[libc] Rewrite unrelicensable portions of stddef.h

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/include/stddef.h b/src/include/stddef.h
index bf792771f36d4f2f24137b9368f3e576906fb5ba..3c056294faafcfdf3ada3adcb2564035405d961e 100644 (file)
--- a/src/include/stddef.h
+++ b/src/include/stddef.h
@@ -1,25 +1,43 @@
 #ifndef STDDEF_H
 #define STDDEF_H
 
-FILE_LICENCE ( GPL2_ONLY );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
-/* for size_t */
 #include <stdint.h>
 
+/** EFI headers also define NULL */
 #undef NULL
-#define NULL ((void *)0)
 
-#undef offsetof
-#if ( defined ( __GNUC__ ) && ( __GNUC__ > 3 ) )
-#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
+/** Null pointer */
+#define NULL ( ( void * ) 0 )
+
+/**
+ * Get offset of a field within a structure
+ *
+ * @v type             Structure type
+ * @v field            Field within structure
+ * @ret offset         Offset within structure
+ */
+#if defined ( __GNUC__ ) && ( __GNUC__ > 3 )
+#define offsetof( type, field ) __builtin_offsetof ( type, field )
 #else
-#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#define offsetof( type, field ) ( ( size_t ) &( ( ( type * ) NULL )->field ) )
 #endif
 
-#undef container_of
-#define container_of(ptr, type, member) ({                      \
-       const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
-       (type *)( (char *)__mptr - offsetof(type,member) );})
+/**
+ * Get containing structure
+ *
+ * @v ptr              Pointer to contained field
+ * @v type             Containing structure type
+ * @v field            Field within containing structure
+ * @ret container      Pointer to containing structure
+ */
+#define container_of( ptr, type, field ) ( {                           \
+       type *__container;                                              \
+       const typeof ( __container->field ) *__field = (ptr);           \
+       __container = ( ( ( void * ) __field ) -                        \
+                       offsetof ( type, field ) );                     \
+       __container; } )
 
 /* __WCHAR_TYPE__ is defined by gcc and will change if -fshort-wchar is used */
 #ifndef __WCHAR_TYPE__