Third commit

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 20 insertions, 5 deletions

diff --git a/libsyscalls.h b/libsyscalls.h
index 4c904b7..066de20 100644
--- a/libsyscalls.h
+++ b/libsyscalls.h
@@ -1129,8 +1129,9 @@ struct libsyscalls_datatype_description {
 	enum libsyscalls_datatype_section section;
 
 	/**
-	 * This is a ~0 terminated array describing the order
-	 * of the bytes the the data type
+	 * This is a ~0 terminated array — but, it can also
+	 * be terminated by the end of the array — describing
+	 * the order of the bytes the the data type
 	 *
 	 * The lowest non-zero values contains the width of
 	 * a byte (in bytes), however no such value exists
@@ -1146,8 +1147,17 @@ struct libsyscalls_datatype_description {
 	 * there is always a value in .byteorder that is 0,
 	 * unless .byteorder[0] is ~0
 	 *
-	 * To avoid problems checking for ~0, use
-	 * the LIBSYSCALLS_IS_BYTEORDER_END macro
+	 * To avoid problems checking for ~0, use the
+	 * LIBSYSCALLS_IS_BYTEORDER_END macro; please also be
+	 * aware that both the type and length can change in
+	 * the future: do not assume it's `unsigned char`,
+	 * and do not assume it has 32 elements, do not only
+	 * `LIBSYSCALLS_IS_BYTEORDER_END` to detect ~0, but
+	 * also check that no more than
+	 * `sizeof(x.byteorder) / sizeof(*x.byteorder)`
+	 * elements are read (where x is the instance of the
+	 * structure) (you should definitely have your own
+	 * macro for that one)
 	 */
 	unsigned char byteorder[32];
 
@@ -1160,8 +1170,13 @@ struct libsyscalls_datatype_description {
 	 * @param   SHIFT  The value to test `struct libsyscalls_datatype_description.byteorder`
 	 * @return  :int   Whether the value is ~0
 	 */
-#define LIBSYSCALLS_IS_BYTEORDER_END(SHIFT)\
+#ifdef UINTMAX_C
+# define LIBSYSCALLS_IS_BYTEORDER_END(SHIFT)\
+	(!~((SHIFT) | ~LIBSYSCALLS_FIELD_MASK_(UINTMAX_C(1), struct libsyscalls_datatype_description, byteorder[0])))
+#else
+# define LIBSYSCALLS_IS_BYTEORDER_END(SHIFT)\
 	(!~((SHIFT) | ~LIBSYSCALLS_FIELD_MASK_(1ULL, struct libsyscalls_datatype_description, byteorder[0])))
+#endif
 };