TOLERATE_MISALIGNED -> ENFORCE_ALIGNED

Author: bkietz

CMakeLists.txt

@@ -78,10 +78,11 @@ option (FLATCC_TRACE_VERIFY
     "assert on verify failure in runtime lib" OFF)
 
 # Some producers allow empty vectors to be misaligned.
-# The following setting will cause the verifier to check for an
-# empty vector before checking alignment of the vector's elements.
-option (FLATCC_TOLERATE_MISALIGNED_EMPTY_VECTORS
-    "don't fail verification if empty vectors are misaligned" OFF)
+# The following setting will cause the verifier to require the index 0
+# position to be element aligned even if the vector is empty (otherwise that
+# position is only required to be aligned to the preceding size field).
+option (FLATCC_ENFORCE_ALIGNED_EMPTY_VECTORS
+    "verify includes full alignment check for empty vectors" OFF)
 
 # Reflection is the compilers ability to generate binary schema output
 # (.bfbs files). This requires using generated code from
@@ -147,8 +148,8 @@ if (FLATCC_TRACE_VERIFY)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DFLATCC_TRACE_VERIFY=1")
 endif()
 
-if (FLATCC_TOLERATE_MISALIGNED_EMPTY_VECTORS)
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DFLATCC_TOLERATE_MISALIGNED_EMPTY_VECTORS=1")
+if (FLATCC_ENFORCE_ALIGNED_EMPTY_VECTORS)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DFLATCC_ENFORCE_ALIGNED_EMPTY_VECTORS=1")
 endif()
 
 

include/flatcc/flatcc_rtconfig.h

@@ -65,11 +65,12 @@ extern "C" {
 
 /*
  * Some producers allow empty vectors to be misaligned.
- * The following setting will cause the verifier to check for an
- * empty vector before checking alignment of the vector's elements.
+ * The following setting will cause the verifier to require the index 0
+ * position to be element aligned even if the vector is empty (otherwise that
+ * position is only required to be aligned to the preceding size field).
  */
-#if !defined(FLATCC_TOLERATE_MISALIGNED_EMPTY_VECTORS)
-#define FLATCC_TOLERATE_MISALIGNED_EMPTY_VECTORS 0
+#if !defined(FLATCC_ENFORCE_ALIGNED_EMPTY_VECTORS)
+#define FLATCC_ENFORCE_ALIGNED_EMPTY_VECTORS 0
 #endif
 
 /*

src/runtime/verifier.c

@@ -270,13 +270,11 @@ static inline int verify_vector(const void *buf, uoffset_t end, uoffset_t base,
     n = read_uoffset(buf, base);
     base += offset_size;
 
-#if FLATCC_TOLERATE_MISALIGNED_EMPTY_VECTORS
+#if !FLATCC_ENFORCE_ALIGNED_EMPTY_VECTORS
     /* This is due to incorrect buffers from other builders than cannot easily be ignored. */
     align = n == 0 ? uoffset_size : align;
 #endif
-    align = align < uoffset_size ? uoffset_size : align;
-    verify(!(base & (align - 1u)),flatcc_verify_error_vector_header_out_of_range_or_unaligned);
-
+    verify(!(base & ((align - 1u) | (uoffset_size - 1u))), flatcc_verify_error_vector_header_out_of_range_or_unaligned);
     /* `n * elem_size` can overflow uncontrollably otherwise. */
     verify(n <= max_count, flatcc_verify_error_vector_count_exceeds_representable_vector_size);
     verify(end - base >= n * elem_size, flatcc_verify_error_vector_out_of_range);