libc/include/llvm-libc-macros/containerof-macro.h

   1 //===-- Definition of the containerof macro -------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIBC_MACROS_CONTAINEROF_MACRO_H
  10 #define LLVM_LIBC_MACROS_CONTAINEROF_MACRO_H
  11
  12 #include "offsetof-macro.h"
  13
  14 #define __containerof(ptr, type, member)                                       \
  15   ({                                                                           \
  16     const __typeof(((type *)0)->member) *__ptr = (ptr);                        \
  17     (type *)(void *)((const char *)__ptr - offsetof(type, member));            \
  18   })
  19
  20 #endif // LLVM_LIBC_MACROS_CONTAINEROF_MACRO_H