1 /* 2 * This file and its contents are supplied under the terms of the 3 * Common Development and Distribution License ("CDDL"), version 1.0. 4 * You may only use this file in accordance with the terms of version 5 * 1.0 of the CDDL. 6 * 7 * A full copy of the text of the CDDL should have accompanied this 8 * source. A copy of the CDDL is also available via the Internet at 9 * http://www.illumos.org/license/CDDL. 10 */ 11 12 /* 13 * Copyright 2017 Toomas Soome <tsoome@me.com> 14 */ 15 16 #ifndef _SYS_CONTAINEROF_H 17 #define _SYS_CONTAINEROF_H 18 19 /* 20 * __containerof macro for private use in illumos. 21 * 22 * __containerof(ptr, type, member) will return pointer to the data 23 * structure of given type, calculated based on the offset of 'member' 24 * in the structure 'type'. 25 * 26 * For this macro to work, we should be certain of the pointer type. 27 */ 28 29 #include <sys/stddef.h> 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 #if !defined(__containerof) 36 37 /* 38 * The extension to support statements and declarations in expressions, 39 * https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html, is available 40 * in gcc >= 3.1. 41 * We perform the assignment below to try and provide additional type safety. 42 */ 43 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)) 44 #define __containerof(m, s, name) ( \ 45 { \ 46 const volatile __typeof(((s *)0)->name) *__m = (m); \ 47 (void *)((uintptr_t)__m - (uintptr_t)offsetof(s, name)); \ 48 }) 49 #else 50 #define __containerof(m, s, name) \ 51 (void *)((uintptr_t)(m) - (uintptr_t)offsetof(s, name)) 52 #endif 53 #endif 54 55 #ifdef __cplusplus 56 } 57 #endif 58 59 #endif /* _SYS_CONTAINEROF_H */ 60