_MALLOC_FUNC
 void*
diff --git a/src/writer.c b/src/writer.c
index bf869967..7e3033a8 100644
--- a/src/writer.c
+++ b/src/writer.c
@@ -1108,7 +1108,7 @@ serd_writer_new(SerdWorld*      world,
   writer->env        = env;
   writer->root_node  = NULL;
   writer->root_uri   = SERD_URI_NULL;
-  writer->anon_stack = serd_stack_new(SERD_PAGE_SIZE);
+  writer->anon_stack = serd_stack_new(SERD_PAGE_SIZE, SERD_PAGE_SIZE);
   writer->write_func = write_func;
   writer->stream     = stream;
   writer->context    = context;
diff --git a/test/test_overflow.c b/test/test_overflow.c
index 5889a867..a4d59368 100644
--- a/test/test_overflow.c
+++ b/test/test_overflow.c
@@ -39,19 +39,21 @@ main(void)
     size_t      stack_size;
   } Test;
 
-  const Test tests[] = {{":s :p :%99 .", 338},
-                        {":s :p <http://", 336},
-                        {":s :p eg:foo", 337},
-                        {":s :p 1234", 307},
-                        {":s :p 1234", 338},
-                        {":s :p (1 2 3 4) .", 352},
-                        {"@prefix eg: <http://example.org> .", 239},
-                        {":s :p \"literal\"", 336},
-                        {":s :p \"verb\"", 275},
-                        {":s :p _:blank .", 307},
-                        {":s :p true .", 307},
-                        {":s :p true .", 341},
-                        {":s :p \"\"@en .", 339},
+  const size_t sizes = 3 * sizeof(size_t);
+
+  const Test tests[] = {{":s :p :%99 .", sizes + 280},
+                        {":s :p <http://", sizes + 276},
+                        {":s :p eg:foo", sizes + 275},
+                        {":s :p 1234", sizes + 177},
+                        {":s :p 1234", sizes + 280},
+                        {":s :p (1 2 3 4) .", 8 * sizeof(size_t) + 357},
+                        {"@prefix eg: <http://example.org> .", sizes + 224},
+                        {":s :p \"literal\"", sizes + 264},
+                        {":s :p \"verb\"", sizes + 263},
+                        {":s :p _:blank .", sizes + 276},
+                        {":s :p true .", sizes + 295},
+                        {":s :p true .", sizes + 329},
+                        {":s :p \"\"@en .", sizes + 302},
                         {NULL, 0}};
 
   SerdWorld* world = serd_world_new();